Prevention and control of corrosion phenomena directed to extend

components and structures durability

Dr. Tiziano Bellezze

ROUND TABLE RUSSIA ↔ ITALYROUND TABLE RUSSIA ↔ ITALYChemical Technologies : Perspectives of developmentChemical Technologies : Perspectives of development

June 4th -7th 2012June 4th -7th 2012Ivanovo State University of Chemistry and Technology, Ivanovo, RUSSIAIvanovo State University of Chemistry and Technology, Ivanovo, RUSSIA

UNIVERSITÀ POLITECNICA DELLE MARCHEDipartimento di Scienze e Ingegneria della Materia, dell’Ambiente ed UrbanisticaFacoltà di Ingegneria, ANCONA (ITALY)

“Corrosion has been the subject of scientific study for more than 150 years. It is a naturally occurring phenomenon commonly defined as the deterioration of a material (usually a metal) or its properties because of a reaction with its environment.”

World Corrosion Organization (2009)

THE CORROSION PHENOMENON

marine environment industrial environment

urban environment

ABOUT THE ENVIRONMENT… (“the enemy”)

ABOUT THE ENVIRONMENT… (impact, preservation…)

automotive scraps appliance scraps

Accumulation of waste materialsAccumulation of waste materials

pipelines failure tank failureRisks of pollution and environmental disastersRisks of pollution and environmental disasters

CONCERNS WITH HUMAN HELTH AND LIFE

tap water natural water

Realise of metals produced by corrosion phenomenaRealise of metals produced by corrosion phenomena

bridge collapse in Minneapolis

on August 1,2007

collapse of ceiling in a swimming pool, Zurich 1985

Accidents due to corrosionAccidents due to corrosion

cooking pot

“Corrosion has a huge economic and environmental impact on virtually all facets of the world’s infrastructure, from highways, bridges, and buildings to oil and gas, chemical processing, and water and wastewater systems.”

World Corrosion Organization (2009)

THE CORROSION IMPACT ON ECONOMY

ANNUAL COST OF CORROSION WORLDWIDE IS ESTIMATED $US 2.2 TRILLION

US estimated costs of corrosion (nace.org)

Infrastructure B$ 22.6

Utilities B$ 47.9

Transportation B$ 29.7

Production & Manufacturing B$ 17.6

Government B$ 20.1

TOTAL B$ 137.9

Fe(OH)2 Fe(OH)2Fe++

Fe++

OH-

OH-

OH-

OH-

O2O2

e- e-e- e-

Fe Fe++ + 2e-anodic reaction

cathodic reaction

O2 + 2H2O + 4e- 4OH-

steel

water media

THE CORROSION OF STEEL

STRATEGIES FOR CORROSION PREVENTION AND CONTROL

• Materials development and selection• Analysis and optimization of industrial processes• Innovative surface protection systems• Monitoring methods using sensors and remote data collection• Development of electrochemical methods/new analytical methods for studying corrosion phenomena • Education, training courses• ...

TO INCREASE STRUCTURES AND COMPONENTS DURABILITY

MATERIALS DEVELOPMENT AND SELECTION

AND

ANALYSIS AND OPTIMIZATION OF INDUSTRIAL PROCESSES

SCHEME OF A DOMESTIC BOILER

EXAMPLES OF LOCALIZED CORROSIONIN STAINLESS STEEL WATER TANKS

INTERNAL SURFACE PASSIVATION OF THE WATER TANKS

HF + HNO3 solution

AISI 304L, AISI 316L e AISI 444 chemical composition

Pitting Resistance Equivalent

PRE = % Cr + 3.3 x %Mo

AISI 304L18.9

AISI 316L24.5

AISI 44424.6

Increasing localized corrosion resistance

SURFACE ASPECT OF STAINLESS STEEL (AS RECEIVED) – F1

AISI 304L AISI 316L

AISI 444

SURFACE ASPECT OF STAINLESS STEEL AFTER PASSIVATION

AISI 304L AISI 316L

AISI 444

Surface finishing F4HF 3% HNO3 13%, r.t., 45’

Surface finishing F8F4 + HNO3 30%, r.t., 30’

Perfect passivity region Imperfect passivity region

F1 F4 F8 F1 F4 F8 F1 F4 F8-0.3-0.2-0.10.00.10.20.30.40.50.60.70.80.91.01.11.2

AISI 444AISI 316AISI 304

Surface Finishing

Po

ten

tial vs S

CE

(V

)

TW1: [Cl-]=132.8 ppm

EXPERIMENTAL RESULTS OBTAINED WITH TW1

F1 F4 HF+HNO3 F8HF+HNO3

HNO3

T. Bellezze, G. Roventi, A. Quaranta and R. Fratesi, Materials and Corrosion 2008, 59 (9), 727-731

INNOVATIVE SURFACE PROTECTION SYSTEMS

SURFACE PROTECTION SYSTEMS: ZINC COATINGS ON STEEL

cathodic reaction: O2 +2 H2O + 4e- 4OH-

e- e-

Zn ++

OH-OH-

O2

anodic reaction: Zn Zn++ + 2e-

Zn++

e- e-steel

water media

zinc

The zinc coating offers:- barrier effect- sealing effect- cathodic protection- recyclability- lower costs with

respect to other coating solutions

car

pylonreinforcing bars

DIFFERENT METHODS TO OBTAIN ZINC COATINGS ON STEEL

electrochemical deposition hot-dip galvanizing

(94% Zn; 6% Fe)(94% Zn; 6% Fe)

(100% Zn)(100% Zn)

(90% Zn; 10% Fe)(90% Zn; 10% Fe) (75% Zn; 15% Fe)(75% Zn; 15% Fe)

100

m

10 10 mm

FURTHER PROTECTION OF ELECTRODEPOSITED ZINC:ZINC COATING PASSIVATION

ZINC

STEEL

CONVERSION LAYER

Use of Cr VI containing baths:Use of Cr VI containing baths:

CrCr22OO772-2- + 14 H + 14 H++ + 6e + 6e- - → 2Cr→ 2Cr3+3+ + 7 H + 7 H22OO

2H2H++ + 2e + 2e-- → H→ H22

Zn → ZnZn → Zn2+2+

STEEL

ZINCZINC

CONVERSION LAYER

local damageself-healing effect

“chromating”

1 μm

Cr VI CONVERSION LAYER (CHROMATING)

Cr VI=

Directive EU End of Life Vehicles 2000/53/EC:• Annex II: Cr VI maximum 2 g per vehicle from 1 July 2003• Amendment Annex II 2002/525/EC : 0 g from 1 July 2007 for

corrosion preventive coatings

• Other oxidant agents similar to chromates: molybdates, vanadates and permanganetes;

• Ce III and Ce IV salts; • Cr III (content of Cr VI reduced more than 100 times) with and

without sealants based on Si and some organic compounds (directed to improve the barrier effect); furthermore, after drying, Cr III + sealant conversion coating has the possibility of self-healing effect (migration of silicates present in the sealant);

• Organic compounds producing metal-organic films (ex. Si compounds);

• …• Use of Cr VI-free conversion layer on zinc alloys (Zn-Ni, Zn-Fe,

…)• …• New strategy: nanocontainers for corrosion inhibitors, released

“on demand”;• …

POSSIBLE ALTERNATIVES TO THE USE OF Cr VI

M. G. S. Ferreira et. al., Chem. Mater. 2007, 19, 402-411

NANOCONTAINERS FOR CORROSION INHIBITORS

2 μm 5 μm

OUR WORK ON THE ALTERNATIVES TO THE USE OF Cr VI

Cr III conversion layer Cr III + sealant conversion layer

Investigations performed using the following techniques:• Electrochemical Impedance Spectroscopy (EIS) in NaCl 5% • Anodic polarization in NaCl 5%• Salt fog spray exposure (ASTM B 117)

Results: the Cr III + sealant conversion layer showed a corrosion resistance comparable with Cr VI conversion layer

T. Bellezze, G. Roventi, R. Fratesi , Surface and Coatings Technology 155 (2002) 221–230

ALTERNATIVES TO CHROMIUM PLATING

The Cr electrodeposition is performed by Cr VI containing baths

Recently, in our research group, an attempt to substitute the chromium coating with a composite zinc coating containing nanoparticles (60 nm) of SiC was done. This coating is particularly indicated in those applications where high hardness is not necessary.

pulsed current

mic

roha

rdne

ss

EDX map of SiC (about 2%) distribution on zinc coating

• decorative chromium plating

• hard chromium plating

MONITORING METHODS USING SENSORS

AND

NEW APPROCHES IN CORROSION STUDIES

MONITORING REINFORCING CORROSION IN CONCRETE WITH THE RISK OF CARBONATION

CO2concrete

steel bar

CO2

H2O

core sampling

pH decreases

MultiProbe A

MultiProbe B

CO2CO2

the cast

Inside carbonation chamber

MONITORING THE CARBONATION DEPTH

Ti ref.

MONITORING THE CARBONATION DEPTH WITH MULTIPROBE B

-50

-25

0

25

50

75

100

125

150

175

200

225

250

60 70 80 90 100 110 120 130 140 150

Time from the cast (days)

Po

ten

tial

vs

TiB

rif

(mV

)

TiB1 TiB2 TiB3 TiB4 TiB5

MONITORING THE CARBONATION DEPTH multiprobes response vs colourimetric test

POSSIBILITY OF MONITORING OTHER CORROSION PARAMETERS

•Chlorides penetration depth•Humidity of concrete matrix (as a function of depth)

•Corrosion potential•Corrosion rate•Aggressiveness of the concrete matrix •etc.

“MULTIPROBES BOX”

CONCLUSIONS

• Corrosion phenomena have many social, economic and health implications on human life.

• For new technological challenges, a cultural training on materials and their degradation is fundamental, both in industrial R&D and in the university research centres.

• Efforts on the monitoring strategies and on the development of new devices and/or new sensors should become a standard practice.

• At the same time, corrosion experts have concluded that a net of 20 to 25% of that annual cost can be saved by applying currently available corrosion control technologies. (WCO, 2009)