Coarse grain WC-Co alloys with high hardness and high toughness, is widely used in mining drilling tools, oil drilling tools, stamping dies, wear resistant parts, high temperature and high pressure resistance, metal pressure processing tools, steel rolling roll ring, hard surface materials and so on. With the rapid development of Chinese economy, the application of tungsten carbide wear-resistant material is widely growing.
Traditional manufacturing processes of coarse tungsten carbide powder are molybdenum wire furnace high temperature reduction and carbon tube furnace high temperature carbonization; in the 90s, mainly the reduction in the middle temperature and the carbonization in high temperature of tungsten oxide doped, this process can produce coarse tungsten carbide powder of about 301xm ~ 401xm; high temperature carbonization adding cobalt and nickel, to get extremely coarse carbide powder; Kennametallne in US developed the aluminum heat production of tungsten carbide and the Russian Research Institute of chemical technology has developed the tungsten concentrate "furnace" thermite reduction method, tungsten carbide can be produced directly from tungsten concentrate, X-ray diffraction analysis of the metal phase containing tungsten carbide obtained by this method shows that the product contains only a tungsten carbide phase, and the grains are coarse; H.C. Stark Co., Ltd. has developed a process that reduction and carbonization treatment to the tungsten oxide powder by the presence of the alkali metal compounds, producing ultra-coarse single crystal tungsten carbide and thus prepare hard metal . Some coarse tungsten carbide powder produced by the processes above has uneven widespread size, incomplete crystallization, and with much fine particles and abroad particle size distribution; some methods have high requirements of equipment or great impact on environment. A lot of information discusses the micro structure of tungsten carbide powder with the presence of native inheritance among tungsten powder, the form and structure of tungsten powder directly affect the properties of tungsten carbide. By studying the carbonization process of tungsten powder re-grading, there is an effective solution to the powder clipping coarse or fine powder, manufacturing coarse grain tungsten carbide powder.
Powder properties can be measured not only by the particle size of the powder, but also the powder size, the structure and composition, particle morphology, surface characteristics of the particles and the like must be considered. After classification treatment, A1 powder grain has better morphology consistency. According to the proportion, the particles, the size and shape suffered different gravity and different resistance of medium in the air, being graded with different sedimentation rates, can effectively change the physical properties of the powder. At the same time, despite the use of airflow and iron container as the carrier grades, there is little effect on the oxygen and the iron powder and other trace elements. Within the range of performance indicators, it will not have a negative impact on the process behind the process.
