UHT Ceramic Matrix Composite Densification with Electrospun Nanofibers
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Solution Overview
Problem
Manufacturing ultra-high temperature ceramic matrix composite structures is challenging due to difficulties in achieving sufficient density and porosity, which conventional methods often fail to address.
Innovation Solution
A system comprising an electrospinning apparatus and an electrospraying apparatus, along with a rapid thermal processing assembly, is used to form ultra-high temperature ceramic matrix composites by dispensing polymeric precursors to create nanofibers, applying a fluid onto these nanofibers, and undergoing pyrolysis and carbothermal/borothermal reduction to enhance density and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used, then the manufacturing process is simple, but the composite material density is insufficient
Solution Approach 1:
The manufacturing process is divided into multiple sequential stages: electrospinning to form nanofiber precursors, pyrolysis to convert to ceramic, and repeated cycles of infiltration and sintering. Each stage addresses specific density requirements, with the segmentation allowing progressive densification from porous nanofibers to high-density ceramic composite structure.
Solution Approach 2:
Polymeric precursors are prepared and electrospun into nanofibers before the actual ceramic formation process. This preliminary action creates a controlled porous framework that guides subsequent ceramic infiltration and sintering, ensuring uniform density distribution before final processing.
2Manufacturing precision
If conventional manufacturing methods are used, then the manufacturing process is straightforward, but porosity control is insufficient
Solution Approach 1:
Different regions of the composite are engineered with different porosity levels. The electrospun nanofibers provide controlled porosity in the green state, while subsequent selective infiltration and sintering create local variations in density. This allows optimization of porosity for specific functions (e.g., thermal insulation vs. mechanical strength) in different zones of the component.
Solution Approach 2:
The manufacturing process employs periodic cycles of infiltration followed by sintering. Each cycle reduces porosity by a controlled amount, allowing progressive densification. The periodic repetition of these steps enables precise control over final porosity levels, with each cycle contributing incrementally to the overall densification process.
3Manufacturing precision
If electrospinning and electrospraying are used, then nanofiber alignment and density are improved, but the manufacturing complexity increases
Solution Approach 1:
Traditional mechanical fiber alignment methods are replaced with electrostatic field-based electrospinning. The electric field between the spinneret and collector automatically aligns polymer jets into straight nanofibers during deposition, eliminating the need for subsequent mechanical alignment steps while achieving superior fiber orientation control.
Solution Approach 2:
The electrospinning process parameters (voltage, flow rate, distance, solvent composition) are precisely controlled to optimize nanofiber alignment and morphology. By adjusting these parameters, the system achieves consistent fiber alignment and density without complex mechanical intervention, transferring control to electrical and fluid dynamic parameters.
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 high-density, ultra-high temperature ceramic matrix composites with improved mechanical and electrical properties, reducing porosity and enhancing oxidation resistance through controlled alignment and matrix material application.
Implementation Method 1
The spinneret is biased at a first DC voltage and the collector is biased at a second DC voltage different than the first DC voltage. The electrospinning apparatus includes a spinneret disposed at a first end of a flowpath and biased at a first DC voltage.
Implementation Method 2
The electrospraying apparatus includes a nozzle biased at a third DC voltage different than the second DC voltage. The nozzle is configured to apply a fluid including a second polymeric precursor onto the plurality of nanofibers deposited on the collector.
Implementation Method 3
The method further includes pyrolyzing the two-dimensional layer with a rapid thermal processing assembly.
Implementation Method 4
The method further includes carbothermally or borothermally reducing the two-dimensional layer.
Data Source
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AI summary
A method for forming an ultra-high temperature (UHT) composite structure includes dispensing a first polymeric precursor (20) with a spinneret (12); forming a first plurality of nanofibers (26) from the first polymeric precursor (20); depositing the first plurality of nanofibers (26) with a collector (16); and applying a fluid (40), with a nozzle (36), onto the first plurality of nanofibers (26) disposed on the collector (16). The fluid includes a second polymeric precursor (42).