为修复已磨损的推瘤刀,利用正交实验,确定出熔覆试验最优激光功率、离焦量和扫描速度分别为1.6kW,20 mm和4mm·s-1;据此进行相关的激光熔覆修复实验.熔覆材料以Ni60自熔性合金粉末为主,随着碳化钨(WC)粉末质量分数的增大,熔覆层的平均显微硬度和相对耐磨性先增大后减小,当WC粉末的质量分数为25％时,熔覆层的平均显微硬度和相对耐磨性分别达到最大值648.7 HV和3.49;在Ni60自熔性合金粉末和WC粉末的混合物中加入稀土CeO2粉末后,熔覆层深度小于1.0mm部分的显微硬度明显提高,超过700HV,能够满足推瘤刀刃口处硬度为56HRC的要求；稀土CeO2粉末的添加量对熔覆层显微硬度的影响不大；当WC粉末和稀土CeO2粉末的质量分数分别为25％和1.5％时,熔覆层的磨损失重仅为3.4 mg.%In order to repair the worn knob removing tool, by use of orthogonal experiments, the optimum laser power, defocusing distance and scanning speed of cladding experiment are determined as 1. 6 kW, 20 mm and 4 mm · S-1 respectively. Accordingly, related experiments of laser cladding repair were carried through. Cladding material mainly consists of Ni60 self-fluxing alloy powder. Along with the augmentation of tungsten carbide (WC) powder mass fraction, the average microhardness and relative wear resistance of cladding layer first increases and then decreases. When WC powder mass fraction is 25%, the average microhardness and relative wear resistance of cladding layer will reach the maximum 648. 7 HV and 3. 49, respectively. After adding rare earth CeO2 powder in the mixture of Ni60 self-fluxing alloy powder and WC powder, the microhardness of part of the cladding layer with the depth less than 1. 0 mm is increased obviously by more than 700 HV, which can meet the requirement of 56 HRC for the hardness of the knob removing tool cutting edge. The addition content of rare earth CeO2 powder has little effect on the microhardness of cladding layer. When the mass fractions of WC powder and rare earth CeO2 powder is 25% and 1. 5% respectively, the wear weight loss of cladding layer is only 3. 4 mg.
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