Temperature Effect on Corrosion Protective Coatings
Low temperatures
There are three general detrimental characteristics to be considered for coatings under cold temperature:
- Adhesion,
- Shrinkage, and
- Brittleness
High temperatures
High temperature and cyclic high temperature create problems for coating application as well. It may cause chloride containing polymers, such as PCV and chlorinated rubber, hydrolyse and leach hydrochloric acid. Some , e.g. styrene polymer, may tend to depolymerize and evaporate from the metal surface. Epoxies can over cure at high temperature will become brittle, shrink and lose adhesion. Only some special types of coating is endured for high temperature application:IOZ and silicon polymer are stable at temperature up to 370oC. Silicon polymer can be heat resistant to 520oC for short period of time (days /weeks). Polysiloxane coating may have higher temperature resistant up to 1079oC
Typical Temperature Range for Coatings
Coating types | Immersion oC | Non-Immersion oC |
Vinyl copolymer | 38 | 65 |
Chlorinated rubber | 38 | 65 |
Coal tar | 50 | 65 |
Coal tar epoxy | 50 | 95 |
Epoxy | 50 | 95 |
Urethane | 38 | 120 |
Expoxy phenolic | 82 | 120 |
Baked phenolic | 82 | 120 |
IOZ | – | 370 |
Silicone | – | 370 |