| 摘要 |
A castable refractory mix is prepared by mixing together an aggregate of high refractoriness e.g. fused alumina, magnesia, mullite, sillimanite, or raw or calcined kyanite, a bonding agent consisting of a calcium aluminate hydraulic cement containing not less than 95% by weight of CaO and Al2O3, a foaming agent and water, and working the mixture to form a foamed castable mass. The cement may form 10 to 25% by weight of the total dry ingredients. The foaming agent may be incorporated into the aggregate-cement mix as a separately produced stable foam or foaming may be produced by agitating the total mix. In an example fused alumina passing a 100 B.S. sieve is mixed with 15% of its weight of a cement having the composition Al2O3 : 70-72%, CaO : 25-29%, SiO2 and Fe2O3 each less than 1%, and a stable foam is produced from a 4% aqueous solution containing an alkyl naphthalene sulphonate and a foam stabilizer. The mix is poured into a mould, cured for 24 hours, airdried for 24 hours and fired to 1500 DEG C. for 4 hours. |
