Process of forming protective coatings on columbium and tantalum using a fluidized bed

Claim 1

IN A PROCESS FOR THE PRODUCTION OF A COATED REFRACTORY-METAL-BASE ARTICLE RESISTANT TO OXIDATION AT HIGH TEMPERATURES, THE STEPS COMPRISING (1) HEATING AN ARTICLE, COMPRISING A REFRACTORY METAL SELECTED FROM THE GROUP CONSISTING OF COLUMBIUM AND TANTALUM AND HAVING TITANIUM AT LEAST AT THE SURFACE THEREOF, IN A FLUIDIZED BED CONSISTIGN ESSENTIALLY OF (A) PARTICLES OF AN OXIDE SELECTED FROM THE GROUP CONSISTING OF SILICA, ALUMINA, THORIA AND ZIRCONIA, (B) A POWDERED METAL SELECTED FROM THE GROUP CONSISTING OF MOLYBDENUM AND TUNGSTEN, (C) SILICON, AND (D) IODINE VAPOR, WHEREBY DEPOSITION ON SAID TITANIUMCOMPRISING REFRACTORY-METAL ARTICLE OF A LAYER OF DISILICIDE OF THE METAL CHOSEN IN (B) IS EFFECTED, AND (2) HEATING SAID METAL-DISILICIDE-COATED ARTICLE IN A FLUIDIZED BED COMPRISING (A) AN OXIDE SELECTED FROM THE GROUP CONSISTING OF SILICA, ALUMINA, THORIA AND ZIRCONA, (B) SILICON, AND (C) IODINE VAPOR, WHEREBY A LAYER OF SILICON IS DEPOSITED ON SAID DISILICIDE-COATED ARTICLE.