STUDIES ABOUT STRUCTURE AND SOME PHYSICAL PROPERTIES OF NICKEL AND ZINC- NICKEL ALLOY LAYERS ELECTROCHEMICALLY DEPOSITED

Nickel electroplating has a great commercial and industrial importance emphasized by increasing of annual global consumption. In ordinary coatings zinc remains the principal metal for industrial applications, especially for coverage of steel products. In the last two decades it was registered an important development of application of electrodeposited alloys due to the market demand for products with high quality coatings. On the first places there are the machine buildings industry and the aerospace industry, also those for electrical components and for fixing devices. Because consumption of heavy metals has to be reduced year by year, until the total elimination, there are searching for new technologies and one of the most promised of them is that of alloys electrochemically coated, such as Zn-Ni, Zn-Co and Zn-Fe are. Layers of nickel and zinc-nickel alloys were electrochemically deposited. The samples were studied by scanning electron microscope (SEM), composition was revealed by energy dispersive of X-rays (EDX) and X-ray diffraction (XRD), reflectance was marked out by reflectance spectroscopy and hardness was measured with a Vickers indenter device. The aim of the study was to optimize electroplating process in order to obtain layers with better mechanical properties (hardness, adhesion), physical properties (reflectance) and chemical stability (non-oxidative surfaces). Also the optical aspect was considered.