柔性钛电极电火花合成TiN涂层

Study of the TiN coating synthesized by EDM of flexible titanium electrode

文中提出一种利用柔性钛电极在钛合金TC4表面合成TiN涂层以改善工件表面性能的新方法.在加工中利用柔性钛电极与钛合金TC4表面进行电火花放电,同时通过钛电极内部向加工区域通入氮气,利用电火花放电能量在工件表面反应生成TiN涂层.测量其表面硬度并利用SEM,XRD等手段对其涂层微观形貌和组分进行测试.结果表明,在TC4工件表面制备出了TiN强化涂层,涂层致密、均匀、连续;TiN涂层厚度超过1 mm;涂层主要由TiN强化相组成,显微硬度高达1 859.6 MPa;涂层表面的放电坑大而浅且存在刮削痕迹,柔性钛电极丝对TiN涂层有较强的刮削涂覆作用;TiN涂层与基体之间相互渗透形成冶金结合.

This paper proposes a new method to improve the surface performance of workpiece,which can synthesize TiN coating on the surface of titanium alloy TC4 by using flexible titanium electrode.During the whole processing the spark discharge occurs between the surface of titanium alloy TC4 and flexible titanium electrode.At the same time nitrogen gas was poured into processing area via the titanium electrode internal tunnels,and TiN coating was produced by using the energy of electric spark discharge.The layer 's surface hardness, microstructure and chemical compositions were tested with microhardness tester,SEM and XRD,respectively.The result showed that strengthened homogeneous and continuous TiN coating was obtained in the coating layer.Moreover,the layer's thickness reaches more than 1 mm and its microhardness is up to 1859.6HV.Discharge craters on the surface of coating is big and bright and have scraping marks,so it can be known that flexible titanium electrode has stronger scraping and grinding effect on TiN coating.In addition,TiN coating interinfiltrate with matrix,forming metallurgic bonding.