Residual Stress Analysis of Cold-Sprayed Copper Coatings by Numerical Simulation
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enya Li, Kang Yang, Dongdong Zhang, and Xianglin Zhou (Submitted April 27, 2015; in revised form July 23, 2015)
In this paper, an analysis on the residual stress evolution of cold-sprayed copper coatings on Cu and Al substrates was performed. To investigate the influences of particle velocity, temperature and material combination on the final residual stresses, an integrated frame of calculation was proposed based on the simulation results obtained from the developed thermo-mechanically coupled Eulerian model. In a single Cu splat, generally speaking, the maximum residual stress and plastic deformation are concentrated at the outside contact zone rather than at the center point of initial impact. The action of friction shear between the particle and substrate during impacting should be considered as one of the essential factors on the final residual stress. And the states of residual stresses can vary significantly depending on the material combination, particle velocity, and temperature. In a single pass Cu coating, the residual stress fluctuates across the coating and there exists both compressive stress and tensile stress within the coating. At a certain range of impacting velocities, the resultant residual stresses increase with the increase of particle velocity. The present simulated results are related to the reported experiments by others, showing that the residual stress states and stress change trend are different from some of the reported results.
Keywords
cold spraying, copper coating, numerical simulation, residual stress
1. Introduction In cold spraying, metallic or dielectric substrates are exposed to a high-velocity (300-1200 m/s) jet of small metallic particles accelerated by a supersonic jet of compressed gas at a temperature lower than the melting point of the spray material. Beyond a critical velocity defined by the material properties and process conditions, metallic or metallurgical bonding is obtained (Ref 1-3). Consequently, the deleterious effects of oxidation, phase transformation, decomposition, grain growth, and other problems inherent in the conventional thermal spraying can be minimized or eliminated (Ref 1, 4). Cold spraying is applied for the surface enhancement of metals to improve their properties such as wear and corrosion resistance, electrical/thermal conductivity (Ref 5). In This article is an invited paper selected from presentations at the 2015 International Thermal Spray Conference, held May 11-14, 2015, in Long Beach, California, USA, and has been expanded from the original presentation. Wenya Li, Kang Yang, and Dongdong Zhang, State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, School of Materials Science and Engineering, Northwestern Polytechnical University, XiÕan 710072, Shaanxi, PeopleÕs Republic of China; and Xianglin Zhou, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, PeopleÕs Republic of China. Contact e-mail: [email protected].
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