粒子非垂直入射对冷喷涂涂层形成的影响分析

当高速粒子喷涂复杂曲面部件时,绝大部分粒子与部件表面将呈一定角度侵切,非垂直入射粒子对涂层形成及特性将产生重要影响.采用有限元数值计算方法,研究冷喷涂材料改性过程中铜粒子与铜基体非垂直碰撞的变形行为.针对单个粒子以相同入射速度不同入射角度的碰撞条件,探讨粒子与基体的结合强度、侵彻深度以及绝热剪切失稳的发生条件.结果表明:有角度碰撞相对于理想垂直碰撞,冷喷涂沉积效果的情况是恶化的,随着入射角度的增大,粒子侵彻深度逐渐减少,粒子与基体的结合强度也逐渐减弱,甚至不会嵌入基体而发生脱离.发生绝热剪切失稳的条件是入射速度的法向分量大于碰撞过程的临界速度.

Effect of non-vertical incidence angles of particles on bonding performance in cold spraying

When high-speed particles are spraying the part with complex bend surface, the majority of particles will intrude and cut off the surface of the part in certain angle, Non-Vertical incidence particles will have an important influence on formation and characteristic of the coating. Based on developed numerical simulation method, the non-vertical impacting behavior of copper particles colliding copper substrate in process of transforming material property was investigated. The join strength, penetration depth and condition of emerging adiabatic shear instability were discussed with single particle of uniform speed and different angles. It is revealed that the deposit effect of cold spray is deteriorating in certain angle collision comparing with the ideal vertical collision; with the increasing incidence angle, the penetration depth of particles is decreased and the join strength is weakened, even can’t be embeded into the substrate and leads to the disengagement. Adiabatic shear instability will take place when the normal component of particle velocity excesses critical value.