corrosion of materials course corrosion of inorganic non-metallic materials aleš helebrant...

Corrosion of Materials Course

Corrosion of Inorganic Non-Metallic Materials

Aleš Helebrant

Department of Glass and Ceramics ICT Prague, Czech Republic

www.usk.cz


Contents

• Inorganic Non-Metallic Materials• Principles of INM corrosion, congruent and incongruent

dissolution• Control mechanisms of dissolution, mathematical

description• Corrosion of ceramics• Corrosion of glass• Enamels as surface layers on metals• Corrosion of concrete

– Typical examples of materials– Corrosion mechanisms– Increasing chemical durability


Literature for further study

• McCauley R.A.: Corrosion of Ceramics. Marcel Dekker, Inc. New York 1995• Clark D.E., Zoitos B.K. (eds.): Corrosion of Glass, Ceramics and Ceramic

Superconductors. Noyes Publications, Park Ridge, New Jersey, 1992• Doremus, R.H.: Chemical durability of glass. In: Tomozawa, M;, Doremus, R.H.

(eds.): Treatise on Materials Science and Technology 17, Academic Press 1979, pp. 41-67

• Helebrant A.: Kinetics of corrosion of silicate glasses in aqueous solutions. Ceramics-Silikáty 41, 147-151 (1997)

• Helebrant A., Jiřička A., Jiřičková J.: Corrosion of glass. Glass Sci. Tech. 77C, 85-94 (2004)

• Jiřička A. et al.: Corrosion modeling of simple glasses from the systems SiO2-Na2O-CaO and SiO2-Na2O-MgO. Glass Sci.Tech. 76, 298-308 (2003)

• Jiřička A., Helebrant A.: Dissolution of soda-lime, silica and high-level waste glass by single-pass flow-through and static tests. In: Environmental Issues and Waste Management Technologies in the Ceramic and Nuclear Industries V (Ceramic Transactions, Vol 107, eds. Chandler G.T., Feng X.), The American Ceramic Society, Westerville, OH, USA, 2000, pp.309-316


Inorganic Non-metallic Materials

• INM– Ceramics– Glass– Inorganic binders (cement, gypsum)– Monocrystals– Glass-ceramics

– Inorganic Non-Metallic Materials = Ceramics (US)– Ceramics (UK) = pottery, construction ceramics,

porcelain, refractories.....

• Traditional INM – based on silicates or silica


Structure of INM

cristobalite


Structure of INM

K2O-SiO2 glass


Structure of INM

silica glass crystalline silica (quartz)


Structure of INM

periclase MgO


Structure of INM

zeolite


Corrosion of INM

• corrosion of metals – electrochemical process

• corrosion of INM – dissolution– reaction with liquids (aqueous solutions, melts)– reaction with gasses

• sometimes connected with subsequent degradation


Dissolution

congruent incongruent

t=0

t>0


Congruent dissolution

solidus liquidus

1) surface reaction

2) transport of surface reaction products into the solution bulk (diffusion)

Which process controls the overal rate of dissolution?


Models of congruent dissolution

• non-steady diffusion

• steady state diffusion

• surface reaction

• surface reaction and steady state diffusion


Diffusion – Fick‘s laws

dxdc

DSdt

mdj i

xc

Dxt

c


Non-steady diffusion

x

c

saturated conc cs

conc. in bulk solution cl

Dt

xerfcccc lsl 4

1)(


Error function

z

y dyezerf0

22)(


0

1

2

3

4

5

6

7

0 10 20 30 40 50

time

m

/S

dxdc

DSdt

md

Dt

ccSm

lS 2

Non-steady diffusion


Steady-state diffusion

x

csaturated conc. cs


h


time

m

/S

ls cchD

Sdtmd

tcchD

Sm

ls

Steady-state diffusion


Surface reaction

x

c


saturated conc. cs


time

m

/S

ls cckSdt

md

tcckSm

ls

Surface reaction


SR comparable with SD

x

csaturated conc. cs


h

c‘<cs


sdsr Sdtmd

Sdtmd

'cckSdt

mds

sr

lsls cckcck

hD

khD

Sdtmd

lsd

cchD

Sdtmd

'

tcckSm

ls

SR comparable with SD


time

m

/S

0VS

ktVS

VS

cc

Sm ls exp10

Saturation effect

corrosion of materials course corrosion of inorganic non-metallic materials aleš helebrant...

Documents

kinetics of corrosion

glass slide

materials science

silica slide

t0t0 slide

chemical durability

steady state diffusion

subsequent degradation