Abstract: The invention is a ceramically-bonded large-area neutron absorber articles of low density having a space filling ofabout 40 to 60% by volume boron carbide+silicon carbide in a B.sub.4 C:SiC ratio of about 9:1 to 1:9 andabout 10 to 20% by volume of free carbon, the remainder pores.They have a density of from about 1.5 to 2.2 g/cm.sup.3 and a flexural strength of from about 20 to 50 N/mm.sup.2 at room temperature measured according to the 3-point method, which strength after the corrosion test of immersion for about 3000 hours in boiling water, drops by less than about 40% of the initial value. Graphite powder may optionally be included with a pulverulent organic resin binder and a wetting agent, molding the mixture under pressure at about room temperature, curing the resin binder at temperatures of up to about 180.degree. C. and then coking the molded plates in the absence of air at temperatures of up to about 1000.degree. C. under a controlled temperature program.

Abstract: 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/cm.sup.3, a flexural strength at room temperature of from 15 to 45 N/mm.sup.2, a compressive strength at room temperature of from 25 to 60 N/mm.sup.2, a modulus of elasticity at room temperature of from 10,000 to 20,000 N/mm.sup.2, and a resistance to ionizing radiation of at least 10.sup.11 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.