Sintering Aid Composition for SiC Ceramic Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional sintering aid compositions used in ceramics disrupt the ordered array of inorganic powders, such as SiC, leading to weakened ceramic strength due to the presence of boron and carbon materials that remain after firing, causing points of failure under stress.
Innovation Solution
A sintering aid composition comprising a material useful for sintering, an amine, and optionally a carboxylic acid, which forms a green body with inorganic powder and is fired to produce a ceramic article with improved strength by reducing disruptions to the ordered array, using specific molar ratios and phases like aqueous solutions for efficient processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional sintering aid compositions containing boron and carbon are used, then the melting point of SiC is reduced enabling sintering at lower temperatures, but the ordered array of SiC spheres is disrupted weakening the ceramic strength
Solution Approach 1:
The patent changes the chemical composition parameters of the sintering aid from traditional boron-carbon fine powders to organic compounds containing nitrogen, oxygen, and hydrogen in specific ratios. This parameter change allows the sintering aid to fulfill its function of lowering sintering temperature while avoiding the harmful disruption of SiC sphere arrays, thereby maintaining ceramic strength.
Solution Approach 2:
The invention uses a composite sintering aid composition comprising multiple organic compounds with specific elemental ratios (N: 0.5-5 wt%, O: 5-20 wt%, H: 5-30 wt%). This composite approach enables the material to provide both the necessary sintering assistance and maintain structural integrity of the ceramic by preventing harmful residue formation.
2Ease of manufacture
If traditional sintering aid materials are used, then sintering can be achieved at achievable temperatures, but residual materials remain in the ceramic article creating points of failure under stress
Solution Approach 1:
The patent employs organic sintering aid compounds that are designed to be completely consumed or volatilized during the sintering process, leaving no harmful residues. These compounds serve their purpose temporarily to enable sintering and then disappear, unlike traditional aids that leave persistent harmful residues. Examples include compounds like (CH3)2NH·B(OH)3 that volatilize cleanly.
Solution Approach 2:
The invention converts the potential harm of sintering aid residues into a benefit by selecting organic compounds that either completely decompose into harmless substances or volatilize entirely during sintering. The nitrogen, oxygen, and hydrogen in these compounds facilitate sintering reactions while ultimately converting to benign byproducts rather than harmful residues.
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 achieves fully dense SiC ceramic articles with improved hardness and reduced grain growth, achieving 15-22% greater Knoop hardness values compared to commercial samples, with specific additives like HX3 and HX4 allowing for efficient distribution of boron and carbon, resulting in pore-free microstructures and finer grain sizes.
Implementation Method 1
Sintering aid compositions act to reduce the melting point of the SiC so that the material can fuse at a lower (and more achievable) temperature
Implementation Method 2
Sintering is the action of fusing of inorganic powders at high temperature to produce a ceramic article or part
Data Source
AI summary
Embodiments of the present invention disclosed herein include a sintering aid composition that has a material useful for sintering, an amine, and optionally a carboxylic acid.