Ceramic-Metal Joining via Insertion Jig and Composite Brazing
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Solution Overview
Problem
Existing methods for joining ceramic and metal members are limited, as they require a recess on the ceramic member, making it difficult to join metal members to ceramic members at flat portions without a recess, leading to inadequate bonding.
Innovation Solution
A method involving the use of an insertion jig with a through hole, where a brazing material with a higher thermal expansion coefficient and a powder with a lower thermal expansion coefficient are used, along with a coating to enhance wettability, to form a joint layer between the ceramic and metal members, allowing for bonding regardless of the presence of a recess on the ceramic member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing joining method using particulate material and brazing material is applied to a flat ceramic surface without a recess, then the particulate material spreads over the surface causing inadequate bonding, but the method cannot be used at all for flat surfaces
Solution Approach 1:
The patent introduces an insertion jig as an intermediary tool that creates a recess structure on flat ceramic surfaces. The jig has a through-hole that forms a cavity when pressed against the ceramic surface, allowing particulate material and brazing material to be contained and properly positioned. This intermediary device enables the joining method to work on both recessed and flat surfaces by temporarily creating the necessary recess structure during the joining process.
Solution Approach 2:
The insertion jig performs preliminary action by pre-forming a recess structure on the ceramic surface before the actual joining materials are applied. The jig is pressed against the flat ceramic surface to create a cavity, which is then filled with particulate material and brazing material. This preliminary recess formation ensures that subsequent material application is effective, regardless of whether the original surface was recessed or flat.
2Ease of manufacture
If only brazing material is used to form the joint layer, then the joining process is simple, but cracking occurs in the ceramic member due to thermal expansion mismatch
Solution Approach 1:
The patent uses a composite joint layer consisting of two distinct materials: brazing material with high thermal expansion coefficient and particulate material with low thermal expansion coefficient. This composite structure combines the advantages of both materials - the brazing material provides strong bonding while the particulate material compensates for thermal expansion differences, preventing cracks during temperature changes. The composite approach resolves the contradiction between simple processing and crack resistance.
Solution Approach 2:
The patent changes the thermal expansion parameters of the joint layer by combining materials with different thermal expansion coefficients. The brazing material (high expansion) and particulate material (low expansion) work together to match the thermal expansion characteristics of the ceramic member, reducing thermal stress and preventing cracks. This parameter adjustment maintains bonding strength while improving thermal compatibility.
3Reliability
If a recess is provided on the ceramic member for joining, then proper bonding can be achieved with existing methods, but the ceramic member structure becomes more complex and requires additional processing
Solution Approach 1:
The insertion jig serves as a temporary intermediary that creates the recess structure only when needed for joining, without permanently modifying the ceramic member structure. The jig is pressed against the flat surface during the joining process to form a temporary cavity, then removed after bonding. This approach maintains bonding quality while avoiding permanent structural complexity in the ceramic member.
Solution Approach 2:
The insertion jig performs preliminary action by temporarily creating a recess structure during the joining process rather than requiring the ceramic member to have a permanent recess. The jig forms the cavity, materials are applied, bonding occurs, and then the jig is removed. This eliminates the need for complex ceramic member design with built-in recesses.
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
This method effectively suppresses cracking due to temperature changes and improves joint strength by forming a joint layer using a brazing material and powder, enabling reliable bonding even on flat ceramic surfaces without a recess, enhancing the durability of the joined body.
Implementation Method 1
fusing the brazing material to impregnate the powder with the brazing material to thereby form a joint layer including the brazing material and the powder
Implementation Method 2
the brazing material including a metal having a larger thermal expansion coefficient than the first member, and a powder of a material having a smaller thermal expansion coefficient than the brazing material
Data Source
AI summary
In a step (a), a guard ring is disposed on a ceramic substrate (a second member) such that one of openings of a through hole of the guard ring is covered with a joint surface of the ceramic substrate. In a step (b), a brazing material made of a metal, a powder made of a material having a smaller thermal expansion coefficient than the brazing material, and a feeding terminal are inserted into the through hole. In a step (c), the brazing material is fused to impregnate the powder with the brazing material to thereby form a joint layer including the brazing material and the powder. In this manner, the joint surface and the joint surface are joined to each other through the joint layer.