High Temperature Composite Sealant with Negative Thermal Expansion
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Solution Overview
Problem
Current high temperature sealant materials, whether silicon or glass-based, are not stable in harsh chemical environments and decompose at elevated temperatures, limiting their application in environments such as blast furnaces and nuclear reactors.
Innovation Solution
A high temperature composite sealant material is developed, comprising a binder, cement or geopolymer, and ceramic filler with negative thermal expansion materials like zirconium tungstate, which is compatible with concrete, ceramics, and metals, providing heat shock resistance and stability in harsh chemical environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon based sealant materials are used, then ease of manufacture is improved, but stability at high temperature deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of alumina (Al2O3) as the base ceramic, zirconium tungstate (ZrW2O8) as the negative thermal expansion material, and silica sol as the binder. This composite structure enables the sealant to maintain dimensional stability at high temperatures while providing mechanical integrity and resistance to thermal shock, directly resolving the contradiction between ease of manufacture and high temperature stability.
2Temperature
If glass based sealant materials are used, then temperature resistance is improved, but chemical stability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by using alumina-based ceramic instead of glass, and incorporates zirconium tungstate with specific negative thermal expansion properties. The silica sol binder concentration and curing conditions are also optimized. These parameter changes result in a material that maintains chemical stability in harsh environments while providing superior temperature resistance compared to traditional glass-based sealants.
3Strength
If negative thermal expansion materials are added to cement matrix, then heat shock resistance is improved, but device complexity increases
Solution Approach 1:
The patent exploits the thermal expansion property by incorporating zirconium tungstate, which has negative thermal expansion, into the cement matrix. This creates a compensatory effect where the negative expansion of ZrW2O8 offsets the positive expansion of the cement matrix during heating, significantly improving heat shock resistance. The simplicity of the mixing and curing process maintains ease of manufacture despite the added functionality.
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 new sealant material maintains stability up to 1,000°C, is impermeable to solvents and oils, and resistant to UV radiation, outperforming existing technologies in durability and chemical resistance.
Implementation Method 1
compensating for the expansion of pavement concrete with a matching contraction of cement-zirconium tungstate (CZT) composites in the joints. The coefficient of thermal expansion (CTE) of the composite should be lower or a match to the positive CTE of concrete (7-12×10−6/° C.). The required value was achieved by adding negative CTE materials to a cement matrix.
Data Source
AI summary
A high temperature composite includes a binder, cement or geopolymer and ceramic filler, negative coefficient of thermal expansion materials of AM2O8 or A2(MO4)3 family or ZrV2O7. The material is compatible with concrete, any ceramics or metals or metal alloy. The material is heat shock resistant and stable in harsh chemical environments and is impermeable to most solvents. The new sealant materials can be used as sealants, heat shock resistant structural materials and coatings.