Refining of dispersion particles synsesized in molten aluminium by thermit reaction

本发明的颗粒弥散复合铝合金具有优异的耐磨性。轻型耐磨材料已被要求用于公交系统的紧急制动设备。这种材料在可加工性方面有困难，并且对于成形，铸造似乎是最佳的。然而，非金属颗粒分散到熔融金属中使复合浆料的生产难度最大化。由于润湿性差，颗粒尺寸越小，颗粒总表面积越大，浆料的硬度越大。作为一种简单易行的氧化铝颗粒分散铝合金浆料的制备技术，将大体积的二氧化硅颗粒混入铝液中，引发铝热反应。在铝硅合金熔体中生成氧化铝相。尽管对于材料二氧化硅只有63vol%的氧化铝，但反应后的颗粒保持材料二氧化硅的尺寸和形状。结果表明，反应后的大颗粒是由200 nm左右的氧化铝颗粒与铝熔体混合而成的多晶复合体，在搅拌温度下，氧化铝相的高表面能激活了晶粒的生长。在氧化铝晶粒长大过程中，生成了直径约5 μm的孤立颗粒。这种细小的颗粒分散到熔融的基体中。通过优化反应温度和搅拌温度，可以得到平均粒径为5 μm的氧化铝颗粒从150 μm的二氧化硅中分散到约15vol%的颗粒分散材料。该材料表现出优异的耐磨性，超过了用作耐磨铝合金的过黄铝合金。

The particles dispersion composite aluminum alloy is excellent in wear resistance. The light wear resistant material has been required for the panic braking equipment of the transit system. Such materials have the difficulty in workability, and for the shaping, the casting seems to be an optimum. However, nonmetal particle dispersion to the molten metal maximizes the difficulty in production of composite slurry. It is getting harder, as the particle size is smaller and as total surface area of particles increase, because of the poor wettability.As simple and easy formation technique of the alumina particle dispersion aluminum alloy slurry, bulky silica particles was mixed into molten aluminium, then the thermit reaction was caused. Alumina phase was produced in molten aluminum silicon alloy. In spite of there being only 63vol% of alumina for material silica, the reacted particles maintained the size and shape of material silica. It became clear that the reacted large particle were polycrystal complex in which the alumina grain of about 200nm mixed with aluminium melt.The grain growth of the alumina phase is activated by the existence of the very high surface energy, while this slurry is retained at the stirring temperature. During the process of grain growth of alumina, isolated particles of about 5 μm in diameter were generated. Such a fine particles dispersed into molten matrix..By optimizing reaction temperature and agitation temperature, it was possible to get particle dispersion material in which alumina particles of averages particle size of 5 μm were made to disperse from the silica of 150 μm to about 15vol%. This material showed the excellent wear resistance which exceeded that of hypereutectic aluminium alloy used as abrasion resistant aluminum alloy.