Method of Preparing Corrosion Resistant Coatings

Abstract

A method for preparing thin double-structured composite corrosion resistant and/or passivating coatings that consist of a thin metal oxide-hydroxide subcoating prepared by anodizing the metal substrate materials near-surface part and then provided with an atomic layer deposition (ALD) topmost nanocoating, of e.g. oxide, nitride, carbonate, carbide etc. or their mixes or laminates, or laminates with ceramic and metallic layers, or laminates with inorganic or organic polymers and ceramic layers.

1-35. (canceled) 
     
         36 . A metal article having a protective coating formed on its surface for preventing corrosion of the metal article, wherein the coating is double-structured, such that the coating has a homogeneous base part, formed of an anodised layer on the surface of the metal article, wherein the pores formed by anodising are irregular tortuous branched cracks that reach through to the underlying metal, the protective coating further comprising at least one nano-layer of another atomic species deposited using atomic layer deposition (ALD), said atomic species being one which is not corroded by materials that would corrode the underlying metal article, and said layer coating the entire surface of the anodised layer including the walls down to the bottom of the irregular branched pores even when they are long and narrow and have a complicated 3D geometry but without closing or corking the pores in the anodised layer, wherein the near surface structure provides a surface for the top layer to adhere to. 
     
     
         37 . A metal article according to  claim 36 , wherein the base part has pores and the top part substantially fills the pores of the base part. 
     
     
         38 . A metal article according to  claim 36 , wherein the metal article is made of an anodisable metal. 
     
     
         39 . A metal article according to  claim 36 , wherein the metal article is made of an anodisable metal, selected from the list of aluminium, magnesium, titanium, vanadium, zinc, niobium, cadmium, hafnium, tantalum or their alloys. 
     
     
         40 . A metal article according to  claim 36 , wherein the top layer comprises an oxide, nitride, carbonate, carbide, or their mixes or laminates, or laminates with ceramic and metallic layers, or laminates with inorganic and/or organic polymers and ceramic layers. 
     
     
         41 . A metal article according to  claim 36 , wherein the top layer comprises at least one layer of material selected from the list consisting of: oxides selected from the list consisting of: aluminum-, titanium-, vanadium-, zirconium-, niobium-, tantalum-, hafnium, scandium-, magnesium-, silicon-, chromium-, molybdenum-, copper-, ruthenium-, silver oxide; nitrides of aluminum-, titanium-, vanadium-, zirconium-, tantalum-, hafnium-, chromium-, molybdenum-, silicon nitride; calcium compounds selected from the list consisting of calcium carbonate, hydroxylapatite; polymers including polysilanes, polysiloxanes, polysilazanes; carbides of, aluminum-, titanium-, vanadium-, zirconium-, tantalum-, hafnium-, chromium-, molybdenum-, silicon carbide, ceramic material produced from an amorphous mixed oxide layer. 
     
     
         42 . A metal article according to  claim 36 , wherein the coating thickness of the anodised base layer and top layer or layers is less than 1 micrometer thick.