Sol-Gel Coating on Porous Substrates
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Solution Overview
Problem
Existing methods for depositing oxide layers on substrates, such as those used in solid oxide fuel cells, face challenges in achieving thicknesses greater than one micrometer without penetration into porous substrates and ensuring homogeneous, dense, and adherent layers, particularly on complex geometries and substrates with open porosity.
Innovation Solution
A process involving a primer layer of a sol-gel solution precursor followed by a dispersion layer, using a sol-gel solution and oxide powder, is applied to the substrate, allowing for controlled deposition and heat treatment to achieve dense, homogeneous oxide layers with thicknesses of 1 to 20 micrometers, utilizing techniques like dipping-withdrawal and heat treatment to ensure adhesion and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sol-gel deposition by dip-removal technique is used, then coating of complex surfaces is achieved, but layer thickness is limited to less than one micrometer
Solution Approach 1:
The patent divides the coating process into multiple sequential deposition steps, where each step applies a portion of the total desired layer thickness. By repeating the dip-removal cycle multiple times, the cumulative layer thickness exceeds one micrometer while maintaining the benefits of sol-gel deposition on complex geometries.
Solution Approach 2:
The patent introduces a preliminary deposition step that applies a first layer with specific properties (potentially different composition or porosity) before subsequent layers. This preliminary action prepares the substrate to support thicker overall deposits while preventing penetration into the porous substrate.
2Length of stationary object
If thicker layers are deposited to achieve desired thickness, then thickness requirement is met, but penetration into porous substrate occurs
Solution Approach 1:
The patent creates a layered structure where different portions of the deposit have different properties. The first layer deposited has specific characteristics (potentially lower porosity or different composition) that act as a barrier, while subsequent layers build up the required thickness. This local differentiation prevents penetration into the porous substrate while achieving the desired overall thickness.
3Ease of manufacture
If conventional deposition methods are used, then simple processes are employed, but homogeneous and dense layers cannot be achieved on porous substrates
Solution Approach 1:
The patent employs a sol-gel solution that forms a composite structure during deposition and heat treatment. The resulting layer combines oxide phases with specific microstructural characteristics that provide both homogeneity and density. The controlled hydrolysis and condensation reactions create a uniform gel network that, upon heat treatment, yields a dense homogeneous ceramic layer suitable for porous substrates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of dense, homogeneous oxide layers with controlled thickness on substrates with complex geometries and open porosity, enhancing adhesion and density, suitable for use in solid oxide fuel cells and high-temperature electrolyzers with improved performance.
Implementation Method 1
On contact with ambient humidity, the precursors hydrolyze and condense, thus forming an oxide network trapping the solvent and resulting in a gel.
Implementation Method 2
On contact with ambient humidity, the precursors hydrolyze and condense, thus forming an oxide network trapping the solvent and resulting in a gel.
Implementation Method 3
The film-forming gel layer is then subjected to a heat treatment step to form a ceramic film.
Implementation Method 4
The assembly consisting of the suspension and the additives, also called 'slip' of strip casting, is then placed on a surface and leveled using a scraper.
Data Source
AI summary
The invention relates to a method of preparing a material based on metal element oxide(s) on a substrate, comprising the following successive steps: a) depositing, by liquid means, on at least one face of this substrate, at least one layer of a sol-gel precursor solution of the constituent metal element oxide(s) of said material; b) depositing, by liquid means, on said layer deposited in a), at least one layer of a dispersion comprising a powder of metal element oxide(s) and a sol-gel solution identical to or different from that used in step a), said solution being the precursor of the constituent metal element oxide(s) of said material and the powder consisting of constituent metal element oxide(s) of said material; c) heat treating said layers deposited in a) and b) in order to transform them into said material.