【作者】 常杰；

【导师】 刘爱国；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2010， 硕士

【摘要】 本文针对目前用于制造金刚石耐磨层的方法存在结合强度低、金刚石烧损等问题,以预置Ni基自溶性合金的Q235钢作为试验用材,选用35~40目(420~500μm)的镀镍金刚石颗粒作为注射材料,采用氩弧熔覆-注射技术制备出低成本的耐磨涂层,为金刚石耐磨层的制备探索一条新途径。以工作电流、送粉量、扫描速度等作为可调参数进行工艺试验,确定制备复合涂层的优化工艺参数,并通过SEM、XRD及EDS对复合涂层组织及金刚石与胎体合金的结合情况进行分析;采用显微硬度仪进行显微硬度测量,摩擦磨损试验机进行磨损性能检测。实验结果表明,镀镍后的金刚石能够顺利进入熔池并在一定深度均匀分布,涂层内组织致密,金刚石颗粒完整,边缘棱角分明。涂层内相组成主要有(Fe,Ni)固溶体、Fe23B6、Ni和C(金刚石)。单道涂层内金刚石周围有一明显未熔化的Ni层,说明金刚石无烧损现象,Ni层与胎体合金属于冶金结合。熔池内不同深度部位金刚石颗粒周围镍层的溶解量不同,上部颗粒低于中部颗粒。多道搭接涂层的非搭接区与单道涂层相同,镀Ni层保存良好,金刚石无烧损。而搭接区内第一次注入的金刚石在二次加热的作用下,镀Ni层完全溶解于胎体金属,金刚石棱角消失,开始烧损。氩弧熔覆-注射金刚石复合涂层的平均显微硬度约为HV0.2360左右,高于氩弧熔覆Ni基合金的硬度值。多道搭接的搭接区自上而下硬度分布均匀波动,未表现出显著的变化。由摩擦磨损实验可得,氩弧熔覆-注射金刚石复合涂层的耐磨性大大提高,单道复合涂层的耐磨性是Q235钢的56倍,多道复合涂层的耐磨性是Q235钢的46倍。金刚石复合涂层的磨损形式以磨料磨损为主,伴随着粘着磨损。磨损后的金刚石颗粒主要有完整、磨耗、破碎三种形态,且其边缘仍保持与胎体合金的良好结合,没有出现裂缝、颗粒脱落。更多还原

【Abstract】 To solve the problems of low bonding strength and thermal damage of diamond in the diamond wear resistance coatings making processes, argon-arc clad injection(ACI) process was investigated in this thesis. The substrate is a Q235 low carbon steel plate. The injected particles are nickel-coated diamond particles of 420~500μm. A new way to make diamond wear resistant coating was proposed.Process experiments were carried on with adjustable parameters, which are operating current, powder flow rate and scanning velocity to determine the optimal parameters. The microstructures and bonding strength of the diamond and matrix were analyzed by means of SEM, XRD and EDS. Microhardness and wear resistance of the coatings were tested.The results show that the Ni-coated diamond particles can enter the molten pool smoothly and distribute in the certain depth uniformly. In the coating, the microstructure is compact, and the diamond particle is complete with edges and corners distinct. The coating consists of (Fe,Ni)solid solution, Fe23B6, Ni and C(diamond). There is an obvious un-melted Ni layer around the diamond with metallurgical bonding to the matrix, The diamond is not thermally damaged. The nickel layer around the diamond particle dissolves less upside than in the middle. The microstructures in non-overlapped area of multi-passes and the single pass coatings are the same. The Ni layer is preserved completely, the diamond particles are not thermally damaged. But in the overlapped area, because of the reheating, the Ni layer around the diamond particle which is injected firstly dissolve completely, and the diamond particle is thermally damaged and becomes round.The microhardness of the composite coating is about HV0.2360, higher than that of coating produced by argon-arc cladding with nickel-based self-fluxing alloy. The microhardness of overlapped area of multi-passes coating fluctuates evenly. The wear resistance of the composite coating produced by ACI is enhanced greatly. Wear resistance of the single pass coating is ahout 56 times higher than that of the Q235 substrate, and that of the multi-passes coating is about 46 times higher than that of Q235 substrate. The composite coating is of adhesion wear primarily and a little abrasion wear at the same time. After the wear test, the diamond particles are of three kinds of appearance, full, worn, and broken. The diamond particles are bonded to the matrix well. No cracks or spallation of diamond are found.更多还原