In particular, the manufacturing method of Nb-Ti, Nb-Ti-Zr, Nb-Ti-Ta alloys as superconducting electrical materials mainly includes mixing, pressing, sintering and smelting of niobium hydride powder and titanium, tantalum, zirconium, hafnium or several powders. Sintering process is divided into low temperature hydrogen removal and high temperature sintering two stages. Adopting the method is beneficial to improve the uniformity of alloy and the process is simple. Direct hydrogenation of niobium ingot to produce hydrogenated niobium powder can obviously improve the utilization rate of metal.
In order to simplify the process and reduce the loss of niobium, the hydrogenated niobium powder can be obtained by direct hydrogenation and crushing of niobium ingot. Direct hydrogenation of niobium ingot can also reduce the contamination of niobium metal. Titanium, tantalum, zirconium, hafnium powder can be hydrogenated powder can also use electrolytic powder.
Niobium ingot should be cleaned with a mixed aqueous solution of hydrofluoric acid and nitric acid before hydrogenation, placed in the furnace after vacuum to 0.01-0.02mpa pressure filled with hydrogen heating up to 500-700 degrees (Celsius), and then cooled to room temperature. Repeated several times after the niobium ingot hydrogen content should reach more than 1%. If the hydrogen pressure is increased, the hydrogenation effect is better, but the pressure resistance of furnace body should be enhanced. If the pressure is too low, the hydrogenation cycle is too long. The hydrogenated niobium ingot can be easily broken into powder of various particle sizes.
According to the predetermined composition and proportion of niobium alloy, niobium powder can be evenly mixed with one or more of titanium, tantalum, zirconium and hafnium powders, and pressed into the desired size of the electrode. It can be molded or isostatic pressed. The pressure is 166-392mpa.If necessary, niobium chips can also be hydrogenated using the same process to produce hydrogenated niobium powder.
Pressed electrodes need to be sintered. Sintering process is divided into low temperature dehydrogenation and high temperature sintering two stages, carried out in a vacuum furnace. The initial stage of sintering is dehydrogenation stage, with the rise of temperature, hydride decomposition into new ecological metal, metal surface fresh, active. High temperature sintering after hydrogen removal, in high temperature sintering, these active metals are easy to diffuse each other to form a variety of solid melts with lower melting point, which is conducive to the elimination of high melting point metal ingot after melting and improve the uniformity.
