多冲碰撞载荷下激光涂层的裂纹损伤及机理分析

对激光涂层进行了多次冲击碰撞试验，并通过SEM等手段分析研究了激光涂层在多冲碰撞载荷下的裂纹形成与扩展机理。研究发现：涂层裂纹多从表层起源，在涂层内应力和反复碰撞压应力的联合作用下逐步扩展；裂纹形状与材料、熔覆工艺及多冲工况相关，裂纹在表面呈横断和网状两大类，在截面呈垂直和网状扩展型两种。用应力集中理论和空位聚集理论解释了裂纹的成核与扩展机制。

Analysis to Flaw Damaging and Mechanism of Laser Coating under Repeated Impact Load

Repeated impact experiments on laser coating were done.The flaws' forming and expanding mechanism had been analyzed and studied,that was happened on the laser coating under repeated impact load by SEM or some other methods.Most of the coating flaws start form the surface,and expand under the combined effect of the coating inner stress and the repeated impact pressure stress.The shape of the flaws is related to the material,cladding process and multiple work conditions.They are traverse and reticular on the surface.There are two kinds of the shapes of the flaws: vertical-expand and net-expand.The mechanism of the flaws' core formation and expansion was explained by using the theory of stress concentration and theory of hollow congregation.