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Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods

Science and Technology on Marine Corrosion and Protection Laboratory, Luoyang Ship Material Research Institute, Qingdao 266101, China
Sunrui Marine Environment Engineering Co., Ltd., Qingdao 266101, China
Author to whom correspondence should be addressed.
Academic Editor: Yasutaka Ando
Coatings 2017, 7(1), 2;
Received: 20 September 2016 / Revised: 28 November 2016 / Accepted: 7 December 2016 / Published: 30 December 2016
(This article belongs to the Special Issue Thermal Spray Technology)
Cold spraying is a promising method for rapid prototyping due to its high deposition efficiency and high-quality bonding characteristic. However, many researchers have noticed that holes cannot be replenished and will grow larger and larger once formed, which will significantly decrease the deposition efficiency. No work has yet been done on this problem. In this paper, a computational simulation method was used to investigate the origins of these holes and the reasons for their growth. A thick copper coating was deposited around the pre-drilled, micro-size holes using a cold spraying method on copper substrate to verify the simulation results. The results indicate that the deposition efficiency inside the hole decreases as the hole become deeper and narrower. The repellant force between the particles perpendicular to the impaction direction will lead to porosity if the particles are too close. There is a much lower flattening ratio for successive particles if they are too close at the same location, because the momentum energy contributes to the former particle’s deformation. There is a high probability that the above two phenomena, resulting from high powder-feeding rate, will form the original hole, which will grow larger and larger once it is formed. It is very important to control the powder feeding rate, but the upper limit is yet to be determined by further simulation and experimental investigation. View Full-Text
Keywords: cold spray; compressed layer; computational fluid dynamics cold spray; compressed layer; computational fluid dynamics
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Huang, G.; Wang, H.; Li, X.; Xing, L. Study on the Growth of Holes in Cold Spraying via Numerical Simulation and Experimental Methods. Coatings 2017, 7, 2.

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