PLATING OF BLACK NICKEL COATINGS

The encountering problems of energy shortage and environmental pollution lead to the attention toward the limitless amount of clean and renewable energy received from the sun in the form of solar radiation. For efficient photothermal conversion the solar In this work electrodeposition technique was used to produce two types of selective black nickel coatings; the first sulfur–bearing coating from solutions containing Ni-sulfate, Zn-sulfate and thiocyanate and the second phosphorus–bearing coating from a hThe objective of this research is to obtain new selective black nickel coatings with improved properties against environmental degradation. Evaluation of optical properties of both sulfur- and phosphorus-bearing coatings was presented. A selectivity (S) vThe black coloration of sulfur–bearing coating was attributed to the deposition of Ni and Zn sulfides (NiS2, ZnS) in conjunction with free Ni, free Zn and intermetallic Ni-Zn (Ni3Zn22). On the other hand, the black coloration of the coatings bearing phospThe new P-bearing coating showed good thermal stability at 250o C and excellent endurance in severe conditions of humidity and high temperatures.