等离子熔-喷WC-17%Co涂层的组织结构(I)

Microstructures of W-17%Co coating produced by plasma melt spraying(Ⅰ)

采用等离子熔-喷技术,在Q235钢表面制作了WC-17%Co金属陶瓷涂层,实现了涂层与基体为冶金结合的高结合强度涂层结构,从而解决了陶瓷涂层结合强度低的关键性难题。采用光学显微镜、SEM、TEM及EDS等方法,对熔-喷涂层接头形貌进行了分析研究。试验结果表明,熔-喷接头具有类似焊接接头的特征,是由涂层、熔合区、扩散区、热影响区所组成。熔-喷涂层与常规的喷涂涂层组织结构大不相同,组织结构比较复杂,主要由M6C(Fe3W3C或Co3W3C)、WC、γ-Fe、Co3O4、γ-Co、FeW3C、Fe2W和W2C等相组成,而且有规律地分布在涂层中的不同区域,根据组织结构的不同,涂层可分为表面层、中间冶金反应层和底层三个区域。

W-17%Co metallic ceramic coating was prepared by plasma melt spraying(PMS) on low carbon steel Q235.Metallurgical bonded coating with high bonding strength had been obtained,and the key problem of low bonding strength for ceramic coating had been solved.Microstructures were analyzed with optical microscope,SEM,TEM and EDS.The results showed that a joint produced by PMS process was similar to a welded joint,and consisted of coating,fusion zone,diffusion zone,and heat affected zone.Microstructures of PMS coating are very different from the sprayed ones.Phases in the coating are very complicated and consisted mainly of M_6C(Fe_3W_3C or Co_3W_3C),WC,γ-Fe,Co_3O_4,γ-Co,FeW_3C,Fe_2W and W_2C.These phases distribute in different regions in the coating.According to the microstructures,the coating can be divided into surface layer,metallurgical reaction layer and bottom layer.