Some comparative properties of Laves- and carbide-strengthened coatings deposited by plasma or detonation gun

Abstract

The microstructures and mechanical properties of a series of plasma and detonation coatings of cobalt and nickel alloys with molybdenum, chromium and silicon were characterized. Two of the coatings were strengthened almost entirely by Laves' phase precipitation while the other two were strengthened by a combination of carbide and Laves' phases. Limited heat treatment studies indicated that the asdeposited structures are supersaturated solutions and further precipitation, particularly of Laves' phases, occurs at elevated temperatures. The elastic moduli and moduli of rupture of the coatings were determined using a ring compression technique. These data were compared with the strain-to-failure data obtained in an expanding ring test. One of the detonation gun coatings with a combination of Laves and carbide strengthening was found to have an unusually high modulus of rupture and strain-to-fracture. The corrosion resistance of the materials in room temperature and boiling solutions of hydrochloric acid, sodium hydroxide, nitric acid and sulphuric acid was also determined.