Patent ID: 9561987
Date: 2017-02-07
CPC Classifications: B29K,C04B,C23C,H01M,H05B,Y02E,Y02P

Claim:
1. A method for depositing at least two layers of an SOFC electrolyte on a substrate that is a main electrolyte layer of the electrolyte, in which the at least two layers are metal oxide crystalline ceramic layers deposited upon the substrate, said substrate being a substantially impermeable mixed ionic electronic conducting electrolyte ceramic material, the method comprising the steps of: (i) depositing a solution of a soluble salt precursor of a metal oxide crystalline ceramic onto a surface of the substrate to define a layer of said solution of said soluble salt precursor on said surface; (ii) drying said solution of said soluble salt precursor to define a layer of said soluble salt precursor on said surface; (iii) heating said soluble salt precursor on said surface to a temperature of between 150 and 600° C. to decompose it and form a layer of metal oxide film on said surface; (iv) sequentially depositing, drying and heating at between 100 and 600° C. at least one additional layer of the solution of the soluble salt precursor to form a plurality of layers of metal oxide film; and (v) firing said substrate with said plurality of layers of metal oxide film at a temperature of 500-1100° C. to crystallise said plurality of layers of metal oxide film into a layer of metal oxide crystalline ceramic bonded to said substrate, said layer of metal oxide crystalline ceramic being ion-permeable, electrically insulating, and gas-permeable and said layer of metal oxide crystalline ceramic providing at least a part of an interlayer for the SOFC electrolyte; (vi) sequentially depositing, drying and heating at between 100 and 600° C. at least one further solution of a further soluble salt precursor of a further metal oxide crystalline ceramic to form a plurality of layers of a further metal oxide film on the interlayer; (vii) firing said substrate with said plurality of layers of a further metal oxide film at a temperature of 500-1100° C. to crystallise said plurality of layers of a further metal oxide film into a further layer of metal oxide crystalline ceramic, said further layer of metal oxide crystalline ceramic being a mixed ionic electronic conducting electrolyte material and said further layer of metal oxide crystalline ceramic providing at least a part of a barrier layer between the interlayer and a subsequently deposited cathode layer; and (viii) subsequently depositing the cathode layer; wherein: each of steps (ii), (iii), (v) and (vii) is performed in an air atmosphere; said interlayer of metal oxide crystalline ceramic is thinner than the main electrolyte layer provided by the substantially impermeable mixed ionic electronic conducting electrolyte ceramic material substrate; and said interlayer is also to electrically insulate the subsequently deposited cathode layer from the main electrolyte layer.