Coarse-grained powder based pressureless sintering boron carbide ceramic preparation method

Abstract

The invention relates to a pressureless sintering boron carbide ceramic preparation method of using more than 2 microns of coarse-grained powder as a raw material. The preparation method comprises the following steps: putting 70-80 wt% of boron carbide (D50 is greater than or equal to 2 microns), 4-8 wt% of powdered carbon, 0.7-2 wt% of yttrium oxide powder and the balance a binder and a dispersant into a mixing container of a ball mill, adding deionized water and ball-milling for pulping so as to obtain slurry with solid content being 25-45 wt%; preparing granulation powder from the slurry by using a spray drying granulating machine; pressing the granulation powder at 100-200 MPa by a dry pressing or isostatic cool pressing process to generate a green body; and putting the green body into a vacuum furnace, and carrying out thermal insulation at 200-2300 DEG C for 0.5-5h to finish sintering by a vacuum or pressureless sintering mode so as to obtain boron carbide ceramic. As the low-cost coarse-grained boron carbide powder is used as the raw material, manufacturing cost of the boron carbide ceramic can be reduced greatly by the pressureless sintering process for large-scale production. The boron carbide ceramic is suitable for 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. Background technique [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