The Effect of Pigment Material on the Optical Absorbance, Emittance, and Wear Resistance of Black Anodized Coatings: A Case Study on 7075 Aluminum Alloy

Producing ideal black coatings with optical absorption and emission followed by desirable wear resistance is crucial for various applications such as space applications. A suitable method for producing these coatings is anodizing aluminum alloys followed by black dying the produced anodic coatings using black organic or inorganic pigments. It is necessary to investigate and optimize the effect of the process parameters to maximize the optical absorption, emission, and the wear resistance of the coatings. These issues have been addressed in this research, and the influence of process parameters and type of pigment has been studied to maximize the absorptivity, emissivity, and the wear resistance of the coatings. For the first time, the effect of pigment on the absorptivity, emissivity, and wear resistance of the coatings was investigated. Unexpectedly , it was observed that the type of pigment had a significant effect on the optical and mechanical properties of the coatings. It was also found that in the anodic coatings containing inorganic pigment, absorptivity increased from 0.85 to 0.95, the emissivity increased from 0.82 to 0.91, and weight loss value in pin‐on‐disk wear test decreased from 6 to 2 mg with increasing the anodizing time from 15 minutes to 45 minutes. In contrary, slight improvement was observed in the coatings containing organic pigments. Despite increasing the anodizing time in the latter case, the absorptivity, emissivity, and the weight loss during wear test changed insignificantly.