High Temperature Wear of Thermal Sprayed Cr_3C_2-25(Ni-20Cr) Coating against Fe Based and Ni Based Mating Surfaces

摘要

Cr_3C_2-25(Ni20Cr) coatings obtained by thermal spraying are well known for their excellent tribological properties. These coatings are suitable for applications requiring harsh environmental conditions. The present investigation is undertaken to understand the nature of the film that forms during sliding of Cr_3C_2-25(Ni20Cr) coating and the substrate 253 MA alloy against Fe based 100Cr6 steel and Ni based PM 1000 alloy at different temperatures. In order to achieve this objective, 253 MA alloy was coated by Cr_3C_2-25 (Ni-20Cr) powders using a JP 5000 HVOF system. The wear and friction behaviour of the coating and the substrate was studied at different temperatures. The worn surfaces and the transverse section of the worn surfaces were characterised using a scanning electron microscopy. The friction coefficient was found to be high at ambient condition, low at intermediate temperature. It increased to higher value at 873 K. It was very low at 1073 K. Several types of glazed layers formed on the worn surface. Based on composition analysis they are classified as transfer layer, mechanically mixed layer, reaction layer and composite layer.