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研究了Al-Ti O_2-B_2O_3系粉末在无过量Al以及过量Al为0%,5%,10%,15%,20%,25%(质量分数,下同)时,球磨时间对机械合金化及燃烧反应的影响规律,计算了不同成分时反应体系的理论绝热温度,对球磨后的粉末进行了X射线衍射(XRD)、差示扫描量热法(DSC)、扫描电镜(SEM)测试分析。结果表明:在球磨过程中,无过量Al以及过量Al为5%,10%,15%时,Al还原Ti O_2反应的理论绝热温度低于1800 K,Al还原B_2O_3反应远高于1800 K,反应产生的热量促使Ti O_2还原反应发生,生成Al_2O_3和Ti B_2。过量Al为20%,25%时,Al还原Ti O_2和B_2O_3反应的理论绝热温度都低于1800K这一临界反应温度,不能发生化学反应。随着球磨时间的增加,粉末的表面能、晶格畸变能、位错能以及晶界能增加,扩散通道缩短,促使自蔓延化学反应的点火温度下降,从未球磨的1000℃以上下降到600℃左右。在球磨过程中,粉末颗粒尺寸首先增加,超过一定时间后,粉末颗粒尺寸减小,发生化学反应后,粉末颗粒尺寸明显减小,达到微纳米级。
The effect of ball milling time on the mechanical alloying of Al-Ti O_2-B_2O_3-based powders with no excess Al and excess Al of 0%, 5%, 10%, 15%, 20% and 25% And the influence law of combustion reaction, the theoretical adiabatic temperature of the reaction system was calculated. The powder after milling was characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy . The results show that the theoretical adiabatic temperature of Al reduction of TiO_2 is less than 1800 K and Al reduction of B_2O_3 is much higher than 1800 K in the absence of excessive Al and excess Al of 5%, 10% and 15% The heat generated causes the reduction reaction of Ti O 2 to generate Al 2 O 3 and Ti B 2. When the excess Al is 20% and 25%, the theoretical adiabatic temperatures for the reaction of Al reduced TiO_2 and B_2O_3 are all lower than the critical reaction temperature of 1800K, and chemical reaction can not occur. With the increase of ball milling time, the surface energy, lattice distortion energy, dislocation energy and grain boundary of the powder can increase, the diffusion channels shorten and the ignition temperature of self-propagating chemical reaction decreases, dropping from above 1000 ℃ to 600 ℃ or so. In the ball milling process, the particle size of the powder increases first, and after a certain period of time, the particle size of the powder decreases. After the chemical reaction occurs, the particle size of the powder decreases obviously to the level of the micro-nano scale.