tlt magazine aug10.pdf

5/20/2018 TLT magazine aug10.pdf

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AN PUBLICATION | AUGUST 2010

ISO 281: 2007

Part II of ourgreat debate.

Follow the money

When science and

politics clash

Presidents Report

In praise of STLEcorporate members

Check out our digital TLTsponsored by Polaris Laboratoriesat www.stle.org


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20 MINUTES WITH...

16 Ricardo J. Hein

Based in Atlanta, this Argentine-

born STLE member is the head of

Conexo, which provides tribology

innovations in domestic andforeign markets.

By Thomas T. Astrene

20 Student Poster Abstracts

Extended abstracts written by

winners of the Student Poster

Competition held at STLEs 2010

Annual Meeting & Exhibition.

Tribological Improvement of

Carbon/Carbon Composites byInfiltration of ZnO/Al

2O

3/ZrO

2

Solid Lubricant Coatings

By Hamidreza Mohseni and

Thomas W. Scharf (Advisor)

LUBRICATION FUNDAMENTALS

22 Follow the money

What happens when national

energy policy clashes with the

reality of engineering science?

Check your wallet for the answer.

By Dr. Robert M. Gresham

BEST PRACTICES

26 Strategic oil analysis:Time-dependent alarms forextended lubricant lifecycles

(Fourth of a five-part series on

oil analysis)

Following these strategies

allows you to calculate rate ofwear generation, a more

insightful metric than total wear.

By Mike Johnson

COMMENTARY

30 In search of a fatigue limit:A critique of ISO Standard281:2007

In Part II of our debate, a leading

figure in the bearings communitypresents his case that the new

standard should be withdrawn.

By Erwin V. Zaretsky

PEER-REVIEWED PAPER (EDITORS CHOICE)

42 Probabilistic Stress-Life(P-S-N) Study on BearingSteel Using AlternatingTorsion Life Test

By Shigeo Shimizu,Kazuo Tsuchiya and

Katsuji Tosha

TLT / AUGUST 2010 / VOLUME 66 / NO. 8

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10 Tech Beat

Size does matter for nanoscalefriction; Extracting soybean oil

with a switchable-hydrophilicity

solvent; Presence of nanobub-

bles on superhydrophobic

surfaces.

By Dr. Neil Canter

54 Newsmakers

This months newsmakersinclude Quaker Chemical, Palmer

Holland, ConocoPhillips and

more.

56 Sounding Board

Readers discuss which profes-sional and personal organiza-

tions they belong to and why.

61 New Products

Diaphragm valves for reactivefluids; Bioscope catalyst

perfusing stage incubator;

Fuel ethanol additive; Automatic

open cup flash point tester; MQL

systems for CNC operations.

65 Advertisers Index

66 Resources

Keep up to date with the latest

technical literature available inprint and online.

67 Tribology Transactions

Review

Take a moment to review theofferings from the most recent

issue of STLEs peer-reviewed

journal.

4 Presidents Report

The value of corporatemembership

6 From the Editor

Remembering Dons octopi

8 Headquarters Report

Business book delivers more than

happiness

68 Selling Points

No really means not now

70 Shop Floor

Enforcing the leash law

72 Cutting Edge

Sliding on cells

PUBLISHER/EDITOR-IN-CHIEFThomas T. Astrene

MANAGING EDITORKarl M. Phipps

CONTRIBUTING EDITORSDr. Neil Canter

Dr. Robert M. GreshamMike Johnson

Jean Van Rensselar

CIRCULATION COORDINATORSMyrna ScottJudy Enblom

DESIGN/PRODUCTION MANAGERJoe Ruck

ADVERTISING SALESTracy Nicholas VanEe

Phone: (630) 922-3459Fax: (630) [email protected]

Dr. Pranesh B. AswathUniversity of Texasat ArlingtonArlington, Texas

Robert F. BakerKing IndustriesNorwalk, Conn.

Dr. John K. DuchowskiHydac FiltertechnikGmbH, Werk 8

Dr. Hong GaoConocoPhillipsPonca City, Okla.

Dr. Seong H. KimPenn State UniversityUniversity Park, Pa.

Dr. Chih LinBaker HughesThe Woodlands, Texas

Dr. Ashlie MartiniPurdue UniversityWest Lafayette, Ind.

Myron McKenzieAmerican RollerBearing Co.Greer, S.C.

Dr. Jun QuOak Ridge NationalLaboratoryOak Ridge, Tenn.

Dr. Brajendra K. SharmaNCAUR/ARS/USDAPeoria, Ill.

Allison TomsGasTOPS Inc.Pensacola, Fla.

Dr. Min ZouUniversity of ArkansasFayetteville, Ark.

Dr. Qian ZouOakland UniversityRochester, Mich.

TRIBOLOGY AND LUBRICATION TECHNOLOGY (USPS 865740)Vol. 66, Number 8, (ISSN-1545-858), is published monthlyby the Society of Tribologists and Lubrication Engineers,840 Busse Hwy, Park Ridge, IL 60068-2376. PeriodicalsPostage is Paid at Park Ridge, IL and at additionalmailing offices. POSTMASTER: Send address changes toTribology and Lubrication Technology, 840 Busse Hwy,Park Ridge, IL 60068-2376.

EDITOREvan Zabawski

The Fluid Life Corp.Edmonton, Alberta, Canada

TECHNICAL EDITORS

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hen I was asked to speak at the corporate member break-fast at STLEs 2010 Annual Meeting in Las Vegas, I thought

of the usual speech to give. I planned on discussing the many ben-efits corporate members re-ceive, including free registra-tion to annual meetings, freeeducation courses and discounts

on exhibit space and the Com-mercial Marketing Forum.

For most companies involvedin STLE, the decision to join as acorporate member becomes ano-brainer when analyzing thecost vs. the benefits. STLE actu-ally loses money when a com-pany utilizes all of its corporatemember benefits. There is cer-tainly a lot of value in the pack-age.

While all of this is interest-ing and relevant, I knew thiswas not the message I wantedto concentrate on in my speech.After giving it some thought andlooking back at the history ofour society, I decided to talk about the role corporate membershave played in STLEs ongoing success.

The formation of our organization back in 1944 as the AmericanSociety of Lubrication Engineers (ASLE) would not have been pos-sible without the support of corporations from the steel industry,lubricant suppliers, lubrication-device manufacturers, additive

suppliers, oil companies and the aluminum industry. If not for thesupport of these titans of industry 66 years ago, our society wouldnot have flourished. The focus in 1944, as it is today, was on creat-ing a society that meets the needs of industry.

Some of the principles established back then include:

1. Encouraging the active cooperation of industry and other multi-disciplinary professions in advancing the knowledge and applica-tion of the art of lubrication.

2. Supporting and stimulating the study and development of thetheory and practice of lubrication techniques in chemistry, phys-ics, engineering and other related sciences.

3. Accumulating and disseminating to lubrication professionalsand industry authoritative and scientific information availablethrough research, testing, field experience, etc.

Education and the dissemina-tion of knowledge were theprinciples upon which our so-

ciety was founded. STLEsfounding fathers recognizedthat an educated workforcebenefits employers. Corpora-tions recognized and em-

braced this concept and sup-

ported ASLE.

The generous support ofour corporate members overthe years has contributed toSTLEs success, and today oursociety is recognized as the

global leader in tribology andlubrication science. Corpo-rate member support comesnot only in the form of duesbut, more important, throughtheir commitment at annual

or local section meetings either through attending or by teachinga course or presenting a paper.

Today, as back when STLE was created, corporations still playan important role in the success of our society. They also realizethe importance of the society and the benefits they reap throughSTLE education and training programs that allow for a more edu-

cated workforce that produces better products and services.STLE grew through the years with the support of corporations.

Even if you are an individual member and your employer pays yourdues, consider this a form of corporate support. It means yourcompany recognizes the benefits and value of STLE membership.

STLE has thrived for more than 66 years due to the supportof a very special group of companies.

PRESIDENTS REPORT

Peter Drechsler

Peter Drechsler is a senior tribology specialist

with The Timken Co. in Canton, Ohio. You can

reach him [email protected].

W

The generous support of our corporate members over the

years has contributed to STLEs success, and today our society

is recognized as a global leader.

4


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STLE-sponsored meetings are a respected venue for presentation of the

latest technical information and for professional development and business

networking opportunities. The Annual Meeting showcases more than 350

technical presentations, application-based case studies and best practice

reports, and discussion panels on technical or market trends. Education

courses support professional development needs and prepare people for one

of STLEs three certification programs. Exhibits and commercial presentations

spotlight the latest products and services of interest to lubrication profes-

sionals. Typical attendance is 1,100 -1,400 people.

If you are interested in presenting at the 2011 meeting, submit a 100-150-

word abstract of the presentation through the STLE website at www.stle.org.

Site opens July 1. Abstracts due Oct. 1, 2010. Notification of acceptance will

be sent in November 2010. You do not need to prepare a full manuscript to be

included on the Annual Meeting program, but a 2-3-page extended abstract is

requested for the Proceedings CD. However, you are invited and encouraged

to submit a manuscript for review and possible publication in the STLE peer-

reviewed journalTribology Transactions.

For more information, please contact:


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hen I first met Don Riddell at a seminar in 1998, his pre-sentation on viscosity grades converted me to 0W-30, an

oil he promised would run better year-round and give better fueleconomyit does. Don had well over 10,000 other students, orconverts, through the latterpart of his 41-year careerwith Imperial Oil, a Canadianpetroleum company largelyowned by ExxonMobil. Though

he passed away on June 19,he left an indelible mark onall members of his audiencewhether at one of his semi-nars or at a local STLE meet-ing, where it was practicallyan annual tradition to havehim present a topic.

As soon as Don would be-gin speaking in his energetic,anecdotal style, you had twoguarantees: (1.) You were going to learn something new, and (2.)

You were about to be entertained. Most of our local members whoare in a position to give presentations will borrow an anecdote ortwo of Dons, and I would like to share the (publishable) one that ismy favorite.

Whether explaining the merits of 0W-30 or simply discussingmultigrade oils, Don would be compelled to talk about the viscosityimprover additive. Rather than wax technical about polymethacry-lates, he would just tell you to picture an octopus swimming in theocean.

When that octopus is swimming in cold water, he would be likethis, Don would say as he would enthusiastically pull his armsaround his body and mimic shivering. But, he would continue, he

would go like this when he swims into a nice, hot current, and thenhe would comically flop out his arms, cock his head and loll out histongue as though he was suffering from the heat.

Paying little attention to the weird stares from the audiencemembers who were wondering where he was going with this, Donwould just smile and carry on with a look that told you to trust him.Now, imagine there are millions of tiny octopusesoctopiwhat-ever, floating around in the oil. The oil wants to thin as it is heated,but if all these octopuses/octopi are flinging their arms, er, tenta-cles out, then the oil isnt going to thin out as much because theyare taking up more space and banging into each other.

At this point, a first-time viewer would have little idea that

they were witnessing a carefully crafted analogy that Don hadbeen using for many, many years, because his energy level fooledyou into thinking he was genuinely excited about this apparentlynew topic, and his delivery always contained quasi-errors.

Now if we take a0-weight oil and cram it fullof octopisee, I got it rightthis time, giving a twin-kling wink as he talked, we

can make that oil behaveless like a 0-weight at thehigher temperature andmore like a 30-weight.Sometimes he would theninterrupt himself and say,Did you know that the Wstands for winter, notweight? Crazy, huh? withan incredulous tone as if hehimself just learned this.

Concluding with, Thats how we make multigrade oils. We stuff

them full of long-chain polymers that act just like octopi.But what happens to the tentacles if we shove the octopi

through tight clearances? Don would ask as he paced around withhis arms sticking out. (If you were lucky enough to be sitting at theright angle, his demonstration would play out like a magic trick.)Making a chopping motion with one hand, against the oppositeshoulder, he would fish for somebody to say they would be cut. Assoon as he got his required response, he would whip his one armbehind him, making it disappear. Whats another word for cut? hewould ask and, seldom waiting for a reply, answer his own ques-tion with Shear.

And in that instant you realize that youre now learning about

the difference between temporary and permanent shear and whymultigrade oils are the most prone to this damagethey are full ofDons octopi.

We miss Don, and his memory will be kept alive in the form ofsharing his anecdotes, even if we cant do an octopus impressionhalf as well as he did.

Evan Zabawski, CLS, is manager of training and

education services for The Fluid Life Corp. in

Edmonton, Alberta, Canada. You can reach him at

[email protected].

FROM THE EDITOR

Evan Zabawski

WPaying tribute to a mainstay of the Canadian lubrication world.

6


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elivering HappinessA Path to Profits, Passion and Purposeis a best-selling business book that made it to my summer

reading list. The author, Tony Hsieh (pronounced Shay), is CEO ofZappos.com, the online shoe and apparel retailer.

When I was presented with a copy as an advance assignmentfor a professional retreat, I had no idea what Zappos was, let alone

why the company and its CEO areso well knownat least to otherpeople! But Hsiehs personal nar-rative and the interwoven storyof Zappos unconventional path tofinancial success inspired me tocomment on this exceptional bookand recommend it as a worthwhileread.

The Zappos story is builtaround the companys relentlesspursuit of creating what they call

WOW experiences for custom-ers, vendors and employees. Forexample, free shipping upgradesand a 365-day, no questions askedreturn policy.

Zappos commitment to serving customers sometimes pushesbeyond the exceptional to the humorous or bizarre. As a test,Hsieh once dared a business associate to make a late night call tothe Zappos 24-hour customer service line and ask if the operatorcould help locate a place to order late night pizza. Another calleronce asked a Zappos employee to answer his questions withoutusing any pronouns. The customer service reps were successful in

both cases!According to Hsieh, it is company culture that sparks this level

of employee commitment and leads to a powerful and valuablebrand. Zappos culture has grown out of a set of 10 core valuesthat define how the company operates internally and externally.The allegiance to these values is so strong that the company of-fers new hires $2,000 to quit in their first week as a way to testtheir commitment to these long-term goals vs. short-term finan-cial gain.

The WOW factor also extends to investors. The company, whichwas founded in 1999 and grew to $1 billion in gross merchandise

sales within a decade, was sold to Amazon.com in 2009 for $1.2

billion.Although Im not one of the lucky 100 investors who got a cut

of this $1.2 billion payday, the consolation prize is the wisdom tobe gained from reflecting on Zappos core values. My favorite isCore Value Number Five, which is to Pursue Growth and Learning.For both personal and professional reasons, its a message that

has broad appeal and immediateimpact.

While a good place to starton this goal might be by gettinga copy of the book, I hope youwill consider STLE as another op-tion for professional growth. Theoptions vary from something assimple as reading copies of TLT tothe challenge of sitting for one ofSTLEs four professional certifica-tion exams. As Hsieh points out,

You have to want to challengeand stretch yourself in order for it(personal and professional growth)to happen.

STLEs HQ staff is adopting thisphilosophy. Each employee has been given the assignment to readat least one business book this year, with STLE covering the cost ofthe book. The catch is that they have to share what they learnedfrom the book with our extended staff of 12 people at one of ourweekly staff meetingssort of a book report for adults. The ex-pected result is that each of us will be exposed to a dozen businessbooks, and our capabilities and culture will be better for having

participated in the experiment.Reading Delivering Happiness convinced me that this sort of

professional development exercise is a great way to counteractthe negative impact of the current recession. Take a look at thebook for yourself and at STLEs suite of professional developmentproducts and opportunities. I am certain youll find it to be an anti-

dote to the daily grind and a way to refresh yoursense of personal and professional enthusiasm.

HEADQUARTERS REPORTEdward P. Salek, CAE/ Executive Director

You can reach Certified Association Executive

Ed Salek at [email protected].

DIf advice from an online shoe CEO fits, why not take it?

8

You have to want to challenge and stretch yourself in

order for personal and professional growth to happen.


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12/76

esearchers continue working to gain a better understanding of friction at the

nanoscale because it has an impact on how materials are prepared for such

applications as nanoscale data storage systems, nanocomposites and nanoelectro-

mechanical devices. One thing that has been learned is that atomic-scale interac-tions are very important in determining how friction behaves at the nanoscale.

In a previous TLT article, work was discussed that correlates friction at the

nanoscale with friction at the macroscale by taking into account that surfaces at

the nanoscale are not smooth but, in fact, are rough with topography similar to a

mountain range.1Atoms and molecules are present at the tops of peaks and can

rub against each other in a fashion similar to frictional behavior at the macroscale.

In looking at materials on the nanoscale, two-dimensional interactions become

very important. Graphene is one such material that is being closely examined be-

cause it consists of individual atomic layers of carbon and is a precursor for graph-

ite. A previous TLT article highlighted work done to show that graphene is the

strongest material ever examined.2

One objective in working with materials at the atomic level is to determine thefrictional effects seen with small numbers of atomic layers. Such work has not been

carried out until now.

STLE-member Robert Carpick, professor in the department of mechanical en-

gineering and applied mechanics at the University of Pennsylvania in Philadel-

phia, and James Hone, professor in the department of mechanical engineering at

Columbia University in New York, headed up a group of researchers that evalu-

ated how friction occurs among atomically thin materials. The materials evalu-

ated are hexagonal boron nitride, graphene, molybdenum disulfide and niobium

diselenide.

Carpick says, Our objective was to evaluate a range of layered materials that

have different lattice constants, elastic constants and electronic properties in order

to see if we could find some commonality for frictional behavior that is indepen-

dent of their different structures and electronic properties.

Graphene and molybdenum disulfide are certainly familiar materials widely

used as solid lubricants. Hexagonal boron nitride is also utilized as a solid lubri-

cant in applications such as a coating for cutting tools. The final material, niobium

diselenide, is not widely known. Carpick says, Niobium diselenide is an exotic

material of interest for its low temperature, superconductivity. As far as we know,

there are no known tribological applications.

The researchers used an atomic force microscope (AFM) in a technique known

as friction force microscopy to measure the frictional forces encountered with

New research reveals that atomic-scale interactions

play a major role in determining how friction behaves.

KEY CONCEPTS

Frictional effects among

atomically thin sheets of

materials with different

structures and electronic

properties were studied.

An atomic force micro-

scope determined that

friction decreases as the

thickness of atomic layers

increases from one to

around four and then

levels off.

A single sheet of atoms

produces more friction

because it more readily

bends to conform to an

AFM tip, leading to more

contact area and higher

friction.

TECH BEATDr. Neil Canter/ Contributing Editor

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atomically thin sheets of these materials. The sheets of these

four materials were prepared by exfoliating them from a bulk

source onto a silicon oxide substrate. The AFM also was

used in a topographic mode to determine the thickness of

the atomic sheets.

The researchers found that

the friction generated for all

four materials increases with

decreasing atomic thickness.

This result may not seem in-

tuitive, but Carpick provides

an explanation.

When a material gets

thin, it also becomes very flex-ible, he says. A macroscale

example is the fact that bend-

ing back a single sheet of pa-

per is far easier than bending

a piece of wood. As the AFM

tip approaches a single sheet

of atoms, an attractive Van

der Waals force occurs be-

tween the tip and the single

sheet, causing the sheet to bend as it conforms to the tip.

This means more contact area and, thus, higher friction.

The researchers also observed that the friction force ex-hibited a stick-slip motion, slipping once for every unit cell

of the lattice for graphene and molybdenum disulfide. The

force required to slip was seen to build up for the first 1-2

nanometers of sliding, consistent with the idea of deforming

the puckered sheet as sliding begins.

Carpick continues, In contrast, thicker sheets of atoms

do not conform as readily because they are stiffer, leading

to a lower level of friction. The bending effect of the single

sheet around the tip is also known as a puckering.

Figure 1 shows the puckering effect as a single atomic

layer of a graphene sheet adheres to an AFM tip. Graphene

atoms moving out of the plane to conform to the tip are

shown in blue and red.

The researchers estimate that a monolayer sheet causes

20% greater friction than bilayers of atoms and 2-3 times

higher friction than bulk sheets of atoms. This phenomenon

was seen regardless of changes in scanning speeds, applied

forces, AFM tips made from different materials and humidity

changes. In the latter case, a reduction in humidity from 30%

to 5% did lead to overall lower friction, but the variation of

friction as a function of thickness remained constant.

Carpick indicates that friction does not continue to de-

crease as the thickness of atomic layers increases. He says,

Friction decreases as the number of atomic sheets increases

to around four but then levels off. The friction seen for four

atomic layers is comparable to friction seen for 50 layers or

when the material is present in a bulk state.

The researchers then

placed the materials on a

surface that they strongly ad-

here to in order to assess the

frictional effect. The surface

used was muscovite mica,

which forces the materials to

be atomically flat when fac-

ing the tip of the AFM.

The result is that no in-crease in friction is seen with

a decrease in atomic thick-

ness for any of the materi-

als. Carpick says, When

the AFM tip encounters the

atomic layers of the materi-

als, they do not come off the

substrate and adhere in the

same fashion as when they

are on the silicon oxide surface.

A second follow-up experiment determined how the

materials perform if suspended over 300-nanometer holesplaced in the silicon oxide substrate. Friction did increase as

the thickness declined in a similar fashion to when the mate-

rials were placed on the silicon oxide substrate.

These results clearly suggest that the thickness depen-

dence of friction at the nanoscale applies to all thin materials

that are either attached loosely to a substrate or suspended

over a substrate. Carpick is hoping that this research will

aid the design and performance of nanoscale mechanical de-

vices.

Further information can be found in a recent article3and

by contacting Carpick at .

1. Canter, N. (2009), Understanding Friction Laws at the

Nanoscale and their Relation to the Macroscale, TLT, 65

(7), pp. 1011.

2. Canter, N. (2009), Graphene: The Strongest Material ever

Examined, TLT, 65(2), pp. 2829.

3. Lee, C., Qunyang, L., Kalb, W., Liu, X., Berger, H., Carpick,

R. and Hone, J., Frictional Characteristics of Atomically

Thin Sheets,Science

,328

(5974), pp. 7680.

As the AFM tip approaches a single sheet of atoms, an attractiveVan der Waals force occurs between the tip and the single sheet,

causing the sheet to bend as it conforms to the tip.

Figure 1 | Adhesion of a sliding AFM tip on a single layer ofgraphene atoms leads to higher friction than on thicker layersdue to a puckering effect. Atoms depicted in blue and red ad-here to the tip and move out of the plane. (Courtesy of the Uni-versity of Pennsylvania)

1 1


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oybean oil is currently obtained from soybeans through a process involving

extraction of the oil from flakes. Hexane is used as a solvent in this process

because it is very compatible with soybean oil and easily removed by distillation.

Philip Jessop, professor of chemistry and Canada Research Chair in Green

Chemistry at Queens University in Kingston, Ontario, Canada, indicates that this

is not an environmentally friendly process. He says, Hexane is a volatile solvent

that can cause a significant amount of smog formation. In Canada, it is estimatedthat 4,400 metric tons per year of hexane are emitted with a third sourced from

oilseed processing. One other factor is that the final distillation process is very

energy-intensive.

In a previous TLT article, the concept of a switchable solvent was introduced.1

Jessop has been looking at this approach to use solvents in a more cost-effective

and environmentally friendly standpoint.

His original switchable solvents could be converted reversibly from a nonpolar

to a polar state. Jessop has been successful in doing this using carbon dioxide as a

reagent. Carbon dioxide is utilized because it is very cost-effective, readily avail-

able and easily removed. Jessop has now reported a new kind of switchable solvent,

which he calls a switchable-hydrophilicity solvent (SHS), meaning it can switch

from a hydrophobic state to a hydrophilic state.The switching process is shown in Figure 2. A hydrophobic organic solvent is

typically insoluble in water, as shown on the left. Reaction with carbon dioxide in

water (carbonated water) switches the solvent to a hydrophilic state that is soluble,

leading to the formation of a homogeneous mixture on the right. Eventually, the

SHS can be isolated in its original hydrophobic state through removal of the carbon

dioxide.

Using a SHS to process soybean oil without the use of hexane and distillation

has potential. The solvent in its hydrophobic state could be used to extract soybean

oil and then switched to a hydrophilic state to enable the oil to be isolated. A suit-

able solvent that can reversibly react with carbon dioxide has now been found.

Carbonation of water produces a weak acid (carbonic acid) which means that the

desirable solvent should be basic. Jessop and his coworkers have known that ami-

A carbon dioxide is used in a new process thatis more environmentally friendly and cost efficient.

S

KEY CONCEPTS

The current method for

extraction of soybean oil

requires the use of a

volatile solvent (hexane)

and an energy-intensive

distillation process.

A switchable-hydrophilicity

solvent has been found to

extract soybean oil withoutthe need for hexane and

distillation.

Green Center Canada

wants to use this concept

to extract residual motor

oil from used plastic

bottles to facilitate

recycling and reduce

waste disposal costs.

T

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We found that the difference in the wavelengths of maximumabsorption for the solvent in the absence and presence of water is

far greater than any other solvent we have ever tested and

shows a change in true solvent polarity. 1 2


15/76

dines, amines and guanidines can react with carbon dioxide

and water to become hydrophilic. Jessop says, We looked at

a number of candidates by varying the number of alkyl groups

attached to these nitrogen-based functionalities. Guanidines

were eliminated as possible solvents because they are too ba-

sic and do not switch back to

a hydrophobic state.

The parameter used to

determine the best possible

choice is the octanol-water

partition coefficient. Jessop

says, We added a tiny amount

of the solvent to a beaker

with one-part octanol and

one-part water. The percent-

age of solvent in octanol vs.water is measured. A higher

value means that the solvent

is more hydrophobic.

The researchers found that

a solvent with a logarithmic

octanol-water partition co-

efficient above seven is too

hydrophobic and will not be

miscible with carbonated wa-

ter. One specific amidine sol-

vent that worked well exhibited a value just above six.

This amidine solvent also happens to change polaritywhen exposed to carbon dioxide. Polarity measurements

were obtained by determining the wavelength of maximum

absorption of Nile Red dye in the absence and presence of

carbon dioxide. Jessop says, We found that the difference

in the wavelengths of maximum absorption for the solvent

in the absence and presence of water is far greater than any

other solvent we have ever tested and shows a change in true

solvent polarity.

The reason for this major change is that the solvent is very

immiscible in water in the absence of carbon dioxide. This

effect changes dramatically when carbon dioxide is added.

This amidine solvent was then used to extract soybean

oil from the soybean flakes. An extraction experiment was

conducted to compare the ability of the amidine to extract

soybean oil vs. hexane. After stirring soybean flakes in both

solvents overnight and then filtering, an equivalent amount

of soybean oil was detected in both solvents.

Carbonated water was then introduced to remove the

amidine solvent from the water. The efficacy of this tech-

nique was evaluated by using 1H nuclear magnetic resonance

(NMR) spectroscopy of deuterium water. After only one wa-

ter wash, 96% of the amidine solvent had been removed.

Jessop anticipates that additional washings will remove the

remaining solvent.

The solvent can then be isolated from the water through

removal of carbon dioxide by heating the mixture at a tem-

perature of 80 C for one hour. Jessop indicates that further

work needs to be done to determine the amount of residual

solvent left in the flakes and

how to remove it. This fac-

tor is important because the

flakes are used in other ap-

plications.

One area of concern for

Jessop is solvent durability.

He says, We are uncertain

that amidine solvents can

be reused in this process

because they can hydrolyzeover time. We have recently

looked at amines which are

chemically more robust. Sev-

eral promising amine candi-

dates have been identified

that will perform better than

the amidine solvent we ini-

tially evaluated.

Jessop also indicates that

further work will be done to

determine how much energy can be saved by not distilling

hexane.

Jessop works with Green Center Canada, which is looking

to commercialize sustainable technologies developed in the

academic community. He says, One new project that Green

Center Canada is working on is to evaluate the ability of

switchable solvents to extract residual motor oil from used

plastic bottles. If an approach can be developed, then recy-

cling of the plastic bottles will become feasible.

Such a process will significantly reduce waste disposal

costs as plastic bottles with residual motor oil now have to

be land-filled in Canada.

Additional information on the use of switchable solvents

to extract soybean oil can be found in a recent article2and by

contacting Jessop at

1. Canter, N. (2006), Analyzing Switchable Solvents, TLT,

62(2), pp. 1516.

2. Jessop, P., Phan. L., Carrier, A., Robinson, S., Durr, C. and

Harjani, J. (2010), A Solvent having Switchable Hydrophi-

licity, Green Chemistry,12

(5), pp. 809814.

Several promising amine candidates have been identified that will performbetter than the amidine solvent we initially evaluated.

Figure 2 | A switchable-hydrophilicity solvent is used in thehydrophobic state to extract soybean oil and then is convertedinto a hydrophilic solvent through the introduction of carbon-ated water. Isolation of soybean oil is then achieved followedby switching the solvent back to its hydrophobic state throughremoval of carbon dioxide. (Courtesy of Queens University)

1 3


16/76

mproved wettability of lubricants on surfaces continues to be an objective for lu-

bricant suppliers. They are striving to improve the ability of lubricants to adsorb

on surfaces, which leads to better friction reduction and wear loss.

One surface type that has been looked at actively is superhydrophobic. In a

previous TLT article, a superhydrophobic surface is defined as one in which water

exhibits a contact angle of approximately 150 degrees.1

One of the key features of a superhydrophobic surface is that of water repel-lency. Water remains a major problem in lubrication systems and any means that

can be done to keep it away from surfaces helps extend the life of the system.

Dr. Antonio Checco, associate scientist at the Brookhaven National Laboratory

in Upton, N.Y., says, One of the perceived reasons for the extreme water repellency

of superhydrophobic surfaces is the presence of small gas pockets near the surfaces.

These bubbles further reduce the amount of surface area that can be in contact with

water, thereby increasing the macroscopic contact angle.

The presence of surface texture encourages the formation of these bubbles.

Checco says, Texturing of surfaces with topographical features such as cavities

promotes the formation and stabilization of bubbles. From a thermodynamic stand-

point, coalescing of small bubbles into larger ones is encouraged. This particular

effect is more likely to occur on flat as opposed to textured surfaces because in the

latter case the bubbles are tightly confined within the surface textures.

On superhydrophobic surfaces that exhibit textures on the nanometer scale,

nanobubbles are expected to form. Firm evidence of the presence of nanobubbles

would be helpful to better determine how these nanotextured surfaces repel wa-

ter. However, nanobubbles on superhydrophobic surfaces have not been directly

probed until now.

Checco and his coworkers devised an approach to confirm the existence of nano-

bubbles of gas on superhydrophobic surfaces. The researchers developed a textured

surface and then immersed it in water. Nanobubbles were detected through the use

of small angle X-ray scattering (SAXS).

The textured surface was prepared through a block copolymer, self-assembly-

based fabrication technique. Checco says, We started with a surface of flat, silicon

wafers similar to the material used in the electronics industry. Subsequently, a thin

film of a block copolymer consisting of polystyrene and poly(- methyl methacry-

I

KEY CONCEPTS

Textured, superhydro-

phobic surfaces, which

encourage the formation

and stabilization of

bubbles, were prepared

and immersed in water.

X-ray scattering analysisshows direct evidence for

the presence of nano-

bubbles on these sur-

faces.

The results show that

water only penetrates

about 5-10 nanometers

into 24-nanometer-

diameter cavities, about15-30 layers of water

molecules.

T

E

C

H

B

E

A

T

Using small angle X-ray scattering, researchers have devised away to detect nanobubbles on superhydrophobic surfaces.

Texturing of surfaces with topographical fea-

tures such as cavities promotes the formation

and stabilization of bubbles.

1 4


17/76

late) was deposited

on the silicon sur-

face.

The block co-

polymer was an-

nealed at 180 C

in a vacuum oven

causing a micro-

phase separation to

occur. This heating

leads to the forma-tion of poly(- meth-

yl methacrylate)

domains within a

polystyrene ma-

trix. Checco adds, The result is the creation of poly(-methyl

methacrylate) cylinders that are perpendicular to the silicon

substrate.

Treatment with ultraviolet light leads to the degradation

of the poly(-methyl methacrylate) cylinder blocks and the

crosslinking of the polystyrene. Checco says, Ultraviolet

light breaks bonds between the polystyrene and the poly(-

methyl methacrylate). With the degradation of the poly(-methyl methacrylate), cylindrical cavities are formed that

are 24 nanometers in diameter, 40 nanometers apart and ar-

ranged in a hexagonal lattice.

These cavities are transferred onto the silicon surface

through an etching process. The right image in Figure 3 is a

scanning electron micrograph of the nanocavities.

To render the surface superhydrophobic, the silicon sur-

face was passivated with a 2.5-nanometer-thick monolayer

of octadecyltricholorsilane. Ultrapure water was then placed

between the textured surface and a thin Mylar film. The

depth of the water layer was approximately 100 microns.

SAXS was used to detect the presence of the nanobubbles.

Checco says, We used SAXS because the size of the cavi-

ties in the textured surface is small enough to scatter x-rays.

SAXS was used to compare the difference between scattered

x-ray intensity in air and when water is placed on top of the

surface.

In analyzing the results, the researchers noted a reduction

in scattered x-ray intensity when water is used. Checco says,

Water is denser than air and should generate less scattered

x-ray intensity if it penetrates into the cavities. The results

show that the scattered x-ray intensity is higher than ex-

pected if water penetrates completely into the cavities. This

strongly indicates

that water penetra-

tion is only partial

and nanobubbles

are present in the

remainder of the

cavities.

Specifically, the

researchers found

that water only

penetrates about 5to 10 nanometers

into the cavities,

which corresponds

to approximately

15 to 30 layers of water molecules.

The left image in Figure 3 is a cartoon illustrating the

nanobubbles shape as inferred from x-ray measurements. In

the center image, the optical profile of a water drop placed on

the nanotextured surface is shown.

The scattered x-ray intensity measurements were taken at

various time intervals to evaluate the stability of the nano-

bubbles. Checco says, We found that the values remainedconstant, which means that the nanobubbles are stable.

Confirmation of the existence of nanobubbles on supe-

rhydrophobic surfaces means that they clearly contribute

to water repellency. One potential application for utilizing

nanobubbles is in reducing the friction encountered by mi-

cro- and nanofluids as they flow into small channels.

Further information can be obtained in a recent article2

and by contacting Checco at

1. Canter, N. (2008), Controlling Surface Wettability, TLT,

64(5), pp. 1213.

2. Checco, A., Hofmann, T., DiMasi, E., Black, C. and Ocko,

B. (2010), Morphology of Air Nanobubbles Trapped at Hy-

drophobic Nanopatterned Surfaces, Nano Letters, 10 (4),

pp. 13541358.

Neil Canter heads his own consulting company,

Chemical Solutions, in Willow Grove, Pa.

Ideas for Tech Beat items can be submitted to

him at

Ultraviolet light breaks bonds between the polystyrene and thepoly(-methyl methacrylate). With the degradation of the poly(-methyl

methacrylate), cylindrical cavities are formed that are 24 nanometers indiameter, 40 nanometers apart and arranged in a hexagonal lattice.

1 5

Figure 3 | The image on the left is a cartoon showing the shape of a nanobubbleinferred from x-ray measurements. The center image is an optical profile of a waterdrop placed on a nanotextured surface and the image on the right is a scanningelectron micrograph of the nanocavities (Courtesy of Brookhaven National Laboratory)


18/76

Based in Atlanta, this Argentine-born STLE member

is the head of Conexo, which provides tribology innovations

in domestic and foreign markets.

By Thomas T. Astrene/Publisher

Ricardo Hein:

The quick file

solution company, in 2004 in

Atlanta, Ga. The company has

three business divisions.

wife, Alejandra Liernur Hein.

Argentina, he has lived and

worked on three continents.

degree in mechanical and marine

engineering from UdeMM

University in Buenos Aires.

Earned a masters in business

administration in strategic

management from DePaul

University in Chicago.

in the lubrication field for

industrial products. Twelve

years in international sales and

lubricant engineering for Castrol,

Shell and Fuchs.

internal and external customers in

75 countries.

and Portuguese.

Our goal in creating three divisions was to give focus to each busi-

ness activity. The first division handles the North American market for

our industrial maintenance products and Rewitec Nanocoating.

The second division is dedicated to market testing instruments. Our

primary focus is on the Optimol SRV tribometer.

The third division markets these innovations in Latin America and

is co-managed by team members in 10 countries in the region. Each of

these divisions responds to each businesss unique challenges using the

knowledge and skill sets of our team members.

To stay competitive our industry needs tools that bring the com-

plexity of field conditions to the lab to decrease time and costs involved

in tribology research. Our SRV machine does just that. It simulates any

field application with dynamic variables, different components, materials

and shapes under any condition.

1 6


19/76

One of our customers, who researches solu-

tions for fretting wear, was able to use the SRV to

reproduce the conditions for fretting to appear in a

four-hour test with high load. The finding evolved

into a recent SAE norm for fretting wear testing.

Other customers use the engine-simulation

module for research in lubricants for modern en-

gines using fuels that change interaction with tri-

bological surfaces. The test results in the lab find

direct correlation in the field. The design of the

SRV is successful because it precisely configures to

specific testing needs.

We market a gear conditioner, RewitecNanocoating, which reverts wear and micropitting

and increases load-carrying capacity. The compo-

nents of the nanocoating intercalates in the metal

surface at the atomic level using the energy from

friction and load. It forms an interspersion of dif-

ferent ions that diffuse into the crystal structure of

the surface layers.

These layers sustain the rolling/sliding components even

where the lubricating film breaks. We are working on wind

turbine gears where we increase the load-carrying area by 18

times on gear surfaces that are affected with micropitting.

In the aggregates and cement industries, we can stop vi-bration stress peaks and smoothen the surface roughness by

3-5 times in large Falk and Symetro gears at full operation.

The benefits for our customers range from doubling the life-

time of mechanical equipment to increasing productivity to

improving operational efficiency.

We are facing a technological change in our industry,

with challenges that range from fuel economy to carbon

emissions to drain intervals. For transportation and mobile

equipment, higher efficiencies, longevity issues and environ-

mental concerns challenge our industrial markets.

We must accept the current conditions as the new norm

without expecting the old market back. These times call

for stronger investment in research and in higher quality

standards for our products in order to answer the demand

for new and more evolved equipment where our previous

products no longer fit. Innovation also must meet the newstandards of quality required by our customers. Lubricant

marketers should also consider accommodating the needs

of the international markets; the payoff is worthwhile. One

should see these challenges as a fresh start and restrategize

from here.

After I graduated as a marine engineer in Argentina, I

was hired by Shell for the lubricants group in 1984 where I

was trained in this field. Later on, working for Fuchs, I had

the opportunity to learn about metalworking and industrial

fluids. Then, working for Optimol/Castrol some years later, I

gained a deep understanding of specialized and performance

products.

Throughout these 25 years, I have worked with many

seasoned lubrication engineers and tribology experts who

shared their knowledge with me. Moving from Argentina to

Germany for six years before coming to the United States

15 years ago exposed me to remarkably different technologi-

We must accept the current conditions as the new norm

without expecting the old market back.

Ricardo (center)with Conexo customers at an industry trade show in

Buenos Aires, Argentina.

We are facing a technological

change in our industry, with

challenges that range from

fuel economy to carbon emissions

to drain intervals. 1 7


20/76

cal mindsets. During those

years, I visited more than 80

countries and was exposed to

innumerable industries and

equipment to which I applied

my knowledge of lubricants.

I would choose what I

do today. While I was com-

pleting my MBA about 10

years ago, I decided to buildmy own company. The idea to

start Conexo and dedicate my

efforts to it did not resolve itself until I found new technolo-

gies and innovations in tribology. I am passionate about this

industry and understand it thoroughly. I feel very confident

working independently in it.

I have to confront

skepticism; that requires re-

searching and documenting

cases to use as references.

In addition, when I export

to different countries on the

continent, I come across dif-

ferent cultures and languag-

es. This requires an open

mind and taking the time to

make sure that communica-tion is clear and accurate.

Finally, being an entre-

preneur requires double the enthusiasm for growing the busi-

ness, especially after the current global financial crisis.

You can reach Ricardo Hein at

Lubricant marketers should consider accommodating the needs

of the international markets; the payoff is worthwhile.

Ricardo and Alejandra Heinpartners in life as well as theinternational tribology company Conexo.

1 8

YOU ALSO GET SEA-LANDS WINNING TECHNICAL SUPPORT AND DEPENDABLE SERVICE.

821 Westpoint Parkway Westlake, OH 44145

440-871-7887www.sealandchem.com E-mail: [email protected]

When you want a certain additive, chances are weve got it right

in stock. We maintain a huge inventory of quality products from

the best names in the business and we get them to you FAST!

Alkylpolyglucosides

Antioxidants

Biocides

Chlorinated Paraffins

Corrosion Inhibitors

Emulsifiers

Esters

Ether Amines Fatty Acids

Fatty Alcohols

Lard Oils

Lubricant Additive Components

Lubricant Additives Packages

Methyl Esters

Neodecanoic Acid

Petrolatum

Polyalkylene Gylcols

Polyalphaolefins

Rust Preventatives

Sulfonates

Sulfurized Compounds Synthetic Lubricants

Vegetable Oils

Waxes

White Oils

C H E M I C A L C O .


21/76


22/76

Carbon/Carbon composite (CCC), a well-recognized struc-

tural material, is known for its high temperature strength

and low relative density.1Since most of its applications in-

volve an oxidizing environment, the improvement in high

temperature oxidation behavior needs to be addressed. Fur-

thermore, fretting wear of uncoated CCC limits its lifetime

in applications, such as bushings in jet engines. A number of

investigators have reported enhancement in oxidation and

wear resistant of CCC in the presence of protective coating

layers.2,3But application of a surface and subsurface coating

system that can preserve its oxidation resistance along with

maintaining lubricity at high temperature remains an issue.

Therefore, the main motivation of this research was to in-

filtrate the porous CCC with atomic layer deposited (ALD)

lubricious oxides, which have been shown to provide good

tribological properties,4and determine the solid lubrication

mechanisms responsible for the improvements in wear resis-

tance with electron microscopy.

CCC contains ~21% total porosity and ~75% open poros-

ity. ALD was used as the deposition technique with metal-

organic precursors of diethyl zinc (DEZ), trimethyl alumi-

num (TMA), tetrakis (dimethylamido) zirconium (IV) and

DI H2O for deposition of ZnO, Al

2O

3, and ZrO

2, respectively.

Pure ZrO2and one trilayer of ZnO/Al

2O

3/ZrO

2of total thick-

ness ~220 nm were infiltrated into the CCC monoliths. To

simulate the fretting wear of uncoated and coated CCC, a

high frequency reciprocating rig (HFRR) was operated at

room temperature with a normal load of 1 N using a 440

C stainless steel (SS) counterface under a stroke length of 1

mm and reciprocating frequency of 20 Hz for 130 min.

STUDENT POSTER ABSTRACT

Hamidreza Mohseni and Thomas W. Scharf (Advisor)

Department of Materials Science and Engineering & Institute for Science and Engineering Simulation (ISES)

University of North Texas, Denton, Texas

Hamidreza Mohseni received

his masters of science and bach-

elors of science degrees from

the University of New South

Wales (2006) and Sharif Uni-versity of Technology (2004),

respectively. Currently, he is a

doctoral candidate working un-

der the guidance of professor

Thomas W. Scharf in the de-

partment of materials science

and engineering at the Univer-

sity of North Texas. His research interests include investigating

the tribological behavior of solid lubricant thin films deposited

by atomic layer deposition and determining tribological mecha-

nisms using FIB-SEM, FIB-HRTEM/HRSTEM and XRD charac-

terization techniques. You can reach him at

2 0

Editors Note:The 2010 STLE Annual Meeting & Exhibitionin Las Vegas has given us another batch of winners from

this years Student Poster Competition, as we will be

publishing the winning abstracts written by studentmembers of STLE in this semiregular feature in TLT. I feel

it is important to foster as much growth and interest as

possible in these upcoming tribologists. The world has

many challenging technical issues, particularly in the en-

vironmental and energy fields that must be solved if we

are to continue evolving as a people. Young people who

are just entering the world of tribology will be the ones

tackling these challenging problems. They are the future

of this planet and the future of our professional society.

Please feel free to contact the authorsperhaps you can

offer some guidance, a mutual research or work opportu-

nity or even employment within your organization. This

is your chance to review tomorrows ideas and talent be-

fore they become todays products and competitors.

Evan Zabawski, CLS

Editor


23/76

The ALD coatings exhibited excellent conformality and pore-

filling down to ~100 microns into the CCC.

Discernible visual differences in the wear track width

and amount of transfer film on the counterface in Figure 1

indicates improved wear resistance with the ALD coatings.

A ~65% improvement in the wear factor (down to 1.5x10-

6 mm3/Nm) was achieved with the ALD infiltration of the

1 trilayer of ZnO/Al2O

3/ZrO

2 compared to uncoated CCC.

Cross-sectional transmission electron microscopy (XTEM)

studies of the worn surfaces were performed to elucidate the

solid lubrication mechanisms responsible for these improve-

ments. Figure 2 shows XTEM images of the 1 trilayer (a)

before and (b) after HFRR testing. Wear is only observed

in the top ZnO layer, in which there was a high density of

sliding (shear)-induced stacking faults inside the wear tracks

shown in (c) in comparison to the unworn trilayer. The cor-

responding FFT-pattern in (d) was indexed to the (0002)

basal plane. Activating subsurface basal stacking faults will

promote intrafilm shear/slip and hence improve wear. Theslip of partial dislocations likely resulted from a dislocation

glide process along the basal planes. Also, a high resolution

scanning TEM (HRSTEM) image and corresponding energy

dispersive x-ray spectroscopy (EDS) elemental line scan are

shown in Figure 2 (e) and (f), respectively. The image and

line scan show the existence of a mechanically mixed layer

(MML) that contained no iron from the counterface. Intra-

film shear with this friction induced subsurface (mechani-

cally mixed layer) aids in shear accommodation (prevents

brittle fracture).

ALD ZnO/Al2O

3/ZrO

2nanolaminates are good candidates for

providing low friction and wear resistant surfaces and inter-

faces in moving mechanical assembles such as CCC bush-

ings that experience fretting wear.

The authors acknowledge the support of UNTs Center for

Advanced Research & Technology (CART).

1. Sheehan J.E., Buesking K.W. and Sullivan B.J. (1994),

Carbon-Carbon Composites, Annu. Rev. Mater. Sci., 24,

pp. 19-44.

2. Huang, J.F., Li, H.J., Zeng, X.R., Deng, F., Xiong, X.B. and

Li, K.Z. (2007), Oxidation Resistant Yttrium Silicates Coat-

ing for Carbon/Carbon Composites Prepared by a Novel In-

Situ Formation Method, Ceramic Inter., 33, pp. 887-890.

3. Park, S.J., Seo, M.K. and Lee, J.R. (2002), Effect of Oxi-

dation Inhibitor on the Low Energy Tribological Behavior of

Carbon-Carbon composites, Carbon, 40, pp. 835-843.

4. Doll, G.L., Mensah, B.A., Mohseni, H. and Scharf, T.W.

(2010), Chemical Vapor Deposition and Atomic Layer De-

position of Coatings for Mechanical Applications, J. Ther-

mal Spray Tech.,19

, pp. 510-516.

2 1

Figure 2 | HRTEM analyses: (a) 1 trilayer before HFRR test, (b) 1trilayer after HFRR test, (c) high density of basal stacking faults

inside the wear track along the reciprocating sliding direction, (d)FFT pattern shows diffraction spot of (0002)-basal planes of ZnO,(e) HRSTEM drift corrected line scan profile of MML and (f)corresponding elemental line profile. Pt is a protective layer forFIB-sectioning.

Figure 1 | Optical images of worn surfaces (Top: transfer films on440 C SS counterfaces and Bottom: wear tracks).

CCC-Uncoated CCC-ZnO/Al2O3/ZrO2CCC- ZrO2


24/76

rom time to time I and others have written about the techni

cal problems besetting the wind turbine industry. In the shor

term, wind turbines have been a boost to our industry in th

way of funded research into how to manage these problems. Ou

friends at ASME have a new technical committee, and STLE wil

form either a new industry council or technical committee focus

ing on the technology. In addition, the Society of Maintenanc

and Reliability Professionals is interested in the condition moni

toring problems associated with wind turbines. So the technica

community is clearly ramping up, thanks to your tax dollars.

Now Ive been accused of being a troglodyte, curmudgeon

grumpy old man or, at the very least, benignly cynical. All ar

likely true, especially when one thinks of politicians as the

intermingle with the economics of science and technology. S

What happens when national energy policy clashes with the reality

of engineering science? Check your wallet for the answer.

LUBRICATION FUNDAMENTALSDr. Robert M. Gresham/ Contributing Editor

F

subsidized. As a result, the government paysa so-called, renewable obligation.

country is on the order of 10 cents a kilowatt

hour.

of a hat pretty soon, new wind turbines will

incur high maintenance costs.

2 2


25/76

when someone suggests politics or

politicians being involved, I imme-

diately resort to the clich, Follow

the Money!

Lets start with the United King-

doms experience, since Europe

seems to be a little ahead of the

U.S. in wind energy. Many of their

wind farms are located in the Cam-

brian Mountains, a pretty windy

place and remote as well. It seems

the debate in the U.K. over the ef-

ficacy of wind farms, as in the U.S.,

is not without a certain hyperbole

on both sides, and the claims seem

to border on the ridiculous. For

example, a spokesman from Re-

newables U.K., says, The U.K. is

the windiest country in Europe, so

much so that we could power thecountry several times over using

this free fuel.

He further claims that existing wind turbines have the

capacity to prevent 3.7 million tonnes of carbon dioxide per

annum. However, on closer inspection, to do this the wind

turbines would have to generate electricity at 100% capacity,

100% of the time. Of course, the wind does not blow 100%

of the time. Further, commercial wind turbines need about

6-10 mph wind to operate and automatically stop at 55 mph

to protect the equipment. When wind is in this outlet range,

electricity is not constant. According to U.K. government fig-

ures, wind turbines operate at only 27% of capacity.That wouldnt be so bad if we could store electricity, but

of course we cant. Thus, you have to either install many

more turbines or have standby alternative generating capaci-

tylike a fossil fuel or nuclear power plant. Germany, which

has the largest number of wind turbines in Europe, is build-

ing five new coal power stations, which it does not otherwise

need, purely to cover the power fluctuations from its wind

farms.

When you follow the money, what you find is that in

the U.K. wind farms are highly government subsidized. The

government pays a so-called, renewable obligation (RO).

The cheapest way to collect the RO is to build a wind farm.

The way it works out, it costs about 2 million to build a

wind turbine. The RO is about 138,000 annually, and with

sales of the generated electricity added an industrious wind

farmer can clear about 300,000. Thats about a 6-7 year pay-

back, not bad. However, in essentially double that time, you

can still get your money back without selling a single spark

of power. Thats a pretty good low-risk deal, unless youre a

taxpayer.

Recently, after 10 years of negative lobbying by the pre-

sumed liberals of New England, the U.S. government ap-

proved the Cape Wind project in Massachusetts. The idea

for this project, youll recall, was to install a huge wind farm

in Nantucket Sound, playground to a large number of sea-

oriented folks, some of whom live in Hyannis Port. Their

opposition was primarily based on aesthetics, or lack thereof,

and some notions about negative environmental impact on

the ecosystem, hazards to sailors, shipping and the like.

For the pro-wind people, this project makes a lot of sense,

as the farm is going to be in a windy place with a relatively

shallow ocean bed and a relatively high density of people

(which reduces transmission distance and cost) and who,

theoretically, should be more culturally predisposed to sucha solution. However, the debate quickly turned into a case of

its OK in your backyard but not mine. Alas, but follow the

money.

According to a May Wall Street Journalarticle, construc-

tion of the Cape Wind project is massively subsidized by the

federal government. This, of course, means that not only will

New Englanders taxes rise but so will mine and yours. But,

hey, were all good guys.

But thats not all.

The going rate for electricity around the country is on the

order of 10 cents a kilowatt hour. Apparently, Cape Wind

folks have asked the state for a 15-year contract at ~20 cents

a kilowatt hour with a 3.5% escalation clause. In other words,

not only will New Englanders taxes rise, but the cost of elec-

tricity, at least from this source, will essentially double. Add

to that is the problem that has STLE all abuzz these days

premature failure of wind turbine gearboxes and some key

bearing systems. Unless we tribological types can pull a rab-

bit out of a hat pretty soon, these brand new wind turbines

are likely to incur high maintenance costs as well.

So, as the folks of Nantucket, Hyannis Port and Marthas

Vineyard are sitting on their verandas and yachts, sipping

Chablis, eating brie and watching their new windmills going

2 3

Many people believe wind turbines will despoil the aesthetics of areas like Nantucket Sound.


26/76

round and round, they can contemplate the fact that they

paid extra to build them, are required to buy the product

(electricity) and must pay about double the normal price for

the privilege. Further, they can only hope that we tribolo-

gists, design engineers, fabricators and operators can fix the

technical problems soon or else their costs will climb dis-

proportionately higher yet. When you follow the money, its

kind of a lousy deal.

But in keeping with my curmudgeonliness, lets look at a

current energy-related crisis and see what happens when we

follow the money again. Of course, Im referring the BP deep-

water oil spilla tragedy by any and all standards. Lets say

we, as a nation, take the approach we

did with nuclear power. We also had

serious problems at Three Mile Island,

followed not long after by Chernobyl.

These two catastrophic events made

us very adverse to risk in the nuclear

power industry in the U.S. So rather

than deal with the problem, we quitbuilding nuclear power plants and be-

came all the more dependant on fossil

fuels as an energy source for electrical

power, further diverting fossil fuels

from other applications.

France on the other hand contin-

ued with nuclear power development

and, with no major negative events,

now derive about 85% of its electric-

ity from nuclear power. To that extent,

France is that much less dependant on

foreign oil.What if, after the BP oil spill crisis

is over or at least mitigated, we con-

tinue to ban most offshore oil drilling,

both deep water and shallow? What if

we raise taxes on oil suppliers to raise

so-called trust funds to mitigate

possible future risk or spills? What if

we excessively tighten the regulatory

environment to near punitive levels?

What if several of these companies

crumble and go into bankruptcy or

just leave the country?

We will be even more dependant

on foreign oil, and prices will signif-

icantly rise. And it is not just gaso-

line prices that will rise but also the

myriad of other products that are de-

rived ultimately from crude oil such

as plastics, synthetic fibers for clothes,

furnishings and a wide variety of addi-

tives that go into foods, paints, fertiliz-

ers, detergents, cosmetics, packaging,

drugsthe list is almost endless.

If this happens our friends in Nantucket Sound might feel

a little smug. Their 20 cents-plus-per-kilowatt hour electric-

ity might suddenly seem like a bargain instead of a lousy

deal.

If you feel like you need a crystal ball to sort all this out,

just remember one rulefollow the money.

You can reach Bob Gresham,

STLEs director of professional development,

at

2 4


27/76

Stop reacting to

individual reports...

...and start managing a more

effective program today!

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28/76

il analysis is a powerful tool in the machine condition monitoring

toolboxif used properly. Much like other technologies, it performs

best within a well-developed plan. When accomplished, a well-devised

plan can provide an effective long-term view into the health of any ma-

chine with lubricated components.

TLT has provided STLE members with information about test methods,

alarm methods and about the best alarm fit for the noted test methods to

construct an effective oil analysis approach. The November 2009 TLT pro-

vides an overview that would be a worthwhile preview to this article. This

article can be found on the STLE Web site ().

The 2009 article indicates that there are three common alarm types for

grading the underlying problems for sumps and lubricated components.

BEST PRACTICESMike Johnson

Fourth of a five-part series on oil analysis (January, April, July, August, December)

O

Following these strategiesallows you to calculate

rate of wear generation,a more insightful metric

than total wear.

actual rate of wear per unit of

time.

with other incremental units,

including production values, miles

or operating cycles.

increase, the rate of top-up

volume should be factored to

reflect dilution effects.

2 6


29/76

These are statistical (alarms used to identify machine wear

problems), absolute (aka aging alarms, used to identify lubri-

cant health and degradation) and percentage-based alarms

(used for lubricant health and contamination monitoring).

The focus of Part IV of this five-part series addresses rate-

of-change (ROC) and volume-compensation alarms. These

are common process alarms and could be effectively used to

track machine conditions operating under a variety of consid-

erations. When coupled with top-up volume normalization,

ROC alarms may help the engineer make decisions about

the lubricants long-term surface protection characteristics,

something difficult to track with routine lubricant-analysis

processes. Accordingly, this approach helps with evaluations

between high-performance and commodity grade products.

Aside from wear debris analysis, this technique also could

be used to measure contamination control effectiveness forhydraulic and circulation systems and improve sump life-

cycle management.

There are a variety of circumstances under which a ROC or

time-dependent alarm is useful. For instance, if the site had

a machine that was sputtering through final cycles/hours/

units of production and it was necessary to stop the machine

before it failed in service, one might use ROC alarms to track

the increase in the selected indicator of failure over short

blocks of time.

For example, suppose a machine has already producedwear debris indicating an aggressive wear pattern from the

routine oil analysis cycle. Perhaps a degraded bearing or gear

surface condition is also evident in vibration data. The oil is

changed and an inspection conducted to obtain corroborat-

ing evidence of a failure symptom. Following conclusion

that a repair is pending, the owner wants to squeeze as much

time from the machine as possible but wishes to

do so safely to avoid collateral damage. An ROC

alarm could provide the owner with a wear de-

bris value per unit of time that tells more about

the ongoing rate of wear development than an

interval reading.

A ROC alarm could be used to measure the

rate of oxidative degradation of a large sump vol-

ume as well. For instance, as oil ages its rate of

degradation often increases. If the oil is hot, wet

and/or contaminated with iron or copper wear

debris, the rate of decay could accelerate.

Coupled with oil top-up volumes, this meth-

od could be used to gauge engine wear for large

industrial engines driving ships, trucks and

earth-moving vehicles. Particularly, as it pertains

to wear debris for engines, the small wear particle

size in engine oil analysis is below typical OEM filter element

capture size, meaning wear data should be well represented.

A ROC alarm is applied to a system where the amount of

change must be considered relative to the amount of time

through which the change occurs.

Consider the data set in Figure 1. This represents the

amount of wear that has occurred in a compressor sump

during a 24-month

period, beginning

with an oil change

(Month 1) and ac-

counting for rou-

tine top-ups that

have occurred dur-ing the analysis pe-

riod.

Figure 2 shows

the iron val-

ues plotted out

over the period

of samples. The

plot would seem-

ingly suggest that

the wear problem

is becoming sig-

nificant. The blacktrend line adds cre-

dence to the con-

cern. However, the

timeline for wear

generation should

be considered.

2 7

Figure 1 | Compressor sump 24-monthiron wear and top-up volume record.

Figure 2 | A 24-month wear debris plot and trend.

The chief concern is the ongoing rate of wear generation.Total wear is important but can be misleading.


30/76

The chief concern is the ongoing rate of wear generation.

Total wear is important but can be misleading. The iron value

shown in Month 24 reflects two years of accumulation, less

leakage, and does not reflect the extent to which the rate of

wear is increasing or not. Figure 3 reflects the same data set

adjusted to reflect wear produced per month.

After accounting for growth over time, it appears that the

rate of wear generation fluctuates between 5 and 30 ppm per

month but is steady. The plateau toward the end of the se-

quence may be explained by a variety of conditions, includ-

ing weather, operational inconsistencies or operating loads.

The formula for normalization for any type of data set,

both process and maintenance measurements, is:

(P0 P-1)Pf=

(T0 T-1)

where:

Pf = Factored data point, in this instance iron

P0 = Current data point

P-1 = Previous data point

T0 = Current time period

T-1 = Previous time period

The values for P, time period, also could be units of pro-

duction, tons, miles, years or any other parameter. The ac-

tual units must be the same, but the nature of the units can

be any parameter defined by the user.

Also keep in mind that the values for V-1should reflect

an actual condition. In this instance, the iron reading for V0,

which is Month 1, follows an oil change. The wear debris

from the previous period is not provided, so the value for V-1

is zero. If the parameter measured (AN/BN, RPVOT hours,

viscosity, etc.) has a definable starting point, use that value.

Wear rate for period zero is not measurable.

Extension of drain intervals is an expected outcome of im-

provements in lubrication practices. Mineral oil lifecycles

should be extendable by a factor of three to five if the lubri-

cant is maintained in a cool, clean (no atmospheric contami-

nants and/or wear debris) and dry state. Heat, contaminants

and moisture all contribute markedly to oxidation and short-

ened lifecycles.

Following the example, assume this

compressor has a 55-gallon sump and

experiences nominal leakage across

separator and seals. Rather than changeoil at the traditional one-year intervals,

the owner is operating on a condition-

based change plan. As time passes, to-

tal wear in the sump increases, as re-

flected in the concentration of wear per

unit of oil (ppm). When oil is added to

the sump, the existing concentration of

wear is diluted, being distributed into

a larger unit of oil volume. If a signifi-

cant amount of oil is added, it can ap-

pear that the rate of wear is less severe

than it truly is. To avoid misinterpre-tation, the top-up volumes should be

factored into the wear rate.

A simple formula to account for added volumes is:

(V0 + V1 + V2 + Vn...)Vn

p=

(V0)

where:

Vnp= Normalized volume per period

V0 = Initial volume

V1 = Period 1

V2 = Period 2

Vn = Period N

In this example, wear debris is factored by the period

(month) to determine the rate of wear. This value can be

further factored by the cumulative top-up for that period to

provide a monthly wear rate accounting for the total amount

of oil added to date.

Treating each monthly data point with the two factors

(P0* P

f*Vn

p) enables the reliability engineer to see the ongo-

ing change in light of both time and top-up volume. When

2 8

Figure 3 | The 24-month wear trend factored to reflect debris generated each month.

There are three common alarm types for grading the underlying problemsfor sumps and lubricated components: statistical, absolute and percentage.


31/76

applied to the data set from Figure 1, the current plot and

trend line, as shown in Figure 4, provides a clearer picture of

the machines health. Comparing Figures 2, 3 and 4, it is ap-

parent that the wear rate is still tolerable for the machine, but

after factoring for top-ups, the rate is twice that perceived

from the ROC values. In both instances, the impression

of dramatic growth in wear over the 24-month period is

lessened.

Whether a compressor sump, gearbox, engine or other ma-

chine type that produces wear debris, factoring data and

then applying rate alarms allows the owner to make more

informed decisions. Showing the allowable wear rate of


32/76

COMMENTARY

Erwin V. Zaretsky, P.E.


33/76

In Part II of our debate, a leading figure in thebearings community presents his case that the new

standard should be withdrawn.

SO Standard 281:2007is based on a mistake. It is a disser-

vice to the technical and industrial communities around

the world. A fatigue limit should not have been includ-

ed in the standard based on available data. I recommend

that ISO withdraw Standard 281:2007.

ISO Standard 281: 2007 incorporates the concept of a fatigue

limit within its bearing life calculation method. Further-

more, this standard assumes that the bearing is made from

AISI 52100 bearing steel, is lubricated with mineral oil and

has values for raceway and ball finishes that are not stated.

It is based on work first published by Stathis Ioannides

and the late Tedric A. Harris at the SKF Engineering and Re-

search Centre in Nieuwegein, The Netherlands, in 1985, as

well as later work published by Ioannides together with G.

Bergling, and A. Gabelli, also of SKF, in 1999. The fatigue

limit used in ISO Standard 281:2007 is a Von Mises stress of

900 MPa (130,500 psi), which corresponds to a maximumHertz contact stress of 1500 MPa (217,500 psi). To many

bearing companies and some engineers, it is the preferred

method to predict ball and roller bearing lives under load

and speed. However, what if a fatigue limit does not exist for

high hardness alloy steels such as AISI 52100? Is a fatigue

limit for through hardened bearing steels a reality or a prod-

uct of imagination? Where is the data?

Before we begin our search for this fatigue limit, we should

unders

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