Optimization of Color Stability in Graphene-based Hybrid Epoxy Coatings for Aerospace Applications Utilizing the Box–Behnken Design

Document Type : Original Article

Authors

1 Department of Chemical Engineering, Yildiz Technical University, P.O. Box: 34220, Istanbul, Türkiye

2 TUSAŞ-Türk Havacılık ve Uzay Sanayii, P.O. Box: 06980, Ankara, Türkiye

Abstract

The present study aimed to investigate the surface color properties of graphene-based hybrid epoxy coatings using the CIE Lab color space (L*, a*, b*), total color difference, and chromaticity coordinates, with multivariate optimization performed through a Box–Behnken experimental design. Within the four-factor, three-level design space, L values ranged from 17.09 to 71.55, a* values from -2.18 to +0.27, b* values from 0.65 to 2.96, and ΔE values from 2.39 to 47.13. The minimum color difference (ΔE = 2.39) was obtained for the formulation containing 0.5 wt. % graphene, 0 wt. % boron carbide, 1 wt. % zinc borate, and 1 wt. % organic fiber, relative to black reference coating used in military aircraft. Response surface models showed high predictive capability, with R² values of 0.9920, 0.9912, 0.9922, and 0.9492 for L*, a*, b*, and ΔE, respectively. Analysis of variance showed that graphene content was the most influential factor affecting all color responses, particularly ΔE, due to its strong light-absorbing effect, which reduced surface lightness and suppressed color difference. The chromaticity coordinates of the coatings were clustered within a narrow region of the diagram (x = 0.31-0.32, y = 0.33-0.34), while the correlated color temperature values were mainly in the range of 4550-5076 K. Overall, the results demonstrated that formulation control and ΔE minimization effectively improved color stability and camouflage compatibility in aerospace and defence coating applications, ensuring strong optical consistency.

Keywords

Main Subjects

References

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