超硬磨具激光增材制造过程中,金刚石极易受到激光直接辐照和高温熔池的影响,出现石墨化等热损伤现象.选取典型的金刚石磨具用金属结合剂CuSn10粉末,采用粉末床熔融(Powder Bed Fusion-laser Beam,PBF-LB)技术制备CuSn10-金刚石复合材料;围绕高能激光束和高温熔池两个影响增材制造过程中金刚石颗粒性能的关键因素,以单颗金刚石颗粒为研究对象,通过有限元模拟分析构建金刚石颗粒的温度场模型,反映了金刚石颗粒在PBF-LB中的热演化过程;阐明了PBF-LB过程金刚石的热损伤机制,发现金刚石发生石墨化转变并不是由激光的直接辐照造成的,而是由高温熔池的热影响导致,CuSn10-金刚石复合材料在PBF-LB过程中石墨化的临界温度为1 491.6℃.建立了PBF-LB工艺-金刚石颗粒温度-石墨化程度-摩擦磨损性能的定量关系,发现随着金刚石颗粒温度的增加,其石墨化程度增加,严重损害了复合材料的摩擦磨损性能.
Abstract
In the laser additive manufacturing process of superhard tools,diamonds are highly susceptible to the direct irradiation of laser beams and the influence of high-temperature melt pools,leading to phenomena such as graphitization and other thermal damage.A typical metal bonding agent CuSn10 powder for diamond abrasives is selected,and the Powder Bed Fusion-laser Beam(PBF-LB)technology is used to prepare CuSn10-diamond composites in this study.Focusing on two key factors affecting the performance of diamond particles in the manufacturing process,high-energy laser beams and high-temperature melt pools,individual diamond particles are selected as the research subject.A finite element simulation analysis is conducted to construct a temperature field model of diamond particles,reflecting the thermal evolution process of diamond particles in PBF-LB.The study elucidates the thermal damage mechanism of diamonds during the PBF-LB process,revealing that the graphitization transformation of diamonds is not caused by direct laser irradiation but is induced by the thermal effects of high-temperature melt pools.The critical temperature for graphitization of CuSn10-diamond composite material in the PBF-LB process is 1 491.6 ℃.Furthermore,a quantitative relationship is established among the PBF-LB process-diamond particle temperature-degree of graphitization-frictional wear performance,demonstrating that with the increase of diamond particle temperature,the degree of graphitization increases,seriously damaging the friction and wear performance of the composite material.
维普
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