Low Infrared Emissivity Coating Based on Graphene Surface-Modified Flaky Aluminum

Area of Science:

• Materials Science
• Surface Chemistry
• Corrosion Engineering

Background:

• Developing advanced coatings with tailored optical and protective properties is crucial for various industrial applications.
• Traditional coatings often face challenges in balancing gloss, emissivity, and long-term durability.
• Graphene's unique properties offer potential for surface modification to enhance material performance.

Purpose of the Study:

• To develop a low infrared emissivity coating using graphene-modified flaky aluminum complex powders (rGO-FAl).
• To evaluate the optical properties (glossiness, reflectance) and infrared emissivity of the developed coating.
• To assess the corrosion resistance and protective effects of the graphene coating in a corrosive environment.

Main Methods:

• Preparation of graphene surface-modified flaky aluminum complex powders (rGO-FAl) via chemical bonding.
• Characterization of Vis-NIR diffuse reflectance and glossiness (at 60°) of coatings with varying rGO-FAl content.
• Measurement of infrared emissivity in the 8–14 μm spectral range.
• Electrochemical impedance spectroscopy (EIS) to evaluate corrosion protection.
• Salt spray corrosion testing (500 h) to assess coating durability and appearance.

Main Results:

• The rGO-FAl complex powders significantly decreased Vis-NIR diffuse reflectance, leading to lower glossiness (e.g., from 12.8 to 6.7 at 60° for a 40% pigment coating).
• The coating maintained low infrared emissivity (0.238–0.247) in the 8–14 μm range.
• EIS measurements showed significantly higher impedance for the Al-rGO test plate, indicating enhanced corrosion protection.
• The coating with 40% rGO-FAl maintained its appearance after 500 h of salt spray testing, outperforming the control coating.

Conclusions:

• Graphene surface modification of flaky aluminum powders is an effective strategy for developing low-gloss, low-emissivity coatings.
• The rGO-FAl coating exhibits superior corrosion resistance and durability compared to coatings with unmodified aluminum powders.
• This advanced coating technology holds promise for applications requiring both aesthetic appeal and robust environmental protection.