Diffusion coating of metals

Claim 1

IN A PACK IMPREGNATION DIFFUSION COATING OF THE CHARACTER DESCRIBED FOR PRODUCING AN OUTER LAYER OF METALLIC CONSTITUENTS DIFFUSED INTO THE SURFACE OF A METAL ARTICLE, THE STEPS WHICH COMPRISE EMBEDDING SAID METAL ARTICLE IN A DIFFUSION COATING PACK INCLUDING A SOURCE OF CHROMIUM AND ALUMINUM AS THE METALLIC MATERIALS TO BE DIFFUSION COATED INTO THE SURFACE THEREOF AND A SOURCE OF VAPORIZABLE HALOGEN FOR DIFFUSION OF SAID MATERIALS INTO SAID METAL ARTICLE, HEATING SAID PACK WITH SAID MATERIALS AND SAID ARTICLE THEREIN EFFECTING VAPORIZING OF SAID HALOGEN AND DIFFUSION OF SAID METALLIC MATERIALS INTO THE SURFACE OF SAID ARTICLE, ALSO PRODUCING IN SAID HEAT AND DIFFUSION COATING STEP RESULTANT COMPONENTS IN SAID PACK INCLUDING CHROMIUM ALUMINIDE WHICH ARE NOT DIFFUSION COATED INTO THE SURFACE OF SAID ARTICLE, REMOVING SAID THUS COATED ARTICLE FROM SAID PACK, EMBEDDING A SUBSEQUENT ARTICLE TO BE COATED IN THE SAME SAID PACK FOR RE-USE THEREOF AND A SUBSEQUENT DIFFUSION COATING OPERATION, INCLUDING IN SAID PACK AT LEAST IN SAID SUBSEQUENT COATING OPERATION A FLUORIDE AS AT LEAST A PART OF SAID VAPORIZABLE HALOGEN COMPONENT, HEATING SAID ARTICLE EMBEDDED IN SAID PACK IN SAID SUBSEQUENT COATING OPERATION FOR DIFFUSION COATING OF SAID METALLIC MATERIALS INTO THE SURFACE THEREOF, AND EFFECTING BY THERMAL REACTION WITH SAID FLUORIDE BREAKDOWN OF SAID RESULTANT CHROMIUM ALUMINIDE COMPONENTS FORMED IN SAID PRECEEDING COATING STEP FOR A DIFFUSION COATING THEREOF INTO SAID ARTICLE IN SAID SUBSEQUENT COATING STEP IN SAID PACK.