Mo, Ta, W, Nb and other refractory metals with high melting point have good stability to active metals such as titanium and zirconium, which can be used to make surface layer of mould shell for precision casting. In the process of shell preparation, a layer of tungsten or tungsten oxide surface is usually formed on the ceramic surface to reduce the reaction between the molten metal and the shell. At present, the shell prepared by this process is mainly used in precision casting of titanium and titanium alloy. Basche penetrates the ceramic shell with a tungsten compound and then calcines it in a reductive atmosphere to reduce the compound, thereby coating the refractory with tungsten, thereby avoiding the reaction of titanium with the refractory at high temperature. However, the tungsten surface shell also has some shortcomings, such as solvent dewaxing method must be used to make the shell, will cause harm to the environment and human health; In addition, the mold deposited on the surface of the mold shell after dewaxing is easy to react with the metal and form pores on the surface of the casting.
Tag: Ta,Nb,titanium, zirconium
