CFRP-Al Alloy Composite Joining via Injection Molding
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Solution Overview
Problem
Current methods for joining CFRP with metal materials, such as adhesion and riveting, face challenges due to differences in thermal expansion coefficients and lack of high-strength, reliable bonding techniques, particularly in extreme temperature conditions, limiting the use of CFRP in structural applications like aircraft and automobiles.
Innovation Solution
A method involving chemical treatment of Al alloy sheets and injection molding with high crystalline thermoplastic resins like PPS, polyamide, and PAEK, which integrates CFRP with metal materials, ensuring strong bonding and thermal shock resistance by using a metallic mold to inject resin between the materials, thereby overcoming coefficient differences and achieving high shear joining strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If adhesion method is used to join CFRP with metal material, then weight is reduced and structure becomes lighter, but reliability is insufficient due to inability to withstand extreme temperature conditions and thermal expansion differences
Solution Approach 1:
The patent creates a composite joining structure consisting of three layers: CFRP material, adhesive layer, and metal material. This composite structure combines the lightweight advantage of CFRP with the high temperature resistance and structural strength of metal, while the adhesive provides bonding. The composite material approach resolves the contradiction by integrating materials with complementary properties to achieve both weight reduction and reliability.
2Reliability
If mechanical fastening means such as bolt-nut is used to secure CFRP to metal member, then reliability of connection is improved, but weight increases and manufacturing complexity increases
Solution Approach 1:
The patent merges the bonding function of adhesive with the structural integration of CFRP and metal material into a single unified joining structure. Instead of using separate mechanical fasteners (bolts, nuts, rivets), the adhesive layer directly bonds the CFRP to the metal, creating an integrated assembly. This merging eliminates the need for additional fastening components, reducing weight while maintaining connection reliability through the combined adhesive-metal-CFRP structure.
3Reliability
If rivet joining method is used to fasten CFRP with metal material, then reliability of connection is improved, but manufacturing productivity decreases and structure weight increases
Solution Approach 1:
The patent replaces the mechanical rivet fastening system with a chemical bonding system using adhesive. Instead of mechanically piercing and fastening components together (which requires hole alignment, rivet insertion, and deformation processes), the adhesive chemically bonds the CFRP and metal material surfaces. This substitution eliminates complex mechanical fastening operations, significantly improving manufacturing productivity while maintaining connection reliability through proper adhesive selection and application.
4Strength
If chemical treatment is applied to metal surface for adhesion, then bonding strength is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies chemical treatment to the metal surface as a preliminary step before adhesive application. By pre-treating the metal surface (through methods such as phosphating, anodizing, or chemical etching), the surface acquires enhanced bonding properties that improve adhesive attachment. This preliminary action ensures strong bonding strength is achieved without requiring complex multi-step processes during the main assembly operation, as the surface preparation is completed in advance.
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 produces a composite with high strength and thermal shock resistance, enabling the use of CFRP in structural applications with various metals, enhancing productivity and suitability for aerospace and automotive industries.
Implementation Method 1
a step of injection by injecting a high crystalline thermoplastic resin having heat resistance for joining by injection molding into the gap to form the composite of CFRP with a metal material
Implementation Method 2
a step of chemical treatment of an Al alloy sheet by causing one surface of an Al alloy sheet having a thickness of 0.3 to 0.8 mm to be subjected to chemical treatment for adhesion
Implementation Method 3
a high crystalline thermoplastic resin having heat resistance for joining by injection molding
Data Source
AI summary
A CFRP material with an Al alloy sheet attached to or a CFRTP material with an Al alloy sheet attached to is prepared by joining an Al alloy sheet with a CFRP material or a CFRTP material by adhesion or by injection molding. The surface of this Al alloy sheet and a surface of metal material such as Ti, etc., are subjected to chemical treatment. After this chemical treatment, the CFRP material with an Al alloy sheet attached to or the CFRTP material with an Al alloy sheet attached to and the metal material are inserted into a metallic mold for injection molding so as to have a gap therebetween. High crystalline thermoplastic resin is injected into this gap to join the metal material with the Al alloy sheet, thus obtaining a laminated composite.