添加WC颗粒对镁合金表面等离子喷涂Al基涂层耐腐蚀和耐磨损性能的影响

Plasma-sprayed Al-based coating with WC-addition for excellent corrosion resistance and enhanced wear protection of Mg alloys

常规热喷涂工艺制备的金属涂层内的粒子界面弱结合导致其不能为基材提供长效的腐蚀防护,因此,采用大气等离子喷涂,实现粒子间的冶金结合,制备高致密Al-15%WC(体积分数)复合涂层。结果表明,由于WC颗粒中C元素的去氯效应,以及超高温熔滴(>1800℃)间的自冶金结合,在最优等离子喷涂条件下制备出无氧化物杂质的涂层。涂层的致密结构使其表现出优异耐腐蚀性能,其腐蚀电流密度比镁合金基体降低4个数量级,比纯铝块材降低2个数量级。WC硬质颗粒的添加使Al-WC复合涂层的耐磨损性能相较纯Al块材提高1个数量级。

Thermal spray processes struggle to create a fully dense coating for corrosion protection in the as-sprayed state due to the poor inter-splat bonding.To tackle this problem,Al−15vol.%WC was utilized as the coating material and applied by atmospheric plasma spraying(APS)to produce a dense coating with self-metallurgical inter-splat bonding.The results show that due to the in-flight particle deoxidizing effect by C element and self-metallurgical bonding of the overheated droplet(>1800°C),dense coating without oxides inclusions is produced under optimized plasma spraying conditions.The fully dense Al−WC coating exhibits excellent corrosion resistance,with corrosion current density lower by four and two orders than that of Mg alloy substrate and bulk Al,respectively.Due to the inclusion of hard WC particles,the Al−WC coating presents one order improvement in wear resistance compared with the bulk Al.