Low Roughness Carbon Fiber Composite X-ray Window

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Solution Overview

Problem

Carbon fiber composite wafers face challenges in machining and patterning due to high surface roughness, which hinders the development of high-strength structures with micrometer-sized features, particularly for applications like x-ray windows where low surface roughness is essential for optimal performance.

Innovation Solution

A carbon fiber composite x-ray window support structure with a low root mean square surface roughness, achieved by using directionally aligned carbon fibers embedded in a matrix, and a manufacturing process involving multiple curing stages with pressure and vacuum to ensure smooth surfaces, combined with laser milling or laser ablation for precise rib and opening formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If carbon fiber composite wafers are used for high strength applications, then strength is improved, but surface roughness increases making machining and patterning difficult

Engineering Contradiction:
Improveyield strengthVSAvoidsurface roughness
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by controlling the curing process conditions (temperature, pressure, time) to achieve optimal surface finish. Specifically, curing at temperatures between 20-200°C with applied pressure (1-100 atm) and vacuum conditions modifies the physical-chemical parameters of the matrix material, resulting in reduced surface roughness (Rq < 500 nm) while maintaining the high strength properties of the carbon fiber composite structure.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If conventional curing processes are used, then manufacturing is simple, but surface roughness remains high greater than 1 micrometer

Engineering Contradiction:
Improvecuring processVSAvoidsurface roughness
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing surface smoothing during the curing process itself rather than as a separate post-processing step. The curing process is designed to simultaneously achieve structural consolidation and surface finish improvement, where the matrix material is cured under controlled pressure and temperature conditions that promote smooth surface formation before final structural assembly.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The curing process parameters are specifically modified to achieve low surface roughness. The patent specifies curing temperatures of 20-200°C, pressure conditions of 1-100 atm, and vacuum conditions that transform the curing process from a simple consolidation step into a dual-function process that also achieves surface smoothing, reducing Rq to less than 500 nm.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If micrometer-sized features are required, then functional performance is improved, but machining and patterning become difficult due to high surface roughness

Engineering Contradiction:
Improvefeature size precisionVSAvoidmachining and patterning
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by achieving the required surface precision (Rq < 500 nm) during the curing process itself, before any subsequent machining or patterning operations. This preliminary surface preparation eliminates the need for extensive post-curing machining and patterning work, making micrometer-sized feature fabrication feasible and precise.

Inventive Principle:
Principle #10Preliminary action

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 solution results in a high-strength x-ray window support structure with a surface roughness of less than 500 nm, enabling improved adhesion and reduced attenuation of x-ray radiation, while maintaining high yield strength and strain, thus enhancing the structural integrity and performance of the x-ray window.

Implementation Method 1

The support structure comprises a carbon fiber composite material (CFC), the CFC material comprising carbon fibers embedded in a matrix

Methodology Applied
Scientific EffectComposite materials: Composite Materials

Implementation Method 2

laser milling or laser ablation for precise rib and opening formation

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentEP2727897B1X-ray window from high strength carbon fiber composite wafer
Publication Date: 2018.08.15 MOXTEK INC
  • EP2727897B1 patent drawingFigure 1~3
  • EP2727897B1 patent drawingFigure 4~6
  • EP2727897B1 patent drawingFigure 7~8

AI summary

A high strength carbon fiber composite (CFC) wafer, and method of making such wafer, with low surface roughness comprising at least one sheet of CFC including carbon fibers embedded in a matrix. The wafer can have a thickness of between 10-500 micrometers. The wafer can have a root mean square surface roughness Rq, on at least one side, of less than 300 nm in an area of 100 micrometers by 100 micrometers and less than 500 nm along a line of 2 millimeter length. The wafer may be cut to form x-ray window support structures, MEMS, or other micrometer sized structures.