单颗粒黏结行为的实验研究

Experimental study on bond behavior of single particle

实验研究了固体桥力作用下的颗粒黏结脖颈成长及抗拉强度变化规律。通过颗粒黏结的动态观测,发现烧结理论能很好地解释脖颈的成长过程,接触时间对脖颈影响相对较小,黏结温度影响较大;通过测量温度场中的脖颈抗拉强度,发现黏结温度升高,抗拉强度先增后减,液相出现后抗拉强度迅速下降;黏结时间增长,抗拉强度逐渐增大,并趋向于一个稳定值;接触压力增大,抗拉强度也随着增大。研究还证实了脖颈抗拉强度低于同温度下的材料强度,脖颈存在晶格缺陷。量纲1脖颈强度在温度低于0.8Tmelt时变化幅度很小,小于材料强度的0.1倍;在高于0.8Tmelt后,量纲1脖颈抗拉强度会迅速增大,直至逼近材料自身的强度。

The neck growth and change of neck tensile strength of particle bonding resulting from solid-bridge force were investigated.Experimental observation indicated that the neck growth process could be well explained by the sintering theory.The effect of bond time on the neck was less than that of bond temperature.With increasing bond temperature,neck tensile strength increased firstly,and then decreased rapidly due to the appearance of liquid phase.The strength increased as bond time increased and then reached a constant value finally.The strength also increased with increasing contact pressure.It was found that neck tensile strength was smaller than material strength at the same temperature and lattice defects existed in the neck.The dimensionless neck strength changed slightly and was smaller than 0.1 times of material strength when temperature was lower than 0.8 times of melting point.When temperature was higher than 0.8 times of melting point,dimensionless neck strength increased apparently and was close to material strength.