When indium tin oxide (ITO) film was prepared using an electron shower, it was found that ITO whiskers grew due to the vapor-liquid-solid (VLS) mechanism. The whisker radius was 10nm and the length 600nm. To grow whiskers, the substrate temperature should be above 200°C and the deposition rate above 6Å/s. Two types of whiskers grew: (a) those grown along the substrate during early growth (t≤30s), and (b) those grown vertical to the substrate at t≥30s. ITO film consisting of (a) whiskers showed high gas-sensing characteristic for NO2 at 200°C. Its sensitivity for 500ppm NO2 was 10 times higher than that of other films consisting of (b) whiskers or plate-like crystals, for example. This shows that ITO film prepared using an electron shower is a potential candidate for semiconductor sensor elements.
The relationship between conditions for preparing WO3 films and their electrochromic properties was investigated. WO3 thin films were prepared by RF magnetron sputtering with various Ar gas pressures and RF powers. Their optical density, coloring efficiency, and response time for coloration and bleaching were measured in a 0.5M solution of KH2PO4. The chemical composition, optical gap, and morphology of prepared WO3 films were measured, and their relationship and electrochromic properties were discussed. The results are as follows: 1. The WO3 film prepared under an Ar gas pressure of 1.0×10-2torr or under an RF power of 100-150W showed the best electrochromic properties. This seems closely related to chemical composition and the optical gap of WO3 films. 2. The coloration response time grew slower with increased Ar gas pressure or decreased RF power. The bleaching response time remained virtually unchanged. These characteristics depend on obtaining fine grains and on the nonhomogeneity of the prepared WO3 films.
High-resistivity NiP films were prepared by electroless deposition while varying the complexing agent species. When complexing agents having -NH2 and=NH groups, e. g., amino acids or amines are used for the NiP bath, higher resistivity NiP films are obtained with electroless deposition. Complexing agents of β-alanine, diethylenetriamine, and sodium L-glutamate were most suitable making higher resistivity NiP films. The highest resistivity was obtained from a diethylenetriamine bath. The resistivity of NiP as-deposited film from a diethylenetriamine bath is 5, 400μΩcm, compared to 160μΩcm for usual NiP films. The most suitable NiP film from the diethylenetriamine bath shows resistivity stable against annealing at about 400°C. High specific resistivity films were found to contain a small amount of carbon. The NiP film from the diethylenetriamine bath contained ca. 3at% carbon, and exhibited a grain structure even at the amorphous state.
In this study, transmission electron microscopy (TEM) was used to characterize the microstructures of as-sprayed, solution-treated, aged CoNiCrAlYTa coatings. The micro-vickers hardness test was used to estimate age hardening of the coatings. The hardness of as-sprayed coatings was about 590Hv. Hardness was decreased to about 560Hv in solution treatment at 1373K for 4 hours. It was increased, however, by aging at 1073K and 1173K after solution treatment. TEM observation showed that the average grain size was about 0.5μm. The γ and β-phases coexisted in as-sprayed coatings. Solution treatment at 1373K coarsened the grain size to about 1.5μm. Wedge-shaped β precipitates in the γ-phase were produced by aging. Needle-shaped α-Co and massive σ precipitates in β phase were clearly produced by aging. These precipitations are therefore thought to contribute to age hardening.
The purpose of this study is to evaluate the thickness, elastic constants, and bond quality of the electroplated metallic layer by using the quantitative analysis of the velocity dispersion of laser surface acoustic waves (SAWs). SAWs were nondestructively generated by a Q-switched YAG laser and monitored using a heterodyne laser interferometer, without inducing thermal damages. The group velocity dispersion obtained by wavelet transform was compared to the analytical velocity dispersion of Rayleigh and Lamb waves. The thickness and elastic stiffness of the well bond layer were estimated by quantitatively analyzing the velocity dispersion of the Rayleigh wave. The velocity dispersion of the 0th order symmetric and antisymmetric Lamb waves was used to estimate the thickness and quality of the delaminated layer. The bond quality could not be estimated, however, because the weak bond area was too small in comparison to the larger SAW propagation distance.
The controllability of the composition of open-beaker phosphoric acids was studied at temperatures in a range from 200 to 300°C. The composition of phosphoric acid and alumina etch rates was measured under the following conditions; (1) water addition, (2) mixed solution with sulphuric acid, and (3) subboiling condensed phosphoric acid (CPA). Adding water to boiling phosphoric acid and thus keeping the acid at the constant boiling point provided a constant acid composition because further dehydration and condensation were avoided. Mixing phosphoric acid with H2SO4 up to about 50vol% has the same effect when water is added. A constant acid composition produces constant etch rates throughout the entire etching period. This enables the estimation of the depths of etch and the amounts of side etching. This, in turn, provides good etching accuracy. The CPA shows further condensation and composition change due to heating even though the acid is kept at temperatures below the boiling point.
The double-zincate processing of aluminum in three different zincate solutions was examined to evaluate the effect of solution composition. Higher concentrations of NaOH and ZnO in zincate solution dissolve both the Al oxide layer and Al substrate more rapidly. This leads to faster Zn deposition. In a solution containing Fe3+ions, Fe codeposition resulted in the growth of rather small, nonhexagonal Zn particles during the first zincate process. In the second zincate process, a stratiform Zn layer grows to cover the Al substrate in a zincate solution without Fe3+ions. Granular Zn is deposited due to Zn growth suppressed laterally by the codeposition of Fe in a solution containing Fe3+ions. Such granular Zn deposition provides a sufficient anchor effect for subsequent electroless Ni plating.
Titanium has a high specific strength and corrosion resistance. Surface treatment or coating is often required to improve surface hardness, however, because of titanium's low durability. In this study, a CO2 laser beam was irradiated in nitrogen to form a hard nitride coating on a pure titanium plate. The hard layer formed by the reaction between titanium and nitrogen consisted of TiN and Ti2N. The surface hardness produced by the treatment exceeded Hv 7.5GPa.