Pressureless sintering preparation method for boron carbide ceramic

Abstract

The invention relates to a pressureless sintering preparation method for boron carbide ceramic, and coarse particle powder with the particle size larger than 2 micrometers is taken as raw materials. The method comprises the following steps that 70-80 wt % of boron carbide powder (D50>=2 micrometers), 4-8 wt% of carbon powder and 0.7-2 wt% of yttrium oxide powder are put into a ball mill mixing container, ball mill slurrying is performed after binding agents, dispersing agents and deionized water are added, and the solid phase content of obtained slurry is 25-45 wt%; the obtained slurry is prepared into granulating powder with a spray drying granulating machine; the granulating powder is pressed into green bodies by adopting a dry-pressing molding technology or isostatic cool pressing molding technology at 100-200 MPa; the green bodies are placed in a vacuum furnace, a vacuum or normal pressure sintering mode is adopted, heat preservation is performed for 0.5-5 h at the temperature of 2000 DEG C-2300 DEG C, sintering is completed, and then the boron carbide ceramic is obtained. According to the pressureless sintering preparation method for the boron carbide ceramic, due to the fact that the coarse particle boron carbide powder which is low in cost is adopted as the raw materials and the pressureless sintering technology capable of achieving scale production is adopted, the preparation cost of the boron carbide ceramic can be greatly lowered, and therefore the method is suitable for the fields of nuclear power, semiconductor equipment, armor protection and the like.

Description

technical field [0001] The invention relates to a method for preparing low-cost boron carbide ceramics by using coarse particle boron carbide powder as a raw material through a pressureless sintering process, belonging to the field of structural ceramics. technical background [0002] Boron carbide ceramics are used as neutron absorbing materials because of their low density, high hardness (second only to diamond and cubic boron nitride), high elastic modulus, corrosion resistance, wear resistance, neutron absorption and high temperature semiconductor properties. Bulletproof materials, wear-resistant nozzles, semiconductor precision structural components, etc., are widely used in nuclear energy, national defense and machinery and other fields. [0003] The covalent bond fraction of boron carbide ceramics is more than 90%, the self-diffusion coefficient is very low, the elimination of pores, the mass transfer mechanism of grain boundaries and volume diffusion require extremel...

AI Technical Summary

Problems solved by technology

The advantage of the pressureless sintering process is that it is suitable for large-scale production and can prepare large-sized and complex-shaped structural components. Due to process limitations, the current pressureless sintering of boron carbide mostly uses ultra-fine powders below 2 microns as raw materials, thereby improving the boron carbide ceramics. Sintering activity, to obtain a densified sintered body, but the grinding process of micron-sized boron carbide ultrafine powder is complicated and the price is high. Therefore, although the price of pressureless sintered boron carbide ceramics is lower than that of hot-pressed products, compared with other Carbide structural ceramics are still expensive

[0004] The higher price of boron carbide ceramics has become the biggest obstacle restricting its large-scale promotion and application