| 摘要 |
<p>Pitch-bonded basic refractories are produced by impregnating basic refractory grains having an open porosity of 25-50% with carbon or a carbonaceous residue, intimately mixing said impregnated grains with bonding pitch, and shaping the mixture. The refractory grains may be calcined dolomite, alumina, silicon carbide, forsterite or mullite but preferably contain at least 95% by weight MgO and not more than 40% SiO2, and may have pores of effective diameter 5-100 microns. The pores may be impregnated with a carbonaceous liquid such as liquid pitch or tar which is subsequently carbonized by heating or converted to a polymerized residue by air-blowing and heating, or they may be impregnated by deposition of carbon from a hydrocarbon gas at a cracking temperature. An amount of 8-11% bonding pitch with a softening point of 65-150 DEG C. may be used, and a minor amount, e.g. 40%, refractory fines of - 200 mesh (U.S. sieve) may be added to the refractory grains. The total carbon content of the refractory shape after carbonization of the bonding pitch may be 5-28% by weight.</p> |
