Method of manufacturing composite refractory objects

Claim 1

METHOD OF PRODUCING REFRACTORY OBJECTS COMPRISING A BACKING AND A FACING WHEREIN THE FACING CONSISTS ESSENTIALLY OF A REFACTORY MATERIAL DIFFERENT FROM THE REFACTORY MATERIAL OF THE BACKING WHICH COMPRISES: POURING INTO A CONTAINER: (1) A FIRST SLURRY COMPRISING REFRACTORY PARTICLES, A LOWER ALKYL SILICATE, WATER, MUTUAL SOLVENT AND A GELLING ACCELERATOR; (2) ON TOP OF THE FIRST POURED SLURRY, A SECOND SLURRY COMPRISING REFRACTORY PARTICLES DIFFERENT FROM THOSE OF THE FIRST SLURRY, A LOWER ALKYL SILICATE, WATER, MUTUAL SOLVENT AND A GELLING ACCELERATOR; THE PROPORTIONS OF WATER, MUTUAL SOLVENT AND GELLING ACCELERATOR BEING ADJUSTSED SO THAT THE GELLING TIME OF THE FIRST SLURRY IS LONGER THAN THE GELLING TIME OF THE SECOND SLURRY, VIBRATING THE MASS DURING GELATION THEREBY TO EFFECT MIGRATION OF REFACTORY PARTICLES FROM EACH POURED LAYER INTO THE ADJACENT LAYER WHEREBY THE RATE OF SETTING OF THE ZONE OF TRANSITION BETWEEN SAID LAYER WILL BE GRADULLY PROLONGED FROM THE LOWER PART OF THE LAYER DEVELOPED FROM THE FIRST POURING TO THE UPPER PARTOF THE LAYER DEVELOPED FROM THE SECOND POURING, AND WHEN THE COMPOSITE OBJECT IS SET, FIRING IT.