Download - Why Study Corr
-
8/12/2019 Why Study Corr
1/66
-
8/12/2019 Why Study Corr
2/66
What is Corrosion?What does it look like?
How do you know when you have it?
-
8/12/2019 Why Study Corr
3/66
What is Corrosion? Metals made by smelting ( reduction of ore)
Metals in air want to return to their oxidized state
Corrosion is a natural process!
-
8/12/2019 Why Study Corr
4/66
-
8/12/2019 Why Study Corr
5/66
Is Corrosion Important? National issue?
International issue?
What industries are affected? Does it affect us personally?
-
8/12/2019 Why Study Corr
6/66
Importance to USA CC Technologies study March 2002
In 2000 about 3.1% of GDP spent on corrosion repair
and control Total cost $276Billion!
Of industries analyzed, the cost was $137.9 Billion
-
8/12/2019 Why Study Corr
7/66
-
8/12/2019 Why Study Corr
8/66
Examples of Corrosion DamageAutomotive problems - body rust
Home examples-
- Plumbing fixtures- Mail box
- Exterior fixtures and fasteners
Concrete cracking
-
8/12/2019 Why Study Corr
9/66
Corrosion Affects Our Safety! Unexpected failures of equipment and devices
Need to replace damaged items
Corrosion weakens structures- Need to evaluate fitness for service when corrosionoccurs
-
8/12/2019 Why Study Corr
10/66
What Does Corrosion Look Like? Rust and tarnish, red blue or gray scale
8 types of damage Fontana
Several others also.
-
8/12/2019 Why Study Corr
11/66
Most Common Forms of Corrosion General attack (uniform wastage)
Pitting/ Crevice attack
Cracking (embrittlement) Galvanic corrosion
-
8/12/2019 Why Study Corr
12/66
Corrosion is Electrochemical Two different reactions occur - oxidation and
reduction
Electron transfer occurs Potential (voltage) driving force required
Oxidation occurs at anode
Reduction occurs at cathode
-
8/12/2019 Why Study Corr
13/66
Corrosion Reactions Oxidation - e.g.
Fe Fe++ + 2e
Reduction e.g.O2+ 2H2O 4OH
-- 4e
Secondary - e.g.
4 Fe+++ O2Fe2O3+ 8H+
-
8/12/2019 Why Study Corr
14/66
-
8/12/2019 Why Study Corr
15/66
-
8/12/2019 Why Study Corr
16/66
-
8/12/2019 Why Study Corr
17/66
-
8/12/2019 Why Study Corr
18/66
Conclusions Corrosion rate depends upon the corrosion products
that form
Solubility of corrosion products determines the rate If solubility is high, the rate is high!
If solubility is low, the rate is low
-
8/12/2019 Why Study Corr
19/66
-
8/12/2019 Why Study Corr
20/66
Potential/pH (Pourbaix) DiagramVery useful way to present data
Developed by Marcel Pourbaix (1966)
Available for all metals and many other elements Shows solubility and potential effects
If solubility is < 10-6 M/l, no corrosion is assumed
-
8/12/2019 Why Study Corr
21/66
Characteristics of Corrosion
ProductsVery thin and dense: protective,e.g., Cr, Al, Ti, 10 to
100 nm thick
Thin: protective but some corrosion occurs, e.g.,Cu,
Zn, Pb 1 to 10 m Thick and porous, e.g., Fe, >100 m Corrosion is a
problem.
Soluble, e.g., Na, K Not able to be used.
-
8/12/2019 Why Study Corr
22/66
There are many ways to prevent or minimize corrosiondamage
-
8/12/2019 Why Study Corr
23/66
Alloying to Resist Corrosion - SteelAdd >13% Cr (stainless steel)
Add >2% Mo to stainless (to resist pitting)
Add Si, P, Cu, Cr ( and others) to obtain weatheringsteel
-
8/12/2019 Why Study Corr
24/66
Alloying to Resist Corrosion -
CopperAdd Ni and Fe (cupronickel) sea water
Add As, Sb, or P to prevent dealloying of brass (Cu + 10to 35% Zn)
Add Al or Si to resist erosion
-
8/12/2019 Why Study Corr
25/66
Metallic CoatingsWidely used to protect steel and to make other metals
more attractive
Zn and Zn alloys on steel Galvanizing
Ni + Cr on steel, brass or zinc to give a bright finish
Cu + Ni + Cr also used for bright finish
-
8/12/2019 Why Study Corr
26/66
Organic Coatings - Paint Barrier layer to keep water away
Adhesion is key to success
Susceptible to thermal damage Susceptible to UV damage
-
8/12/2019 Why Study Corr
27/66
Electrochemical Protection Cathodic protection reduce the potential and also
corrosion rate - widely used underground and in seawater
Anodic protection increase potential to produce aless soluble corrosion product used in some chemicalplants
-
8/12/2019 Why Study Corr
28/66
Corrosion Inhibitors Used in water systems:
- Automotive cooling systems
- Cooling towers- Boilers, especially high pressure steam
Temporary preservatives for metals
- Volatile corrosion inhibitors
Paints and primers
-
8/12/2019 Why Study Corr
29/66
Quiz Time!What is the most corrosive substance we can think of?
Corrosion damage only causes metals to becomethinner True or False?
How does corrosion affect me?
-
8/12/2019 Why Study Corr
30/66
Answers!Water!!!
False! Corrosion also causes cracking, pitting, staining,wedging in crevices, loss of electrical conductivity, andfailure of components
What is your answer?
-
8/12/2019 Why Study Corr
31/66
Break Time
-
8/12/2019 Why Study Corr
32/66
-
8/12/2019 Why Study Corr
33/66
Careers in Corrosion
Technician - Education High school diploma + interest in chemistry or
technology
Associates degree possible night school - notrequired at entry level
- Chemistry
- Electrical technology
- Materials science
-
8/12/2019 Why Study Corr
34/66
Careers in Corrosion
Technician-Work Lab technician
- Chemistry laboratory
- Materials laboratory- Materials or chemical company
Field technician civil engineering
- Pipeline monitoring
- Bridges, tunnels etc.
-
8/12/2019 Why Study Corr
35/66
Careers in Corrosion
Civil Engineer - Education Civil, mechanical or electrical SB
MBA or MS (not required but often helpful)
PE license NACE Certification
-
8/12/2019 Why Study Corr
36/66
Careers in Corrosion
Civil Engineer - Work Engineering firm or consultant
- Cathodic protection design
- System monitoring and evaluation State or local government
- Specify protection systems for bridges, tunnels, otherfacilities
- Inspection and monitoring
-
8/12/2019 Why Study Corr
37/66
Mat., Chem., Chem. Eng.
Education High School Diploma
College SB, Major: Mat. Eng., Chem., Chem. Eng., orMech.Eng.
Grad school optional, MBA, MS or PhD
Certification NACE (optional)
PE License (optional)
-
8/12/2019 Why Study Corr
38/66
Mat.,Chem.,Chem. Eng.
Work Chemical, materials, petroleum, auto firm
- Engineering
- Safety- Research (PhD)
- Plant Maintenance
Engineering or consultant firm
-
8/12/2019 Why Study Corr
39/66
NACE International Short courses, some with certification
Annual meeting and show
Standards development Local sections
Symposia
Books, videos and computer products
-
8/12/2019 Why Study Corr
40/66
NACE International
The Corrosion SocietyAddress: P.O.Box218340, Houston,TX77218-8340
Phone: 281-228-6200
Website: www.nace.org
-
8/12/2019 Why Study Corr
41/66
ASTM International Standards development, Vol.03.02
Training courses
SymposiaAddress:100 Barr Harbor Drive, West Conshocken,
PA 19428-2959
Website: www.astm.org
Corrosion committee: G-1
http://www.astm.org/http://www.astm.org/ -
8/12/2019 Why Study Corr
42/66
Corrosion Testing Used for a variety of purposes
Standard test methods available
Some tests are simple and easy to runASTM corrosion tests are in Volume 03.02 of the
Annual Book of ASTM Standards
-
8/12/2019 Why Study Corr
43/66
Corrosion Testing-PurposesAccelerated tests to demonstrate products durability
Acceptance tests to show that a material meetsstandard
Monitoring tests to show changes in a systemcorrosivity
Research tests to determine mechanism of corrosion
-
8/12/2019 Why Study Corr
44/66
Standard Tests Usually corrosion tests have many parameters
Corrosion tests often give results that are difficult toreproduce Standardization helps reproducibility
Consensus standard tests: ASTM and NACE
-
8/12/2019 Why Study Corr
45/66
Accelerated Test ExampleASTM G48 Pitting and Crevice Corrosion Resistance
Ferric chloride, 6%solution
72Hrs at 22o
C (room temperature) Report pitting or crevice corrosion
Simulates sea water attack of stainless steels
-
8/12/2019 Why Study Corr
46/66
-
8/12/2019 Why Study Corr
47/66
-
8/12/2019 Why Study Corr
48/66
Acceptance Test - Al AlloysASTM G 69, Test of metallurgical condition of Al
alloys
Measure potential,E, in salt solution
Cu increases E, Zn reduces E
Heat treatment determines condition
Condition affects strength and corrosion tendencies
-
8/12/2019 Why Study Corr
49/66
ASTM G 69 Continued Solution: 1M Na Cl + 2.7%H2O2, 22
oC
Surface preparation: 00 steel wool rub
1 Hour immersion Measure potential every 5 minutes after 30 minutes
against SCE electrode
Average result: -750+/-10mV for pure Al
Al foil is pure Al
-
8/12/2019 Why Study Corr
50/66
-
8/12/2019 Why Study Corr
51/66
Monitoring Test ASTM C 876 Corrosion of steel rebar in concrete
Potential indicates when corrosion of steel is occurring
Copper/copper sulfate reference cell Chloride causes steel to corrode
Deicing salt usually reason for problem
Sea water also causes problems
-
8/12/2019 Why Study Corr
52/66
-
8/12/2019 Why Study Corr
53/66
-
8/12/2019 Why Study Corr
54/66
Procedure ASTM C876 Place electrode on concrete surface
Measure potential with volt-meter
If potential varies with time prewet surface with 25ml/ldetergent solution
Record potential at several points on the surface
-
8/12/2019 Why Study Corr
55/66
Analyze DataArrange values in ascending order and number the
values sequentially
Determine plotting position,f
f = r/(n +1) where r is the measurement number, andn is the total number of values
Plot on probability paper
-
8/12/2019 Why Study Corr
56/66
-
8/12/2019 Why Study Corr
57/66
ASTM C876 Report Potential > -0.20 V, rebar is not corroding
Potential
-
8/12/2019 Why Study Corr
58/66
Demonstration of CorrosionA simple test to show local cathodes and anodes with a
corroding specimen
Uses indicators to show where reactions occur
Phenolphthalein turns red at cathode (OHiongenerated there)
K3Fe(CN)6turns blue at anode
-
8/12/2019 Why Study Corr
59/66
Demonstration Test
MaterialsAgar agar
Salt (NaCl)
5%K3Fe(CN)
6solution
1% Phenolphthalein solution (in alcohol)
2 steel nails, bright finish (e.g.: 10d)
1 steel nail, galvanized (e.g.:10d)
Copper wires
-
8/12/2019 Why Study Corr
60/66
Demonstration test
Procedure Prepare 250 ml of 3%salt (7.5g) and 2% agar agar
solution
Boil to dissolve agar agar
Add 5ml K3Fe(CN)6solution and 1ml ofphenolphthalein solution
Pour into 2 dishes, one with bright nail, one withbright nail wired to galvanized nail
-
8/12/2019 Why Study Corr
61/66
Demonstration Test
Procedure ContinuedAllow the solutions to cool and watch colors develop
Where do are the red areas? (cathodes)
Blue areas? (anodes)
What does it mean when no blue areas develop on thebright nail wired to the galvanized nail?
-
8/12/2019 Why Study Corr
62/66
-
8/12/2019 Why Study Corr
63/66
-
8/12/2019 Why Study Corr
64/66
Follow-up NACE Foundation NACE Foundation wants to help high schools withprograms and information
NACE local sections can provide technical people to
run field trips or lead experimental demonstrations Contact Teri Elliott, phone 281-228-6210
Website: www.nace.foundation.org
-
8/12/2019 Why Study Corr
65/66
Summary Corrosion is an important issue Corrosion technology shows where chemistry can be
used to prevent problems
Corrosion tests can provide good hands-on experiencefor students
Many opportunities for careers in corrosion prevention
-
8/12/2019 Why Study Corr
66/66
Thank You!Questions please?