Refractory Metal Carbide Coating on Porous Substrates
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Solution Overview
Problem
Existing methods for producing refractory metal carbide coatings on substrates face challenges in achieving homogeneous coatings due to infiltration of porous substrates, leading to inhomogeneous patterns and increased susceptibility to cracking, especially in high-temperature applications.
Innovation Solution
A method involving an aqueous suspension with an agglomerate former, such as tetrabutylammonium hydroxide or polyvinyl alcohols, is used to form refractory metal carbide agglomerates larger than the pore entrance diameter of the substrate, preventing infiltration and ensuring a uniform coating through controlled sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If suspension-based coating is applied to porous substrates, then coating can be applied to complex geometries with flexibility in layer thickness, but the porous substrate infiltrates the suspension leading to inhomogeneous coating pattern
Solution Approach 1:
The patent changes the particle size parameter of the refractory metal carbide to a specific range (0.1-10 μm) that prevents infiltration into porous substrates while maintaining coating homogeneity. This parameter optimization resolves the contradiction between coating flexibility and pattern uniformity.
Solution Approach 2:
The patent introduces an agglomerate former as an intermediary substance that mediates between the suspension and porous substrate. This agglomerate former prevents direct infiltration of carbide particles into the substrate pores while allowing controlled coating formation, thus maintaining both flexibility and homogeneity.
2Ease of manufacture
If infiltration occurs in porous substrates, then coating can be applied, but cracks form during sintering process reducing coating reliability
Solution Approach 1:
The patent performs preliminary action by controlling particle aggregation before coating application. By pre-forming agglomerates of specific size ranges and using agglomerate formers, the patent prevents infiltration-related defects before sintering, thereby ensuring crack-free coatings and high reliability.
Solution Approach 2:
The patent optimizes particle size parameters (0.1-10 μm) and agglomerate size parameters to prevent infiltration into porous substrates. This parameter control eliminates the root cause of cracking during sintering, maintaining both ease of manufacture and coating reliability.
3Temperature
If conventional hot pressing is used for refractory metal carbides, then high-temperature resistance is achieved, but production of complex geometry components is difficult and costly
Solution Approach 1:
The patent replaces the conventional hot pressing mechanical system with a suspension-based coating system followed by sintering. This substitution enables coating of complex geometries with arbitrary layer thicknesses while maintaining the high-temperature resistance properties of refractory metal carbides.
Solution Approach 2:
The patent changes the manufacturing approach from bulk hot pressing to surface coating with controlled particle size parameters (0.1-10 μm). This parameter optimization allows flexible manufacturing of complex geometries while preserving the high-temperature performance of the carbide coating.
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 approach results in a homogeneous, crack-free refractory metal carbide coating with enhanced mechanical stability and adhesion resistance, effectively protecting substrates from corrosive media in high-temperature applications while offering cost-effectiveness and flexibility in geometry and layer thickness.
Implementation Method 1
an aqueous suspension which comprises water, at least one agglomerate former, and particles of at least one refractory metal carbide, the particles of the at least one refractory metal carbide forming agglomerates in the aqueous suspension
Implementation Method 2
the substrate is subjected to a sintering process after step b)... a mechanically stable coating by the final sintering process (high abrasion and adhesion resistance)
Implementation Method 3
the applied green sheet show a uniform or homogeneously thick course and thus a uniform compaction can take place
Implementation Method 4
protect the substrate from corrosive media in high-temperature applications... high mechanical stability and adhesion resistance
Data Source
AI summary
The invention relates to a method for producing coated substrates. In the method, an aqueous suspension is first produced which contains water, at least one agglomerate former, and particles of at least one refractory metal carbide, said particles of the at least one refractory metal carbide forming agglomerates in the aqueous suspension. The at least one aqueous suspension is then applied onto a porous substrate, and the substrate then undergoes a sintering process. According to the invention, the diameter of each agglomerate is greater than the pore entrance diameter of each pore of the porous substrate. The invention additionally relates to a coated substrate which is produced or can be produced using the method according to the invention and to the use of such a coated substrate.