Steel sheet provided with a zinc coating

Abstract

A steel sheet is provided with a coating. The coating includes at least one layer of zinc, obtained by a jet vapor deposition method in which a ratio between a pressure inside the deposition chamber P chamber and a pressure inside the zinc ejection chamber P eject is between 2·10 −3 et 5.5·10 −2 A method for fabricating the steel sheet is also provided.

What is claimed is: 
     
         1 - 8  (canceled) 
     
     
         9 . A steel sheet offering temporary protection against corrosion provided with a coating comprising at least one layer of zinc, obtained by a jet vapor deposition method in which a ratio between a pressure inside a deposition chamber P chamber  and a pressure inside a zinc ejection chamber P eject  is between 2·10 −3  and 5.5·10 −2 . 
     
     
         10 . The steel sheet according to  claim 9 , wherein the deposition chamber is maintained at a pressure P chamber  between 6·10 −2  mbar and 2·10 −1  mbar. 
     
     
         11 . The steel sheet according to  claim 9 , wherein a distance d between an upper portion of a slot  8  of the zinc ejection chamber and the steel sheet to be coated is between 20 and 60 mm. 
     
     
         12 . The steel sheet according to  claim 9 , wherein the at least one layer of zinc is a top layer of the coating. 
     
     
         13 . The steel sheet according to  claim 9 , wherein the coated steel sheet is a Very High Strength steel. 
     
     
         14 . A method for the fabrication of a coated sheet comprising the steps of:
 providing a sheet in a deposition chamber;   maintaining the deposition chamber at a pressure P chamber;      maintaining an ejection chamber that is located inside the deposition chamber at a pressure P eject , a ratio of the pressures P chamber  to P eject  being between 2·10 −3  and 5.5·10 −2 ; and   coating the sheet with zinc with a sonic vapor jet.   
     
     
         15 . The method according to  claim 14 , wherein the deposition chamber is maintained at a pressure P chamber  between 6·10 −2  mbar and 2·10 −1  mbar. 
     
     
         16 . The method according to  claim 14 , wherein a distance d between an upper portion of a slot of the ejection chamber and the steel sheet to be coated is between 20 and 60 mm. 
     
     
         17 . An installation for coating a steel sheet comprising:
 a deposition chamber having a pressure P chamber ;   an ejection chamber located inside the deposition chamber, the ejection chamber having a pressure P eject ,   a steel sheet running through the deposition chamber; and   a sonic vapor jet for coating the steel sheet inside the deposition chamber;   a ratio of the pressures P chamber  to P eject  being between 2·10 −3  and 5.5·10 −2 .   
     
     
         18 . The installation according to  claim 17 , wherein a distance d between an upper portion of a slot of the ejection chamber and the steel sheet to be coated is between 20 and 60 mm. 
     
     
         19 . The installation according to  claim 17 , further comprising an evaporation crucible containing zinc that is connected to the ejection chamber. 
     
     
         20 . The installation according to  claim 17 , wherein the pressure P chamber  of the deposition chamber is between 6·10 −2  mbar and 2·10 −1  mbar.