A research team at the National Institute for Materials Science (NIMS) in Japan has developed a coating technology utilizing eco-friendly, low-friction zinc oxide (ZnO) material. When applied to bearing balls, this material retains its low-friction properties, reducing the bearing's friction coefficient by approximately one-third.
Addressing worsening global environmental and energy issues requires reducing friction in drive mechanisms, such as engines. Since mechanical drive components become extremely hot during engine operation, any friction-reducing technology used in such environments must also be heat-resistant.
Researchers focused on ZnO for its friction-reducing and heat-resistant capabilities, identifying the underlying friction-reduction mechanism at the nanoscale. Leveraging nanotechnology, they developed a fundamental technique to apply low-friction ZnO coatings by controlling the material's crystal orientation. Applying this to commercial high-performance bearings-specifically by coating the bearing balls and controlling the ZnO crystal orientation through the rotation of the balls within the cage-the team successfully reduced the friction coefficient by about one-third.
The resulting bearings were integrated into a small jet engine, achieving a 1% reduction in fuel consumption. Additionally, researchers worked on miniaturizing generators for use in emergencies where fuel supplies might be scarce. They successfully developed a small jet engine generator equipped with ZnO-coated bearings; weighing approximately 40 kg-making it portable by two adults-the unit generates 8,000 W of power, sufficient to meet the electricity needs of two households.
This low-friction ZnO coating is suitable not only for bearings but also for any mechanical drive component requiring energy efficiency and friction reduction. It is versatile enough for use under a wide range of conditions, including temperatures from room level to high heat, as well as in oil, vacuum, and atmospheric environments.
