TC4钛合金硼碳共渗层的组织和性能研究

Study on Microstructure and Property of Borocarburized Case in TC4 Titanium Alloy

通过在900℃进行固体渗碳10 h,后于950℃(低于β转变温度)在由供硼剂B_4C和无水Na_2B_4O_7、催化剂氧化镧以及一定量石墨组成的介质中进行固体渗硼12 h,在TC4钛合金试样表面制备了硼碳共渗层。检测了渗层的形貌、相组成、亲水性、硬度和耐摩擦磨损性能。结果表明,渗层由TiB_2、TiB和TiC三相组成,外层以TiB_2为主,表面较光亮、光滑和平整,粗糙度R_a为0.216,结构与多孔陶瓷类似,硬度约为2 637 HV0.1,亲水性良好;次表层以TiB为主,硬度约为1 600 HV0.1;内层以TiC为主,硬度约为802 HV0.1。渗层韧性良好,且与基体金属结合牢固,耐摩擦磨损性能明显优于基体。

A borocarburized case was produced in TC4 titanium alloy specimen by firstly pack carburizing at 900 ℃ for 10 h, and then pack boronizing at 950 ℃ （below β transition temperature） for 12 h in a boronizing medium consisting of BaC and anhydrous Na2B4O7 as a boron supply agent, lanthanum oxide as a catalyst, and a certain amount of graphite. The appearance, phase constituents, hydrophilicity, hardness, and frictional wear resistance were checked. The results were as follows ： the case was composed of three phases such as TiB2 ,TiB and TiC ; the outer area was predominantly TiB2, and exhibited relativelyright, smooth and fiat appearance, toughness R, of 0.216, structure similar to a porous ceramic, hardness of about 2 637 HV0. 1, and good hydrophilieity; the sublayer was predominantly TiB, had hardness of about 1 600 HV0.1 ; the inner area was predominantly TiC, had hardness of about 802 HV0.1. Moreover, the borocarburized case possessed good toughness, was well bonded to the basis metal, and was appreciably superior to the matrix in frictional wear resistance.