Because of spherical tungsten carbide powder (WC) has the properties of high hardness, wear resisting and chemical property and acid and alkali resistant, it has widely potential application value in the fields of fuel cell anode, cathode catalyst material, gas sensor, petroleum catalyst, photocatalyst material. 

Tungsten oxide (WO₃) with low dimensional nanostructure is a kind of important functional material, especially the WO₃ nanometer single crystal. Since it has good gas sensitive, light corrosion resistance, electrochromism, gasochromism, thermochromism and photochromism and other properties, it is widely used in gas sensor, visible light catalyst, flat-panel display, and other fields. The raw materials of tungsten trioxide nanometer single crystal are soluble tungstate, WO₃ceramics material, metal tungsten and tungsten hexachloride, with the manufacturing method of ion exchange, hydrothermal, gas phase deposition and sol-gel method, etc. 

Heavy liquid method is the most accurate measure for nondestructive separation of material, and the most accurate method for accurately measuring the relative density of single grain material. Usually, the heavy liquid can be divided into three categories as following:

1. Halogen hydrocarbons which have the relative density within 0.86 ~ 3.32, but they are very easy to volatilize with a small viscosity and poison; 

2. Salt aqueous solution which has the big proportion, and easily soluble, with its relative density of 1.0 ~ 4.3, however, most of them are expensive, or with the property of unstable, toxicity, easy to react; 

3. Salts and their mixture with low melting temperature, while the specific gravity can reach to 4.7, and the nitrate or halide with mercury, silver, thallium, tin, antimony is generally used. The defect of this kind of heavy liquid is that the temperature should be raised when it is used, and mostly of them will easily react with water and minerals, and the extremely toxic.