The microstructure of the electroless Ni-P films obtained from the various kinds of plating baths containing sodium hypophosphite as a reducing agent, was examined by electron microscopic and diffraction method in the initial stage of deposition. The Ni-P films obtained from each bath consisted of many crystal particles forming aggregates. The sizes of aggregates were found to be dependent on plating rate and also on the phosphorus content of the film. The growth rate of the aggregate increased with increasing plating rate and decreasing phosphorus content. In respect to the morphology of phosphorus compounds, it was found that phosphorus in the as-deposited films existed in a form of Ni₇P₃; however, they transformed to Ni₃P when the film was heat-treated at 400°C.

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Aluminum sheets (99.99%) were anodized in various carboxylic acid solutions containing a small amount of sulfuric acid, and the surfaces of the oxide films and of the substrates separated from the films were observed by SEM. Observations revealed that the morphorogy of anodic oxide films depended upon the field-assisted film dissolving action of the carboxylic acids, chemical dissolving action on aluminum, and local field-assisted dissolving action of the dilute sulfuric acid contained in the solution. The addition of sulfuric acid in carboxylic acids, which are commonly used for the formation of barrier type films, caused formation of a local abnormally grown porous film. This sort of film was produced also in a dilute sulfuric acid bath. In monocarboxylic acids, the addition of sulfuric acid ceased pittings, resulting in formation of abnormally grown films. But in the case of polyoxymonocarboxylic acid, such as gluconic acid, which has a very strong chemical dissolving action, the addition of 0.5g/l sulfuric acid could not be effective to inhibit pittings. In the other carboxylic acids that are used for formation of porous type films, addition of sulfuric acid produced colored porous films which developed into darker abnormally grown films. In this case, the cell dimensions of porous films were proportional to the bath voltage which could be lowered by the addition of sulfuric acid.

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Some of factors affecting the burning phenomena of aluminum surfaces during anodic oxidation have been investigated in an oxalic acid bath under galvanostatic conditions. The burning phenomena visually occurred at the place of specimen where higher current flowed and the cooling effect by the agitation of the electrolyte was poor. The measurement of the temperature distribution of specimens' surface revealed that the burning occurs at the place of the highest temperature rise before the start of the burning. The temperature at the surface of burning gradually increased with time before the period of a large temperature increase during which the burning appeared. The onset of the large temperature increase with time preceded the burning phenomena. The bath voltage at the start of the burning was not affected by applied current densities, but it increased with decreasing concentration of oxalic acid. The thickness of the oxide film at the burning decreased with increasing applied current densities.

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The growth of ζ (FeZn₁₃) particles in drosses in galvanizing bath has been studied. Iron was added in a form of FeCl₂ to a Zn-Pb bath to an amount of super-saturation. After holding the bath at 470°C for the pre-determined time from 1 to 40hrs, the bath in a graphite crucible was cooled as it was. The dross formed at the bottom was inspected by a quantitative microscopic method. Mean particle size of ζ in dross was determined by a method of the ferrite grain size test for the ferritepearite mixed structures.
The mean particle size of ζ, expressed in size number N, decreases linearly with the logarithm of holding time. The proportional constant, -2.0, indicates that ζ particles grow proportionally to 0.3 power of the holding time. This experimentally derived exponent coincides with the theoritically derived value by Greenwood with the aid of Fick's law and Thomson-Freundrich equation. Thus the growth mechanism is thought to be based on diffusion. Namely, iron diffuses from smaller particles to larger ones by the difference in iron solubility between the bath contacted with smaller particles and that with larger ones.

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During anodization of Al plate in organic acid baths at low temperatures and high current densities, bright spots appeared at the corners of the plate, spreading over the surface. After anodization, oxide films in this region turned dark brown and thicker than in the remaining region where burning did not occur. To determine the local temperature of these spots, an infra-red emission thermometer was used, which enables to detect the temperature of region as small as 0.76mm². The color of the burnt region is closely related to the built-in color of anodized aluminum and the mechanism of developing the color of burning is discussed in the terms of the temperature rise at the bottom of pores. Supposedly the high energy electrons accelerated by an electric field excite organic acids which are eventually converted into ammorphous carbon.

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The charging properties of powders for electrostatic coating are essential factors concerning adhesive strength between substrate and powders. Electrostatic charging and decaying behavior of several plastic powders has been examined by surface potential measurement. Water absorbed on the powders affects decay velocity (α) as shown in the next formula
α=α₀exp(β⋅m)
α₀……decay velocity in dry state, β……constant, m……weight of absorbed water
However, the depth of trap also affects these decay phenomena. Activation energy of epoxy resin powder is 0.88eV. The decay of charge is achieved by the following mechanism. The surface corona charges of the layer move to the inner part and are combined to induced opposite sign charges on the back. Moreover, decay velocity agreed with Inoue's experimental values concerning ZnO-resin mixed films.

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