Multi-Layer Vacuum Panel Edge Seal for Thermal Stress Relief
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Solution Overview
Problem
Conventional vacuum insulated glass panels face issues such as de-tempering of glass substrates, high manufacturing costs, and poor durability due to thermal stress and edge seal failures.
Innovation Solution
A vacuum insulating panel design featuring a multi-layer edge seal with specific coefficients of thermal expansion for each seal layer, combined with a laser sintering process to form the edge seal, which reduces transient thermal stress and improves adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer edge seal is used in vacuum insulated glass panels, then the manufacturing process is simple, but the seal fails due to thermal stress and de-tempering of glass substrates
Solution Approach 1:
The edge seal is divided into multiple layers (first seal layer, second seal layer, third seal layer) with different coefficients of thermal expansion. Each layer serves a specific function: the first seal layer provides initial sealing, the second seal layer with intermediate CTE buffers thermal stress, and the third seal layer ensures hermetic sealing. This segmentation allows the seal to accommodate thermal expansion differences between glass substrates while maintaining structural integrity.
Solution Approach 2:
The edge seal uses composite material structure with layers having different CTE values. The first seal layer has CTE of 7.0-7.9×10^-6/K, the second seal layer has CTE between the first seal layer and glass substrate, and the third seal layer has CTE matched to the second glass substrate. This composite structure creates a gradient that reduces thermal stress concentration and prevents de-tempering of the glass substrates.
2Reliability
If high temperature processing is used to form the edge seal, then the seal hermeticity is improved, but the glass substrates undergo de-tempering and lose mechanical strength
Solution Approach 1:
The patent changes the thermal expansion parameters of the seal layers to match the glass substrates. By selecting materials with specific CTE values (first seal layer: 7.0-7.9×10^-6/K, second seal layer: intermediate value, third seal layer: matched to second glass substrate), the seal structure accommodates thermal expansion during heating, reducing thermal stress and preventing de-tempering while still achieving hermetic sealing.
Solution Approach 2:
The patent utilizes differential thermal expansion principles by designing a multi-layer seal structure where each layer has a different CTE. The gradient in CTE values allows the seal to expand and contract at different rates during temperature changes, absorbing thermal stress and preventing glass substrate de-tempering while maintaining seal integrity at elevated temperatures.
3Strength
If the seal material has high adhesion to glass, then the seal bonding is improved, but the thermal stress concentration increases leading to edge seal failure
Solution Approach 1:
The seal is segmented into multiple layers with different adhesion characteristics and CTE values. The first seal layer provides initial bonding to the first glass substrate, the second seal layer with intermediate CTE acts as a stress buffer zone, and the third seal layer bonds to the second glass substrate. This segmentation distributes thermal stress across layers rather than concentrating it at the glass-seal interface, maintaining bonding strength while improving thermal durability.
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 maintains the thermal tempering of glass substrates, reduces the center to edge stress gradient, and enhances the mechanical durability and hermeticity of the vacuum insulating panel, while also reducing manufacturing costs.
Implementation Method 1
a laser sintering process to form the edge seal
Implementation Method 2
wherein a coefficient of thermal expansion (CTE) of the second seal layer is greater than a CTE of the first seal layer, a CTE of the third seal layer is greater than the CTE of the first seal layer, the CTE of the second seal layer is less than a CTE of the first glass substrate, and the CTE of the third seal layer is less than a CTE of the second glass substrate
Implementation Method 3
Providing a vacuum in the space between the substrates reduces conduction and convection heat transport, and thus provides insulating properties
Data Source
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AI summary
A vacuum insulating panel includes first and second substrates (e.g., glass substrates), a hermetic edge seal, a pump-out port, and spacers sandwiched between at least the two substrates. The gap between the substrates may be at a pressure less than atmospheric pressure to provide insulating properties. The vacuum insulating panel may include a multi-layer edge seal structure with coefficients of thermal expansion (CTEs) of layers of the seal structure optimized for CTE grading.