冷喷涂Cu粒子参量对其碰撞变形行为的影响

采用有限元数值计算方法研究了冷喷涂过程中Cu粒子与Cu基体的碰撞变形行为，探讨了粒子速度、温度对其碰撞基体后的变形行为、界面温度变化与粒子和基体的接触面积的影响．结果表明，随粒子碰撞速度的增加，粒子扁平率与碰撞界面温度增加、接触面积增大．证实了存在使碰撞界面发生绝热剪切失稳变形的临界速度，该速度与粒子沉积的临界速度一致．当粒子速度大于产生绝热剪切失稳变形的临界速度时，粒子的变形扁平率显著增加，且界面温度与有效接触界面面积也显著增加；随碰撞前粒子温度的增加，碰撞界面的温度也显著增加．高达粒子材料熔点的界面温度与有效接触面积的显著增加，将有助于粒子与基体之间冶金结合的形成．

Effect of parameters of cold sprayed Cu particles on its impacting behavior

The impacting behavior of Cu particle upon Cu substrate in cold spraying was studied using the finite element analysis, involving the effects of particle velocity and temperature prior to impact on the deformation behavior, temperature increment and contact area at the particle-substrate interface. It was found that with increasing the particle impact velocity the flattening ratio, temperature increment and contact area at the interface increase. It was confirmed that the critical velocity for the onset of shear instability of particle was consistent with that for particle deposition. As the particle velocity is higher than the critical one, the flattening ratio, temperature increment and contact area at the interface increase more significantly, which will benefit the formation of the bond between particle and substrate. With the increase of particle temperature the temperature at the interface increases significantly. The relatively high temperature achieved the melting point of particle material at the localized contact zone may promote the formation of the metallurgical bonding in the coating.