Potato Shaped Graphite Prepregs for Z-Direction Conductivity
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Solution Overview
Problem
Fibre reinforced composite materials, particularly those used in aerospace applications, face challenges in achieving adequate electrical conductivity in the 'Z' direction due to the presence of insulating resin interlayers, making them vulnerable to electromagnetic hazards like lightning strikes without compromising mechanical properties.
Innovation Solution
Incorporating potato shaped graphite (PSG) particles into the resin interlayers of prepregs, which are coated with conductive materials to enhance electrical conductivity while maintaining mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive particles are added to increase electrical conductivity in the Z direction, then electrical conductivity improves, but weight increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the conductive particles by using potato shaped graphite with specific characteristics (particle size distribution, shape factors, and surface area-to-volume ratio) to optimize conductivity while minimizing weight. The unique potato shape provides higher surface area for electrical contact while maintaining lower density compared to traditional spherical or irregular carbon particles.
Solution Approach 2:
The invention creates a composite interleaf material combining potato shaped graphite particles with thermosetting resin, forming a multi-phase composite structure that provides both electrical conductivity and mechanical integrity. The composite leverages the conductive properties of graphite while the resin matrix provides structural support and adhesion.
2Reliability
If conventional conductive particles are used, then electrical conductivity increases, but mechanical properties deteriorate
Solution Approach 1:
The patent optimizes particle size distribution and shape parameters of the potato shaped graphite to balance conductivity and mechanical properties. The specific particle size range (D50 between 5-50 μm) and shape characteristics provide adequate conductivity while minimizing disruption to the resin matrix continuity and fibre-matrix bonding.
Solution Approach 2:
The potato shaped graphite particles create a controlled porous network within the interleaf that facilitates electrical conduction pathways while maintaining resin flow during curing and ensuring proper impregnation of the fibrous reinforcement, thereby preserving mechanical integrity.
3Reliability
If high concentration of conductive particles is used, then electrical conductivity improves, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the concentration parameter of conductive particles to achieve adequate conductivity at lower loadings (0.1-5 wt%). This reduced concentration simplifies the manufacturing process by minimizing particle aggregation issues, reducing mixing complexity, and facilitating easier impregnation during prepreg production.
Solution Approach 2:
The invention concentrates conductive particles specifically in the interleaf regions between fibrous plies rather than distributing them uniformly throughout the entire composite. This localized placement provides targeted conductivity enhancement in the Z direction while minimizing overall particle content and manufacturing complexity.
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
Significantly increases electrical conductivity in the 'Z' direction of composite materials, providing enhanced protection against electromagnetic hazards without detrimental effects on mechanical properties, and allows for the use of lower concentrations of conductive particles.
Implementation Method 1
Incorporating potato shaped graphite (PSG) particles into the resin interlayers of prepregs, which are coated with conductive materials to enhance electrical conductivity
Data Source
Figure 1
Figure 2
AI summary
A prepreg comprising a fibre reinforced curable resin, the prepreg containing electrically conductive particles in the range of from 0.5 to 10% by weight based on the resin, the electrically conductive particles comprising potato shaped graphite.