Low energy plasma coating

Abstract

A method of coating an aluminum alloy or magnesium alloy component, including cleaning and drying surfaces of the component to be coated; suspending a powdered coating material in a carrier gas and feeding the suspended powdered coating material through a plasma torch in a flowing gas; heating the coating material in the plasma torch to a molten or semi-molten state using a nominal power below 25 kW; and depositing the coating material with the plasma torch directly on the surfaces to be coated. The component may be made of a magnesium alloy containing at one or more of zinc, cerium and zirconium, or of an aluminum alloy containing one or more of magnesium, silicon, copper and chromium. The powder material may be made in majority of aluminum.

1 . A method of coating an aluminum alloy or magnesium alloy component, the method comprising:
 cleaning and drying surfaces of the component to be coated;   suspending a powdered coating material in a carrier gas and feeding the suspended powdered coating material through a plasma torch in a flowing gas;   heating the coating material in the plasma torch to a molten or semi-molten state using a nominal power output below 25 kW; and   depositing the coating material with the plasma torch directly on the surfaces to be coated.   
     
     
         2 . The method as defined in  claim 1 , depositing the coating material with the plasma torch is performed while maintaining a temperature of the surfaces to be coated below 400° C. 
     
     
         3 . The method as defined in  claim 1 , wherein the plasma torch has a power output of at most 16 KW. 
     
     
         4 . The method as defined in  claim 1 , wherein depositing the coating material with the plasma torch directly on the surfaces to be coated includes depositing the coating material directly on the surfaces made of a magnesium alloy containing at least one material selected from the group consisting of zinc, cerium and zirconium. 
     
     
         5 . The method as defined in  claim 3 , wherein the magnesium alloy has a composition by weight including from 3.5% to 5.0% of zinc, from 0.75% to 1.75% of total rare earths with a cerium of content of at least 45% of the total rare earths, and from 0.40% to 1.0% of zirconium. 
     
     
         6 . The method as defined in  claim 1 , wherein depositing the coating material with the plasma torch directly on the surfaces to be coated includes depositing the coating material directly on the surfaces made of an aluminum alloy containing at least one material selected from the group consisting of magnesium, silicon, copper and chromium. 
     
     
         7 . The method as defined in  claim 6 , wherein the aluminum alloy has a composition by weight including from 0.8% to 1.2% of magnesium, from 0.4% to 0.8% of silicon, from 0.15% to 0.40% of copper, and from 0.04% to 0.35% of chromium. 
     
     
         8 . The method as defined in  claim 1 , wherein suspending the blended powdered coating material includes suspending a powder material made in majority of aluminum. 
     
     
         9 . The method as defined in  claim 8 , wherein the powder material includes, by weight, from 11% to 13% of silicon. 
     
     
         10 . The method as defined in  claim 1 , wherein depositing the coating material includes accelerating the molten or semi-molten coating material to a speed of from 200 to 300 m/s. 
     
     
         11 . The method as defined in  claim 1 , wherein depositing the coating material includes projecting the coating material at a rate of from 8 to 12 g/min. 
     
     
         12 . The method as defined in  claim 1 , wherein suspending the powdered coating material in a carrier gas includes suspending the powdered coating material in argon, and feeding the suspended powdered coating material through a plasma torch in a flowing gas includes feeding the suspended powered coating material in a primary gas flow of argon with a secondary gas flow of hydrogen smaller than the primary gas flow. 
     
     
         13 . A method of coating an aluminum alloy or magnesium alloy component, the method comprising:
 cleaning and drying aluminum alloy or magnesium alloy surfaces of the component to be coated;   suspending a coating material made in majority of aluminum in a carrier gas and feeding the suspended powdered coating material through a plasma torch in a flowing gas;   heating the coating material in the plasma torch to a molten or semi-molten state; and   depositing the coating material with the plasma torch directly on the surfaces to be coated.   
     
     
         14 . The method as defined in  claim 13 , wherein depositing the coating material includes depositing the coating material directly on the surfaces made of magnesium alloy containing at least one material selected from the group consisting of zinc, cerium and zirconium. 
     
     
         15 . The method as defined in  claim 14 , wherein the magnesium alloy has a composition by weight including from 3.5% to 5.0% zinc, from 0.75% to 1.75% of total rare earths with a cerium of content of at least 45% of the total rare earths, and from 0.40% to 1.0% of zirconium. 
     
     
         16 . The method as defined in  claim 13 , wherein depositing the coating material includes depositing the coating material directly on the surfaces made of aluminum alloy containing at least one material selected from the group consisting of magnesium, silicon, copper and chromium. 
     
     
         17 . The method as defined in  claim 16 , wherein the aluminum alloy has a composition by weight including from 0.8% to 1.2% magnesium, from 0.4% to 0.8% silicon, from 0.15% to 0.40% copper, and from 0.04% to 0.35% chromium. 
     
     
         18 . The method as defined in  claim 13 , wherein suspending the blended powdered coating material includes suspending a powder material made in majority of aluminum. 
     
     
         19 . The method as defined in  claim 13 , wherein the plasma torch has a power output below 25 KW. 
     
     
         20 . A method of coating a magnesium alloy component containing at least one material selected from the group consisting of zinc, cerium and zirconium, the method comprising:
 suspending an aluminum-based powdered coating material in a carrier gas and feeding the suspended powdered coating material through a plasma torch in a flowing gas;   heating the coating material in the plasma torch to a molten or semi-molten state; and   depositing the coating material with the plasma torch directly on clean and dry surfaces of the component to be coated, the plasma torch having a power output below 25 KW.