Metallic components in coal gasification pilot plants are exposed to severe corrosive atmospheres and high temperatures. The life of these components, usually fabricated of stainless steels, may sometimes be increased if the surfaces are coated with chromium or aluminum. The uniform corrosion of materials is evaluated from weight change measurements. However, the exposure of both coated and uncoated engineering alloys to high temperatures and oxygen and sulfur containing environments will often result in grain boundary penetration, which is not adequately evaluated by weight change measurements only. This note reports the corrosion and grain boundary penetration of an aluminum coated Type 316 stainless steel exposed to a coal gasification environment.
Coupons of an aluminum diffusion coated Type 316 stainless steel (nominal composition) were produced as previously reported: Type 316 stainless steel coupons are sealed in a retort filled with aluminum powders and heated for ~ 120 ks (~36 h) in the...
