Barrel finishing sometimes called mass finishing is a process in which mechanical means are used to remove burrs in a mass production scale. It can perform multiple tasks simultaneously, but removes all edges and surfaces exposed to interaction with the media. Deburring of the plated workpieces is therefore considered to be difficult. Plated workpieces are now made by shearing, punching or forming plated sheets or ribbons. There is a need to investigate method of deburring or radiusing the workpiece edges in minimizing the thinning of the plated layer. Methods using centrifugal and vibratory barrel finishing along these lines are shown, and film thickness after deburring is indicated. In ordinary barrel finishing methods, the plated layer is removed from the cut or worked edges of the workpieces. It is shown that deburring and plating can be performed simultaneously using mechanical plating methods, and the limitation of the deburring abilities of these methods is shown.
When AlN thin films are applied to surface acoustic wave (SAW) devices, c-axis oriented films and a-axis oriented films are necessary for the longitudinal wave and transversal wave, respectively. In general, when AlN thin films are prepared by sputtering and ion plating methods, the crystallographic orientation is dominantly c-axis; it is difficult to prepare films with an a-axis orientation. In this study, AlN thin films were prepared by a new PVD method: the electron shower. It was found that a-axis orientation films could be prepared readily. The crystallographic orientation varied from a-axis to c-axis when the substrate voltage was changed from +20V to -400V. A high hardness (Hv 2200), high electrical resistivity (1013Ωcm) film was obtained at -200V.
A porous silicon layer (PSL) was prepared on single crystal p-type Si (100) wafers with electrochemical etching in HF aqueous solutions of various concentrations to explore the optimum PSL preparation conditions for no exfoliation of the PSL from the substrate and for good reproducibility of visible luminescence with high intensity. The surface morphology and microstructure of the PSL were observed using various microscopic techniques (SEM, TEM and CLSM) and the surface compound of PSL was identified by FT-IR. In addition to the photoluminescence (PL), the electroluminescence (EL) emitted from the PSL during anodic oxidation in KNO3 aqueous solution was measured to examine the luminescence mechanism. The microstructure of PSL prepared on Si with low specific resistivity (ρ=0.1Ωm) was columnar, whereas that prepared on Si with high specific resistivity (ρ=1kΩm) was granular and randomly oriented. The microstructure of PSL also changed depending on the HF concentration. The EL and PL intensities of PSL were both higher for ρ=1kΩm than for ρ=0.1Ωm and increased with decreasing HF concentration. The exfoliation of PSL from the substrate of ρ=1kΩm was prevented by using low current density in electrochemical etching. The optimum PSL preparation conditions were finally obtained when the specimen with specific resistivity of ρ=1kΩm was electrochemically etched in 10.4wt% HF aqueous solution under a galvanostatic condition of i=10Am-2 for 15ks. The TEM images of PSL with high magnification (5×105) suggest that the quantum confinement effect is operative in the visible luminescence.
Purple Au-Al alloy films were deposited on glass substrates using a radio frequency ion plating method. Au-Al alloys were used as source materials. The effects on the film of the source alloy composition and the evaporation time were studied. The color tones of the deposited films were measured using spectral reflectance and their crystal structures were studied by X-ray diffraction. As a result, a composition of Au 80%-Al 20% was chosed as the most suitable source alloy. The color tone of a film deposited from a single evaporation source changed from white to purple as the evaporation time increased. The intensity of the X-ray diffraction pattern of the AuAl2 sharpened as the color tone of the film became more purpler. The purple color of the film became brighter after 1hour of heat annealing at 550°C in an atmosphere of Ar (8×103Pa).
To investigate effective ultrasonic-cleaning, the electrochemical impedance of a model cell and the ultrasoundpressure distribution of a cleaning bath have been measured. The relation between cleaning efficiency and ultrasound pressure was discussed. An electrochemical impedance cell with a blind hole, into which two stainless steel parallel plate-electrodes were mounted, was filled with mineral oil, and immersed in a cleaning solution containing sodium dodecylbenzenesulfonate and ortho sodium silicate, at room temperature. The solution was stirred by an ultrasonic generator mounted on the side wall in the bath. Soundpressure distribution patterns in the cleaning bath were obtained. No correlation was observed between the soundpressure and the oil residual amount. However, the correlation coefficient between the differential soundpressure and the oil residual amount obtained was -0.95. Electrodialysis currents migrating through a cation exchange membrane were measured in the ultrasonic-cleaning bath. The electrodialysis limiting currents decreased with increasing oil residual amounts. From this result, the oil residual amount was proportional to the diffusion film thickness of the surface
A thin-layered catalyst supported on a thermo-conductive metal surface makes it possible to design a compact reactor that doubles in function as a heat exchanger. A Pt/Al2O3/Al catalyst was prepared by anodic oxidation (AO) of commercial aluminum in oxalic acid solution followed by hot water treatment in choloroplatinic acid solution. During and after AO, the produced alumina layer was dissolved into the oxalic acid electrolyte. The porosity of the layer increased with the treatment time (pore widening). The final thickness of the alumina layer was controlled by balancing the formation and dissolution rates. The maximum thickness and maximum porosity of the alumina layer were 350μm and 0.79, respectively. The platinum content increased as the thickness and porosity of the alumina layer increased, the maximum Pt content was 15.8g-Pt/m2. Platinum dispersion was about 0.5 for all catalysts. The catalytic activity for cyclohexane dehydrogenation increased with the platinum content. The maximum steady state reaction rate was 12mol/(h·m2) at 473K under 0.1atm of cyclohexane.
PVD and CVD ceramic coatings have been developed to improve the corrosion resistance of stainless steel. In films coated by processes such as rf sputtering, piercing defects such as pinholes inevitably exists and these defects play a significant role in corrosion. In this study, various oxide films were coated on stainless steel by rf sputtering and pinhole defects in the coating films were evaluted using an electrochemical and an optical technique. The electrochemical technique was to evaluate the total defect area of the film using the value of the critical passivation current density in the course of anodic polarization in an 0.5kmol/m3H2SO4+0.01kmol/m3 KSCN solution, which restricts the passivation of the substrate steel. The optical technique was to evaluate film defects by observing the dynamic scattering of liquid crystal molecules induced by current flow through the film defects (a liquid crystal was inserted between the oxide film and a tranparent electrode). The defect probabilities of the films obtained through the two techniques showed good agreement. The optical techniques can observe the defects in films non-destructively, though it is limited to use with insulating films on conductive substrates.
The adsorption-desorption behavior of Cr (VI) ions on the surfaces of fine silica particles was examined by atomic absorption spectrometry and by electric conductivity measurement of solutions so as to analyze an anticorrosion function of silica particles in dry-in-place chromate coatings. Among chromium species, Cr (VI) ion shows high rate of adsorption due to coordination bonds formed with the Si atoms of silica particles. In an aqueous solution of less than pH5.5, Cr (VI) ions are adsorbed on the surfaces of silica particles. At pH8.5-11, desorption of already-adsorbed Cr (VI) ions occurs through a reaction that is mainly SN1D ligand substitution of OH- and Cr (VI) ions. An anticorrosion mechanism of silica particles in dry-in-place chromate coatings was surmised to be as follows. In acidic regions, where metal is corroded, Cr (VI) ions in the chromate coating are adsorbed and fixed on the silica particles. In basic regions, Cr (VI) ions that were previously adsorbed are desorbed through the substitution reaction. These desorbed Cr (VI) ions contribute to the corrosion resistance of metal substrates as an inhibitor.