纳米钼粉的微波烧结及致密化行为（英文）

Microwave sintering of Mo nanopowder and its densification behavior

为了满足冶金、机械、国防、航空航天等高技术领域应用对组织均匀细小的高性能钼粉的需要,对纳米钼粉的微波烧结工艺和致密化机理进行研究。在本实验中,纳米钼粉和微米钼粉分别在不同温度和不同时间下进行常规烧结和微波烧结。结果表明:随着烧结温度的升高,相对密度和硬度的增速先快速增加随后增速减缓,相对密度迅速达到95%,随后趋于稳定。采用微波烧结技术,在1873 K下烧结30 min获得相对密度为98.03%、平均晶粒尺寸为3.6μm的纳米钼粉。对纳米钼粉的微波烧结动力学进行研究,发现其致密化是体积扩散机制和晶界扩散机制共同作用的结果。计算得到的纳米钼粉的微波烧结激活能为203.65 kJ/mol,远低于常规烧结方式的激活能,证明微波烧结有利于增强粉末的原子扩散性能和致密化过程。结果表明,微波烧结是制备高性能钼产品的一种经济可行的方法。

In order to prepare high-performance Mo with fine and homogeneous microstructure to meet the demand of high-technology applications such as metallurgical,mechanical,national defense,aerospace and electronics applications,the microwave sintering process and densification mechanism of Mo nanopowder were studied.In this experiment,Mo nanopowder and micropowder were used for conventional sintering and microwave sintering at different sintering temperatures and sintering time,respectively.The results showed that with the increase in the sintering temperature,the increase rates of the relative density and hardness increased rapidly at first and then slowed down.The relative density rapidly reached 95%,followed by a small change.Mo nanopowder with a relative density of 98.03% and average grain size of 3.6 μm was prepared by microwave sintering at 1873 K for30 min.According to the analysis of the sintering kinetics,its densification is attributed to the combination of volumetric diffusion and grain boundary diffusion mechanisms.The calculated sintering activation energy of Mo nanopowder was 203.65 kJ/mol,which was considerably lower than that in the conventional sintering,suggesting that the microwave sintering was beneficial to the enhancement in the atom diffusion and densification for the powder.The results confirm that the microwave sintering is a promising method to economically prepare molybdenum with high properties.