Microstructure and wear behaviors of laser clad NiCr/Cr_3C_2-WS_2 high temperature self-lubricating wear-resistant composite coating

摘要

The high temperature self-lubricating wear-resistant NiCr/Cr_3C_2-30%WS_2 coating and wear-resistant NiCr/Cr_3C_2 coating were fabricated on 0Cr18Ni9 austenitic stainless steel by laser cladding. Phase constitutions and microstructures were investigated, and the tribological properties were evaluated using a ball-on-disc wear tester under dry sliding condition at room-temperature (17℃), 300℃ and 600℃, respectively. Results indicated that the laser clad NiCr/Cr_3C_2 coating consisted of Cr_7C_3 primary phase and γ-(Fe,Ni)/Cr_7C_3 eutectic colony, while the coating added with WS_2 was mainly composed of Cr_7C_3 and (Cr,W)C carbides, with the lubricating WS_2 and CrS sulfides as the minor phases. The wear tests showed that the friction coefficients of two coatings both decrease with the increasing temperature, while the both wear rates increase. The friction coefficient of laser clad NiCr/Cr_3C_2-30%WS_2 is lower than the coating without WS_2 whatever at room-temperature, 300℃, 600℃, but its wear rate is only lower at 300℃ It is considered that the laser clad NiCr/Cr_3C_2-30%WS_2 composite coating has good combination of anti-wear and friction-reducing capabilities at room-temperature up to 300 ℃.