After the 1990s, ultra-fine ammonium paratungstate has been common concerned around the world. compared to tungsten powder of conventional size, the sintering temperature of Ultra-fine ammonium paratungstate can be greatly reduced, if the particle size distribution is narrow, material organizational structure will remain nano-sized grains after sintering.
Preparation of ultra-fine ammonium paratungstate has been researched a lot both in China and abroad, such as gas evaporation method and high-energy ball milling method as physical methods. There is a method by controlling hydrogen flow, dew point, temperature, or change the way through hydrogen, called added dopant optimize the traditional process method, and this method is simple, reliable, good quality and low cost. There is a method by changing yellow tungsten to tungsten halide, blue tungsten oxide, violet tungsten oxide as raw materials for the production of ultrafine tungsten powder, but which the most suitable raw material for the production of ultrafine tungsten powder is is unclear currently. There is also a electrolytic method by using molten salt electrolysis tungsten oxide, which requires high technical conditions and the productivity is low.