Two-Phase Primer Layer for Composite Coating Adhesion
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Solution Overview
Problem
Composite materials, such as carbon fibre reinforced polymers (CFRP) and glass fibre reinforced polymers (GFRP), face challenges with low interface strength of spray coatings due to the low softening point of polymeric resins and mismatches in elastic modulus and thermal expansion coefficients, leading to erosion and delamination issues during thermal spraying, limiting their use in applications requiring wear resistance and thermal protection.
Innovation Solution
A two-phase primer layer with a predefined distribution of reinforcing material elements bound by a polymeric phase is applied to the composite substrate, providing a textured surface that enhances mechanical interlock and interface strength, allowing a single coating layer to be reliably adhered without the need for multiple intermediate layers, thereby preventing delamination and optimizing coating process parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal spray coating is applied directly to composite substrate, then coating provides wear resistance and thermal protection, but interface strength is insufficient due to low softening point of polymeric resins and mismatches in elastic modulus and thermal expansion coefficients
Solution Approach 1:
A primer layer is introduced as an intermediary between the composite substrate and the thermal spray coating. This primer layer serves as a mediator that is compatible with both the polymeric matrix of the composite substrate and the inorganic coating materials, thereby improving interface strength and preventing delamination while allowing the coating to provide wear resistance and thermal protection
Solution Approach 2:
The solution employs a composite coating system consisting of a primer layer and a thermal spray coating layer. The primer layer itself is a composite material designed to bridge the organic-inorganic interface, combining compatibility with polymeric resins and providing a suitable surface for inorganic coating adhesion, thus resolving the fundamental incompatibility between direct spray coating and composite substrates
2Reliability
If multiple intermediate layers or graded coatings are used to achieve high interface strength, then coating adhesion improves, but process complexity and minimum achievable coating thickness increase
Solution Approach 1:
The primer layer combines multiple functions into a single layer: it provides adhesion promotion, surface texturing for mechanical interlock, and compatibility bridging between the composite substrate and thermal spray coating. This consolidation of functions into one layer simplifies the overall coating process while maintaining high interface strength, avoiding the need for multiple separate intermediate layers
3Productivity
If high velocity spray particles are used for thermal spraying, then coating deposition efficiency increases, but erosion of the composite substrate occurs
Solution Approach 1:
The primer layer acts as a protective cushion applied before the thermal spray coating process. It absorbs and distributes the impact energy of high-velocity spray particles, preventing direct erosion of the composite substrate while allowing efficient coating deposition. This prior protection enables the use of high deposition efficiency parameters without substrate damage
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 two-phase primer layer ensures high interface strength between the composite substrate and the coating layer, reducing processing defects and enabling the use of composite materials in applications requiring wear resistance and thermal protection while minimizing coating thickness and material mass.
Implementation Method 1
a reinforcing phase of material elements bound in a predefined distribution by a polymeric phase and at least partially exposed at an outer surface of the primer layer so as to provide a surface texture
Data Source
Figure 1~2
AI summary
A coated composite material comprising a composite substrate comprises a polymeric matrix with fibre reinforcement, a surface of the composite substrate being coated with a two-phase primer layer E and a coating layer A adhered to said outer surface of the two-phase primer layer E. The two-phase primer layer E comprises a reinforcing phase of material elements bound in a predefined distribution by a polymeric phase and at least partially exposed at an outer surface of the primer layer so as to provide a surface texture.