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In a breakthrough in passive cooling, the research group of Prof.Smrutiranjan Parida in the Metallurgical Engineering and Material Science Department, Indian Institute of Technology, Bombay (IIT Bombay) has developed a new type of coating material that can effectively reflect the sun’s heat and reduce the amount of heat conducted by the material, thus providing thermal insulation.
?The material also creates a hydrophobic (water-repelling) epoxy composite coating, which reduces heat conduction and imparts high infrared reflectance in a thin coating of just about 65 micrometers. The group tested the coating in a condition simulating a hottest summer day where the temperature on the coated surface was 60 °C. The novel composite coating on the surface decreased the temperature under the coated panel by 15 to 21°C.
?This performance is better than any previously reported coatings. The composite coating also boasted a high solar reflectance of sunlight in the near-infrared (NIR) region of the spectrum, exceeding 72%. At a thickness of just 0.065 to 0.1 millimeters when coated onto a metal surface, the new material can outperform other coatings that are usually three to twenty times thicker, making the new coating not just more efficient but also cost-effective
?. Interestingly, owing to the surface modifications of its fillers, the composite coating also proved extremely resistant to corrosion. In tests involving exposure to Sodium Chloride (NaCl) solution, a kind of salt-water test, the coating revealed an incredible 99% corrosion protection efficiency. This demonstrates that the coating can protect metal surfaces from the deteriorating effects of their environment, increasing longevity and decreasing maintenance costs.
?The patent pending work is published in ACS Applied Materials & Interfaces 2023, 15, 51737?51752.