Molybdenum powders are mainly used in preparing molybdenum metal materials and molybdenum alloy materials by powder metallurgy technology, electrical and electronic fields and some chemical engineering fields. The quality of molybdenum powders directly affects the quality of molybdenum products and molybdenum alloys. The quality of molybdenum powders is closely related to the preparation technology. Molybdenum powders preparation technology has always been the focus of molybdenum metallurgy industry. The research progress of molybdenum powders preparation technology was reviewed by consulting a large number of literatures and references. According to different preparation principles and processes of molybdenum powders, the existing preparation methods of molybdenum powders were classified into three categories: reduction method, decomposition method and induction plasma spheroidization technology. (1) Reduction method: according to different reducing agents, the reduction methods to prepare molybdenum powders were subdivided into hydrogen reduction method, metal reduction method and carbon reduction method. Hydrogen reduction was the most common method to prepare molybdenum powders in industry. This method mainly used molybdenum oxide as raw material to prepare molybdenum powders through one-stage reduction method, two-stage reduction method and three-stage reduction method. The one-stage reduction process was not complicated, but the purity of molybdenum powders was low and the quality of molybdenum powders was poor. Molybdenum powders prepared by two-stage reduction had good quality and fine particle size, which was the most frequently-used method in industry. Three-stage reduction was further deoxidization at higher temperature to prepare some special molybdenum powders. In addition, by adjusting the mechanism in the reduction process of molybdenum powders, the purpose of controlling the particle size of molybdenum powders could be achieved, and it could provide ideas for industrialized large-scale preparation of nano molybdenum powders and large-size molybdenum powders. Ammonium molybdate could also be used as raw material for hydrogen reduction. Ammonium molybdate could be reduced to molybdenum powders by decomposition-reduction method and direct hydrogen reduction method. In essence, the direct hydrogen reduction method was the superposition of each stage of decomposition-reduction method. The difference between them was that hydrogen was injected during the decomposition stage and slight reduction was occurred. The temperature required by hydrogen reduction method was lower and the molybdenum powders prepared was of high purity. However, the particle size of molybdenum powders prepared was slightly larger. The metal reduction method contained calcium thermal reduction, aluminum thermal reduction, zinc thermal reduction and magnesium thermal reduction. Among them, the molybdenum powders prepared by calcium thermal reduction or aluminum thermal reduction had many impurities. The two methods were not suitable for industrial production of molybdenum powders. Magnesium thermal reduction and zinc thermal reduction had certain research value. The particle size of molybdenum powders prepared by metal thermal reduction method was fine, but it was easy to introduce new impurities. Carbon reduction method was worth to research. At present, the challenge of preparing molybdenum powders by carbon reduction method was that the addition of carbon content couldn't be precisely controlled, which led to the situation of insufficient reduction or excessive reduction to produce molybdenum carbide. The molybdenum powders prepared by carbon reduction method had fine particle size. Carbon reduction method had low cost, safe operation and had bright development prospect. (2) Decomposition method: three methods were introduced: carbonyl thermal decomposition method, molybdenum chloride thermal decomposition method and molybdenum concentrate thermal decomposition method. The particle size of molybdenum powders prepared by carbonyl thermal decomposition method was fine. The molybdenum powders had high chemical purity and good sintering performance. It was not the first choice for the industrial production of molybdenum powders because the preparation of carbonyl molybdenum was not as convenient as that of molybdenum oxide. The thermal decomposition of molybdenum chloride was simple and it could prepare high purity molybdenum powders. However, it would cause environmental pollution. The process of thermal decomposition of molybdenum concentrate was simple, but the quality of molybdenum powders prepared was poor. The thermal decomposition process of organic precursor containing molybdenum was also simple and didn't require expensive reagents, but it was not suitable for the industrial production of molybdenum powders because of the complex process. (3) Plasma spheroidization technology was characterized by high temperature, high enthalpy and controllable atmosphere, which was especially suitable for the preparation of spherical and ultrafine powders of refractory metals. The molybdenum powders prepared by plasma spheroidization had the advantages of high spheroidization rate, high sphericity, low impurity content, controllable particle size and so on. Different preparation methods could produce molybdenum powders with different quality and performance, so as to meet the needs of molybdenum powders in different fields. In recent years, with the rapid expansion of the application field of molybdenum powders, the preparation methods of molybdenum powders were constantly developing. In the application field of traditional molybdenum powders, the preparation technology of molybdenum powders should be improved and optimized; in the emerging application field of molybdenum powders, molybdenum powders preparation technology should be innovated combined with the development of science and technology. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.
