| abstract |
Stable magnesium containing silicate sols are produced by preparing a solution of silicon alkoxide and of magnesium alkoxide and optionally of aluminum alkoxide in solvent wherein the atomic ratio of Mg to Si ranges from 0.3:1 to 4:1 and simultaneously reacting said alkoxides with peroxy compound or peroxy compound and water. Water presence, rate of addition of reactant, quantity of solvent and temperature of reaction are controlled to negate formation of precipitate. For a magnesium silicate sol, preferably the silicon alkoxide is tetraethylorthosilicate, the magnesium alkoxide is magnesium methoxide, the solvent is methanol and 30% H 2 O 2 is used as a reactant. For a magnesium aluminosilicate sol, preferably the silicon alkoxide is tetraethylorthosilicate, the magnesium alkoxide is selected from the group consisting of magnesium-s-butoxide and magnesium-2-(2'-methoxyethoxy)ethoxide, the aluminum alkoxide is aluminum isopropoxide, the solvent is sec-butanol and 2-(2'-methoxyethoxy)ethanol and 30% H 2 O 2 is used as a reactant. A magnesium silicate sol containing unreacted alkoxy can be reacted with HF to produce a magnesium fluoride silicate sol. The sols are used for coating by forming a layer thereof on a substrate and drying. The coating can be converted to ceramic by firing in the case of substrates which are not harmed by the firing method. The sols are used to produce fibers by a process comprising the steps of concentrating, converting to gel fibers, drying and firing. |