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1165 |
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Monday, June 02, 2008, Room 05 4:40 PM Powders, Wires, Gases 2 New powder mixtures and cored wires, support and distribution of industrial gases for thermal spraying |
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Characterizations of cold sprayed Ni-Al2O3 composite coating with relatively large Ni-coated alumina powder |
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Wen-Ya Li* / Shaanxi Key Laboratory of Friction Welding Technologies,
Northwestern Polytechnical University, P.R.China Chao Zhang / LERMPS-UTBM, France Hanlin Liao/ LERMPS-UTBM, France Jinglong Li/ Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, P.R. China Christian Coddet/ LERMPS-UTBM, France |
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Recently, the emerging cold spraying technique has been widely applied for many coatings of metals, alloys, composites, and even cermets and nanostructured materials owing to its unique characteristics compared to the converntional thermal spraying processes. This process has great potential in most of industries, such as aerospace, automotive and chemical engineering. The previous studies indicate that the fabrication of metal matrix composites (MMCs) by cold spraying is effective and promising. As reported, the deposition of MMCs could be obtained throuth the spraying of the simple powder mixtures or the ball-milled feedstocks. When light materials, such as SiC and Al2O3, were used as reforcements, it is diffcuclt to obtain a high volume fraction of hard phase in the composite just through the simple powder mixture. Therefore, the ball-milling of the powder mixture may be an effective method to increase the volume fraction of hard phase. In this study, it was found that a dense Ni-based composite could be deposited with the Ni-coated alumina powder. However, there is no report focusing on this interesting applications. In this paper, the deposition features of Ni-Al2O3 composite coating by cold spraying with relatively large Ni-coated Al2O3 powder were investigated. More attention has been paid on the microstructure evolution of the coatings by optical microscope, scanning electron microscope and X-ray diffraction. It was found that a very dense Ni-Al2O3 composite coating can be deposited under certain conditions. The coating had the same phase structures as the feedstock. The volume fraction of Al2O3 in the composite was about 29±6%, which is a little less than that in the feedstock (nominal: 40-45%) due to the rebound of part of the alumina particles upon impacting. |