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| Abstract No.: |
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| Title: |
Plasma sprayed Al alloy coating with enhanced lamellar bonding through novel self-bonding strategy
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| Authors: |
Chang-Jiu Li / Xi'an Jiaotong University, P.R. China
Haroon Rashid* / Xi'an Jiaotong University, P.R. China
Xiao-Tao Luo/ Xi'an Jiaotong University, China
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| Abstract: |
Thermally sprayed aluminum coatings are widely used for corrosion control. The coating with conventional lamellar structure and limited interface bonding due to oxide formation presents certain porosity in the coating which deteriorates the properties of atmospheric plasma sprayed Al coatings. In this study, it was found that when the impacting Al particles are heated to 2000ºC or above, they will melt pure Al substrate at the point of impact resulting in metallurgical bonding. However, how to limit in-flight oxidation of Al is another key factor to form metallurgical bonding between lamellae since oxide on splat surface hinders the bonding formation. Thus, a novel strategy to limit Al oxidation by in-situ metallurgical reaction is proposed. To confirm the novel idea the experiment was conducted using Al-WC composite powders aiming at creating high temperature droplets by plasma spraying and reducing Al oxidation by carbide. The Al-15vol%WC composite powders were prepared by mechanical alloying of Al with WC particles at 2µm size. The temperature of spray particles was measured by DPV-2000 in-flight particle diagnostic system. The microstructure was characterized by SEM and tensile test was conducted to measure the cohesive and adhesive strength of the coating. The corrosion behavior of the Al-sprayed Mg alloy was evaluated electrochemically. Results showed that the coating presents a dense microstructure with well bonded lamellae following the present strategy creating oxide-free high temperature droplets over 2000oC. The electrochemical test results reveal that Mg alloy coated by the composite coating presents a comparable behavior with that of bulk Al.
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