UDC 621.162 © Anna Gajewska-Midziałek, Benigna Szeptycka, Aleksander Nakonieczny THE STRUCTURE OF THE NANOCRYSTALLINE ELECTROCHEMICAL COMPOSITE COATINGS NI-B AND THEIR TRIBOLOGICAL PROPERTIES The structure and wear resistance was investigated for d.c. – plated Ni composite deposits prepared from a low – concentration Watts electrolyte, with and without additive agents and dispersive B particles. <...> The dispersed phase and additives used in the bath were shown to affect the composition and structure of the electrodeposited composite layer. <...> An increase in the content of B particles in the coating and in the size of [111] nickel crystallites led to increased roughness of Ni-B coatings. <...> The microhardness of the deposited Ni-B layers increased as the size of [111] nickel crystallites decreased. <...> The results suggest that as the effect of the organic compounds employed the nanostructure of the nickel matrix. <...> The wear resistance of the Ni-B composite coatings is five times higher than of nickel coating. <...> This work was supported by European Union – European Social Fund. <...> INTRODUCTION The electrodeposition technique is used in the formation of composite layers with a nickel matrix [1, 2]. <...> Electroplated nanocrystalline nickel coatings have several advantages over conventional coarse-grain coatings such as greater strength, microhardness, diffusion coefficient, electrical resistance, specific heat, coefficient of thermal expansion, plasticity, adhesion, corrosion resistance [3] and wear resistance, as well as a lower elasticity modulus, exceptionally soft magnetic properties [4, 5] and thermal stability up to a temperature of 573 K. Advances in electrodeposition of nanocomposite coatings [6] have opened up prospects for obtaining layers with exceptional properties. <...> The inclusion of nanoparticles can give an increased microhardness and corrosion resistance, modified growth to form a nanocrystalline metal deposit and a shift in the reduction potential of a metal ion [7-10]. <...> The presence of boron in the nickel coating reduces the diffusive migration of atoms and vacancies in the crystal lattice, increases resistance to plastic deformation, reduces both the size of crystallites during electrocrystallization as well as their growth during recrystallization, and strengthens the nickel matrix [11]. <...> Inclusions of boron at the surface affect both the layer’s corrosion behaviour, as well as its mechanical and physical properties, as shown in the report by Medeliene et al [12]. <...> The structure and composition of composite coatings have a significant <...>