不同自润滑相尺寸和分布位置对自润滑表面膜形成的影响

采用分步高能球磨、快速感应烧结制备Ni基耐高温自润滑涂层IS304(IS:Induction Sintering), 涂层中高温润滑相BaF₂/CaF₂尺寸仅为1mm左右、低温润滑相Ag尺寸小于2mm, 并且BaF₂/CaF₂主要分布于强化相Cr₂O₃中.摩擦实验中当温度为室温~250℃时,IS304涂层的摩擦系数较高, 由于润滑相尺寸的细化以及润滑相BaF₂/CaF₂分布位置的改变,使得摩擦副在高速瞬时接触中产生的瞬态温升可以有效地激活BaF₂/CaF₂的自润滑性能,最终在压力及摩擦力的作用下形成自润滑表面膜, 使得IS304涂层在280℃时即可具有较低的摩擦系数

Effect of Size-refinement and Distribution of Lubricants on the Formation of Self-lubricating Films

Ni-based high temperature self-lubricating IS304 (IS: Induction Sintering) composites with BaF₂/CaF₂and Ag particles as lubricants were prepared by ball milling and induction sintering techniques. The microstructure of the IS304 composites is dense and the size of selflubricating particles is very fine. BaF₂/CaF₂ particlesare in dimension of about 1 μm and particles are less than 2 μm respectively,while some BaF₂/CaF₂ particles are distributed in Cr₂O₃particles. The synthesized IS304 composites exhibite high friction coefficientin the temperature range from roomtemperature to 250℃. However, thefriction coefficient dramatically decreased at 280℃ while the friction coefficient of coarsecomposites dramatically decreased at 330-350℃ in the same test condition due to the formation of self-lubricating fluoride films. The fluoride films formed on the worn surface of synthesized composites is attributed to the size refinement and appropriate distribution offluorides, which can lead toa higher temperature rise (flash temperature) at the instantaneous contactingsurface.