Process for depositing an electrically conductive layer and assembly of the layer on a porous support substrate

Abstract

A process for depositing an electrically conductive, preferably perovskitic layer uses a pulsed sputtering process. The layer has a low diffusivity for the elements in the iron group and is especially suitable for use in solid oxide fuel cells (SOFC). An assembly of the electrically conductive ceramic layer on a porous support substrate is also provided.

1 . A process for depositing an electrically conductive ceramic layer, the process comprising the following steps:
 producing the layer by a pulsed sputtering process.   
   
   
       2 . The process according to  claim 1 , wherein the layer has a perovskitic structure. 
   
   
       3 . The process according to  claim 1 , which further comprises using an oxide-ceramic sputtering target in the pulsed sputtering process. 
   
   
       4 . The process according to  claim 1 , which further comprises using a sputtering target in the pulsed sputtering process, and a concentration of elements in the sputtering target differs at most by 5% from a concentration of respective elements in the layer. 
   
   
       5 . The process according to  claim 1 , which further comprises depositing the layer at a frequency of a pulsed voltage of 1 to 1000 kHz. 
   
   
       6 . The process according to  claim 1 , which further comprises depositing the layer at a frequency of the pulsed voltage of 10 to 500 kHz. 
   
   
       7 . The process according to  claim 1 , which further comprises depositing the layer at a frequency of the pulsed voltage of 100 to 350 kHz. 
   
   
       8 . The process according to  claim 1 , which further comprises depositing the layer with a voltage root-mean-square value of +100 to −1000 V. 
   
   
       9 . The process according to  claim 1 , which further comprises depositing the layer with a voltage root-mean-square value of +100 to −500 V. 
   
   
       10 . The process according to  claim 1 , which further comprises depositing the layer with a mean power density of 1 to 30 W/cm 2 . 
   
   
       11 . The process according to  claim 1 , which further comprises using an inert gas as a process gas with a pressure of 1×10 −4  to 9×10 −2  mbar. 
   
   
       12 . The process according to  claim 11 , which further comprises using argon as the process gas. 
   
   
       13 . The process according to  claim 1 , wherein the layer has a structural formula ABO 2 , where A includes one or more elements selected from the group consisting of La, Ba, Sr and Ca; and B includes one or more elements selected from the group consisting of Cr, Mg, Al, Mn, Fe, Co, Ni, Cu and Zn. 
   
   
       14 . The process according to  claim 1 , which further comprises depositing the layer with a thickness of 0.1 to 5 μm. 
   
   
       15 . The process according to  claim 1 , which further comprises depositing the layer with a density >99% of a theoretical density. 
   
   
       16 . The process according to  claim 1 , which further comprises depositing the layer with an impurity content <0.5% by weight. 
   
   
       17 . The process according to  claim 16 , wherein the impurity content is <0.1% by weight. 
   
   
       18 . The process according to  claim 1 , which further comprises depositing the layer on a component used in a solid oxide fuel cell (SOFC). 
   
   
       19 . The process according to  claim 18 , which further comprises depositing the layer on a porous substrate. 
   
   
       20 . An assembly, comprising:
 a porous support substrate having a density of 40 to 70% of a theoretical density and a predominantly open-pored structure and being formed of sintered grains of an Fe-based alloy including 15 to 35% by weight Cr, 0.01 to 2% by weight of one or more elements selected from the group consisting of Ti, Zr, Hf, Mn, Y, Sc, rare earths, 0 to 10% by weight Mo and/or Al, 0 to 5% by weight of one or more metals selected from the group consisting of Ni, W, Nb, Ta, 0.1 to 1% by weight O, a remainder Fe and impurities; and   an electrically conductive ceramic PVD layer with a thickness of 0.1 to 5 μm deposited on said porous support substrate.