Elimination of the Environmental Dangers of Chromium Plating by Using of Ni-W-B Electroplated Nanocomposite from Tartrate Baths without Ammonia

Tungsten-Nickel-Boron alloy (W-Ni-B) deposition is a potential substitute for hexavalent chrome, because of surface corrosion and wear resistance, and high hardness. The objective of the current work was to the electroplating process and study in detail the effect of bath chemistry, operating conditions on chemical composition, microstructure and properties of Ni-W-B alloys deposited from tartrate electrolyte, in the absence of ammonia or ammoniums salts. Ni-W-B alloy coatings are electrodeposited by pulse plating method with frequency of 0.11 Hz, from a bath contains of nickel sulfate, sodium tungstate, sodium borate and sodium potassium tartrate on stationary working electrodes. The surface morphology studies of coating, by SEM, AFM, and STM, confirmed the globular structures each of these globular were contain of smaller structures, which their sizes are about 2-6 nm Structural study of coating by XRD confirms existence of the nanocrystalline structure or amorphous or mixture of them. Calculation of grain sizes by use of XRD and scherrer equation shows that they are in nano sizes. As-plated deposits have hardness around 825 VHN, which it shows that they are amorphous structure.

کلیدواژه ها:

Electrochemical deposition ، Ni-W-B ، Amorphous structure ، nanocomposite ، SEM ، hard chrome