Slip-casting process

Claim 1

A SLIP-CASTING PROCESS, IN WHICH THE SLURRY USED TO FORM THE WET CASTING ON THE POROUS MOULD IS AN AQUEOUS SLURRY CONSISTING ESSENTIALLY OF A FINELY-DIVIDED REFRACTORY MATERIAL, A SILICA SOL WHOSE SILICA CONTENT IS IN THE RANGE OF FROM 10% TO 30% BY WEIGHT, AND A STABILIZING AMOUNT UP TO 1% BY WEIGHT OF AN ORGANIC STABILIZING AGENT SELECTED FROM THE GROUP CONSISTING OF A NON-IONIC SURFACEACTIVE AGENT AND A CATIONIC SURFACE-ACTIVE AGENT, SAID SLURRY HAVING A PH SUCH THAT THE SLURRY REMAINS HOMOGENEOUS ON STANDING, SAID REFRACTORY MATERIAL BEING COMPOSED OF PARTICLES WHICH PASS THROUGH OF 200 MESH BRITISH STANDARD SIEVE AND BEING SELECTED FROM THE GROUP CONSISTING OF ALUMINA, CARBORUNDUM, CHROMITE, SILICA, ZIRCONIUM SILICATE AND SILIMANITE, SAID CATIONIC SURFACEACTIVE AGENT BEING SELECTED FROM THE GROUP CONSISTING OF QUANTERNARY AMMONIUM SALT SURFACE-ACTIVE AGENTS AND GELATIN, THE WEIGHT RATIO OF SILICA TO THE FINELY DIVIDED REFRACTORY MATERIAL BEING FROM 6 TO 12 PARTS BY WEIGHT OF SILICA FOR EACH 175 PARTS BY WEIGHT OF THE REFRACTORY MATERIAL.