多颗粒沉积模型预测铜和铝冷喷涂层微观形貌

Morphology prediction of cold-sprayed Cu and Al coatings through multi-particles deposition simulation

采用有限元软件ANSYS/LS--DYNA建立了15个颗粒与基板的冷喷涂沉积模型,通过多颗粒沉积模型预测工艺条件、不同颗粒/基板组合的沉积行为和微观形貌;制备了Al和Cu冷喷涂涂层,观察了涂层截面形貌和颗粒变形特征,并与模拟结果进行对比.结果表明,多颗粒沉积模型可预测喷涂条件对颗粒沉积过程及涂层微观特征的影响,以及不同颗粒/基板组合的界面微观形貌.当碰撞速度低时,颗粒变形不充分,颗粒交界处易形成孔洞;随着速度增加,颗粒流变填充孔洞,涂层致密.与颗粒相比,硬基板涂层/基板界面平滑,机械互锁作用小;软基板形成射流状金属挤入颗粒之间,增加结合作用.

A deposition model of 15 particles onto a substrate was established using the finite element program ANSYS/LS-DYNA. Based on the multi-particle deposition model, the deposition behavior and morphology as well as the interface characteristic were predicted for different particles/substrate cases. Al and Cu coatings were prepared by cold spraying. The cross section of the coatings and the characters of particle deformation were observed by scanning electron microscopy and compared with the simulated results by the multiparticle deposition model. The results demonstrate that the multi-particle deposition model can predict the effect of process conditions on the deposition behavior, microscopic characteristic, and interface morphology for different particles/substrate cases. When the impact velocity is low, particle deformation is not sufficient, which easily results in holes at the junction of particles ; however, the holes disappear gradually with increasing impact velocity. Compared with particles, for a hard substrate, the coatings/substrate interface is smooth, which weakens the interlock; while for a soft substrate, the substrate deforms severely to form jet-like metal, which squeezes into particles to increase the bonding.