Ceramic Joint Protrusion Pore Control for Strength
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Solution Overview
Problem
Ceramic joined bodies tend to have lower mechanical strength at joints compared to other parts, due to higher porosity and fracture origins, which affects their reliability and thermal conductivity.
Innovation Solution
A ceramic joined body is created using aluminum oxide-based sintered bodies with a joint layer and protrusions, where the average diameter of closed pores in the protrusions is between 0.8 and 1.5 times that of the sintered bodies, and the area ratio of closed pores is 2% or less, to reduce fracture origins and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a joint material is interposed between ceramic sintered bodies and heat treatment is applied with pressure, then the porosity ratio of the joint layer can be controlled to 3 to 30%, but the mechanical strength at the joint becomes lower than the ceramic sintered bodies
Solution Approach 1:
The invention utilizes a protrusion with controlled closed pores (average diameter 0.8-1.5 times that of the sintered body, area ratio 2% or less) to create a porous structure that optimizes both mechanical strength and stress distribution. The controlled porosity in the protrusion allows for stress dispersion while maintaining structural integrity, resolving the contradiction between porosity control and joint strength.
Solution Approach 2:
The invention changes the pore size parameter of the protrusion to be within a specific range (0.8-1.5 times the sintered body pore diameter) and controls the area ratio to 2% or less. This parameter optimization allows the joint to achieve both controlled porosity and high mechanical strength by preventing excessive stress concentration that would occur with larger or more numerous pores.
2Ease of manufacture
If porosity is increased in the joint region, then manufacturing flexibility is improved, but fracture origins increase and reliability decreases
Solution Approach 1:
The invention employs a protrusion with specifically controlled closed pores (area ratio 2% or less, average diameter 0.8-1.5 times the sintered body pores). This controlled porous structure provides manufacturing flexibility while minimizing fracture origins, as the limited and sized-controlled pores do not act as significant stress concentration points that would compromise reliability.
3Strength
If the joint layer is made denser to improve strength, then mechanical strength increases, but residual stress increases and thermal conductivity may be affected
Solution Approach 1:
The invention introduces a protrusion with controlled closed pores (area ratio 2% or less) that acts as a stress-distributing element. The porous structure of the protrusion allows for residual stress reduction by providing compliance and stress dispersion pathways, while the controlled porosity maintains sufficient density for mechanical strength and preserves thermal conductivity by avoiding excessive void spaces.
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 improves the mechanical strength and reliability of the ceramic joined body by minimizing the size and distribution of fracture origins, reducing residual stress, and preventing fluid leakage, while maintaining thermal conductivity.
Implementation Method 1
a step of sintering the composite molded body
Data Source
AI summary
A ceramic joined body includes a first aluminum oxide-based sintered body, a second aluminum oxide-based sintered body, an aluminum oxide-based joint layer located between the first aluminum oxide-based sintered body and the second aluminum oxide-based sintered body, and an aluminum oxide-based protrusion connected to the aluminum oxide-based joint layer, where the average diameter for closed pores of the aluminum oxide-based projection is 0.8 times or more and 1.5 times or less as large as the average diameter for closed pores for each of the first aluminum oxide-based sintered body and the second aluminum oxide-based sintered body.