纳米陶瓷粉末在爆炸压实过程中的破碎行为研究

 在爆炸压实过程中，纳米颗粒所受冲击载荷发生显著变化的时间远远大于应力波传过颗粒特征长度所用时间；同时，陶瓷颗粒在爆炸冲击过程中主要表现为脆性。基于以上两个事实提出了弹性假设，推导了颗粒在压实过程中的受力状态。回顾了判断脆性材料破坏的三个准则，即Hugonoit弹性极限、动态屈服强度和理论剪切强度，并从这三种判据的交集值出发来判断爆炸压实过程中陶瓷颗粒是否有发生破碎的可能。通过具体计算得出颗粒内存在两个最大剪应力的位置：一个位置发生在距颗粒接触面0.5 nm范围以内，此处剪应力最大；另一个位置发生在距接触面较远处。这一结果为解释陶瓷粉末颗粒在爆炸压实过程中存在塑性行为和破碎行为提供了理论依据。

Research of Fragmentation of Nano-Ceramic Powders during Explosive Consolidation Process

In explosive consolidation of nano-powders,the duration in which the loading changed markedly on nano-particles by shock wave is far longer than the time of stress wave propagating through the character length of the particles;and the ceramic powders behave brittleness during explosive shock consolidation.The elastic hypothesis is put forward based on the two facts mentioned above,and the hypothesis is used to deduce the stress status in particles during the process of consolidation.The three criteria of brittleness fracture of damage(Hugonoit elastic limit,dynamic yield strength and theoretical shear strength) are reviewed.The probability of fracture of ceramic particles is estimated by the intersection value of the three criteria.Based on the calculation,it is concluded that there are two maximal shear positions:one is located in the depth of 0.5 nm in particle from the contact surface,where the shear stress is maximum;the other is located further from the surface.This result offers a reference for interpreting the plasticity and fracture during the process of explosive consolidation.