Tungsten Carbide Button Material Optimization (2/2)

Gradient structure optimization, also known as multi-phase alloy, its main feature is the tissue composition gradient distribution. The principle is obtained by vacuum sintering carbide containing η phase and change the distribution of Co binder phase in the carburizing atmosphere, so that different parts of the distribution of the content of different Co. That was the lowest outermost Co, known as Co-depleted layer, an intermediate for the high content of Co-rich, inner layer of WC, Co, η phase three-phase microstructure. As a result, when the gradient structure in tooth carbide ball mining or drilling operations, WC content in the outer layer of high, high hardness, wear resistance, because the intermediate layer has a high content of Co good toughness, so rock breaking load correspondingly higher. In addition, domestic researchers also study the carburizing time, carburizing temperature and carburizing atmosphere affecting the gradient structure of cemented carbide buttons that an appropriate increase in carburizing temperature is conducive to the migration to the liquid phase Co sintered body inside, different size of the sintered body, should choose different carburizing times.

Improving tungsten carbide buttons properties by adding trace elements is common in the production. Trace elements commonly added tantalum (Ta), molybdenum (Mo), phosphorus (P), a nickel (Ni), titanium carbide (TiC), tantalum carbide (of TaC) and so on. Ta and Mo as the trace elements added to the WC-Co cemented carbide system, Ta, and Mo dispersion complex carbide layer is formed between the WC particles and part of the Mo Co binder phase, which play an enhanced when worn the role of grain boundaries, thereby increasing the fracture toughness carbide button. And added Ni, P elements can be formed with the bonding phase Co Ni-Co-P alloy, Ni-P alloy, and Co-P alloys, which their eutectic temperature are significantly lower than Co itself eutectic temperature, so that the desired temperature drop obtained sintering, sintering more fully, densification is improved. TiC and TaC can improve the binder phase composition and microstructure of the grain boundaries to some extent, thereby enhancing the thermoplastic resistance, wear resistance and thermal shock resistance of tungsten carbide buttons, but it will decrease the strength of tungsten carbide buttons and increase the cost of manufacturing and using.