Composition useful as mortar or coatings refractories

Abstract

This invention relates to a composition comprising: ceramic refractory particulates made from alumina, one or more rare earth oxides, one or more oxides of a transition metal, the transition metal being Sc, Zn, Ga, Y, Cd, In, Sn, Tl, or a mixture of two or more thereof; an alumina and phosphate containing composition; and water. The composition is free of SiO 2 or substantially free of SiO 2 , and is useful as a mortar or coating for molten aluminum or steel contact refractories.

1 . A composition, comprising:
 ceramic refractory particulates made from an as-batched refractory composition which comprises alumina particulates, one or more rare earth oxides, and one or more oxides of a transition metal, the transition metal being Sc, Zn, Ga, Y, Cd, In, Sn, Tl, or a mixture of two or more thereof, the as-batched refractory composition being fired to form a ceramic refractory;   a phosphate and alumina containing composition; and   water;   the composition being free of SiO 2  or substantially free of SiO 2 .   
     
     
         2 . The composition of  claim 1  wherein the ceramic refractory is in the form of a solid structure which is ground to form the ceramic refractory p articulates. 
     
     
         3 . The composition of  claim 1  wherein the ceramic refractory is in the form of pellets or briquettes which are reduced in size to form the ceramic refractory p articulates. 
     
     
         4 . The composition of  claim 1  wherein the as-batched composition for making the ceramic refractory particulates further comprises chopped ceramic fibers containing nanofibrils, alumina fibers, or a mixture thereof. 
     
     
         5 . The composition of  claim 4  wherein the chopped ceramic fibers comprise strands of ceramic fiber chopped to a median length in the range from about 0.1 to about 5 cm, and having a median diameter in the range from about 1 to about 50 microns. 
     
     
         6 . The composition of  claim 4  wherein the nanofibrils extend the surface area of the chopped ceramic fibers by at least about 100 times the surface area of the chopped ceramic fiber without the nanofibrils. 
     
     
         7 . The composition of  claim 4  wherein the alumina fibers have a surface area in the range from about 50 to about 500 square meters per gram. 
     
     
         8 . The composition of  claim 4  wherein the alumina fibers have a median diameter in the range from about 1 to about 5 microns. 
     
     
         9 . The composition of any of  claim 4  wherein the alumina fibers comprise amorphous alumina and crystalline alumina. 
     
     
         10 . The composition of  claim 1  wherein the alumina particulates in the as-batched refractory composition comprise dehydrated boehmite, calcined boehmite, or a mixture thereof. 
     
     
         11 . The composition of  claim 1  wherein the as-batched refractory composition further comprises alumina aggregate. 
     
     
         12 . The composition of  claim 1  wherein the rare earth oxide in the as-batched refractory composition comprises an oxide of Pr, La, Ce, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or a mixture of two or more thereof. 
     
     
         13 . The composition of  claim 1  wherein the rare earth oxide in the as-batched refractory composition comprises Pr 6 O 11 , and the transition metal oxide in the as-batched refractory composition comprises Y 2 O 3 . 
     
     
         14 . The composition of  claim 1  wherein the ceramic refractory particulates have an average particulate size in the range up to about 150 microns. 
     
     
         15 . The composition of  claim 1  wherein the phosphate and alumina containing composition comprises an alumina adhesive. 
     
     
         16 . The composition of  claim 1  wherein the phosphate and alumina containing composition comprises a phosphate-bonded alumina coating system. 
     
     
         17 . The composition of  claim 1  wherein the phosphate and alumina containing composition comprises an aluminum phosphate. 
     
     
         18 . The composition of  claim 1  wherein the phosphate and alumina containing composition comprises monoaluminum phosphate. 
     
     
         19 . The composition of  claim 1  wherein the phosphate and alumina containing composition comprises alumina particulates and monoaluminum phosphate. 
     
     
         20 . The composition of  claim 1  wherein the water comprises distilled water. 
     
     
         21 . The composition of  claim 1  wherein the composition comprises from about 10 to about 35% by weight ceramic refractory particulates; from about 50 to about 85% by weight of the alumina and phosphate containing composition; and from about 5 to about 15% by weight water. 
     
     
         22 . The composition of  claim 1  wherein the composition is in the form of a coating composition. 
     
     
         23 . The composition of  claim 1  wherein the composition is in the form of a mortar composition. 
     
     
         24 . A process for treating a refractory comprising applying the composition of  claim 1  to a refractory, curing the composition, and firing the cured composition. 
     
     
         25 . The process of  claim 24  wherein the refractory is used for contacting molten aluminum and the cured composition is fired at a temperature up to about 815° C. 
     
     
         26 . The process of  claim 24  wherein the refractory is used for contacting molten steel and the cured composition is fired at a temperature up to about 1700° C.