Study of the mechanical properties of single- layer and multi-layer metallic coatings with protective-decorative applications

Abstract

Abstract. Single thin coating of matt nickel (Nimat), a mirror bright copper (Cubright), a mirror bright nickel (Nibright) and their combinations were electrochemically deposited on brass substrate with thickness 500 µm. The basic aim was electrodeposition of two-layer Cubright/Nimat and Nibright/Cubright systems, and three-layer Nibright Cubrigh/Nimat system, which are among the most widely applied protective and decorative systems in light and medium operating conditions of corrosion. The thicknesses of the obtained films varied from 1 µm to 3.25 µm. They were investigated via nanoindentation experiments, in order to characterize their basic physical and mechanical characteristics, related with their good adhesion and corrosion protective ability, as well as ensuring the integrity of the system "protective coating/substrate" to possible mechanical, dynamic and/or thermal stresses. As a result, load-displacement curves were obtained and indentation hardness and indentation modulus were calculated using the Oliver & Pharr approximation method. The dependence of the indentation modulus and the indentation hardness on the depth of the indentation, surface morphology and structure of the obtained coatings, their texture and surface roughness were investigated too. The obtained results showed that the three-layer Nibright/Cubright /Niimat/CuZn37 system has highest indentation modulus and indentation hardness, following by two-layer Nibright/Cubright system and single layer coatings.

Nanoindentation investigations of electrodeposited on steel substrate corrosion protective zinc coating additionally improved by Cr III conversion layer

“…The use of the aforementioned advance approach for characterization in a local area allows evaluating the influence of the different layers on the mechanical characteristics of the whole system (substrate-multilayer). In our previous works [23,24] we started with investigations of single layers and then continued to develop this approach investigating different multilayer systems [25].…”