The correlation between scratch adhesion and hardness has been investigated for nitride coatings deposited on metal substrates with various levels of hardness using arc ion plating. The intrinsic film hardness of TiN, CrN and (Ti0.45 Al0.55) N was separated from the composite hardness measured by micro Vickers tests using a model proposed by Ichimura et al. The critical load in the scratch test increases proportionally to the product of the scratch depth δcr and the composite hardness Hcr at the critical load. δcr for the same coating on non-nitriding substrates is almost constant. In addition to this result, δcr for coatings on nitrided steels was larger than that of coatings on substrates without nitriding. Both results suggest that δcr is an important parameter influenced by the intrinsic properties of deposited film and the true adhesion strength between the film and substrate.
The electrochemical depositions of Zn-Ni alloy from ambient temperature molten salt electrolytes (ZnCl2-NiCl2-1-ethyl-3-methylimidazolium chloride (EMIC)-ethanol system) were investigated. The Ni content in the Zn-Ni alloy deposits could be controlled continuously from 18.8 to 93.0mol% by changing the bath composition and current density. In order to confirm the presence of amorphous structures on Zn-Ni alloy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used. The X-ray diffraction patterns of the alloy, in which Ni content was from 40.7 to 71.7mol%, showed a very broad peak indicating the presence of amorphous structure. The surface of the Zn-Ni deposits was very smooth and uniform. Moreover, the results of DSC measurements for the alloys showed exothermic peaks which are considered to be due to the amorphous-to-crystalline transformation and crystal growth. From these experimental results, it was confirmed that amorphous Zn-Ni alloys could be deposited electrochemically from ambient temperature molten salt electrolyte containing ethanol.
In the cathodoluminescence (CL) spectra of type II natural diamond and high-quality chemical-vapor-deposited diamond, both a free-exciton recombination radiation peak originating from high crystallinity (perfection of the crystal structure) and a band A peak originating from low crystallinity (imperfections in the crystal structure) are observed. In this study, a homoepitaxial diamond film has been synthesized on a single-crystal diamond (100) substrate using the combustion flame method and the film quality is evaluated by CL analysis. Crystal defects are mechanically introduced into the diamond film to study the change in the CL spectrum. Results indicated: 1) High-quality diamond with a negligible levels of nitrogen impurities and few crystal defects can be synthesized at a high rate (100μm/h) using the combustion flame method. 2) The band A peak corresponding to a crystal defect is broad around a wavelength of 430nm regardless of nitrogen impurities. 3) Mechanically introduced cracks (crystal defects) decrease the intensity of the FETO peak, while the intensity of the band A peak increases.
Fusion bonding was conducted for anisotropically-etched Si wafers; the effects of surface morphology and thermally grown oxides on the wafers in relation to bondability were examined. Wafers with or without thermally grown oxides of a thickness of about 2μm were cleaned in RCA solutions to render their surfaces hydrophilic; they were then placed in face-to-face contact at room temperature, followed by in situ infrared inspection. After annealing at 1100°C in nitrogen for at least 1h, bond strength was measured using a four-point bending test. The wafers without thermally grown oxides provided better bonding results than those with oxides. After annealing, a bond strength of 10-20MPa was obtained, independent of the duration of annealing. Wafers with thermally grown oxides that were removed through immersion in an HF solution provided surface morphology and bonding results that were as good as those from polished wafers. Based on these results, a check valve structure was fabricated using anisotropic etching in a KOH solution and fusion bonding of wafers free of thermally grown oxides. Flow resistance for the forward flow of the fabricated check valve was one-three hundredths lower than that for the backward flow, indicating that the valve is highly one-directional.
The effects of organic additives in a Ni sulfamate bath were investigated in order to form microprobes with a high aspect ratio. Results without the usage of additives confirmed that Ni deposits have a low aspect ratio because of in-plain spread. With the addition of propargyl alcohol, however, the form of Ni deposit changes from a flat to an oval shape. The surface morphology improved with the addition of sodium salt of saccharin, but the probe shape was flattened. Finally, the addition of PEG-4000 to a bath containing propargyl alcohol and saccharin produced probes with a fine, smooth surface and a high aspect ratio. Thus, results confirmed that satisfactory probes could be obtained with Ni electrodeposition.
Chromium-free conversion coating films composed of Mn (II) -silicate were studied by salt spray tests, measurements of polarization resistance and surface analysis. Corrosion resistance of the film was better than the film consisting of each own component. The top of the film was composed with mainly silicate, however, inside of the film was mixture of Mn (II) and silicate. Total amounts of Mn (II) and Si in the film were an important factor for the corrosion resistance.