Oxide-Ceramic Fiber Composite Material
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Solution Overview
Problem
Current oxide-ceramic fiber composite materials for extreme thermal conditions are either very expensive to produce or have insufficient mechanical properties due to high fiber content, which affects their thermoshock and thermofatigue resistance, and existing preparation methods result in materials with low tensile and bending strengths.
Innovation Solution
A process involving calcination of oxide-ceramic powders at high temperatures to create a slip with low dynamic viscosity and high solids content, allowing for infiltration of continuous fibers and subsequent sintering to produce a composite with adjustable fiber content and excellent mechanical properties at reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high fiber content (more than 30% by volume) is used to improve damage tolerance and quasiductile behavior, then mechanical properties and thermoshock resistance are improved, but production cost increases significantly due to the high price of continuous oxide-ceramic fibers
Solution Approach 1:
The patent applies parameter changes by precisely controlling the fiber volume fraction within a specific range of 10-40% (optimally 20-35%), rather than using conventionally high fiber contents. This parameter optimization achieves the necessary damage tolerance while significantly reducing the expensive fiber consumption, thereby resolving the contradiction between reliability and manufacturing cost.
Solution Approach 2:
The patent employs composite materials by combining continuous oxide-ceramic fibers with a specifically formulated oxide-ceramic matrix system (Al2O3-SiO2-MgO-CaO). The matrix composition is optimized to provide both mechanical strength and processability, enabling the composite to achieve adequate damage tolerance at lower fiber contents compared to conventional monolithic ceramics or high-fiber composites.
2Ease of manufacture
If low solids content slip is used to reduce viscosity for complete fiber infiltration, then ease of manufacture is improved, but matrix shrinkage increases during drying and sintering, worsening mechanical properties
Solution Approach 1:
The patent applies parameter changes by optimizing the solids content of the slip to a specific range of 30-60% (weight percent), which represents a compromise between viscosity and shrinkage. This parameter optimization allows sufficient fiber infiltration while limiting matrix shrinkage during drying and sintering, thereby maintaining mechanical properties.
Solution Approach 2:
The patent utilizes porous materials by controlling the matrix to have a porosity of 30-70% after sintering. This porosity level is optimized to accommodate the fiber network structure while providing adequate mechanical strength and thermal insulation. The controlled porosity helps manage shrinkage effects during processing.
3Ease of manufacture
If conventional laminating technologies are used to prepare fiber-reinforced ceramic members, then ease of manufacture is improved, but the materials exhibit low tensile and bending strengths, worsening mechanical properties
Solution Approach 1:
The patent applies parameter changes by optimizing several critical parameters: fiber volume fraction (10-40%), slip solids content (30-60%), and sintering temperature (1000-1500°C). These parameter optimizations work together to achieve both ease of manufacture through conventional laminating technologies and improved mechanical properties with tensile strengths of 50-200 MPa and bending strengths of 100-400 MPa.
Solution Approach 2:
The patent employs composite materials with a specifically designed oxide-ceramic matrix system (Al2O3-SiO2-MgO-CaO) that enhances interfacial bonding between fibers and matrix. This composite structure, combined with controlled porosity (30-70%), improves stress transfer efficiency and mechanical properties while maintaining manufacturability through conventional processing techniques.
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 process achieves high strength and damage tolerance without fiber coating, with bending specimens maintaining 60% of maximum bending stress after initial bending and 25-30% after further bending, while minimizing shrinkage and production time, resulting in a cost-effective material with improved thermal resistance.
Implementation Method 1
a) calcinating an oxide-ceramic powder while retaining a free flowing property
Implementation Method 2
e) drying the green body
Implementation Method 3
f) sintering the green body to form the oxide-ceramic fiber composite material
Data Source
AI summary
The invention relates to a particularly low-cost and flexible process for the preparation of a sintered ceramic fiber composite material consisting of oxide-ceramic continuous fibers and an oxide-ceramic matrix, and to a fiber composite material prepared by such process.