Influence of stirring conditions on Ni/Al₂O₃ nanocomposite coatings

Abstract

The influence of the stirring conditions in the electrolyte on the structure and properties of Ni/Al₂O₃ nanocomposite coatings was studied. The coatings were produced by electrochemical reduction on a copper substrate in a Watts bath modified by nickel grain inhibitor, cationic surfactant and low concentrated nanometric alumina. The process has been carried out with different types of agitation (mechanical, ultrasonic stirring and with a copper rotating disc electrode). The structures of the produced coatings were characterised by scanning and transmission electron microscopy as well as X-ray diffraction. The influence of Al₂O₃ particles on the microhardness of composite coatings was also analysed. The adhesion of the composite coatings to the substrate and coefficient of friction were determined by means of the scratch test. The studies have shown that the bath stirring method affects the content and distribution of the alumina, as well as the properties of the produced composite Ni/Al₂O₃ coatings.

Keywords:

• Nickel coating
• Al₂O₃ particles
• Electrodeposition
• Nanoindentation
• Scratch test

Acknowledgements

The study was performed in the framework of the research project of the National Science Center entitled ‘Composite nanomaterials produced by electrochemical method’ (2012/05/B/ST8/01555).