Researchers develop ultra-black paint for cars

Chinese researchers have developed a new ultra-black paint capable of absorbing 99.9 percent of incoming light, potentially revolutionizing automotive coatings. The material, created by a team led by Zhiwei Liu at the Nippon Paint Company in Shanghai, combines carbon black pigment with microscopic carbon nanotubes to achieve its extreme darkness. This innovation builds upon earlier work by scientists who have long sought to create increasingly darker surfaces, with applications ranging from aerospace to consumer goods. The research was inspired by BMW’s demonstration of Vantablack, a similarly dark material composed of vertically aligned carbon nanotubes, which the automaker showcased in a concept vehicle in 2019. While Vantablack absorbs 99.96 percent of visible light, reflecting just 0.04 percent, the new formulation developed by Liu's team reflects only 0.08 percent of light, making it appear even deeper black under certain conditions. According to Liu, the challenge lies in improving the practical application of such materials within the auto industry, where complex requirements for paint durability and application methods remain unresolved. The process used to develop the paint involves mixing 140 grams of carbon black pigment with 60 grams of carbon nanotubes and additional components. The mixture is ground for five hours in a wet mill to ensure the pigments distribute evenly along the nanotubes, minimizing clumping. This careful blending allows the material to absorb nearly all incident light while scattering any remaining reflections multiple times through the structure of the nanotubes. To test the stability of their creation, Liu and his colleagues subjected the paint to rigorous conditions. They placed samples in a centrifuge spinning at 4000 revolutions per minute and exposed them to an environment with 40 degrees Celsius and 95 percent humidity for 14 days. Despite these extreme tests, the paint showed minimal changes, suggesting it could withstand real-world conditions required for automotive use. The potential appeal of this ultra-black finish extends beyond aesthetics. In China, deep black car finishes are considered particularly elegant and are often associated with luxury vehicles. Liu noted that such finishes have long been viewed as premium choices due to their visual impact and luxurious undertones. This aligns with market trends where consumers seek distinctive features that enhance the perceived value of high-end automobiles. While the technical achievements of Liu’s team represent a significant advancement, challenges remain in translating laboratory success into mass production. The complexity of applying such advanced materials consistently across different vehicle models poses hurdles for manufacturers. However, the successful testing of the paint under extreme conditions indicates that these obstacles might be surmountable with further refinement. The study detailing the development of this ultra-black paint has been published in the journal Matter & Light, marking a milestone in the field of optical engineering. Researchers continue to explore ways to optimize the balance between light absorption and practical usability, aiming to bring this cutting-edge technology closer to commercial viability in the automotive sector.