Beneficial Effects of Synchronous Laser Irradiation on the Characteristics of Cold-Sprayed Copper Coatings
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JTTEE5 24:836–847 DOI: 10.1007/s11666-015-0246-y 1059-9630/$19.00 ASM International
Beneficial Effects of Synchronous Laser Irradiation on the Characteristics of Cold-Sprayed Copper Coatings Bo Li, Lijing Yang, Zhihong Li, Jianhua Yao, Qunli Zhang, Zhijun Chen, Gang Dong, and Liang Wang (Submitted November 3, 2014; in revised form January 24, 2015) Cold spray (CS) is an emerging materials deposition technique in which metallic particles are accelerated to a high velocity in a supersonic gas flow and then impinged onto a substrate to form a coating at a temperature well below the melting point of sprayed materials. The coating microstructure and properties are greatly influenced by particle preheating and substrate softening. This article presents a study of CS process of copper powder, with assistance of synchronous laser irradiation. The influence of synchronous laser irradiation on the Cu coating characteristics was investigated. The results show that the coating surface with laser irradiation is smoother than that without laser irradiation. The peak coating thickness is increased by about 70% as synchronous laser irradiation is employed, indicating an improvement in deposition efficiency. It is also found that with synchronous laser irradiation the coating is denser and the coating-substrate interfacial bonding is better as compared with that without laser irradiation. Moreover, the EDS and XRD analyses find Cu oxidation occurrence in the SLD coating, but the oxide is trivial. The aforementioned improvements on the coating largely arise from particle preheating and substrate softening by synchronous laser irradiation in the CS process.
Keywords
cold spray, deposition efficiency, interfacial bonding, microhardness, synchronous laser irradiation
1. Introduction Cold spray (CS) is a relatively new materials deposition technique whereby metal powders ranging in particle size from 5 to 100 lm are accelerated to a high velocity in a supersonic gas flow and then impinge onto the substrate or already deposited coating at a temperature well below the melting point of sprayed materials (Ref 1-3). Intensive plastic deformation induced by the high-velocity impact occurs in solid-state particle, substrate (or already deposited coating) or both, enabling the formation of a less-oxidized cold-sprayed coating. In the past few years, a wide range of pure metals, metallic alloys, polymers, and composites have been successfully deposited onto a variety of substrate materials using CS process (Ref 4-11). One of the most widely used concepts in CS process is the critical velocity which is material-dependent (Ref 12). The critical velocity for a given powder is the velocity that Bo Li, Lijing Yang, Zhihong Li, Jianhua Yao, Qunli Zhang, Zhijun Chen, Gang Dong, and Liang Wang, Research Center of Laser Processing Technology and Engineering, Zhejiang University of Technology, Hangzhou 310014, P.R. China and Collaborative Innovation Center of High-end Laser Manufacturing Equipment, Hangzhou 310014, Zhejiang P.R. China. Contact e-mai
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