| 摘要 |
The subject of the invention is thin large-area neutron-absorber plates having a volume composition of from 40 to 60% and preferably from 45 to 60% by volume of boron carbide, from 25 to 5% by volume and preferably 15 to 5% by volume of free carbon, the remainder being pores, a density of from 1.4 to 1.8 g/cm3, a flexural strength at room temperature of from 15 to 45 N/mm2, a compressive strength at room temperature of from 25 to 60 N/mm2, a modulus of elasticity at room temperature of from 10,000 to 20,000 N/mm2, and a resistance to ionizing radiation of at least 1011 rad, which plates may be produced by mixing boron carbide powder, containing at least 75% by weight of boron and a proportion of boron oxide of less than 0.5% by weight, and having a particle size distribution of at least 95% finer than 50 mu m and, optionally, graphite powder with a pulverulent organic resin binder and a wetting agent, shaping the mixture under pressure at room temperature, curing the resin binder at temperatures of up to 180 DEG C., and then coking the shaped plates with the exclusion of air at temperatures of up to approximately 1000 DEG C. with a controlled temperature increase. |
