Polymer-Derived Ceramic Resin Crosslinking for High Yield
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Solution Overview
Problem
Existing polymer derived ceramics (PDCs) face challenges in achieving high ceramic yield and mitigating shrinkage during conversion, necessitating improvements in their formation process.
Innovation Solution
A method involving the reaction of boric acid and 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane to form a polymeric resin, followed by incorporating a chemical crosslinking agent that provides free-radicals at low temperatures, and crosslinking the resin before pyrolysis to enhance ceramic yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preceramic polymers are pyrolyzed to form ceramic materials, then high-temperature properties and resistance to oxidative and corrosive environments are achieved, but ceramic yield is insufficient and shrinkage occurs during conversion
Solution Approach 1:
The patent changes the chemical composition parameters of the preceramic polymer by incorporating specific ratios of polysiloxane (containing Si-O-Si bonds), polycarbosilane (containing Si-C-Si bonds), and boron-containing units. This compositional parameter optimization ensures that upon pyrolysis, the ceramic product achieves high yield (minimizing substance loss) while maintaining the desired high-temperature stability and chemical resistance properties
Solution Approach 2:
The patent creates a composite preceramic polymer system combining multiple polymer types (polysiloxane, polycarbosilane, and boron-containing units) before pyrolysis. This composite approach allows the final ceramic material to inherit beneficial properties from each component while achieving synergistic effects that improve both ceramic yield and structural properties, resolving the contradiction between material performance and yield
2Reliability
If preceramic polymers are pyrolyzed to form ceramic materials, then high-temperature properties and resistance to oxidative and corrosive environments are achieved, but significant shrinkage occurs during conversion
Solution Approach 1:
The patent optimizes the chemical composition parameters of the preceramic polymer, specifically controlling the ratios of Si-O-Si, Si-C-Si, and boron-containing units. This parameter optimization controls the pyrolysis reaction pathways and gas evolution characteristics, thereby minimizing volumetric shrinkage while preserving the formation of a dense, structurally sound ceramic that maintains high-temperature properties and chemical resistance
Solution Approach 2:
The patent creates local structural features within the ceramic by incorporating boron-containing units at specific positions in the polymer chain. During pyrolysis, these localized boron-rich regions form specific ceramic phases or structural motifs that act as structural supports, maintaining the overall shape and reducing shrinkage while locally providing enhanced chemical resistance and high-temperature stability
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 ceramic yield of greater than or equal to 80.0% with reduced shrinkage and porosity, suitable for high-temperature and chemically resistant applications.
Implementation Method 1
incorporating a chemical crosslinking agent in said polymeric resin wherein said chemical crosslinking agent provides a source of free-radicals at temperature of less than or equal to 225° C.; heating said polymeric resin containing said chemical crosslinking agent and crosslinking said polymeric resin at temperatures at or below 225° C.
Implementation Method 2
pyrolyzing said crosslinked resin produced in step (c) and forming a ceramic at a ceramic yield of greater than or equal to 80.0%
Data Source
AI summary
The present invention stands directed at polymer derived ceramic material. More specifically, boric acid and 2,4,6-trimethyl-2,4-6-trivinylsilazane are reacted to form a polymeric resin followed by the addition of a crosslinking agent and then subsequent crosslinking and pyrolysis to provide an improved ceramic yield.