厚度对HVOF喷涂WC-12Co涂层结构的影响

Effect of Thickness on Microstructure of HVOF Sprayed WC-12Co Coatings

利用HVOF制备了WC-12C0涂层,喷涂原始粉末为微纳米复合粉,涂层的厚度分别为0.5,1,2,3,4 mm。采用扫描电镜(SEM)、X射线衍射仪(XRD)分析了涂层的显微结构和相组成,并对涂层的孔隙率进行了测量。结果表明,厚度对涂层的表面形貌与表面粗糙度无明显的影响,但对截面显微结构有较大影响,厚度小于1 mm的涂层沿厚度方向显微结构无明显变化,而厚度大于1 mm的涂层中部组织比较致密,孔隙率小,涂层与基体结合区域及近表面区域组织较为疏松。所有涂层均出现了分解与脱碳,涂层越厚分解越严重,出现的W_2C和Co_3W_3C相越多。

WC-12Co coatings were sprayed by HVOF with a composite mixture of microstructure powder and nanostructure powder as starting materials. The thicknesses of the coatings were 0.5 mm, 1 mm, 2 mm, 3 mm and 4 mm. SEM and XRD were used to analyze the microstructure and phase composition of the coatings, respectively. Porosity of the coatings was also tested. Results show that thickness has little influence on surface microstructure and roughness of the coating; on the contrary, thickness has great influence on section microstructure. For the coating thicker than 1 mm, microstructure of the middle part is denser than the interracial and the upper area; however, microstructure changes little along the deposition direction for the coating thinner than 1 mm. Decomposition and decarburization happen in all the coatings; furthermore, more serious decomposition occurs with the increase of the coating thickness; as a result, more W2C and Co3W3C appear.