Coating method of separator for fuel cell and separator for fuel cell

Abstract

The method for coating a separator for a fuel cell according to one form of the present disclosure includes the steps of: vaporizing a metal nitride precursor to obtain a precursor gas; introducing a metal nitride coating layer-forming gas containing the precursor gas and a reactive gas to a reaction chamber; applying a voltage to the reaction chamber so that the precursor gas and reactive gas may be converted into a plasma state, thereby forming a metal nitride coating layer on a substrate; introducing a carbon layer-forming gas containing a carbonaceous gas to the reaction chamber; and applying a voltage to the reaction chamber so that the carbonaceous gas may be converted into a plasma state, thereby forming a carbon coating layer on the metal nitride coating layer.

What is claimed is: 
     
         1 . A method for coating a separator for a fuel cell, the method comprising:
 vaporizing a metal nitride precursor to obtain a precursor gas;   introducing a metal nitride coating layer-forming gas containing the precursor gas and a reactive gas to a reaction chamber;   applying a voltage to the reaction chamber so that the precursor gas and reactive gas may be converted into a plasma state, thereby forming a metal nitride coating layer on a substrate;   introducing a carbon layer-forming gas containing a carbonaceous gas to the reaction chamber; and   applying a voltage to the reaction chamber so that the carbonaceous gas is converted into a plasma state, thereby forming a carbon coating layer on the metal nitride coating layer.   
     
     
         2 . The method for coating a separator for a fuel cell of  claim 1 , wherein the metal nitride precursor is a material selected from the group consisting of titanium nitride, chromium nitride, molybdenum nitride, tungsten nitride, copper nitride, and niobium nitride precursor. 
     
     
         3 . The method for coating a separator for a fuel cell of  claim 1 , wherein the metal nitride precursor comprises a compound represented by the following Chemical Formula 1: 
       
         
           
           
               
               
           
         
         wherein each of R 1  to R 8  independently represents a substituted or non-substituted C1 to C10 alkyl group, and Me is Ti, Cr, Mo, W, Cu, or Nb. 
       
     
     
         4 . The method for coating a separator for a fuel cell of  claim 3 , wherein:
 the metal nitride precursor further comprises a compound represented by the following Chemical Formula 2   
       
         
           
           
               
               
           
         
         wherein each of R 9  to R 16  independently represents a substituted or non-substituted C1 to C10 alkyl group, and Me is Ti, Cr, Mo, W, Cu, or Nb. 
       
     
     
         5 . The method for coating a separator for a fuel cell of  claim 4 , wherein each of R 1  to R 16  represents a methyl group (CH 3 ). 
     
     
         6 . The method for coating a separator for a fuel cell of  claim 1 , wherein the step of vaporizing a metal nitride precursor to obtain a precursor gas is carried out at a temperature ranging from 50° C. to 80° C. 
     
     
         7 . The method for coating a separator for a fuel cell of  claim 1 , wherein the reactive gas is one of a nitrogen compound gas and a nitrogen gas. 
     
     
         8 . The method for coating a separator for a fuel cell of  claim 7 , wherein the reactive gas is one of NH 3  and N 2 . 
     
     
         9 . The method for coating a separator for a fuel cell of  claim 1 , wherein the carbonaceous gas is selected from the group consisting of C 2 H 2 , CH 4 , C 6 H 12 , C 7 H 14 , and combinations thereof. 
     
     
         10 . The method for coating a separator for a fuel cell of  claim 1 , wherein the metal nitride coating layer-forming gas further comprises an inert gas and hydrogen gas. 
     
     
         11 . The method for coating a separator for a fuel cell of  claim 1 , wherein the carbon coating layer-forming gas further comprises an inert gas. 
     
     
         12 . The method for coating a separator for a fuel cell of  claim 1 , wherein the step of forming a metal nitride coating layer and the step of forming a carbon coating layer are carried out at a temperature ranging from 100° C. to 200° C. 
     
     
         13 . The method for coating a separator for a fuel cell of  claim 1 , wherein the step of introducing a metal nitride coating layer-forming gas to a reaction chamber, the step of forming a metal nitride coating layer, the step of introducing a carbon layer-forming gas to the reaction chamber, and the step of forming a carbon coating layer are repeated at least once. 
     
     
         14 . The method for coating a separator for a fuel cell of  claim 13 , wherein the step of introducing a metal nitride coating layer-forming gas to a reaction chamber, the step of forming a metal nitride coating layer, the step of introducing a carbon layer-forming gas to the reaction chamber, and the step of forming a carbon coating layer are repeated 5 to 50 times. 
     
     
         15 . The method for coating a separator for a fuel cell of  claim 1  further comprising a step of introducing a reactive gas to the reaction chamber and activating the plasma to carry out nitriding of a topmost layer. 
     
     
         16 . A separator for a fuel cell comprising a substrate, and a metal coating layer and carbon coating layer formed on either surface or both surfaces of the substrate, wherein
 the metal nitride coating layer comprises metal nitride in an amount of 10 at % to 30 at %, and metal oxides and a metal oxynitride in an amount of 0.1 at % to 10 at %.   
     
     
         17 . The separator for a fuel cell of  claim 16 , wherein the metal nitride coating layer is a material selected from the group consisting of titanium nitride, chromium nitride, molybdenum nitride, tungsten nitride, copper nitride, and niobium nitride. 
     
     
         18 . The separator for a fuel cell of  claim 16 , wherein the metal nitride coating layer comprises the metal nitride in an amount of 12 at % to 18 at %, and metal oxides and a metal oxynitride in an amount of 2 at % to 7 at %. 
     
     
         19 . The separator for a fuel cell of  claim 16 , wherein the metal nitride coating layer has a thickness of 10 nm to 50 nm. 
     
     
         20 . The separator for a fuel cell of  claim 16 , wherein the carbon coating layer comprises carbon with an SP2 structure and carbon with an SP3 structure. 
     
     
         21 . The separator for a fuel cell of  claim 20 , wherein the carbon coating layer comprises carbon with an SP2 structure in an amount of 1.5 to 5 times that of carbon with an SP3 structure on a weight basis. 
     
     
         22 . The separator for a fuel cell of  claim 16 , wherein the carbon coating layer has a thickness of 1 nm to 15 nm. 
     
     
         23 . The separator for a fuel cell of  claim 16 , wherein a topmost layer of the separator for a fuel cell is a carbon layer. 
     
     
         24 . The separator for a fuel cell of  claim 23 , wherein the topmost layer of the separator for a fuel cell is nitrided. 
     
     
         25 . The separator for a fuel cell of  claim 16 , wherein the metal nitride coating layer and the carbon coating layer are alternately formed with each other a plurality of times. 
     
     
         26 . The separator for a fuel cell of  claim 25 , wherein the metal nitride coating layer and the carbon coating layer are alternately formed with each other 5 to 50 times. 
     
     
         27 . The separator for a fuel cell of  claim 25 , wherein the total thickness of the metal coating layers and carbon layers alternately formed with each other a plurality of times is 0.1 μm to 10 μm.