Structure and properties of chromium-carbide composite materials and coatings

Eutectic chromium-carbide composites show promise as materials for coatings applied by the plasma spray-deposition technique. Use of composite powdered mixtures of chromium and carbides enables coatings to be obtained having phase compositions identical with those of cast alloys. The plasma spray-deposited Cr-TiC, Cr-TaC, and Cr-NbC coatings investigated were found to be superior in wear resistance to sintered alloys of the same compositions and to both cast and plasma spray-deposited chromium. The chromium-carbide composite coatings retained their good wear resistance up to 1000°C. The best results were obtained with Cr-11% TiC and Cr-27% TaC materials. Coatings of this type would appear to be particularly suitable for service under conditions of high-temperature wear in an oxidizing atmosphere, such as are encountered in metallurgical and power generating installations and gas turbine engines.