Coating Carbon Fiber Plastic with Sulfur Trioxide

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Solution Overview

Problem

Existing methods for coating carbon fiber reinforced plastic components often result in unsatisfactory metal layer adhesion, particularly when compared to glass fiber reinforced plastics, due to poor wetting and interaction between carbon fibers and the coating, limiting the mechanical stability and durability of the components.

Innovation Solution

A method involving pre-treatment of carbon fiber reinforced plastic components in gaseous sulfur trioxide followed by metal layer deposition, including seeding with palladium and a combination of electroless and galvanic deposition, significantly enhances metal layer adhesion by improving wetting and closing gaps between carbon fibers, with preferred treatment times and additional surface roughening techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional coating methods are used on carbon fiber reinforced plastic components, then the coating process can be completed, but the metal layer adhesion is unsatisfactory

Engineering Contradiction:
Improvemetal layer adhesionVSAvoidcoating quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The component undergoes preliminary treatments before coating: nitric acid treatment to activate the surface, followed by gaseous sulfur trioxide treatment to create a receptive surface for metal deposition. These preparatory actions ensure the carbon fiber surface is chemically activated and ready for strong metal layer adhesion.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Gaseous sulfur trioxide acts as an intermediary substance that mediates between the carbon fiber surface and the metal layer. It creates a chemical bridge that enables strong adhesion, with the treatment time controlled at 10-60 seconds to optimize the intermediary effect without over-treating the surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If treatment time in gaseous sulfur trioxide is increased to improve adhesion, then metal layer adhesion improves, but production throughput decreases

Engineering Contradiction:
Improvemetal layer adhesionVSAvoidproduction throughput
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The treatment time in gaseous sulfur trioxide is optimized to a specific parameter range of 10-60 seconds. This parameter change achieves the optimal balance between adhesion quality and production efficiency, avoiding both insufficient treatment and excessive processing time.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

A relatively short treatment time of 10-60 seconds is applied, which is sufficient to achieve the necessary surface activation for strong adhesion without excessive treatment. This partial action approach maintains high production throughput while achieving reliable metal layer adhesion.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If carbon fibers are treated to improve wetting, then metal layer adhesion improves, but surface roughness increases

Engineering Contradiction:
Improvemetal layer adhesionVSAvoidsurface roughness
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The gaseous sulfur trioxide treatment parameters (time: 10-60 seconds, temperature, concentration) are optimized to achieve sufficient surface activation for good wetting and adhesion while minimizing excessive surface roughening. This parameter control ensures both adhesion quality and acceptable surface finish.

Inventive Principle:
Principle #35Parameter changes

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 improved adhesion and mechanical stability of the metal layer on carbon fiber reinforced plastic components, enabling their use in load-bearing structures with increased torsional rigidity and reduced risk of sharp-edged fragments in the event of breakage, while also being cost-effective and lightweight.

Implementation Method 1

The inventors have observed as a possible reason for the good adhesion properties achieved with the method according to the invention that the wetting of the carbon fiber-reinforced plastic components can be improved by treatment in gaseous sulfur trioxide.

Methodology Applied
Scientific EffectWetting: Wetting

Implementation Method 2

the component can (after the pre-treatment) be placed, for example, in an acidic, ionogenic palladium solution, with palladium ions accumulating on the component surface

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 3

These can then be converted into palladium nuclei, for example in a reducing bath.

Methodology Applied
Scientific EffectReduction: Reduction

Implementation Method 4

The metal, for example chemically deposited nickel, accumulates on the palladium nuclei, and an initially thin layer is formed ('seed layer')

Methodology Applied
Scientific EffectChemical deposition: Chemical Vapour Deposition

Implementation Method 5

this can then be reinforced, preferably galvanically, i.e. electrochemically in a bath

Methodology Applied
Scientific EffectGalvanic deposition: Electrodeposition

Data Source

PatentEP2743375B1Method of coating a component
Publication Date: 2023.07.05 DR ING MAX SCHLOTTER

AI summary

The method comprises pretreating a carbon fiber-reinforced plastic component with gaseous sulfur trioxide for 10 seconds to 10 minutes, chemically depositing a metal layer as a seed in a bath, rinsing the component with water, and sand-blasting the component before the steps of pretreatment and treatment with nitric acid. The carbon fibers are embedded in a thermosetting material. The deposition step includes seeding a component in the bath metal layer. The seeding step includes treating the component with ionogenic palladium solution, and electrically energizing the bath.