Codeposition of Hydrophilic and Hydrophobic Silica with Copper from Acid Copper Sulfate Baths

The influence of the hydrophobicity of silica particles on the electrodeposition of composite coatings from acid copper sulfate solutions on rotating disk electrodes was studied. Spherical, nearly monodisperse hydrophilic and hydrophobic silica particles were used. The hydrophilic silica particles were prepared by the Stöber process. These particles were made hydrophobic by a treatment with oligodimethyl siloxane‐α,ω‐diol. The effect of cetyl trimethyl ammonium hydrogen sulfate (CTAHS) and sodium 1-dodecane sulfonate on the codeposition behavior was investigated. Hydrophilic silica did not codeposit from surfactant‐free nor from surfactant‐containing acid copper sulfate solutions, but up to 4 wt % (≅ 14 vol %) of hydrophobic silica codeposited from solutions containing 15 g/L of silica particles and . The codeposition rate of hydrophobic silica slowly decreased with time. The amount of codeposited particles was highest for a current density of and a rotation speed of 400 rpm. © 2000 The Electrochemical Society. All rights reserved.