Silicon dioxide films were fabricated by anodizing single-crystal silicon wafers in a 0.04kmol m-3 HNO3 ethylene glycol solution at 25∼70°C for analysis by XPS with Ar sputtering and capacitance measurement. In anodization, a constant 100mA current was applied up to an anode potential of 200V, then the potential was maintained at this value. The maximum anode potential was reached 200V at 45°C, and the current decay in potentiostatic periods was slowest at this temperature. XPS O 1s and Si 2p spectra showed that anodic oxide film formed at 45°C is thicker than any film formed at other temperatures, and that the film/substrate interface of samples anodized at 45°C is relatively rough compared to that fabricated at other temperatures. Anodic oxide film capacitance was minimum at 45°C.
Diamond films were synthesized by microwave plasma chemical vapor deposition (CVD) on carbon steels with various surface treatments, including gas carbonitriding, carburizing and TiN coating. Films were analyzed for their crystallinity using Raman microprobe spectroscopy. On pure iron substrates and carbon steel with gas carbonitriding and carburizing, diamond films containing amorphous carbon grew over the powder-like graphite that was formed. On TiN-coated carbon steel substrates, diamond films with excellent crystallinity grew without the formation of the powder-like graphite. This suggests that the TiN layer inhibits Fe atom diffusion. Crystallinity and the ratio of amorphous carbon contents of diamond film have little dependence on the carbon content of the steels used in this study.
Mild steel substrates were treated with B-ion implantation or dynamic ion mixing in which B-ion implantation and Ti-deposition were conducted simultaneously. Prior to treatment, some substrates were implanted with C-ions to confirm the location of the original substrate surface. Compositional depth profiles of surface regions were obtained by using Auger electron spectroscopy (AES). For B-ion implantation, implanted B species accumulate with the outward transport of Fe atoms followed by growth of a monolithic B layer. For dynamic ion mixing, this outward Fe-atom transport is enhanced further, apparently due to the trapping of sputtered Fe atoms by condensing Ti atoms on the surface. This Fe-Ti reaction causes Fe atoms to be incorporated into the growing B layer, resulting in the formation of a 3μm-thick boronized layer at less than 200°C.
Cu/Co multilayer electrodeposition has been studied using a dual-pulsed current from pyrophosphate solutions. A pure copper layer is obtained with a current density lower than the diffusion-limited one of cupric ion. The cobalt content in the alloy layer increases with applied current density, and reaches about 95at.%. When the copper layer becomes thicker than 20nm and the alloy layer thicker than 15nm, the multilayer film becomes smooth. The well-defined modulation in the copper and cobalt composition was observed for Cu/Co multilayer deposits by Auger electron spectroscopy with Ar sputtering. The copper-content depth profile varies within the alloy layer, when the alloy layer is quite thin at a few nanometers. This compositional variation may be due to diffusion-layer disorder by hydrogen evolution or the cobalt hydroxide film formation on deposits.
Gravimetric analysis was conducted on Ag-ZrB2 composite layers electrodeposited from an AgCN bath in which ZrB2 particles were suspended to obtain the ZrB2 content. It has been observed that the codeposition rate of ZrB2 particles depends on plating current density and on the plating solution stirring rate, so the effects of plating current density and the stirrer rotation rate for the electrolyte solution on ZrB2 content in composite layers were investigated. The optimum plating condition maximizing the ZrB2 content was found to be at 5A·dm-2 and 900rpm by two-way layout experimentation. A linear relationship between the ZrB2 content and the amount of Ag-ZrB2 composite deposited was found by regression analysis. Thus, it appears that the determination of ZrB2 content from the amount of the Ag-ZrB2 composite is possible.
The correlation between the redox behavior of surface compounds formed in dilute sulfuric acid and the heat treatment temperature (HTT) of 2 D-C/C composites whose fibers are made of PAN was investigated by using X-ray diffraction analysis (XRD) and cyclic voltammetry (CV). XRD results indicate that the reflection intensity increased with HTT but that the half-value width decreased. These results suggest that the graphite structure developed with increasing HTT. Cyclic voltammograms were measured for both x-y planes parallel to woven laminates and x-z planes perpendicular to these. For both planes, the current corresponding to the formation of phenol-type compounds (at 0.3V-0.4V) was suppressed with increasing HTT, i.e, the graphite structure development. The anodic currents between 0.3V and 0.4V for the x-z plane at the same HTT was lower than those for the x-y plane. The current corresponding to the formation of carbonyl compounds (at 0.8V), in contrast increased with HTT. The reduction current observed from 1.0V increased with decreasing HTT.