Process for thermal plasma spraying of doped semiconductor oxide-based coatings

Abstract

A process for the preparation of a composite multilayer product with selective optical properties comprises the operation of depositing, by thermal plasma spraying of powders, a coating of semiconductor oxides doped with oxides of elements chosen from the group consisting of transition metals and metals in the groups III-A and V-A of the periodic table of elements, in which the coating obtained maintains the composition and doping of the thermal plasma sprayed powders substantially unchanged. The figure shows the X-ray diffraction spectrum of a coating deposited according to the process of the present invention.

1 . Process for the preparation of a composite multilayer product with selective optical properties, characterised in that it comprises the stage of depositing by thermal plasma spraying of powders, on a base made of structural material with low density and/or high thermal resistance, a coating of semiconductor oxides, doped with oxides of elements chosen from the transition metals and metals in groups III-A and V-A of the periodic table of elements so that the coating obtained maintains the composition and doping of the thermal plasma sprayed powders substantially unchanged.  
     
     
         2 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 1 , in which coatings with a composition chosen from the following are deposited: indium oxide doped with stannous oxide and/or cadmium oxide, zinc oxide doped with aluminium oxide and/or indium oxide, stannous oxide doped with antimony oxide and/or zinc oxide and/or fluorine, cadmium oxide doped with stannous oxide, and their combinations.  
     
     
         3 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 2 , in which coatings with a composition chosen from the following are deposited: indium oxide doped up to 15% with stannous oxide and/or up to 5% with cadmium oxide, zinc oxide doped up to 5% with aluminium oxide and/or up to 5% with indium oxide, stannous oxide doped up to 10% with antimony oxide and/or up to 35% with zinc oxide and/or with fluorine since the F/Sn ratio is between 0.15 and 0.30, and cadmium oxide doped up to 35% with stannous oxide.  
     
     
         4 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 3 , in which coatings with a composition chosen from the following are deposited: indium oxide doped with 10% stannous oxide, indium oxide doped with cadmium oxide, zinc oxide doped with 2% aluminium oxide, zinc oxide doped with indium oxide, stannous oxide doped with approximately 3% antimony oxide, stannous oxide doped with percentages of zinc oxide from 10 to 35%, stannous oxide doped with fluorine according to a ratio F/Sn=0.25, and cadmium oxide doped with 33% stannous oxide.  
     
     
         5 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 1 , in which said low density structural material is chosen from the group comprising aluminium, aluminium alloys, titanium, titanium alloys, composite products with polymeric matrix, composite products with carbon fibres.  
     
     
         6 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 5 , in which the composite product with carbon fibre is of the type C—C or C—SiC.  
     
     
         7 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 1 , in which the material with low density and/or high thermal resistance is a composite product with carbon fibres.  
     
     
         8 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 7 , in which the composite product with carbon fibres is of the type C—C or C—SiC.  
     
     
         9 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 1 , in which the structural material with high thermal resistance is chosen from the group comprising steel and superalloys of nickel and cobalt.  
     
     
         10 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 1 , in which at least one intermediate layer is deposited between the base and the doped semiconductor oxide coating.  
     
     
         11 . Process for the preparation of a composite multilayer product with selective optical properties as in  claim 10 , in which at least one intermediate layer is deposited chosen from the group comprising metals, such as titanium, nickel, aluminium, chromium, iron, cobalt, silicon, yttrium and their respective alloys, oxides of metals such as indium, cadmium, zinc, tin, aluminium, titanium and tungsten, if necessary doped with elements such as tin, aluminium, antimony and fluorine, and combinations of said metals and oxides.