亚微米Al2O3颗粒表面稀土改性对Al基复合材料界面润湿性的影响

采用液相包裹法对亚微米Al2O3颗粒表面进行稀土氧化物Y2O3改性.通过表面改性前后颗粒增强Al基复合材料制备过程中,Al熔体在颗粒间渗透压力的变化,研究了颗粒表面Y2O3改性前后与Al熔体间界面润湿性的变化;同时利用真空座滴法对界面润湿性的变化进行了评定.结果表明:Al熔体在表面经Y2O3改性的Al2O3颗粒中的渗透压较改性前显著降低;颗粒表面改性后与Al熔滴间的接触角明显减少且与颗粒表面Y2O3包裹程度有关;说明颗粒表面经Y2O3改性后与Al基体间的润湿性得到了明显的改善,且6061Al较2024Al对Al2O3颗粒具有更好的润湿效果;其改善的主要原因是Y2O3与基体Al发生了界面反应,体系产生了反应润湿的结果.

Effect of surface modification of sub-micron Al2O3 particles by rare-earth on interfacial wettability of Al matrix composites

Liquid coated approach was used in rare-earth modification on the surface of sub-micron Al2O3 particles. The wetting behaviour of molten aluminum on the as-received and coated Al2O3 powders was investigated by the change of osmotic pressure between the molten aluminum and particles during the preparation of Al composites. At the same time, the change of the interracial wettability was examined by the sessile drop method. The results show that the osmotic pressure between the melted aluminum and the Al2O3 particles coated by Y2O3 is obviously dropped. The contact angle of the coated-particles by Al decreases clearly and it is related to Y2O3 content on the surface of Alz 03 particles. The results show that the wettability of the coated-Al2O3 particles by liquid alumimum is dramatically improved, and the wetting effects of AI2O3 particles by 6061A1 are better compared to 2024A1. The main reason for the improvement of the wettability can be suggested that it results from reaction wetting in the system due to the interface reaction of Y2O3 with Al matrix.