ANALYSIS OF CHROME-BLACK SOLAR-ABSORBER SURFACES

The 52Cr(p,γ) 53Mn resonance reaction and the 16O(p,γ) 17F direct-capture reaction have been used to determine quantitatively the chromium and oxygen depth distributions in a series of electroplated chrome-black solar absorbers. In conjunction with SEM investigations, the chemical and structural composition of the films have been studied as a function of plating time. Two stages of deposition were identified. The commencement of the second stage correlated well with the reported minimum in the thermal emittance of the films. The unusual oxide compositions are consistent with the absorbers being Cr/Cr2O3 cermet films.