Low pressure sintering's main function is to reduce the microscopic pore in cemented carbide. The porosity of the sintered body in the vacuum sintering stage has been eliminated. Microscopic pore pressure stage mainly eliminated.
Low porosity is an important symbol of high quality hard alloy, try to reduce the porosity in the cemented carbide in the production, is one of the main pursuit of carbide workers.
Carbide densification and capillary force, the wettability of liquid phase for solid phase and the surface tension of the liquid has a close relation with the associated, as in the process of sintering temperature, when a liquid phase, due to the capillary pressure, the liquid phase to the surface of WC mobile, because the liquid has good wettability to WC phase, liquid phase was attached to the surface of WC, because the surface tension of the liquid phase, driven by liquid package WC mobile, strong contraction occurs at this point. In WC mobile liquid package, in the process of contraction, exists in the gas is out of briquetting, due to the flow of the liquid phase, a part of the porosity of the sintered body is liquid closed, with the augmentation of the contract, enclosed within the pore pressure, when the surface tension is equal to or less than the pressure in the pore, closed pore preserved in the alloy, microscopic pore space.
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