Castable-refractory die composition essentially free of calcium aluminate and method of using
Abstract
Abstract A CASTABLE-REFRACTORY MATERIAL HAVING GOOD GREEN STRENGTH, EXCELLENT DIMENSIONAL STABILITY WHEN FIRED AT ABOUT 1800 TO 3500*F., GOOD HARDNESS AND STRENGTH AFTER BEING FIRED AND THERMAL CHARACTERISTICS, SUITING IT FOR USE WITH PORCELAINS USED TO MAKE DENTAL PROSTHESES IS OBTAINED BY MIXING (40 TO 100 PARTS OF MAGNESIUM OXIDE WITH UP TO 32 PARTS OF GLASS AND ABOUT 15 TO 25 PARTS OF AMMONIUM DIHYDROGEN PHOSPHATE (UP TO 40 PARTS OF THE MAGNESIUM OXIDE BEING REPLACEABLE WITH ALUMINA) TO FORM A DRY MIXTURE AND THEN BLENDING 20 PARTS OF THE DRY MIXTURE WITH APPROXIMATELY 4 PARTS OF COLLOIDAL SILICA SOL OF 40% SOLIDS CONTENT. THE NOVEL COMPOSITION IS SUPERIOR TO OTHERS PREVIOUSLY USED THAT CONTAINED CALCIUM ALUMINATE IN SEVERAL RESPECTS, TENDING TO EXHIBIT A MORE CONTROLLABLE COEFFICIENT OF THERMAL EXPANSION GREATER ASFIRED HARDNESS AND STRENGTH AS EVIDENCED BY A BHN OF ABOUT 50, AND LESSENED TENDENCY TOWARD SPALLING AND STRUCTURAL BREAKDOWN AFTER REPEATED FIRING, AND THERMAL STABILITY IN ALL RESPECTS AT TEMPERATURES UP TO 3300*F.
Inventors
- 👤 Kristin Brigham
- 👤 Ronald C Vickery
Bibliographic Details
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