Formation rate, formation coefficient and C. R. value for anodizing of aluminum in alkaline solutions (LiOH, NaOH, Na₃PO₄ and NH₄OH-NH₄F) were investigated. The bath composed of NH₄OH-NH₄F showed the highest formation coefficient, formation rate and C. R. value among the above alkaline baths, and the relation between bath temperature and current density gave a straight line relationship in the region of 10°C-40°C. Fluoride and water contents in the film increased in proportion to bath temperature, whereas the sp. gr. of the film decreased. The most excellent bath that showed the highest C. R. value had the following contents: 2.3M of NH₄OH, 0.1M NH₄-tartrate, 0.3M NH₄F and 0.1M (NH₄)₂CO₃.

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The effect of treating condition on gas nitrosulfidizing of steel was investigated in an atmospher of carrier gas, NH₃, and H₂S gases mixture in the temperature range of 540°C to 630°C for 30-180min. The weight of terated specimen and the thickness of nitrosulfidized layer increased exponentially with the treating temperature. The hardness of surface slightly decreased with increasing treating temperature and that of compound layer reached the maximum value at 570°C. X-ray diffraction indicated that the surface products were FeS, Fe_1-xS, Fe₃N, Fe₄N, etc. at each treating temperature.

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A new method has been developed to activate the surface of insulating substrates (glasses and ceramics), when they are to be plated with nickel or its alloys by electroless plating. In this method, very small amounts of some catalytic metals (e.g. palladium) have been deposited on the surface of insulating substrates by a r.f. sputtering method. The characteristic features are: 1) Very homogeneous films of nickel and its alloys can be obtained securely and easily. 2) By sputtering of active metals through the mask onto the insulating substrates, plated films of any pattern can be obtained. 3) The sputtered silver film has been found to be effective for activating the insulating substrates, though it has been recognized till now that the bulk silver is inactive for electroless plating of nickel. The electric potentials of silver films, sputtered or vacuum deposited on the insulating substrates, have been measured, when they are immersed in the plating solution of nickel. With these results, together with the observation of their surfaces by SEM, some consideration has been made on the origin of the phenomena described in 3).

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This report describes the chromizing capability relating to the depth of chromium layer and a method for measuring the depth. The measurements were made by electric resistance and thermoelectromotive force methods with chromized carbon steel and nickel wires. The electric resistivity of chromized carbon steel wire increases in proportion to the depth of chromium layer. It has become clear that the electromotive force of the sensor consisted of chromized carbon steel wire-nickel wire increases proportionally to the depth of chromium layer. This is the same with the chromized nickel wire-nickel wire sensor. Thus the gas chromizing process can be controlled by measuring the electromotive force of these sensors.

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Internal stress of chromium coatings has been investigated by means of a spiral contractometer and an X-ray stress analyzer. In the spiral contractometer method, an increase in the deflection of dial pointer is observed with thin coatings less than 5μm in thickness, irrespective of their deposition conditions. Thus these coatings are characterized by high tensile stress. A peak deflection value is obtained, in the region of 8-10μm thickness, with the bright coatings deposited at the temperatures of 40, 50 and 55°C. After the peak value is reached, the deflection gradually decreases and eventually shifts to the negative side. However, the deflection of the dial pointer for the grey chromium coatings deposited at 30°C increases linearly. A decrease in deflection is caused by compressive stress of build-up layers formed after the peak value is reached. Measurements by the X-ray stress analyzer reveal that the internal stress of thin layers of less than 3μm thickness is also tensile. This finding coincides with that obtained from the measurements by the spiral contractometer. But, as the thickness of deposit increases, the stress measurable within the depth of X-ray penetration changes to compression. This can explain the peak and the subsequent decrease in deflection as measured by the spiral contractometer. The values measured by these two different methods are found to agree closely. The internal stress of chromium electrodeposited by applying direct current is very different from that of chromium obtained by applying a single phase full-wave rectified direct current.

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