Electrodeposited composite coatings for protection from high temperature corrosion

Summary

Corrosion and wear resistance of metallic coatings can be modified through the codeposition of metallic or nonmetallic panicles in the matrix layer.

Direct electrolytic codeposition of ternary or quarternary chromium based alloys is very difficult due mainly to the different deposition potentials of the codeposited metals as well as electrolyte instability The electrolytic deposition of a four component alloy system can be achieved in two stages by deposition of a composite layer of Ni-Co-Zr and either under or over coating chromium. The four components are then alloyed by diffusion at about 1000°C under vacuum.

Using modulated pulse-plating current regulates the alloy ratio of Ni to Co. reduces the codeposition of the hydrogen and enables deposition of the alloy on carbon fibre components.