| 摘要 |
<p>The composition disclosed is an improved black chromium plating bath useful, for example, for solar selective coatings. The bath comprises an aqueous solution of sulphate-free chromic acid containing nitrate, borate and fluorosilicate ions. Such a bath can be employed at room temperature or higher, e.g. in the temperature range 30 DEG C to 50 DEG C, and at a low current density, e.g. 0.07 to 0.28 A/cm<2>, to obtain a good quality black chromium deposit, which is quite coherent and has a high absorptivity to emissivity ratio, e.g. about 8.</p> |
