摘要
分别以熔融Na2B4O7和Na2B4O7+Al为渗硼剂,在钛金属表面渗硼,以期获得含TiB2和TiB双层结构的硼化层。通过X射线衍射(XRD)分析涂层表面的物相结构。结果表明,单独以Na2B4O7作为渗硼剂时基体表面没有生成硼化物,主要生成Na2Ti4O8。在Na2B4O7中添加10%Al(质量分数)后,钛表面有明显的TiB2和TiB生成。温度升高有利于TiB2的生成,但会抑制TiB的生成。热力学分析表明,与单独用Na2B4O7做渗硼剂相比,以Na2B4O7+Al为渗硼剂时生成活性B原子的反应趋势较大,因而活性B原子的浓度较高。动力学分析表明,低温时由于B原子在TiB相中的扩散速度大于其在TiB2相和Ti相中的扩散速度,因而有TiB和TiB2生成。高温时由于B原子在Ti相中的扩散速度大于其在TiB相中的扩散速度,因而主要生成TiB2。
In order to obtain borides with a dual boride layer comprised of titanium diboride（TiB2） and titanium boride（TiB）,molten salts boronizing on Ti metallic surface using Na2B4O7 and Na2B4O7＋Al as boronizing agent was carried out.Phase conposition of coating layer was characterized by X-ray diffraction（XRD）.The results show that the coating layer is predominantly composed of Na2Ti4O8 and hardly boride when Na2B4O7 is used as boronizing agent alone.However,TiB2 and TiB are formed obviously in coating layer while 10%Al is added into Na2B4O7 agent.The growth of TiB2 can be accelerated but the growth of TiB is inhibited with increasing temperature.Reacting tendency of production of B is stronger with agent of Na2B4O7 alone than that of with agent of Na2B4O7＋10%Al based on thermodynamics.The diffusion rate of B is higher in TiB phase than that of in TiB2 and Ti phase at lower temperature based on dynamics analysing,so TiB2 and TiB are formed in the coating layer.In contrast,the coating layer is mainly consisting of TiB2 because the diffusion rate of B is higher in Ti phase than that of in TiB phase at higher temperature.
出处
《粉末冶金材料科学与工程》
EI
北大核心
2012年第1期50-54,共5页
Materials Science and Engineering of Powder Metallurgy
基金
国家自然科学基金资助项目(21063003
51064004)
