| 摘要 |
<p>The prod. obtd. by sintering SiC powder contg. 0.2-10 wt.% uniformly dispersed B, calculated as B carbide and present as B carbide, opt. in solid soln. in SiC is prepd. by (a) mixing C powder, 20 micron or less particle size, Si metal powder and B203 powder such that molar % of each component falls in a given area of a specified C-Si-B203 ternary diagram, and (b) heating in oxidising atmos. contg. 0.3-35 vol.% 02 to induce a spontaneous continuous, instantaneously completed reaction at 800-1450 deg. C. The area is defined by points k, l, m, n, representing mol./ C, Si, B203 of: 62.4, 37.4, 0.2; 34.9, 64.9, 0.2; 52, 39, 9; 69, 22, 9. The prods. are prepd. by compression moulding the SiC powder before or during heating at 1900-2250 deg.C. in an inert atmos. or under reduced pressure. The prods. are useful for heat and chemically resistant structural parts for automobile engines, crucibles, mortars, pestles and tools. They have bulk densities over 80%, e.g. 92%, and are pred. without use of sintering accelerator, opt. with sintering at atmos. pressure, from a simply prepd. SiC powder.</p> |
