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采用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电镜(SEM)、能谱分析(EDS)以及磨粒磨损实验机研究了20%Cr_3C_2对等离子堆焊钴基合金涂层组织结构和耐磨性能的影响,并采用X射线衍射的Rietveld精修方法研究了添加Cr_3C_2前后钴基合金涂层的相组成及其相对含量变化。结果表明,等离子堆焊钴基合金涂层主要由初晶α(Co)固溶体及其间的(α(Co)+M_7C_3)共晶组织构成,具有亚共晶的组织特征,M_7C_3呈网状分布在α(Co)固溶体上。20%Cr_3C_2(质量分数)的加入使涂层的结晶方式转变为具有离异共晶特征的过共晶形式,条状或块状M_7C_3、未熔的大块状Cr_3C_2以及沉淀析出的小块状Cr_3C_2分布在α(Co)固溶体上。20%Cr_3C_2的加入细化了钴基合金涂层的组织,提高了M_7C_3的相对含量,而α(Co)的相对含量则有所降低。等离子堆焊钴基合金涂层的磨粒磨损机制主要为脆性剥落和犁削,含20%Cr_3C_2的钴基合金涂层的耐磨性能是未添加Cr_3C_2钴基合金涂层的约1.8倍,其磨粒磨损机制以轻微犁削为主。
The effects of 20% Cr 3 C 2 on the microstructure and mechanical properties of Co-based alloy coatings deposited by plasma arc welding were studied by OM, XRD, SEM, EDS and abrasive wear tester. Wear resistance, and X-ray diffraction Rietveld refined method before and after the addition of Cr 3 C 2 Co-based alloy coating phase composition and relative content changes. The results show that the coating of Co-based alloy is mainly composed of α (Co) solid solution and (α (Co) + M_7C_3) eutectic during plasma surfacing, with hypoeutectic microstructure and M_7C_3 α (Co) solid solution. The addition of 20% Cr 3 C 2 (mass fraction) transformed the crystallization of the coating into a hypereutectic form with segregation of eutectic, stripped or massive M_7C_3, unmelted massive Cr_3C_2 and precipitated small Cr_3C_2 Distribution in the α (Co) solid solution. The addition of 20% Cr 3 C 2 refined the microstructure of the Co-based alloy coating, increased the relative content of M_7C_3, and decreased the relative content of α (Co). The abrasive wear mechanism of plasma-treated cobalt-based alloy coating is mainly brittle flaking and plowing. The wear resistance of cobalt-based alloy coating containing 20% Cr_3C_2 is about 1.8 times that of the non-added Cr_3C_2 cobalt-based alloy coating Abrasive wear mechanism with a slight plow-based.