Porous Ceramic Transducer Bodies With Multi-Stage Pre-Firing
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Solution Overview
Problem
Existing manufacturing processes for porous piezoelectric or electrostrictive ceramics for acoustic transducers are laborious and limited in design flexibility, often resulting in structural issues like cracking and deformation, especially for thicker bodies, and require additional steps like grinding and applying glass surfaces, which increase complexity and cost.
Innovation Solution
A multi-stage pre-firing process involving preliminary, intermediate, and final heating stages to decompose pore-forming particles and remove organic materials, allowing for injection molding of ceramic bodies with improved structural integrity, enabling thicker and more complex designs without the need for post-sintering machining or glass surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pore-forming particles are introduced into green body mixture to enhance porosity, then acoustic matching and performance are improved, but structural integrity deteriorates causing cracking and deformation
Solution Approach 1:
The patent applies preliminary action by performing pre-firing treatment before final sintering to decompose pore-forming particles and remove organic binders in advance. This preliminary decomposition prevents gas buildup during subsequent sintering that would cause cracking, while still achieving the desired porosity for acoustic matching.
Solution Approach 2:
The patent segments the firing process into multiple distinct stages: pre-firing at lower temperature to decompose organics and pore-formers, then sintering at higher temperature to achieve final density and porosity. This segmentation allows each stage to optimize for its specific function without compromising structural integrity.
2Manufacturing precision
If conventional firing process is used to remove pore formers, then porosity is achieved, but additional burn out process at higher temperatures is required increasing complexity and risk of cracking
Solution Approach 1:
The patent merges the pore-former decomposition and organic binder removal into a single pre-firing stage performed before sintering. This combines multiple decomposition functions into one integrated process step, eliminating the need for separate burn-out operations and reducing overall process complexity.
Solution Approach 2:
By performing pore-former decomposition as a preliminary action before sintering, the patent eliminates the need for post-sintering burn-out processes. This preliminary removal of organic materials prevents cracking during sintering and eliminates additional high-temperature processing steps.
3Length of moving object
If thicker ceramic bodies are manufactured, then acoustic transducer performance is improved, but structural problems like cracking and deformation worsen
Solution Approach 1:
The patent applies preliminary decomposition of pore-forming particles and organic binders through pre-firing before sintering thicker ceramic bodies. This preliminary action prevents gas buildup and structural stress during the sintering of thick sections, enabling production of thicker transducers without cracking or deformation.
4Adaptability or versatility
If injection molding is used to form ceramic preforms, then manufacturing flexibility and design freedom are improved, but fold lines, cold flow regions, and macroscopic stress regions are introduced
Solution Approach 1:
The patent uses preliminary pre-firing treatment to decompose pore-forming particles and organic materials before sintering injection-molded ceramic preforms. This preliminary decomposition relieves macroscopic stresses and eliminates cold flow regions and fold lines created during injection molding, enabling production of complex-shaped thick transducers with uniform structure.
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 process facilitates the production of thicker, structurally sound porous ceramic bodies with enhanced performance, reducing manufacturing complexity and cost while allowing for flexible transducer designs and improved acoustic coupling.
Implementation Method 1
decomposing pore-forming particles by heating the green body at an intermediate pre-firing temperature that is higher than the preliminary pre-firing temperature
Implementation Method 2
extracting the binder material from the green body by heating the green body at a preliminary pre-firing temperature
Implementation Method 3
sintering the green body at a sintering temperature that is higher than the final pre-firing temperature in order to form the porous ceramic body
Data Source
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AI summary
A process for preparing a porous ceramic body includes forming a green body with a mixture of ceramic material powder, binder material, and pore-forming particles. The process further includes extracting the binder material, decomposing the pore-forming particles, and removing residual organic materials from the green body at respective, progressively higher pre-firing temperatures. After these three stages, the green body is sintered at a still-higher temperature to form the porous ceramic body. Embodiments facilitate manufacturing and can render most or all surface grinding unnecessary, allowing electrode deposition directly onto substantially non-porous surfaces of the porous ceramic body that are naturally formed during sintering. Advantageously, the green body may be formed into net shape by injection molding the mixture that includes the pore-forming particles, and embodiments can result in porous ceramic bodies that are much thicker than currently available, with better structural integrity.