Ideal solar heat panels excel with increasing absorptance (α) in the solar wavelength region (0.3 - 2.5μm) and decreasing emissivity (ε) in the infrared wavelength region (3.0μm or more). Also, in consideration of thermal stability and thermal conductivity, black chromium plating is superior.
| Type of plating | Features & characteristic value |
|---|---|
| Black chromium plating (1) Sargent bath |
- Film composition: CrOx-Cr - Optimum plating thickness: 180nm - Primary plating: Nickel plating - Absorptance of light (α): 0.96 Emissivity of light [ε(t°C): 0.1 at 100°C] - Thermal stability: 350°C |
| (2) Trivalent chromium bath | - Film composition: Cr-Co - Optimum plating thickness: 180nm - Primary plating: Nickel plating - Absorptance of light (α): 0.96 Emissivity of light [ε(t°C): 0.10 at 100°C] - Thermal stability: 200°C |
(From “Kino Mekki Himaku no Bussei” edited by Denki Mekki Kenkyukai; Nikkan Kogyo Shimbun Ltd.)
Black-chromium-plated solar collector
Types of plating
