Sol-gel-derived lanthanum-modified lead zirconate titanate (PLZT) thin films with a La/Zr/Ti
ratio of 10/65/35 and a lead lanthanum titanate (PLT) thin seeding layer were successfully
deposited on an indium tin oxide (ITO)-coated soda lime glass substrate at 500°C. Effects of
excess lead addition of different concentrations in the precursor solution on the electrical
properties of the resultant PLZT thin films were investigated. As a result, the relative
permittivity increased and the dissipation factor decreased with the increase of excess lead
concentration. Excess lead of 30 mol% was indispensable for obtaining PLZT thin film with
good ferroelectricity. In addition, the resultant films showed more than 60% transmittance in
the visible region.
In this study, Ni-W/carbon nanotube (CNT) composite platings are electrodeposited onto steel plate as a possible coating material for the polymer electrolyte membrane fuel cell (PEMFC) bipolar plate, which requires high corrosion resistance under acidic environment and low contact resistance. The dispersibility of CNT in the plating bath is improved by surface modification of CNT through hydrothermal treatment in mixed acid solution. The change in electrodeposition behavior of Ni-W plating by CNT addition is investigated by cathodic polarization measurement. The corrosion resistance under acidic environment is evaluated using 0.5M H2SO4 solution and contact resistance of the composite platings is measured and compared with Ni and Ni-W plating. The surface modification of CNT through hydrothermal treatment is found to increase the CNT content in the Ni-W/CNT composite plating up to 0.33 mass.% and sufficient incorporation of hydrothermally treated CNT in Ni-W plating results in low contact resistance and enhanced corrosion resistance than pristine Ni-W plating.
Metal-carbon composite platings have potential applications in various fields. We previously reported the preparation of nickel-nanocarbon composite platings using a Wood's bath. The maximum carbon content was 1.2 mass%, but the maximum current efficiency of plating was 12%. The present study focuses on improving the current efficiency of the electroplating process used to prepare nickel-carbon black composites in a Watts bath contained carbon black. The microstructure and carbon content in the nickel plating were evaluated. The current efficiency was greater than 90%, but the carbon content of the composite plating layer was approximately 0.6 mass%. The incorporation of carbon black particles into the plating layer was influenced by the adsorption of particles onto the cathode surface, the supply of particles to the surface, and the electrodeposition rate. The carbon content in the plating layer was highest near the cathode surface and decreased with increasing thickness of the plating layer. The grain size of electrodeposits with carbon black was larger than that of deposits without carbon black. The space between grains was increased with increasing grain size. The corrosion resistance was diminished, indicating that the boundary was the originating point of corrosion.
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