Chromium-Aluminum Diffusion Coating

ELCOAT 37 is a coating developed for the protection of nickel and cobaltbase superalloys against attack at high temperatures (700-950°C metal temperature). It is ideally suited for the protection of first stage blades operating in hostile turbine environments. It also performs well in peak shaving applications.

The coating has a total thickness of approximately 85-micron. Analyses of the coating by SEM and EDX show three different protective zones. The first is the outer layer, approximately 30-micron thick, containing 30% chromium and 8% aluminum. The intermediate zone is made of mainly NiAl with chromium precipitates. The inner, chromium-rich diffusion zone is in the base material/substrate and has approximately 30-micron thickness.

It has a balanced chemical composition which results in improved protective qualities of both nickel and cobalt base superalloys. At higher temperatures, the coating is an alumina former, meaning it protects well against oxidation. At lower temperatures, the oxide formation shifts to chromia, which provides corrosion protection.

Elbar B.V., 36, 5943 AD Lomm, PO Box 4339, ZG Arcen, , AN, 5944. Tel: +31 (0)77 4738666; Fax: +31 (0)77 4732785.