精炼炉或坩埚用来精炼金属材料时 ,特别是熔炼高熔点金属时 ,总会给金属造成一定的污染 ,因此 ,近年来已开发成功了一系列无容器的金属精炼技术 ,最典型的方法有 :(1)微重力下的熔炼 ,通常指在宇宙环境中的熔炼 ;(2 )自由落下技术 ;(3)给被精炼金属施加以能将重力平衡的外力进? Refining furnaces or crucibles used to refine metallic materials, especially when melting refractory metals, always cause some metal contamination. Therefore, a series of vesselless metal refining techniques have been developed successfully in recent years. The most typical method : (1) smelting under microgravity, usually referred to as smelting in the cosmic environment; (2) free-fall technology; (3) application of external force to the refined metal to balance the force of gravity;