Document Type : Original Article
Authors
1
Department of Chemical Engineering, Yildiz Technical University, 34220, Istanbul, Türkiye.
2
TUSAŞ-Türk Havacılık ve Uzay Sanayii, 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.
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