TC4钛合金间歇式真空渗氮工艺研究

Research on Intermittent Vacuum Nitriding Process for TC4 Titanium Alloy

为了改善TC4钛合金的表面硬度,在氮气为正压和负压条件下对其进行间歇式真空渗氮处理。通过X射线衍射、自动维氏硬度测试和电化学极化曲线分析了不同压力下渗氮层的相结构、组织、显微硬度和耐蚀性。结果表明,TC4钛合金经真空渗氮处理后,表层均可获得由TiN_(0.3)、TiN、Ti_3AlN和Al_3Ti等相组成的改性层。在负压下,表层中氮化物数量较少,但渗层较厚,硬度梯度平缓。在正压时,表层氮化物数量增多,渗层厚度及硬度却降低。氮化后的TC4钛合金耐蚀性提高。

In order to improve the surface hardness of TC4 titanium alloy, the intermittent vacuum nitriding treatment under the conditions of nitrogen for the positive pressure and negative pressure was carried out. The phase structure, microstructure, mierohardness and corrosion resistance of the infiltration layer under different pressures were analyzed by X-ray diffraction, automatic vickers hardness test and electrochemical polarization curve methods. The results show that after vacuum nitriding treatment, the modified layer with the composition of TIN0.3, TiN, Ti3A1N and AI3Ti phases on the surface of TC4 titanium alloy can be obtained. Under negative pressure, the nitride quantity in the surface layer is less, but the carbonitriding layer is thicker, and the hardness gradient is gentle. Under positive pressure, the nitride quantity in surface layer increases, and the thickness and hardness of the carbonitriding layer decrease. The corrosion resistance of TC4 titanium alloy after nitriding increases significantly.