【摘要】 采用等离子熔覆工艺制备了多层Ni60A+WC增强Fe基梯度涂层,增强相Ni60A+WC比例按10%(质量分数)逐层递增,研究了梯度涂层中WC颗粒的溶解及碳化物析出。结果表明:等离子熔覆加热阶段梯度涂层各层中WC颗粒均发生溶解,溶解的特征与WC大小及其内部缺陷有关,据此可将WC的溶解分为扩散式、芯部溶解式、溃散式、及扩散-芯部溶解复合式四种类型;在等离子熔覆凝固阶段,各层均析出富W型碳化物,析出位置及形貌与Ni60A+WC在每层的熔覆量有关,随着熔覆量的增加,富W型碳化物的析出特征依次为沿晶界呈网状→颗粒状→颗粒状+块状→小块状+簇团状→大块状+等轴状析出。析出的碳化物随着Ni60A+WC熔覆量的增加而增加且在各层中分布较均匀,测得梯度涂层的宏观硬度随着层数的增加呈线性递增分布。更多还原

【Abstract】 The dissolution and precipitation of WC in the multilayered Ni60A+WC reinforced Fe-based graded coating fabricated by Plasma cladding were studied,in which the content of Ni60A+WC increased by 10%mass fraction layer by layer.The results show that the dissolution of WC in each layer of the graded coating during the plasma cladding heating stage was closely related to the particle size and inner defect.The dissolution characteristics of WC are classified into four types:diffusing,core dissolution,crumbling,and diffusing complex core-dissolution.The shape characteristics of the precipitated W-rich carbides in the graded coating during the solidification process are relevant to the contents of Ni60A+WC.With the increasing of the contents for the Ni60A+WC from 10%to 50%,the shapes of W-rich carbides are transferred from reticulation,grain,grain mixed with block,block mixed with cluster to big block mixed with equiaxial structures,and the quantity of the precipitated W-rich carbides increased layer by layer.As a result,the hardness of the graded coating linearly increases gradually.更多还原