TC4钛合金表面激光合金化Ti-Si-C涂层的研究

Research of Laser Alloying Ti-Si-C Coating on TC4 Titanium Alloy

以Ti-Si-C单质元素混合粉末为原料,采用激光合金化技术在TC4钛合金表面成功制备出Ti-Si-C合金涂层。利用金相显微镜(OM)、扫描电子显微镜(SEM)及其配备的能谱仪(EDS)、X射线衍射仪(XRD)、显微硬度计以及摩擦磨损试验机,分析了涂层的组织形貌、成分和物相,测试了涂层的显微硬度及与YG6在干摩擦磨损条件下的摩擦磨损性能。结果表明:在激光功率P=2.0 k W,扫描速度v=9 mm·s^(-1),光斑直径D=2 mm下制备的涂层整体均匀致密、无裂纹,与TC4基体具有较高的冶金结合性;涂层组织主要由α-Ti基体、网状分布的Ti_3Si C_2,Ti_5Si_3/β-Ti共晶体(室温下为Ti_5Si_3/α-Ti)和弥散分布的Ti C相组成;Ti-Si-C涂层的显微硬度值沿层深变化比较平缓,平均硬度为HV 649,比TC4基体(HV 360)提高了80%;涂层平均摩擦系数为0.38,比钛合金基体(0.45)降低了16%;涂层的磨损体积为0.048 mm^3,耐磨性是钛合金基体(0.13 mm^3)的2.71倍。

Ti-Si-C alloy coating was successfully fabricated by laser alloying on the surface of TC4 titanium alloy using Ti, Si and C mixture powders. Microstructure morphology, composition and phase of the coating were investigated by optical microscope （ OM ）, scanning electron microscope（ SEM ） , energy dispersive spectroscopy （EDS） and X-ray diffraction（XRD） , respectively. Microhardness and tribological properties of the coating were measured under dry lubrication using YG6 by micro-hardness tester and muhi-function friction and wear testing machine. The results showed that under the laser power of 2.0 kW, scanning speed of 9 mm.s 1 and spot di- ameter of 2 ram, the coating was uniform, dense and crack-free, and bad good metallurgical combination with TC4 matrix. Microstructure of coating was consisted of α-Ti matrix, network-distributed Ti3 SiC2 and Ti5Si3/β-Ti eutectic （ appearing as Ti5Si3/α-Ti at room temperature） and dispersed TiC. The average micro-hardness of the coating（ HV 649） increased by 80% than that of the TC4 matrix （HV 360） with a gentle trend along coating depth. The average friction coefficient of the coating （0.38） decreased by 16% than that of TC4 matrix （0.45）. The wear volume was 0. 048 mm^3 , and the wear resistance was 2.71 times that of TC4 titanium alloy matrix （0.13 mm^3）.