Gel-Casting Molded Article Bonding Strength
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Solution Overview
Problem
Existing methods for bonding two different materials together in molded bodies using the gel-casting process result in insufficient bonding strength between the materials, leading to lower strength and durability in the final fired product.
Innovation Solution
A method where the first molded part is formed using the gel-casting process, and the second molded part is also formed using the gel-casting process in contact with the first part, allowing a curing reaction to occur between the second material slurry and unreacted gelling agent in the first material slurry, enhancing the bonding strength between the two parts. This process ensures that the bonding surfaces of the first and second molded parts are strongly bonded, resulting in a higher strength and durability when the molded body is fired.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the first molded part is formed without using the gel-casting process and the second molded part is formed by the gel-casting process, then two kinds of molded parts of different materials can be bonded together, but the bonding strength between the bonding surfaces is insufficient
Solution Approach 1:
The molded body is divided into multiple molded parts formed by different processes (gel-casting and non-gel-casting). Each part can be independently formed and then bonded together, allowing optimization of each part's formation process while achieving overall bonding. This segmentation enables the first molded part to be formed without gel-casting while the second part uses gel-casting, resolving the contradiction between manufacturing ease and bonding strength.
Solution Approach 2:
A bonding agent or intermediate layer is introduced at the bonding interface between the first and second molded parts. This intermediary substance facilitates strong bonding between the differently-formed parts, compensating for the insufficient bonding strength that would otherwise result from combining different formation processes. The intermediary enables reliable bonding while maintaining the manufacturing flexibility of using different processes for different parts.
2Strength
If the bonding strength between the bonding surfaces of two kinds of molded parts is increased, then the strength and durability of the fired body are improved, but the surface flatness at the boundary region becomes more difficult to maintain
Solution Approach 1:
Different surface treatment or bonding approaches are applied to different regions of the bonding interface. The local quality principle allows the bonding surface to have enhanced properties (such as roughness or chemical activity) specifically at the interface region to improve bonding strength, while the overall surface flatness requirements are maintained in the exposed regions. This localized approach enables strong bonding without compromising overall surface quality.
Solution Approach 2:
Surface preparation and treatment are performed in advance on the bonding surfaces before the final bonding step. This preliminary action includes steps such as surface roughening, cleaning, or applying primers to the bonding interfaces, ensuring that when the parts are bonded, strong adhesion is achieved. By preparing the surfaces beforehand, the bonding strength is enhanced without requiring excessive pressure or heat that would compromise surface flatness.
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 method achieves a significantly higher bonding strength between the materials, resulting in a fired body with improved strength and durability, with a difference in level on the surface boundary between the materials being 20 times or less the median diameter of the particles, ensuring sufficient bonding strength.
Implementation Method 1
a material slurry which contains a material powder, a dispersant, and a gelling agent is molded, and the molded material slurry is caused to set through curing reaction effected by the gelling agent
Implementation Method 2
a curing reaction can proceed between the second material slurry and an unreacted gelling agent remaining in the first material slurry (the first molded part), thereby strongly bonding the bonding surfaces of the first and second molded parts to one another
Data Source
Figure 1~3
Figure 4(a)~4(b)
Figure 5(a)~5(b)
AI summary
A second mold is placed on a planar surface of a first mold having the planar surface, thereby forming a first mold cavity. The first mold cavity is filled with a first material slurry which contains a first material powder, a dispersant, and a gelling agent, so as to mold the slurry, and the molded slurry is caused to set, thereby forming a first molded part on the planar surface of the first mold. A third mold is placed on the planar surface of the first mold from which the second mold is removed and on which the first molded part is formed, thereby forming a second mold cavity. The second mold cavity is filled with a second material slurry which contains a second material powder different in material from the first material powder, a dispersant, and a gelling agent, so as to mold the slurry in such a manner that the slurry comes into contact with the first molded part, and the molded slurry is caused to set, thereby forming a second molded part on the planar surface of the first mold. By this procedure, there can be provided a molded body in which two types of molded parts of different materials are bonded together and which exhibits high bonding strength between the bonding surfaces of the two types of molded parts.