W1813N无磁不锈钢表面激光熔覆Ni60与WC-12Co/Ni25涂层的组织结构和磨损行为

Microstructure and Wear behavior of Hard Ni60 alloy and Soft Ni25-based WC-12Co Coatings Prepared by Laser Cladding on W1813N Non-magnetic Stainless Steel

摘要:

利用激光熔覆技术分别在W1813N无磁性不锈钢表面制备高硬度镍基自熔性合金Ni60（60HRC）涂层和低硬度Ni25基WC-12Co复合涂层。利用扫描电子显微镜（SEM）、能谱（EDS）、X射线衍射仪（XRD）和台阶仪，分析激光熔覆制备Ni60涂层和WC-12Co/Ni25复合涂层的显微组织、相组成和磨损行为。利用显微硬度、摩擦系数、磨痕轮廓对比两种涂层的耐磨性和磨损机制。结果表明，Ni60涂层显微组织主要为树枝晶和等轴晶，且Cr23C6, Cr2B等强化相弥散分布在?-Ni和FeNi固溶体晶界；而WC-12Co/Ni25复合涂层中WC-12Co颗粒弥散镶嵌于低硬度Ni25基质，复合涂层中WC-12Co颗粒体积比达到32.5%。复合涂层中最大和最小显微硬度差异达到648 HV。尽管两种涂层的摩擦系数相近，但复合涂层的磨损体积仅为Ni60涂层的10%，Ni60涂层表面的磨痕特征为犁沟状和塑性粘附，复合涂层磨痕表面为WC碎屑和塑性粘附，因此Ni60涂层的磨损失效机制为磨粒磨损和粘着磨损，而复合涂层磨损机制为粘着磨损，以上结果表明WC-12Co/Ni25复合涂层具有更好的耐磨性。

Abstract:

The hard Ni60 (60HRC) self-fluxing alloy powder and soft Ni25-based WC-12Co composite powder are deposited onto the W1813N non-magnetic stainless steel using laser cladding. The microstructure, phase composition and worn track characteristics of Ni60 coating and WC-12Co/Ni25 composite coating produced with laser cladding are analyzed using scanning electron microscopy(SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD) and a step profiler. The micro-hardness, friction coefficient, profile of worn track and wear mechanism both coatings are investigated. The results show that the microstructure is mainly fine dendrite and equiaxed crystal in the LC Ni60 coating, and the hard Cr23C6, Cr2B phases distributed in the grain boundary of γ-Ni and FeNi solid solution, while WC-12Co particles in the composite coating are uniformly embedded in the Ni25 matrix，and the volume fraction of WC-12Co in the composite coating is 32.5%. The difference value between minimum and maximum hardness in the WC-12Co/Ni25 composite coating reaches up to 648 HV. Therefore the mean friction coefficients both coatings are similar, the volume loss of the LC WC-12Co/Ni25 is only 10% of the LC Ni60. The surface abrasive behaviors of the LC Ni60 coating are ploughed shape and adhesive scraps, but the surface abrasive behaviors of the LC WC-12Co/Ni25 composite coating are adhesive scraps and WC debris. The wear mechanism of the Ni60 coating is abrasive wear and adhesion wear, while the wear mechanism of the WC-12Co/Ni25 coating is adhesion wear. These demonstrate that the WC-12Co/Ni25 coating exhibits better wear resistance than the LC Ni60