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2506 |
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Effects of spray nozzle design and gas temperature on cold sprayed magnesium alloy coating and its composite |
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Xinkun Suo* / Chinese Academy of Sciences, P.R. China Xueping Guo/ LERMPS, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, France Wenya Li/ Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, China Marie-Pierre Planche/ LERMPS, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, France Rodolphe Bolot/ LERMPS, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, France Hanlin Liao/ LERMPS, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, France Christian Coddet/ LERMPS, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, France |
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In this paper, two types of convergingdiverging Laval nozzles with different cross-section shapes and expansion ratios were used to spray AZ91D magnesium alloy and its composite powders. A commercial AZ91D powder and its mixture with 30 vol.% SiC powder were used as feedstocks. The velocities and temperatures of in-flight particle under different operating conditions were simulated by using FLUENT software. The simulated results show that the in-flight particle through the rectangular cross-section nozzle has a lower temperature than that obtained through the circular cross-section nozzle. The resulting coatings were characterized by using optical microscopy, scanning electron microscopy, and a microhardness tester. The coating observations show that the AZ91D coating and its composite can only be correctly deposited by using the rectangular cross-section nozzle. The increase of the gas temperature has a great effect on the coating microstructure, porosity and microhardness. Furthermore, the observation of the composite coating produced under the gas temperature of 600oC shows that the SiC content in the composite is about 23 vol.%. The microhardness of the composite is improved to 140 HV due to the enhancement of SiC particles, compared to 98 HV for the pure AZ91D coating. |