镁对氢化钛烧结致密化的影响

以氢化钛粉末和镁粉为原料,利用模压工艺制备纯钛,主要研究了镁对氢化钛粉末烧结致密化的影响。结果表明,少量镁的添加能够促进氢化钛粉末的烧结致密化,而过量镁则降低烧结密度,镁添加量为0.5%(质量分数,下同)时效果最优,将烧结体相对密度由96.5%提高到98.7%。通过对烧结过程动力学、镁还原氧化钛反应的热力学和动力学,以及烧结体成分进行分析,发现少量镁促进氢化钛烧结致密化的机理为:真空烧结时镁从坯体中挥发,形成的镁蒸气对粉末颗粒表面的氧起到净化作用,提高了烧结活性,从而提高烧结密度。

Effect of Magnesium on the Densification Behavior of Titanium Hydride

Using titanium hydride powder and magnesium powder as starting materials, pure titanium was prepared by the press-sintering process. Magnesium was used as the addition and its effect on the sintering densification behavior of titanium hydride were studied. The results show that a bit of magnesium could accelerate the densification process, while excessive magnesium decreases the relative density. The optimal amount of magnesium is 0.5 wt% and the relative density is improved from 96.5% to 98.7%. By investigating the sintering kinetics, thermodynamics and kinetics of titanium dioxide reduction by magnesium and EDS element mapping analysis of the sintered sample, the densification mechanism was clarified. In the sintering process, magnesium volatilizes from the green body and the magnesium vapor reduces the oxidation film of the powder particles, thus improving the sintering activity and enhancing the sintered density.