A new black nickel formula was developed which had a solar absorptance of 0.92 and an infrared emittance (at 100° C) of <0.10 after 14 days at 38° C (100° F) and 95 percent relative humidity. This compares to coatings prepared with a previous NASA formula which had their solar absorptance degraded from 0.90 to 0.72 after the same period of humidity exposure. The electroplating bath and conditions were changed to obtain the more stable coating configuration. The effect of bath composition, temperature, pH, and plating current density and time on the coating composition, optical properties and durability were investigated.
J. H. Lin,
R. E. Peterson,
"Improved Black Nickel Coatings For Flat Plate Solar Collectors", Proc. SPIE 0085, Solar Energy Utilization II, (15 February 1977); doi: 10.1117/12.954940; https://doi.org/10.1117/12.954940