钛合金粉末的无氧钝化及活化烧结机制

粉末冶金技术是降低钛合金制造成本的重要途经，但因钛的高活性和低扩散系数，一直存在高氧含量和低烧结密度的问题。为同时解决这两个瓶颈问题，我们创新性地将气-固流化技术引入到粉末冶金钛合金制备过程中，利用SnCl4(气)-Ti(固)气-固表面反应，提出了一种既可以防止钛合金粉末表面在成形致密化过程中的氧化，又能提高烧结致密度的新思路。即采用气-固流化技术在钛合金粉末表面制备无氧钝化层阻隔氧的吸附和渗入，烧结过程中该钝化层又能起到促进烧结作用。重点研究气-固反应过程中钛合金粉末的无氧钝化行为和钝化层的形成机理，以及钝化层的阻氧效果；研究烧结过程中无氧钝化层的热分解规律，和分解反应产物促进烧结致密化规律，揭示钛合金活化烧结机理，并建立无氧钝化—活化烧结—综合性能的关联机制，为发展低氧高性能钛合金奠定理论和技术基础。

Powder metallurgy technology is an important way to reduce the production cost of titanium alloy. However, due to its high activity and low self-diffusion coefficient, titanium alloy always has the problems of high oxygen content and low sintering density. To solve both bottlenecks simultaneously, this project provides a novel route that can not only prevent the oxidation of titanium alloy powder in the forming densification process, but also improve the sintering density based on SnCl4 (gas)/Ti (solid) gas-solid surface reaction, in which gas-solid fluidization technology is creatively introduced into the preparation process of powder metallurgy titanium alloy. This is to prepare an anaerobic passivation layer on the titanium alloy powder surface by gas-solid fluidization technology to block the adsorption and infiltration of oxygen, which can also promote sintering densification during sintering. The anaerobic passivation behavior and formation mechanism of anaerobic passivation layer of titanium alloy powder in the gas-solid reaction process will be studied, as well as the oxygen inhibition effect of the passivation layer. The thermal decomposition law of the anaerobic passivation layer during sintering will be also studied. The effects of decomposition reaction products on promoting sintering densification will be investigated to reveal the activated sintering mechanism of titanium alloy. This aims to establish the internal relevance among anaerobic passivation, activated sintering, and comprehensive performance. Finally, a theoretical and technical foundation for the development of low-oxygen and high-performance titanium alloy will be laid.