Corrosion properties of ultrasonic electrodeposited nanocrystalline and amorphous patterned Ni-W alloy coatings

摘要

Ni-W alloy coating is a kind of promising environmental friendly alloy to substitute for hard chrome plating, for its excellent functional properties. Their properties depend mainly on the structure and defect, such as cracks. The crack is catastrophe to both physical and chemical properties and crystalline state also affect their properties and application. In this work, nanocrystalline nickel tungsten alloy (nc Ni-W) coating, amorphous nickel tungsten alloy (a Ni-W) coating and crystalline nickel tungsten alloy (c Ni-W) coating were prepared under ultrasonic direct current (UDC) electroplating. The aim of the present study is to achieve structure control and high surface quality of Ni-W alloy coatings, and investigate corrosion properties of these coatings to explain the contradiction of better corrosion resistance of nc Ni-W coating than a Ni-W coating in experiment and theory. Thus X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) were used to examine the composition, crystalline state, microstructures and defects of the samples. Moreover, potentiodynamic polarization test was used to study the corrosion behavior of electroplated nickel-tungsten alloys.