钛合金表面激光熔覆Ti-Al/WC涂层组织与性能的研究

Research on Microstructure and Properties of Laser Cladding Ti-Al/WC Coating on Titanium Alloy Surface

为改善钛合金表面耐磨性不足的问题,在钛合金表面制备Ti-Al/WC复合涂层,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)对熔覆层的物相及显微组织进行分析,使用显微硬度计及摩擦磨损实验对涂层性能进行测试。结果表明:未添加WC时,熔覆层为柱状晶组织,主要由α_(2)-Ti_(3)Al及γ-TiAl组成。添加WC后,熔覆层组织呈等轴晶状,组织中出现(α_(2)+γ)片层结构,随着WC添加量的提高,大量原位生成的TiC在熔覆层中弥散分布,提高了熔覆层的显微硬度,熔覆层平均硬度约为基体的1.4~1.9倍。当WC含量为20 wt%时,TiC呈树枝晶状或花瓣状在熔覆层中弥散分布,结合区冶金结合良好,没有裂纹、气孔等缺陷,此时熔覆层具有最佳的耐磨性,约为基体的4.2倍。

In order to improve the titanium alloy surface wear resistance problem,in the preparation of Ti-Al/WC composite coating on titanium alloy surface,using X-ray diffraction(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS),the phase and microstructure of the cladding layer were analyzed.The microscopical hardness tester and friction and wear experiment were carried out on the coating performance tests.The results show that the cladding layer without WC is columnar crystal structure,mainly composed ofα_(2)-Ti_(3)Al andγ-TiAl.After adding WC,the microstructure of the cladding layer is equiaxed and(α_(2)+γ)lamellar structure appearing in the microstructure.With the increase of WC addition amount,a large amount of TiC in situ disperse in the cladding layer,which increases the microhardness of the cladding layer.The average hardness of the cladding layer is about 1.4-1.9 times than that of the matrix.When WC content is 20wt%,TiC diffuses in the cladding layer in dendritic or petal shape,and the bonding zone has good metallurgical bonding without cracks,pores and other defects.In this case,the cladding layer has the best wear resistance,which is about 4.2 times than that of the matrix.