Solar energy absorber comprising nickel support with coating - of nickel oxide and chromium oxide giving 85 per cent min. absorption coefft.

摘要

A solar energy absorber consists of a nickel support with a uniform coloured coating comprising =90% nickel oxide and 1-10% chromium oxide with an absorption coefficient of =0.85 at =25 degrees C in the wavelength range 0.2-20 mu. Pref., apat from the usual impurities, the nickel support has a max. sulphur content of 0.005% and carbon content of 0.08%. The surface of the nickel support is pref. treated with a soln. contg. an acid oxidising 1-4.2 mol/1 hexavalent-chromium from chromium trioxide and/or =1 soluble chromate or bichromate, other than manganese salts, 2-4 mol/l. free bisulphate ions from sulphuric acid and/or =1 sulphate or bisulphate, other than manganese sulphate or bisulphate, for a sufficient period to produce an oxidic nickel from the support and =1 metal from the soln. The prefd. treatment temp. is 50-75 degrees C.