IMPROVING HIGH-TEMPERATURE OXIDATION OF INCOLOY-800H BY LASER CLADDING

High-power laser cladding has been used to prepare NiCrAl alloy plus z irconium oxide composite layers on an Incoloy 800H base. The metallogr aphic structure before oxidation, the evolution of initial phases and the high-temperature oxidation (1300 K) behaviour of the coating were studied by means of optical and scanning electron microscopy. The resu lts indicate that the new laser-produced alloy has a better oxidation resistance than the base metal as its weight gain is lower. This appea rs to be due to the formation of ceramic and metallic oxides on the su rface of the specimen, which prevent the spread of alloy elements towa rds the exterior, and the entry of oxygen into the material.