Effect of Thiourea on the Properties of a Cu–Al₂O₃ Coating Prepared via Jet Electrodeposition

Abstract

Cu–Al₂O₃ nanocomposite coatings were jet electrodeposited from an electrolyte containing Al₂O₃ nanoparticles and added thiourea. The effects of the thiourea concentration on the surface morphologies, microstructures, growth structures, incorporated Al₂O₃ nanoparticle contents, and mechanical performances of the composite coatings were examined. The results revealed that the adsorption of Al₂O₃ increased from 4.6 at% to 9.3 at% with the addition of thiourea, and grain refinement from 61 nm to 33 nm was achieved. Thiourea additions in the concentration range of 0–15 mg/L increased the microhardness by 79% compared with that of the coating fabricated without thiourea. The mechanisms by which thiourea influenced the deposition quality and mechanical properties of the coating are discussed.

Fig. 4 SEM images of the microstructures of the Cu–Al₂O₃ coatings with thiourea concentrations of (a) 0 mg/L, (b) 5 mg/L, (c) 10 mg/L, and (d) 15 mg/L.