Chromia spray powders
AssigneeSaint-Gobain Ceramics & Plastics, Inc.
InventorsSung H. Yu, Howard Wallar
Life of this patent
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Abstract
Particles particularly useful for thermal spraying a wear resistant coating on to a substrate comprise an essentially single phase crystalline structure comprising from 45 to 99% by weight of chromia and 55 to 1% by weight of alpha alumina.
Claims11
A powder which comprises an essentially single-phase, thermosprayable powder comprising from 45 to 99% chromia and correspondingly 55 to 1% of a compound selected from the group consisting of compounds isostructural with chromia, precursors of such compounds and mixtures thereof, all proportions being by weight and calculated on the basis of the combined weights of the chromia and the isostructural compound, or if appropriate of the precursor expressed in terms of the isostructural equivalent, and less than 200 ppm of each of any compound effective to stabilize chromium in the hexavalent state.
A process for the production of a thermosprayable powder which comprises mixing a compound selected from the group consisting of compounds isostructural with chromia, precursors of such compounds and mixtures thereof, in the form of a powder having a content of alkali metal and alkaline earth metal oxide impurities of not more than 120 ppm of each, with a chromia powder also having less than 120 ppm of any impurity effective to stabilize chromium in the hexavalent state, the powders being mixed in proportions to give, upon firing, an essentially single phase crystalline powder comprising from 45 to 99% of chromia and from 55 to 1% of the isostructural compound, all proportions being by weight, and firing the mixture at a temperature of from 1300 to 1500° C. to produce the said essentially single-phase crystalline powder.
Dependencies are inferred from the claim text.