The preparation method of billet or tantalum alloy billet includes the following steps: a) pressing tantalum powder or tantalum alloy powder to form the billet and pre-sintering the pressed formed billet in a vacuum sintering furnace; b) The blank obtained in step a) is sintered by vacuum vertical melting to obtain tantalum blank or tantalum alloy blank. In this application, tantalum billet or tantalum alloy billet is prepared by pre-sintering and vacuum vertical melting sintering. Among them, pre-sintering in vacuum sintering furnace is induction sintering, so that the uniformity of billet after sintering is consistent, and then vacuum vertical melting sintering is carried out. Since the pre-sintering stage before vacuum vertical melting sintering makes the uniformity of billet better, the billet goes through vacuum vertical melting sintering. It can also ensure the uniformity of the billet, so that the performance uniformity of the billet is better.
The disadvantages of electron beam smelting tantalum and tantalum alloy rods are large loss, about 3%, and low direct yield. Second, low processing efficiency and high cost; The main reason for the loss of bar is that a large number of low-melting metals and gas impurities are volatilized in the process of electron beam melting and pickling, which also causes the loss of part of tantalum metal, and its direct yield is significantly reduced. But the processing efficiency is low mainly in the electron beam melting after peeling, forging after turning, so will produce a lot of waste; On the other hand, the electron beam melting process is a large amount of energy consumption process, and the cost of forging and extrusion is higher than that of rolling process, so its cost is higher, and at present only plansee companies abroad adopt this method.
At present, powder metallurgy method is a common method for preparing tantalum or tantalum alloy processing bars, which has the advantages of about 0.8% loss, high efficiency and low cost compared with electron beam melting technology. However, there are still shortcomings in powder metallurgy technology methods, such as: Vertical melting sintering is carried out by the power fixture, the sintered body achieves the purpose of sintering by heating itself, and the temperature that the fixture can withstand is lower than the temperature of the sintered body, so the fixture must be cooled. During the cooling process, due to heat conduction, the temperature at both ends of the sintered body is lower than the middle part, so the sintered body must be cut out at both ends after sintering. However, the uniformity of the sintered body after the removal of the end is still different, resulting in uneven product performance.
