Surface-treated titanium material excellent in oxidation resistance, production method thereof, and engine exhaust system

Abstract

Disclosed are a surface-treated titanium material that is excellent in oxidation resistance and allows the excellent oxidation resistance to last for a long period of time and the surface treatment itself to be applied safely at a low cost; the production method thereof; and an exhaust system thereof. A surface-treated titanium material produced by forming an oxidation-resistant baked film 5 μm or more in thickness on a substrate comprising commercially pure titanium or titanium-base alloy, and said baked film is formed by filling the gaps among particles comprising Al alloy containing Si by 10 at % or less or commercially pure aluminum with chemical compounds comprising a metallic element M (M represents one or more of Ti, Zr, Cr, Si and Al) and C and/or O.

1 . A surface-treated titanium material excellent in oxidation resistance, wherein: said surface-treated titanium material is produced by forming an oxidation-resistant baked film 5 [μm or more in thickness on a substrate comprising commercially pure titanium or titanium-base alloy; and said baked film is formed by filling the gaps among particles comprising Al alloy containing Si by 10 at % or less or commercially pure aluminum with chemical compounds comprising a metallic element M (M represents one or more of Ti, Zr, Cr, Si and Al) and C and/or O.  
   
   
       2 . The surface-treated titanium material according to  claim 1 , wherein said particles comprise Al alloy containing Si by 2 to 10 at %.  
   
   
       3 . The surface-treated titanium material according to  claim 1 , wherein said metallic element M contains Si.  
   
   
       4 . The surface-treated titanium material according to  claim 3 , wherein the chemical bond of Si and O exists in said baked film and the ratio Si/O satisfies the expression 0.4 <Si/O <2.  
   
   
       5 . The surface-treated titanium material according to  claim 1 , wherein a titanium oxide layer is formed between said baked film and said substrate.  
   
   
       6 . The surface-treated titanium material according to  claim 1 , wherein a hot-dip aluminum-plated layer is formed on said substrate beforehand and said oxidation-resistant baked film is formed on said hot-dip aluminum-plated layer.  
   
   
       7 . The surface-treated titanium material according to  claim 1 , wherein said chemical compounds comprising said metallic element M and C and/or O are formed by baking one or more kinds of organometallic compounds selected from among acetylacetone titanium solution, acetylacetone zirconium solution, chromium acetate, silicone, silica sol, alumina sol, and aluminum isopropoxide.  
   
   
       8 . A method of producing a surface-treated titanium material excellent in oxidation resistance, wherein an oxidation-resistant film is formed on a substrate comprising titanium or titanium-base alloy by: coating said substrate with a solution containing Al alloy particles containing Si by 10 at % or less or commercially pure aluminum particles and organometallic compounds comprising a metallic element M (M represents one or more of Ti, Zr, Cr, Si and Al) and C and/or O; and baking them.  
   
   
       9 . The method of producing a surface-treated titanium material according to  claim 8 , characterized by applying blasting treatment with hard particles to said baked film.  
   
   
       10 . An engine exhaust system made of said surface-treated titanium material according to  claim 1.