电弧电压对低能等离子喷涂WC-Co涂层组织及性能的影响

使用烧结破碎的WC-12%Co粉末,采用轴向送粉等离子喷涂系统制备WC-Co涂层。保持电弧电流不变,增加工作气体中的氢气含量来提高电弧电压,以研究电弧电压对于涂层微观结构的影响。使用X射线衍射仪(XRD)分析WC-Co涂层的脱碳相变,使用扫描电子显微镜(SEM)观察粉末的熔化程度、扁平化状态和涂层的微观结构,使用MH-6维氏硬度计和MM200磨损试验机分别测量了涂层的显微硬度和耐磨性。结果表明,提高电弧电压有利于粉末的熔化。根据熔化程度的不同,粉末会呈现四种典型的扁平化状态。提高电弧电压促使碳化钨脱碳生成的W_2C和Co_3W_9C_4,涂层中硬质相体积增加,钴基体积减小。适当提高电弧电压有利于增加涂层的硬度和耐磨性,但过高的电弧电压会恶化涂层质量,反而降低涂层的硬度和耐磨性。

Effects of Arc Voltage on Microstructure and Properties of WC-Co Coatings Prepared by Low Power Plasma Spraying

To study the influence of arc voltage on the microstructure of the WC-Co coatings, WC-12% Co powders were used to deposit WC-Co coatings with the plasma spraying system of axial powder feeding under different arc voltages at constant arc current. The arc voltage was adjusted by changing the hydrogen content in the working gas. The decarburization of WC-Co coatings was analyzed by XRD. The melting status of powder particles, the flattening status, and the microstructure of the coatings were observed by SEM. The Vickers hardnesses and abrasion performance of coatings were also measured. The experimental results show that the powder particles can be better melted under the higher arc voltage. The flattening of the powder particles on the substrate surface presents four typical shapes in accordance with the melted status of the powder particles. Increasing arc voltage promotes the decarburization of tungsten carbide and produces W₂C and Co₃W₉C₄, and increasing hard phases contributes to the reduction of Co content in the coating. Proper enhancement of the arc voltage increases the hardness and abrasive resistance of the coatings; however, the excessively high arc voltage deteriorates the coating quality.