激光熔覆WC/CoCrFeNiMo复合涂层的组织与耐磨耐蚀性能

Microstructure and wear and corrosion resistance of laser cladding WC/CoCrFeNiMo composite coatings

用激光熔覆技术在Q235钢表面制备不同WC含量的WC/CoCrFeNiMo高熵合金复合涂层,用扫描电子显微镜和X射线衍射分析仪分析涂层的物相组成、显微组织,用摩擦磨损试验机测试涂层的耐磨性能,通过极化曲线和电化学阻抗谱测试涂层在质量分数为3.5%的NaCl溶液中的腐蚀行为。结果表明:高熵合金复合涂层主要由FCC相、σ相和少量的WC、W_(2)C、Co_(4)W_(2)C相组成;随WC含量的增加,复合材料涂层的硬度上升,平均显微硬度最高可达430.7HV_(0.3),比未添加WC的纯高熵合金涂层提升了42.4%;在15 N载荷下,添加质量分数为20%的WC增强颗粒的复合涂层耐磨性最优,其磨损机制以磨粒磨损为主,并伴随少量的粘着磨损和氧化磨损;当WC的质量分数为25%时,复合涂层具有最高的自腐蚀电位、最小的自腐蚀电流、最大的Nyquist图曲率半径和低频区阻抗模、最宽的相位角曲线峰,表明涂层的耐蚀性最佳。

The WC/CoCrFeNiMo high⁃entropy alloy composite coating with different WC content was prepared on the surface of Q235 steel by laser cladding technology.The phase composition and microstructure of the coating were analyzed by scanning electron microscope and X⁃ray diffraction analyzer,and the wear resistance of the coating was tested by friction and wear testing machine.The corrosion behavior of the coating in 3.5%NaCl solution was measured by polarization curve and electrochemical impedance spectroscopy.The results show that the high entropy alloy composite coating is mainly composed of FCC phase,σphase and a small amount of WC,W_(2)C and Co_(4)W_(2)C phases.With the increase of WC content,the hardness of the composite coating increases,and the average microhardness reaches 430.7HV_(0.3),which is 42.4%higher than that of the pure high⁃entropy alloy coating without WC.Under 15 N load,the composite coating with 20%WC reinforced particles has the best wear resistance,and its wear mechanism is mainly abrasive wear,accompanied by a small amount of adhesive wear and oxidation wear.When the mass fraction of WC is 25%,the composite coating has the highest self⁃corrosion potential,the smallest self⁃corrosion current,the largest curvature radius of Nyquist diagram,the impedance mode in the low frequency region,and the widest phase angle curve peak,which indicates the best corrosion resistance of the coating.