Cast bodies, castable compositions, and methods for their production

1. A castable composition producing, when cast with a water content of 2.8 wt % or less, a cast product having a porosity equal to or less than 10 volume percent when measured after exposure to 230 degrees F., wherein the composition has a property selected from the group consisting of:

(a) the composition contains at least four grain fractions, of which three adjacent grain fractions are separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the three adjacent grain fractions have remaining weight percentages that are, with respect to the respective immediately larger particle size fractions and in order of decreasing particle size, smaller, larger and smaller in value;

(b) the composition contains at least four grain fractions, of which three adjacent grain fractions are separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the three adjacent grain fractions have remaining weight percentages that are, with respect to the respective immediately larger particle size fractions and in order of decreasing particle size, larger, smaller, and larger in value; and

(c) the composition contains at least four grain fractions separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the remaining weight percentages are at least 40% in each of the at least four grain fractions.

2. A castable composition according to claim 1 , wherein the cast product has a property selected from the group consisting of (a) a modulus of rupture equal to or greater than 1000 pounds per square inch as measured after exposure to 230 degrees F., and (b) a cold crushing strength equal to or greater than 3000 pounds per square inch as measured after exposure to 230 degrees F.

3. A castable composition according to claim 1 , having a porosity equal to or less than 15 volume percent after exposure to 1500 degrees F.

4. A castable composition according to claim 1 , producing, when cast with a water content of 2.8 wt % or less, a cast product having a modulus of rupture equal to or greater than 1000 pounds per square inch after exposure to 1500 degrees F.

5. A castable composition according to claim 1 , producing, when cast with a water content of 2.8 wt % or less, a cast product having a cold crushing strength equal to or greater than 3000 pounds per square inch after exposure to 1500 degrees F.

6. A castable composition according to claim 1 , comprising a coarsest refractory grain fraction comprising at least 50% by weight of the dry composition, and wherein the coarsest refractory grain fraction is separated from a smaller grain fraction by a gap having a ratio of largest particle diameter of the gap range to smallest particle diameter of the gap range being at least the square root of 2.

7. A castable composition according to claim 1 , in which the composition contains at least four grain fractions, of which three adjacent grain fractions are separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the three adjacent grain fractions have remaining weight percentages that are, with respect to the respective immediately larger particle size fractions and in order of decreasing particle size, smaller, larger and smaller in value.

8. A castable composition according to claim 1 , in which the composition contains at least four grain fractions, of which three adjacent grain fractions are separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the three adjacent grain fractions have remaining weight percentages that are, with respect to the respective immediately larger particle size fractions and in order of decreasing particle size, larger, smaller, and larger in value.

9. A castable composition according to claim 1 , wherein the composition contains at least two grain fractions separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the at least two grain fractions are entirely composed of particles with diameters less than 100 micrometers.

10. A castable composition according to claim 1 , wherein the composition contains at least three grain fractions separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the at least three grain fractions are entirely composed of particles with diameters less than 100 micrometers.

11. A castable composition according to claim 1 , wherein the composition contains at least four grain fractions separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two, and the remaining weight percentages are at least 40% in each of the at least four grain fractions.

12. A castable composition according to claim 1 , wherein the composition contains at least five grain fractions separated by gaps having a particle diameter ratio of the largest particle diameter of the gap range to the smallest particle diameter of the gap range of at least the square root of two.

13. A castable composition according to claim 7 , wherein at least two of the gaps each contain less than 10 percent by mass of the mass of the dry composition.

14. A castable composition according to claim 1 , wherein the cast product has a density that is at least 80.7% of the theoretic density.

15. A castable composition according to claim 1 , wherein the cast product has a density that is at least 83.6% of the theoretic density.

16. A castable composition according to claim 1 , comprising at least 95 wt % alumina.

17. A castable composition according to claim 16 , wherein the cast product has a bulk density of at least 190 pounds per cubic foot after exposure to 230 degrees F.

18. A castable composition according to claim 16 , wherein the cast product has a bulk density of at least 195 pounds per cubic foot after exposure to 230 degrees F.

19. A method for producing a cast product, comprising, (a) providing a mold having a cavity which corresponds to the size and shape of the product, (b) filling the cavity with a castable composition according to claim 1 , (c) optionally subjecting the castable composition of the invention to compacting and/or vibration, (d) curing the castable composition to form the cast product, and (e) separating the mold from the cast product.

20. A method for producing a cast product, comprising, (a) providing a mold having a cavity which corresponds to the size and shape of the product, (b) filling the cavity with a castable composition according to claim 1 , (c) subjecting the castable composition of the invention to a compression process, (d) curing the castable composition to form the cast product, and (e) separating the mold from the cast product.