In this article,the absence of self-replenishing of cold spray is studied by examining the thick coating deposited around the pre-drilled microsize hole.Thick copper coating was deposited around the microsize holes(ab...In this article,the absence of self-replenishing of cold spray is studied by examining the thick coating deposited around the pre-drilled microsize hole.Thick copper coating was deposited around the microsize holes(about 200 and 500μm) using cold spraying methods on copper substrate,the cross-section of cavity around the hole were observed with SEM to investigate the characteristics of cavity.Computational methods were also used to investigate the original formation reason of the cavity.The results indicate:the original formation reason of cavity is that particles are too closed when impact onto the substrate.The repellant force between the particles perpendicular to the impaction direction will lead to porosity if the particles are too close.Much lower flatten ratio occurred for succeeding particle if the particles are too close at the same point because the momentum energy convert to the former particle's deformation.A high probability of above two phenomenon resulting from high powder feeding rate will form the original cavity.In relative wider cavity,coating can be deposited in the bottom,while in the relative narrow cavity,coating can not be deposited.The thickness of the coating in the cavity is much thinner than coating around the cavity.The cavity grow larger and larger on pre-drilled holes just as the regime effect of cold spray of fixed location deposition.展开更多
基金Science and Technology Foundation of State Key Laboratory for Marine Corrosion and Protection(9140C2505030805)
文摘In this article,the absence of self-replenishing of cold spray is studied by examining the thick coating deposited around the pre-drilled microsize hole.Thick copper coating was deposited around the microsize holes(about 200 and 500μm) using cold spraying methods on copper substrate,the cross-section of cavity around the hole were observed with SEM to investigate the characteristics of cavity.Computational methods were also used to investigate the original formation reason of the cavity.The results indicate:the original formation reason of cavity is that particles are too closed when impact onto the substrate.The repellant force between the particles perpendicular to the impaction direction will lead to porosity if the particles are too close.Much lower flatten ratio occurred for succeeding particle if the particles are too close at the same point because the momentum energy convert to the former particle's deformation.A high probability of above two phenomenon resulting from high powder feeding rate will form the original cavity.In relative wider cavity,coating can be deposited in the bottom,while in the relative narrow cavity,coating can not be deposited.The thickness of the coating in the cavity is much thinner than coating around the cavity.The cavity grow larger and larger on pre-drilled holes just as the regime effect of cold spray of fixed location deposition.
