Silicon Carbide Vitrified Product Corrosion Resistance
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Solution Overview
Problem
Silicon carbide-based products used in high-temperature environments suffer from corrosion due to their porosity, leading to a reduced lifespan, and existing protective layers may degrade over time, necessitating a solution for enhanced corrosion resistance and longevity.
Innovation Solution
A sintered support composed of silicon carbide grains with a matrix containing crystallized SiAlON phases and a protective layer made of glass or glass ceramic, with specific chemical compositions and formulations that include manganese, improves corrosion resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is applied to silicon carbide products to improve corrosion resistance, then corrosion resistance is improved, but the protective layer may degrade over time reducing lifespan
Solution Approach 1:
The patent modifies the chemical composition parameters of the protective layer by incorporating specific amounts of manganese (0.5-5% MnO), aluminum (1-10% Al2O3), and silica (70-90% SiO2) to create a vitrified layer with improved stability. This chemical parameter optimization prevents degradation by forming a more resilient protective barrier that maintains its integrity in harsh environments.
Solution Approach 2:
The patent creates a composite protective layer combining multiple materials: glass ceramic matrix with crystallized phases and vitrified regions. This composite structure integrates the benefits of different materials - the glass ceramic provides structural integrity while the vitrified phases offer chemical resistance, creating a synergistic protective system that extends product lifespan.
2Temperature
If silicon carbide products are used in high-temperature environments, then high-temperature resistance is improved, but porosity increases making them susceptible to corrosion
Solution Approach 1:
The patent optimizes the sintering parameters (temperature, time, atmosphere) to control the pore structure of the silicon carbide body. By controlling the sintering process, the material achieves adequate density to reduce porosity while maintaining high-temperature resistance, thereby decreasing corrosion susceptibility without sacrificing thermal performance.
Solution Approach 2:
The patent introduces a protective coating as an intermediary layer between the porous silicon carbide body and the corrosive environment. This coating acts as a mediator that prevents direct contact between corrosive agents and the porous structure, allowing the material to maintain both high-temperature resistance and reduced corrosion susceptibility.
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
The solution significantly enhances the lifespan of silicon carbide products by providing excellent resistance to corrosion from gases, water vapor, and chlorides, making them suitable for harsh environments.
Implementation Method 1
the matrix comprising more than 3% of crystallized SiAlON phase
Implementation Method 2
the protective layer being made of glass or glass ceramic
Implementation Method 3
1% ≤ manganese expressed in the form MnO ≤ 20%
Data Source
Figure 1~2
AI summary
Product comprising - a sintered support constituted of an "aggregate" constituted of particles having a size of greater than 100 µm, the balance of said support being the "matrix", and - a protective layer at least partially covering the surface of said support, the aggregate representing more than 60% and less than 95% of the weight of said support and being constituted, for more than 80% by weight, of silicon carbide grains, the protective layer being constituted of a glass or of a glass-ceramic, and having the following chemical analysis, in percentages by weight on the basis of the oxides: - 45% = SiO2 = 90%; - 1% = manganese expressed in the form MnO = 20%; - 2% = aluminium expressed in the form Al2O3 = 15%; - other elements, apart from oxygen, expressed in an oxide form: = 25%.