Method for suppressing reaction of molten metals with refractory materials
A method is described for improving resistance to chemical attack by aluminum or magnesium in refractory components. In one method, a slurry is formed comprising-calcium silicate-containing refractory material and a barium-containing compound. This slurry is placed in a mould, then dewatered to form a component which is hydrothermally processed to form a final component. In a second procedure, a silica-containing porous refractory component is impregnated with an aqueous solution of an oxide or hydroxide of barium or strontium and thereafter dried in air.
1 . A method of making an unfired refractory component that is resistant to reaction with molten aluminum or magnesium, comprising:
(a) forming a slurry comprising calcium silicate-containing refractory material and a barium- or strontium-containing compound;
(b) placing the slurry in a mould;
(c) dewatering the slurry to form the component; and
(d) hydrothermally processing the component to form a final product.
2 . A method according to claim 1 wherein the barium- or strontium-containing compound is a barium-containing compound selected from barium sulphate, barium oxide and barium hydroxide.
3 . A method according to claim 2 wherein the barium sulphate is a powder or a slurry.
4 . A method according to claim 2 wherein the barium oxide or the barium hydroxide is an aqueous solution.
5 . A method according to claim 4 wherein the aqueous solution is prepared with water at a temperature of at least 30° C.
6 . A method according to claim 4 wherein the aqueous solution is prepared with water at a temperature of at least 40° C.
7 . A method of stabilizing a silica-containing porous refractory component against reactions with molten aluminum or magnesium, comprising:
(a) forming an aqueous solution of an oxide or hydroxide of a group II alkali earth;
(b) impregnating the component with the solution; and
(c) drying the impregnated component in air.
8 . A method according to claim 7 wherein the group II alkali earth is selected from barium and strontium.
9 . A method according to claim 7 further comprising impregnating the component with a sulphuric acid solution and drying the component in air, after step (c).
10 . A method according to claim 7 wherein the porous refractory component is a fired component.
11 . A method according to claim 7 wherein the porous refractory component is an unfired component.
12 . A method according to claim 7 wherein the aqueous solution is formed at a temperature of at least 30° C.
13 . A method according to claim 7 wherein the aqueous solution is formed at a temperature of at least 40° C.