热扩散对脉冲电流烧结初期驱动力的影响

基于温度梯度引起的热扩散通量是烧结颈部物质迁移的额外驱动力,建立了氧化铝颗粒非等径两颗粒模型,引入将热传播速度定义为有限值的广义热弹性理论,研究了脉冲电流烧结初期热扩散对烧结驱动力的影响。数值计算表明,脉冲电流烧结过程的热扩散通量远大于颈部曲率驱动的空位扩散通量,说明在烧结初期热扩散提供的驱动力占主要地位。小颗粒越小,热扩散与空位扩散通量的比值越大,越容易烧结。

Influence of thermal diffusion flux on driving force in the initial stage of pulse electric current sintering

The thermal diffusion flux caused by temperature gradient is defined as the additional driving force for neck material migration.The effect of temperature gradient on driving force for unequal-sized A12O3 powders at the initial stage of pulse electric current sintering (PECS) was investigated in this work.The generalized thermoelastic theory was introduced to the thermal-mechanical interaction.The numerical simulation results show that the thermal diffusion flux is much higher than the vacancy diffusion flux driven by neck curvature,implying that the thermal diffusion provides the main driving force at the initial stage.The smaller the particles,the greater the ratio of thermal diffusion and vacancy diffusion flux,and the easier to promote the sintering.