Electrochemical formation of organic thin films and composite plating using surfactants with an azobenzene group are explained. These surfactants lose their dispersing ability by reduction, which enables formation of organic thin films and high particle content Ni/ceramic particle composite plating. Mechanisms of these formations are discussed based on adsorption behavior of these surfactants. Properties and applications of the organic thin films and the composite coatings are also discussed.
The electrodeposition of Zn–Sb alloy from ethylene glycol (EG) solvent was investigated. ZnCl2 and SbCl3 or antimony potassium tartrate (APT) were used as zinc and antimony ion sources, respectively. The phases deposited from the EG-ZnCl2–SbCl3 (85.0:14.7:0.3 mol%) bath at 393 K were hcp Zn containing little amount of Sb or elemental Sb and it was difficult to control the composition of Zn–Sb alloy. In contrast, Zn–Sb alloys containing 2.0∼71.6 mol% Zn were obtained from the EG-ZnCl2-APT (85.0:13.6:1.4 mol%) bath at the constant current densities of 50∼300 A m−2 at 393 K. Amorphous-like Zn–Sb alloys having a composition near Zn4Sb3, which is expected as a thermoelectric material with a high figure of merit, were obtained by the electrodeposition at current densities of 150∼300 A m−2 in this bath.
A poly(2-N-phenylamino-4,6-dimercapto-S-triazine) (PPDT) layer was first prepared on the iron surface electrochemically. The PPDT layer strongly adsorbed on the surface because of the polar triazine rings of the PPDT molecules. The fact that no electrochemical response of the PPDT layer covered electrode to dissolved Fe(CN)63− exhibited that the PPDT layer is an insulator layer with less permeability to dissolved species, acting as a diffusion barrier against agents causing corrosion such as H2O and O2. A conductive polymer polyaniline (PANI) layer could be electrodeposited on the PPDT layer using the PPDT layer covered electrode. The obtained PANI/PPDT bilayer coating greatly lowered the anodic current peak ascribed to the anodic dissolution of iron and the corrosion current. The high anti-corrosion ability was due to a hybrid effect of the PANI layer as an in-situ oxidant and the PPDT layer as a diffusion barrier.
We investigated the preparation and characterization of the Pb–Zr–Ti–Nb–Si–O ferroelectric thick film by the electrophoretic deposition method. A ferroelectric material of (Pb,Si)(Zr1−x−yTixNby) Oz was prepared by the solid state method. The obtained samples were single phase, and the metal composition was controlled. The powder was charged into the acetone-iodine based electrodepositon bath after it was ultrasonically suspended. The maximum amount of the deposit was obtained when 1.5 g/l I2 and 5.0 g/l ferroelectric powders were added to a 100 ml acetone bath, and a uniform coating was obtained with an applied voltage at 180 V. The thickness of the film was controlled by changing the deposition time. The heat treatment condition of the deposited thick film was investigated and the conditions were 1000°C, O2, and 120 sec. The obtained thick film was relatively dense and uniform with a thickness of 15–30 µm at center position. Furthermore, the microstructure of the thick film was homogeneous. Based on these results, we obtained relatively good P-E hysterisis loops using Nb substituted Pb–Zr–Ti–Nb–Si–O thick films.