Titanium and titanium alloys have been widely used in national defense and civil fields because of their excellent properties. With the rapid development of the national economy, especially in aerospace, automobile manufacturing, weapons, and ships, the demand for titanium materials is increasing. However, the production cost of titanium alloy materials is high, and the near net forming process can improve the utilization rate of titanium alloy materials and reduce the production cost. Powder metallurgy in the near net shape forming process is one of the most promising processes for titanium processing at present, so titanium powder and titanium hydride powder as raw materials of powder metallurgy have broad development prospects. And with the rapid development of traditional improved titanium powder metallurgy, laser rapid prototyping, electron beam powder metallurgy, and 3D printing manufacturing, the market demand for low-cost, high-quality titanium and its alloy powder is bound to increase sharply in the future.
The hydrogenation dehydrogenation method is to prepare titanium powder by using the reversible absorption characteristics of titanium to hydrogen. According to the physical and chemical properties of the titanium hydrogen system, titanium and its compounds absorb hydrogen at a certain temperature and hydrogen pressure. After hydrogen absorption to a certain extent, titanium is hydrogen embrittled and easy to be crushed by mechanical forces such as ball milling. The crushed powder containing a large amount of hydrogen is called titanium hydride powder. Pure titanium powder without hydrogen is obtained by dehydrogenation of titanium hydride under high temperature and vacuum conditions. This is a classic method for preparing titanium powder invented by the United States in 1955. The powder produced by this method has a wide particle size range, low cost, no strict requirements for raw materials, and the process is easy to realize. After years of improvement and promotion, it has become the main method of preparing titanium powder at home and abroad. The powder is widely used in aerospace, metallurgy, chemical industry, medical and other fields. However, the titanium powder produced by this method has the following problems:
1) The O and N contents of titanium powder prepared by hydrogenation and dehydrogenation are high, which can not meet the requirements of powder quality for the preparation of high-performance titanium and titanium alloys;
2) The cost of titanium powder prepared by hydrogenation and dehydrogenation is much lower than that prepared by atomization, but the powder has a small compaction density, poor fluidity, and irregular shape, which is difficult to directly meet the requirements of new powder metallurgy technologies such as metal injection molding, 3D printing, and laser rapid prototyping;
3) At present, the raw materials for preparing titanium powder by hydrogenation and dehydrogenation are commercial sponge titanium or residual titanium. On the one hand, the price is expensive, on the other hand, it is exposed to the air for a long time, its surface and internal pores absorb more water and air content, and the exhaust dehydration before hydrogenation is not complete, which will affect the quality of titanium powder, that is, increase the content of oxygen and nitrogen in titanium powder, especially the content of oxygen. Therefore, the realization of sponge titanium powder joint production is also of great significance for the production of low-cost, high-quality titanium powder.
