TA2纯钛表面激光熔覆WC7Co/TC4复合涂层的组织演变特性

Characteristics of Microstructure Evolution of WC7Co/TC4 Composite Coating Produced by Laser Cladding on TA2 Pure Titanium Substrate

摘要:

选用抗氧化性和韧性良好的WC7Co陶瓷颗粒作为增强相,利用激光熔覆的方法在TA2纯钛表面制备WC7Co/TC4复合耐磨涂层,借助扫描电子显微镜、能谱仪、X射线衍射仪和显微硬度计,分析表征复合涂层显微组织特征、WC7Co陶瓷颗粒界面反应行为以及复合涂层中相的演变规律。结果表明:根据激光熔覆过程中WC7Co颗粒的演变状态,复合涂层中存在2种典型显微组织,分别为未分解WC7Co颗粒强化组织和WC7Co分解后与Ti反应生成的W、TiC和Ti的共晶组织;复合涂层中WC7Co颗粒与TC4基质结合界面形成了2～3μm的反应层,反应生成物主要为W和TiC;复合涂层中的物相主要为Ti固溶体、W单质及TiC、VC、Co_3W_3C、W_2C等化合物。

Abstract:

The WC7Co ceramic particles with oxidation resistance and good toughness were selected as enhancement phase,and the WC7Co/TC4 composite wear-resistant coating was prepared on the surface of TA2 pure titanium substrate by laser cladding. The microstructure characteristic,interfacial reaction behavior of WC7Co particles and evolution of phase composition of composite coating were analyzed by means of scanning electron microscope,energy dispersive spectrometer,X-ray diffraction and microhardness tester. The results show that there are two typical microstructures of the composite coating according to the evolution state of WC7Co particles during the laser cladding process,which are the eutectic structure of W,TiC and Ti generated by the dissolved WC7Co particles and composite structure of undissolved WC7Co paritcles,respectively. A 2 ～ 3 μm reaction layer composed by W and TiC is formed in the bonding interface between WC7Co particles and TC4 matrix. The main phases of composite coating are Ti solid solution,W,TiC,VC,Co3W3 C,W2C and so on.