Method of manufacturing a tank

Abstract

The invention relates to a method of manufacturing at least one hollow element of a fuel system ( 3 ), especially a casing of a fuel tank. It comprises the following steps: (a) introducing the element or elements to be treated into a treatment chamber ( 2 ) equipped with at least one microwave generator, (b) injecting a reaction gas into the chamber while enabling the gas to enter inside the said elements, (c) subjecting this gas to microwave radiation delivered by the microwave generator ( 4 ), at a frequency and intensity chosen so as to create a plasma in the chamber and to bring about the coating of a material, arising from the decomposition of the reaction gas, on the said element or elements, preferably on both the inner and outer faces of the said element or elements.

1 . Method of manufacturing at least one hollow element of a fuel system ( 3 ), especially a casing of a fuel tank made of plastic, characterized in that it comprises the following steps: 
 (a) introducing the element or elements to be treated into a treatment chamber ( 2 ) equipped with at least one microwave generator,    (b) injecting a reaction gas into the chamber while enabling the gas to enter inside the said elements,    (c) subjecting this gas to microwave radiation delivered by the microwave generator ( 4 ), at a frequency and intensity chosen so as to create a plasma in the chamber and to bring about the coating of a material, arising from the decomposition of the reaction gas, on the said element or elements, preferably on both the inner and outer faces of the said element or elements.    
     
     
         2 . Method according to the preceding claim, characterized in that, between the steps a) and b), the chamber is evacuated such that the absolute pressure therein is less than 0.05 mbar (5 Pa).  
     
     
         3 . Method according to any one of the preceding claims, characterized in that the reaction gas is a hydrocarbon compound, preferably with at least 5 carbon atoms, in particular an alkane or an alkene or a mixture thereof, preferably a mixture of methane and propane.  
     
     
         4 . Method according to either of claims  1  and  2 , characterized in that the reaction gas is a siloxane, preferably hexamethyldisiloxane in vapour form.  
     
     
         5 . Method according to any one of the preceding claims, characterized in that the reaction gas is injected at a nominal pressure of between 0.05 mbar (5 Pa) and 0.5 mbar (50 Pa).  
     
     
         6 . Method according to any one of the preceding claims, characterized in that the element or elements placed in the chamber comprise at least one element attached thereto, such as a valve ( 15 ) or an electrical connector, in addition to the tank casing.  
     
     
         7 . Element of a fuel system, especially a tank casing, comprising a substrate layer having an inner surface and an outer surface, characterized in that each of these surfaces is coated with at least one material which is different from that of the substrate, arising from the decomposition of a chemical compound under the effect of plasma-generating microwave radiation.  
     
     
         8 . Element according to the preceding claim, characterized in that the substrate layer comprises, on each face, a layer of the same material or several layers of different materials, the thickness of each layer being between 0.3 and 1 μm.  
     
     
         9 . Element according to either of claims  7  and  8 , characterized in that the coating material comprises carbon with a polymer tendency and/or silica.  
     
     
         10 . Fuel tank made of high-density polyethylene comprising, on at least one of its inner or outer faces, a coating of carbon and/or of silica with a polymer tendency.