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

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

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BaF_2/CaF_2尺寸仅为1μm左右、低温润滑相Ag尺寸小于2μm,并且BaF_2/CaF_2主要分布于强化相Cr_2O_3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BaF_2/CaF_2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BaF_2/CaF_2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.

Ni-based high temperature self-lubricating IS304（IS：Induction Sintering） composites with BaF2/CaF2 and 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 self lubricating particles is very fine.BaF2/CaF2 particles are in dimension of about 1μm and particles are less than 2μm respectively,while some BaF2/CaF2 particles are distributed in Cr2O3 particles.The synthesized IS304 composites exhibite high friction coefficient in the temperature range from room temperature to 250℃.However,the friction coefficient dramatically decreased at 280℃while the friction coefficient of coarse composites 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 of fluorides,which can lead to a higher temperature rise（flash temperature） at the instantaneous contacting surface.