Patent ID: 7622195

Claim:
A process of coating an article, comprising: (1) applying a ceramic compound to at least one surface of an article to form a layer of ceramic compound; (2) applying at least one inert compound upon said ceramic compound layer to form a protective layer, wherein said at least one inert compound comprises a first inert compound comprising a cubic crystalline structure of formula (I): A 3 B 2 X 3 O 12 (I) where A comprises at least one of the metals selected from the group consisting of Ca +2 , Gd +3 , In +3 , Mg +2 , Na + , K + , Fe +2 , La +2 , Ce +2 , Pr +2 , Nd +2 , Pm +2 , Sm +2 , Eu +2 , Gd +2 , Tb +2 , Dy +2 , Ho +2 , Er +2 , Tm +2 , Yb +2 , Lu +2 , Sc +2 , Y +2 , Ti +2 , Zr +2 , Hf +2 , V +2 , Ta +2 , Cr +2 , W +2 , Mn +2 , Tc +2 , Re +2 , Fe +2 , Os +2 , Co +2 , Ir +2 , Ni +2 , Zn +2 , and Cd +2 ; where B comprises at least one of the metals selected from the group consisting of Zr +4 , Hf +4 , Gd +3 , Al +3 , Fe +3 , La +2 , Ce +2 , Pr +2 , Nd +2 , Pm +2 , Sm +2 , Eu +2 , Gd +2 , Tb +2 , Dy +2 , Ho +2 , Er +2 , Tm +2 , Yb +2 , Lu +2 , In +3 , Sc +2 , Y +2 , Cr +3 , Sc +3 , Y +3 , V +3 , Nb +3 , Cr +3 , Mo +3 , W +3 , Mn +3 , Fe +3 , Ru +3 , Co +3 , Rh +3 , Ir +3 , Ni +3 , and Au +3 ; where X comprises at least one of the metals selected from the group consisting of Si +4 , Ti +4 , Al +4 , Fe +3 , Cr +3 , Sc +3 , Y +3 , V +3 , Nb +3 Cr +3 , Mo +3 , W +3 , Mn +3 , Fe +3 , Ru +3 , Co +3 , Rh +3 , Ir +3 , Ni +3 , and Au +3 ; and where O is oxygen; and (3) heat treating said article.