| 摘要 |
<p>#CMT# #/CMT# The process for protecting a surface of a substrate made of an intermetallic alloy against corrosion, comprises preparing the substrate, electrolytically depositing a gold coating on the surface of the substrate with a part of bath of gold plating, and annealing the coated substrate in controlled conditions for provoking a limited diffusion of the gold in the surface. The preparation of the substrate includes pre-treating the substrate surface by sanding, treating the surface by acid attack, and rinsing the surface. The gold coating has a thickness of 20-40 mu m. #CMT# : #/CMT# The process for protecting a surface of a substrate made of an intermetallic alloy against corrosion, comprises preparing the substrate, electrolytically depositing a gold coating on the surface of the substrate with a part of bath of gold plating, and annealing the coated substrate in controlled conditions for provoking a limited diffusion of the gold in the surface. The preparation of the substrate includes pre-treating the substrate surface by sanding, treating the surface by acid attack, and rinsing the surface. The gold coating has a thickness of 20-40 mu m. The annealing is carried out at high temperature of 900[deg] C and reduced pressure of 10 -> 3> Pa to form a phase of titanium aluminide trigold, titanium aluminide digold and titanium aluminide monogold. An additional coating of other material is deposited on the gold coating to form an underlayer that protects against the corrosion. An additional annealing step is included for regenerating the gold coating in case of halogenous corrosion. The halogenous corrosion results in depletion of volatile halogens. An independent claim is included for a part comprising a substrate made of an intermetallic alloy. #CMT#USE : #/CMT# The process is useful for protecting a surface of a substrate, which is made of an intermetallic alloy and is useful in a part of an aeronautical gas turbine engine, against corrosion (all claimed), where the part is turbine blade. #CMT#ADVANTAGE : #/CMT# The process ensures efficient protection of the substrate surface of the turbine blade by uniformly and easily depositing a gold coating with low density and good mechanical properties on the surface, and avoids the risk of deterioration of the surface during annealing. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The figure shows a micrographic view of a sample comprising a gold coating deposited on the substrate. #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Components: The gold plating includes a sodium sulfite solution containing metallic gold. The intermetallic alloy is gamma -titanium aluminide alloy and alpha 2-tri-titanium aluminide alloy. The additional coating includes gold, oxides, sulfides and halides of platinum, palladium, osmium, rhodium, iridium and ruthenium, and a ceramic based on oxides, carbides and nitrides. The volatile halogens include aluminum trichloride, aluminum trifluoride, titanium tetrachloride or titanium tetrafluoride.</p> |
