| 摘要 |
<p>1374458 Refractory NIPPON CRUCIBLE CO Ltd 23 Dec 1971 [25 Dec 1970] 60080/71 Heading C1J A composition substantially consists of (A) graphite and a carbonaceous binder, these yielding free bonding carbon after burning of the composition in a reducing atmosphere, (B) alumina and (C) silicon carbide, the total amount of bonding carbon, (B) and (C) being at least 85% by wt. based on the total weight of refractory formed by the above burning of the composition, the graphite being 8-37 wt. per cent of the total weight of bonding carbon, (B) and (C), and the weight ratio of bonding carbon: (B) : (C) being 10-38 : 60-80 : 2-18. The composition also contains 2-6% by wt. glassy matter (e.g. having a softening point of 800‹ to 1200‹ C.). Particle size details are given for the alumina and graphite. The production of 3 refractory materials is exemplified using selections from the following starting materials, electrocast or sintered alumina, natural graphite, silicon carbide powder, silicon powder, ferrosilicon powder, glass material, pitch and tar. The starting compositions were heated to 100- 300‹ C. above the pitch softening temperature, mixed, compressed, shaped in a mould preheated to 80‹ to 100‹ C. under pressure and then burned at about 1300‹ C. in a reducing atmosphere.</p> |
