Influence of current density on microstructure and properties of electrodeposited nickel-alumina composite coatings

Highlights: • Current density of the electrodeposition affects the incorporation of Al₂O₃ in Ni matrix. • Ni/Al₂O₃ composite coatings exhibit changes in crystallographic texture. • The pitting corrosion effects were observed in Ni/Al₂O₃ coatings. • Residual stresses were decreased with increasing current density and coating thickness. - Abstract: Electrodeposition process is a very promising method for producing metal matrix composites reinforced with ceramic particles. In this method insoluble particles suspended in an electrolytic bath are embedded in a growing metal layer. This paper is focused on the investigations of the nickel matrix nanocomposite coatings with hard α-Al₂O₃ nano-particles, electrochemically deposited from modified Watts-type baths on steel substrates. The influence of various current densities on the microstructure, residual stresses, texture, hardness and corrosion resistance of the deposited nickel/alumina coatings was investigated. The surface morphology, cross sections of the coatings and distribution of the ceramic particles in the metal matrix were examined by scanning electron microscopy. The phase composition, residual stresses and preferred grain orientation of the coatings were characterized using X-ray diffraction techniques. The coating morphology revealed that α-Al₂O₃ particles show a distinct tendency to form agglomerates, approximately uniformly distributed into the nickel matrix