Dry sliding wear behavior of SS316L composites containing h-BN and MoS2 solid lubricants

Abstract

Mechanical properties and wear behavior of stainless steel supplemented with different solid lubricants were investigated. Hexagonal boron nitride (h-BN), molybdenum disulfide (MoS2), and a mixture of h-BN/MoS2 embedded in 316L stainless steels (SS316L/h-BN, SS316L/MoS2 and SS316L/h-BN/MoS2) were prepared by powder metallurgy method. Various solid lubricant contents (10, 15 and 20vol%) were mixed with 316L stainless steel powders and then sintered at 1200°C in H2 atmosphere for 60min. Dry sliding wear behavior of the composites was investigated using a pin-on-disc test rig at sliding speeds of 0.1 and 0.2m/s and an applied load of 3N. The experimental results showed that small boride phase and h-BN powder occupied the pores in the microstructure of the SS316L/h-BN composite, whereas the MoS2 second phase occupied the pores of the sintered 316L matrix in the microstructure of the SS316L/MoS2 composite. The addition of h-BN decreased the sintered density and hardness, whereas that of MoS2 produced the opposite effect. The results showed that the MoS2 composite had higher wear resistance than the h-BN composite, but the h-BN composite yielded better friction reduction. Furthermore, the addition of an h-BN/MoS2 mixture could promote the hardness and wear resistance of the composites. The incorporation of h-BN and MoS2 had the potential to provide friction reduction in SS316L composites as compared with sintered 316L stainless steel. The dry sliding wear process of stainless steel composites with added h-BN, MoS2 and h-BN/MoS2 involved adhesive wear, abrasive wear, oxidative wear and delamination wear mechanisms of the compacted layer.