(1. School of Metallurgy Engineering，Xi’an University of Architecture and Technology，Xi’an 710055，China) (2. State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China)
Zirconium alloy extrusion is the key process for producing nuclear fuel components, and traditional lubrication methods already can’t meet the process and property request. Therefore, systematic research on the lubricating properties and failure modes of extrusion lubricants is needed. In this work, the heat-resistant MoS2-based bonded solid lubricating coating was prepared on the surface of zirconium alloy. Lubricating properties of the coating under hot extrusion conditions were studied by high-temperature ball-on-disk tribological tester. Surface morphology and microstructure of the coatings and wear tracks were analyzed by SEM and 3D optical digital microscope, the change of binder and lubricant particles in the coating at high temperatures was analyzed by EDS, the change of the coating composition at the wear tracks was analyzed by Raman spectroscopy. The coating has excellent lubricating property at high-temperature tribological test after holding at 400 and 600 ℃ for 10 min, and its friction coefficient is all about 0.05. This is attributed to the fact that MoS2 still maintains an excellent layered structure at high temperatures, and there is no friction chemical phenomenon under high temperature and strong load. However, after holding at 600 ℃ for 60 min, MoS2 is oxidized and failed because of a long time heat preservation, the lubrication property is greatly reduced. In this work, considering heating temperature and holding time of the extrusion process, the lubricating properties and failure modes of MoS2-based bonded solid lubricants under high temperature and strong load condition were investigated, which may provide theoretical basis for metal forming.