Polymer-Derived Ceramic Foam Composition for Low-Shrinkage Strength
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Solution Overview
Problem
Existing ceramic and carbon-based foams face issues such as high shrinkage, cracking, and increased density due to high sintering temperatures, leading to structural instability and limited temperature stability.
Innovation Solution
Development of inorganic resin-based or polymer-derived ceramic foams using siloxane polymers and unique fillers, which can bond with various materials, utilize volatiles as blowing agents, and react with water to create controlled porosity, allowing for lower sintering temperatures and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional ceramic sintering process is used at high temperatures (greater than 1,400°C), then ceramic foam can be formed, but significant shrinkage occurs which increases effective density and causes cracking
Solution Approach 1:
The patent changes the sintering temperature parameter from traditional high temperatures (>1,400°C) to lower temperatures (800-1,200°C) by using polymer-derived ceramic precursors. This parameter change resolves the contradiction by enabling ceramic foam formation at temperatures that do not cause excessive shrinkage and cracking, while still achieving the desired ceramic structure and properties.
Solution Approach 2:
The patent introduces polymer-derived ceramic precursors as an intermediary material between the organic foam template and the final ceramic structure. These precursors form a transitional phase during heating that converts to ceramic at lower temperatures, acting as a mediator that avoids the direct high-temperature sintering process that causes shrinkage and cracking.
2Stability of the object's composition
If high sintering temperatures are used to form ceramic foams, then ceramic structure is achieved, but structural instability and cracking occur
Solution Approach 1:
The patent changes the thermal processing parameters from high-temperature sintering (>1,400°C) to lower-temperature pyrolysis (800-1,200°C). This parameter change maintains ceramic structure formation while eliminating the excessive thermal stress that causes cracking and structural instability, thereby improving reliability.
Solution Approach 2:
The patent uses composite materials consisting of polymer-derived ceramic precursors combined with fillers (such as silica, alumina, or carbon). This composite approach allows the formation of stable ceramic structures at lower temperatures, reducing thermal stress and preventing cracking while maintaining structural integrity.
3Temperature
If polymer-derived ceramic precursors are used to lower sintering temperature, then processing temperature is reduced, but new fabrication challenges arise
Solution Approach 1:
The patent employs polymer-derived ceramic precursors that self-convert to ceramic structures through controlled pyrolysis. The material itself provides the necessary chemical transformations and structural formation during heating, eliminating the need for complex external sintering processes and reducing fabrication complexity despite the temperature reduction.
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 foams achieve higher strength and lower density, with temperature stability up to 1,400°C, overcoming the limitations of traditional methods by using siloxane polymers that convert to ceramics at lower temperatures and incorporate fillers for enhanced structural integrity.
Implementation Method 1
The foams can be pyrolyzed to convert them to ceramic, producing high strength ceramic foams
Implementation Method 2
Carbon-based foams can be made in a similar method to ceramic foams, or they can use the volatiles in the carbon source as the blowing agent
Implementation Method 3
Adsorbed water on powdered coal, coke, or graphite can be used as a blowing agent to form the porosity
Data Source
AI summary
Foam compositions comprising an inorganic resin matrix or a polymer-derived ceramic matrix are provided, as well as methods of fabricating the same. The foams may or may not contain additional functional fillers to control mechanical and/or thermophysical properties. The foam materials can include a novel combination of tailorable inorganic siloxane resins with unique fillers, and unique methods of producing the desired porosity. Unlike related art foams, the foams of embodiments of the subject invention can be inorganic-resin-based, and can be closed cell foams or semi-closed cell foams.