材料期刊网

采用同轴送粉等离子熔覆工艺在Q235基体上制备了多层65%Ni60A-35%WC体积梯度涂层。采用OM、SEM、EDS、XRD等研究了涂层与基体、涂层与涂层的界面及组织特征,测量了涂层的硬度（HRC）。结果表明：涂层与基体界面处元素Cr、Ni由涂层向基体扩散;靠近界面约223μm范围内基体内的晶粒尺寸约长大了1.75倍;梯度涂层内部界面上层与层枝晶交错生长,形成联生结晶;梯度涂层由下至上的组织特征为：粗大树枝晶逐渐过渡为细小杂乱无方向性的致密组织;WC颗粒周围的Ni与基体Fe互熔,形成冶金结合;梯度涂层物相成分主要由Cr2Ni3、FeCr0.29Ni0.16C0.06、Fe3Ni2、CrFe7C0.45、BNi2、WC等组成;梯度涂层内硬度（HRC）值与65%Ni60A-35%WC体积分数成正相关关系。

Multi-layers of 65%Ni60A-35%WC/Fe30 grandient coating were prepared on Q235 steel surface using coaxial feeding plasma cladding process.Microstructure and properties of the coating were analyzed by means of optical microscope,scanning electron microscopy,EDS analysis and hardness test.The results show that the grain size of Q235 steel near the interface between the coating and substrate increases significantly,and some Cr and Ni element are diffused from coating to the substrate.The interfaces between the layers in the from coating exhibit the epitaxial solidification,and the microstructure changes from coarse columnar crystal to cellular dendrites to thin disorder nondirectional compact dendrites from the bottom layer to the top layer in the coating.The metallurgical bonding between Ni coated WC and matrix Fe is obtained.XRD results show that the coating contains Cr2Ni3,FeCr0.29Ni0.16C0.06,Fe3Ni2,CrFe7C0.45,BNi2,and WC.It is found that hardness of the coating increases with increasing the volume ratio of 65%Ni60A-35%WC.