Antipathogenic copper coatings: electrodeposition process and microstructure analysis

Copper coatings are an important group of decorative-protective materials characterised by high corrosion resistance, excellent thermal and electrical conductivity, which lately gained more significance due to their antimicrobial activity. The main aim of the presented research was to electrodeposit homogenous copper coatings from the non-cyanide electrolyte solution in galvanostatic conditions on steel (1.4024) and nickel (Ni201) substrates, commercially used for surgical instruments. The effect of substrate finishes used in the production line, by shot peening with glass balls, corundum treatment and brushing on the coatings surface formation, was investigated. The substrates’ and coatings’ microstructural properties were analyzed by scanning and transmission electron microscopy, atomic force microscopy, and X-ray diffraction analysis. The current efficiency of the copper reduction on nickel and steel substrates was found to be above 95%. The copper layers adhere to both substrates, except those deposited on a brushed surface. Regardless of the substrate used, they have a nanocrystalline structure with an average crystallite size of 30 nm. Moreover, the coating surface morphology, which affects the nature of interaction with microorganisms, was effectively modified by the appropriate substrate finishing without changing the electrodeposition conditions.