Bonded Ceramic Assembly Silicon Gradient Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bonded ceramic assemblies face challenges in maintaining bond strength when subjected to rapid heating, particularly due to thermal stress and expansion, which leads to potential cracking and reduced durability over time.
Innovation Solution
A bonded ceramic assembly is developed with a bonding layer containing aluminum, calcium, magnesium, rare earth elements, and silicon, where the silicon content is higher at the surface than in the interior, creating a gradient that inhibits thermal expansion and compressive stress, thereby maintaining bond strength even under rapid heating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a bonding layer is used to bond multiple ceramic substrates, then the part size and complexity can be increased, but the bond strength is reduced under rapid heating conditions
Solution Approach 1:
The bonding layer is designed with non-uniform silicon content distribution, where the surface region contains higher silicon content (3-10 mass% as SiO2) compared to the interior region. This local quality variation creates a gradient that modifies thermal expansion behavior at the surface, reducing thermal stress concentration and maintaining bond strength under rapid heating conditions while still enabling large part sizes through multi-substrate bonding.
2Ease of manufacture
If the bonding layer has uniform composition, then manufacturing is simplified, but thermal stress causes cracking and reduced durability under rapid heating
Solution Approach 1:
The bonding layer composition is designed with specific parameter ranges: aluminum content of 33-65 mass%, calcium and magnesium total content of 27-60 mass%, and rare earth element content of 2-12 mass%. Crucially, the silicon content is controlled to be 3-10 mass% at the surface region, creating a compositional gradient that changes the thermal expansion parameters at the surface compared to the interior, thereby reducing thermal stress and improving durability under rapid heating.
3Strength
If the bonding layer contains high aluminum content, then bond strength is improved, but thermal expansion causes stress and cracking during rapid heating
Solution Approach 1:
The bonding layer is formulated as a composite material containing multiple oxides: aluminum oxide (33-65 mass%), calcium oxide and magnesium oxide (27-60 mass%), rare earth element oxides (2-12 mass%), and silicon oxide (3-10 mass% at surface). This composite composition combines the high-temperature stability of aluminum oxide with the thermal expansion modulation provided by silicon oxide, creating a material that maintains bond strength while reducing thermal expansion stress during rapid heating.
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 bonded ceramic assembly effectively resists bond strength reduction and thermal stress, ensuring durability and stability during extended use, even when exposed to rapid temperature changes.
Implementation Method 1
the silicon content, in terms of oxide, of the surface of the bonding layer is greater than in the interior of the bonding layer
Implementation Method 2
creating a gradient that inhibits thermal expansion and compressive stress
Data Source
AI summary
The bonded ceramic assembly of the present disclosure includes a first substrate made of ceramic, a second substrate made of ceramic, and a bonding layer positioned between the first substrate and the second substrate. The bonding layer contains aluminum, at least one of calcium and magnesium, a rare earth element, silicon, and oxygen. Out of a total 100 mass % of all of the components making up the bonding layer, the bonding layer contains from 33 mass % to 65 mass % aluminum in terms of oxide, a total of from 27 mass % to 60 mass % calcium and magnesium in terms of oxide, and from 2 mass % to 12 mass % rare earth element in terms of oxide. The silicon content, in terms of oxide, of the surface of the bonding layer is greater than the silicon content, in terms of oxide, of the interior of the bonding layer.