WC-Ni增强Fe基梯度涂层的制备及组织性能

Preparation,Microstructure and Performance of WC-Ni Reinforced Fe-based Graded Coating

利用等离子熔覆同轴双筒送粉工艺,在Q235基板上制备了多层WC-Ni成分渐变的梯度涂层,结果表明:涂层中WC颗粒大部分被溶解,在随后的快速冷却中,有两类碳化物组织析出,组织特征与WC-Ni的含量有关。当WC-Ni含量小于20%时,析出粗大树枝晶基体混合片层状共晶碳化物组织;当WC-Ni含量大于30%时,析出块状初生碳化物组织。未完全溶解的WC颗粒呈圆角形,并与基体之间形成合金过渡层。梯度涂层中各层间形成了冶金过渡,其主要物相有γ-Fe、WC、Fe3C、Fe3W3C、Cr7C3。涂层的硬度明显高于基体,但受WC的溶解及析出碳化物的大小及分布不均影响,梯度涂层的硬度分布波动起伏较大。

A multilayer graded coating of WC-Ni reinforced Fe-based matrix was prepared on Q235 steel plate by plasma cladding with a coaxial feeding powder system. Results show that most of the WC particles are dissolved in the Fe-based matrix, and two types of carbides are precipitated in the follow cooling stage. One is coarse dendrites mixed with lamellar eutectics carbides when WC-Ni content is less than 20% ; the oth er is polygonal block primary carbides when WC-Ni content is more than 300/00. The half-dissolved WC patti cles are all with round angles, and an alloy reaction layer forms between the particles and the matrix. The main phases of the coating are γ- Fe, WC, Fe3C, Fe3W3C, and Cr7C3. Microhardness of the graded coating is higher than that of the substrate; however is fluctuated through the coating due to the dissolution of WC and the inhomogeneous distribution of the precipitated carbides.