Interfacial Bonding Strength and Wear Resistance of TaC-Reinforced Layer Prepared on Bearing Steel Surface by Hot Pressing

摘要

To solve the problems of surface wear and fracture of bearing rings, tantalum carbide (TaC)-reinforced layer was prepared on the surface of GCr15 bearing steel by in-situ hot pressing diffusion method to improve the comprehensive properties of bearing steel surface. As-obtained TaC layer exhibited uniform thickness and dense structure, and the phase composition mainly consisted of TaC and very small amount of alpha-Fe phase. The interface between reinforcement layer and matrix showed good metallurgical bonding, and no other impurities were generated. Along normal direction of layer base, grain size of TaC in reinforcement layer decreased gradually (200-50 nm), showing gradient distribution. Volume fraction of TaC particles reached 98%, and the maximum microhardness of reinforcement layer reached 2400 HV0.05. Comprehensive analysis of tensile test shows that mainly intergranular fracture of TaC particles occurred inside reinforcement layer, indicating that bonding strength between reinforcement layer and matrix was higher than cohesive strength of reinforcement layer by 320 MPa. In friction and wear experiment, when wear distance of reinforcement layer was 8 times that of steel matrix, wear rate was only 0.33 times (loading 20 N), and wear mechanism was mainly adhesive wear and abrasive wear. Overall, reinforcement layer obtained by in-situ solid-state hot pressing diffusion exhibits good wear resistance and high bonding strength with the matrix and shows good protective effect on the steel matrix.

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