Conditions favorable to the deposition of Si₃N₄ on pure steel substrates by means of an inductively coupled, externally heated plasma discharge were determined, and comparisons made with reducedpressure CVD. A push-pull Hartley RF (13.56MHz) oscillator with a maximum output of 70W was designed using a triode. The reactive gases-NH₃ and SiN₄-were diluted with Ar to a prescribed concentration. Test pieces of pure steel measuring 5×5×0.5mm were prepared, their surfaces were polished using diamond paste, and the Si₃N₄ was deposited onto the surfaces.
It was found that the optimum distance between the test pieces and the oscillator electrode was 25cm, and the optimum ratio of NH₃ and SiH₄ gases was 1:2.5. Investigating the effect of reaction temperature and deposition time under these conditions, it was found that in the case of plasma CVD, 800°C was a boundary value above which film thickness decreased, while the rate of film growth varied with deposition time depending on whether the reaction temperature was below or above 750°C. Comparison with reduced-pressure CVD indicated that this was due to the effect of Coulomb discharge, and it was found by differential thermal analysis and X-ray diffraction that in Si₃N₄ at 746°C or less, deposits were amorphous.
Further, at 800°C, film growth proceeded rapidly, reaching 12.5μm after 30min but thereafter decreased and was only 15μm after 240min. In reduced-pressure CVD, film growth proceeded linearly for 60min and thereafter almost linearly although with a decreased slope, reaching 12.5μm after 240min at 800°C.
Investigation of the apparent activation energy of the growth of the Si₃N₄ including a diffusion layer in the initial reaction period gave a value of 20kcal/mol at 750°C or less for plasma CVD, and 12 kcal/mol at 700-800°C for reduced pressure CVD.

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In a previous paper reference, it was reported that mirror bright electrodeposits of tin-nickel alloy were obtained from an acidic chloride bath containing N-(1-naphthyl) ethylenediamine dihydrochloride (NEDA) as brightener. In this paper, a spectrophotometric method for the determination of NEDA adsorbed in the alloy is established.
In order to keep the structure of the brightener intact, the alloy deposits were dissolved in dilute hydrochloric acid which was used in the plating bath, at 60-65°C. The color development is based on the coupling reaction of NEDA with the diazonium salt of sulfanilamide to form an azo compound, which has an absorption maximum at 540nm. Although tin (II) dissolved from the alloy reacted with the diazonium salt, greatly inhibiting the color phenomenon, this could be masked effectively with SbCl₃ solution. The calibration curve for NEDA was rectilinear in the range of 0-400μg/100mL. The precision of analytical values was good, and the coefficients of variation were less than 1% (n=8).

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The composition of Cu-Zn alloy electrodeposits prepared from pyrophosphate baths by the potentiostatic electrolysis method was studied as a function of the deposition potential. The electrodeposits were analyzed by atomic absorption spectroscopy, ESCA and X-ray diffraction. The composition of the deposits changed greatly at deposition potentials (E_den) vs. Ag/AgCl (sat. KCl) ranging from -1.2 to -1.3V.
The deposits prepared at E_dep≥-1.2V were copper with small inclusions of ZnO. At E_den≤-1.2V, on the other hand, metallic Zn was observed in the deposits and their Zn content increased markedly. ZnO inclusion was still observed, however, at E_dep≥-1.3V. Thus, brass deposits that form α-solid solutions without ZnO inclusion can only be obtained at E_dep<-1.3V.

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Abrasive wheel wear tests of metal plates, hard anodic oxide coating, plated Cr and chemical nickel plating specimens were carried out, and the effect of abrasion factors (grain size of the abrasive papers, pressure between the specimen and the abrasive paper, speed of reciprocation) on the amount of abrasion, and the reproducibility of the test values were studied. Reproducibility of some of the abrasive Taber tests, which were similar of the abrasive wheel wear test, were also investigated.
The following results were obtained. The amount of abrasion by the abrasive wheel wear test was mainly influenced by the grain size of abrasive paper and the pressure between the abrasive paper and the specimen, and was not substantilly affected by the speed of reciprocation. The coefficient of fluctuation of the amount of abrasion by the abrasive wheel wear test was about 6% for the runs, it was assumed that reproducibility of the test values was satisfactory. Matters for attention (shape of specimen, treatment of abrasive paper, method of measuring the amount of abrasion, etc) were clarified. In case of the abrasive Taber test if a CS-32 rubber wheel to which abrasive paper had been attached was used instead of a CS-17 grinding wheel and the abrasive paper was renewed every 100 revolutions, good test values reproducibility was obtained, and the rate of abrasion increased, shortening the test time.

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