Impact of Manufacturing Processes on Electrical Conductivity of Carbon Fiber Composites

Introduction

Manufacturing processes such as Pultrusion, Roll-Wrapping, and Resin Film Infusion (RFI) significantly influence the electrical conductivity of carbon fiber composites.

Key factors affected by these processes include Fiber Alignment, Resin Content, and the degree of Graphitization.

Fiber alignment is crucial as it determines the pathways for electrical current, with better alignment generally leading to higher conductivity.

Resin content impacts the composite's overall conductivity, as the resin itself is typically non-conductive.

Graphitization, a process that rearranges carbon atoms into a more ordered structure, can enhance the electrical conductivity of carbon fibers.

Figure 1: The fabrication process of conductive carbon fibers

Manufacturing Techniques

Pultrusion: A continuous process where fibers are pulled through a resin bath and then through a heated die to form a composite.

Roll-Wrapping: Involves wrapping resin-impregnated fibers around a mandrel, followed by curing.

*8Resin Film Infusion (RFI)**: A process where dry fibers are laid into a mold and resin is infused under vacuum.

Figure 2: Fiber composites manufacturing process.Image Source: Formlabs

Wet Lay-Up: Fibers are manually placed in a mold and resin is applied using a brush or roller.

Prepreg Lamination: Pre-impregnated fibers with resin are laid into a mold and cured under heat and pressure.

Factors Influencing Conductivity

Fiber Alignment: Proper alignment of fibers creates efficient pathways for electrical current.

Resin Content: Higher resin content can reduce overall conductivity as resin is typically non-conductive.

Graphitization: Rearranging carbon atoms into a more ordered structure can enhance conductivity.

Surface Treatment: Oxidation and other treatments can improve the bonding and conductivity of fibers.

Doping: Introducing foreign elements can modify the electronic properties and enhance conductivity.

Enhancing Conductivity

Carbon Nanotube Incorporation: Adding CNTs can create conductive pathways within the composite.

Graphene Coating: Applying a layer of graphene can significantly improve conductivity.

Doping Techniques: Introducing metals or conducting polymers can enhance electrical properties.

Surface Modification: Techniques like plasma treatment can improve interfacial contact and electron transfer.

Fiber Orientation: Aligning fibers in the direction of electrical flow can enhance conductivity.

Figure 3: Overview of advantages of carbon fiber as a thermal conductive filler.

Applications

Aerospace: Used in aircraft and spacecraft components for lightweight and conductive properties.

Automotive: Utilized in body panels, chassis components, and battery systems for electric vehicles.

Electronics: Employed in printed circuit boards, connectors, and electromagnetic shielding.

Renewable Energy: Used in wind turbine blades and electrodes for fuel cells and supercapacitors.

Medical: Applied in prosthetic limbs, orthopedic implants, and electrodes for neurostimulation.

Figure 4: The production process of carbon fiber fabric.Image Source: EUROPLAS