Reflective Coating System for High-Temperature Vacuum Use

A substrate of nickel coated with a thin layer of silver and further coated with a thin protective layer of silicon dioxide has been found to constitute an optically reflective substrate/coating system that is suitable for use at high temperature in vacuum. This system was developed originally for use on space solar dynamic and solar thermal power systems and, in particular, on secondary solar-radiation concentrators, which are expected to operate at temperatures in the range of 400 to 800 °C. This substrate/coating system might also be applicable to hot optical components of terrestrial solar electric-power systems, solar-powered wastewater-treatment systems, solar-powered fiber-optic illumination systems, and laboratory optical instruments.