Microscopic characteristics and properties of titaniferous compound reinforced nickel-based wear-resisting layer via in situ precipitation of plasma spray welding

Abstract

TiC, TiB2 particles reinforced nickel-based composite wear-resistant layer can be generated by NiCrBSi, Ti and Si composite powder via plasma spray welding. Research has shown that composite powder spray welding layer mainly consisted of γ-Ni, FeNi3 and β1-Ni3Si matrix phases, as well as TiC, TiB2, CrB, M7C3, M23C6, SiC, TiSi2 and other hard phases inlaid in the matrix. Fine TiB2, TiC, M7C3, M23C6 and all SiC, CrB, TiSi2 are dispersed in the matrix, which can refine the sprayed-layer structure effectively. The grown TiB2 (6–50 µm) can be observed on the NiCrBSi+Ti+Si mixed powder spray-welding layer, TiB2 shows stepped growth through screw dislocation. The microhardness of NiCrBSi+Ti and NiCrBSi+Si spray-welding layer was lower than that of NiCrBSi+Ti+Si mixed powder spray-welding layer, and their abrasive resistance was 19 times and 26 times of that of H13 substrate respectively. When the content of added Ti and Si is 15%, the best properties of the NiCrBSi+Ti+Si mixed powder spray-welding layer are obtained with the microhardness reaching up to 980 HV0.5, which is approximately 2 times greater than that of the pure NiCrBSi spray-welding layer. Furthermore, its wearing capacity is merely 6.5 mg, so that the wear-resistance property is more than 5 times that of the pure NiCrBSi spray-welding layer, and even 50 times that of the H13 base material. However, the toughness of the spray-welding layers will be reduced, and even cracks that run through the entire spray-welding layer will be generated.