激光熔覆Ni基WC复合材料制备自磨刃割刀
Preparation of Knife with Self-sharp Edge by Laser Caldding Ni-based WC Composite Coating
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摘要: 为提高农用割刀耐磨性并使割刀形成自磨刃，利用半导体激光器，采用同轴送粉方式在65Mn刀具刃口一侧表面制备Ni基WC复合材料。使用SEM、EDS及XRD分析激光功率对熔覆层材料的微观组织、化学成分和物相组成的影响；采用显微硬度计、摩擦磨损试验机对熔覆层材料的硬度和耐磨性能进行检测。结果表明：激光熔覆形成的复合材料层与基体之间形成冶金结合，组织均匀致密；熔覆过程中部分WC颗粒熔解并与Ni基合金粉作用，形成了大量WC、W2C、Ni31Si12、Fe3Ni3B、Cr7C3、Cr23C6及CrB等硬质相，使得熔覆层硬度提高。随着激光功率的提高，熔覆层与基体之间元素扩散增加，但是熔覆层硬度有所降低。熔覆层平均硬度在1000（HV 0.2）左右，耐磨性能提高，满足农用割刀形成自磨刃的性能要求。Abstract: To increase wear-resistant and form self-sharp edge of agricultural knives，Ni-based WC coating was prepared on one side of cutting edge at knives of 65Mn steel by using semiconductor laser equipment under the way of coaxial powder feeding.Microstructure，chemical and phase composition of coating were analyzed utilizing SEM，EDS，and XRD.The micro-hardness and wear-resistant were investigated by micro-hardness tester and wear-resistant tester.Results showed that the laser cladding composite was uniform and dense in microstructure and metallurgical combination was formed between laser cladding and matrix.Part of WC particles was melted and decomposed during coating preparation.At the same time，a large number of hard phases（WC，W2C，Ni31Si12，Fe3Ni3B，Cr7C3，Cr23C6，CrB，etc）were generated，which increased hardness of coating layer greatly.As the increase of laser power，the atomic diffusion between coating and knife matrix was improved.But coating hardness reduced slowly.Average hardness of coating was about 1000（HV 0.2），which increased wear-resistant and satisfied requirement of self-sharp edge of agricultural knives.
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