Gravimetric and electrochemical studies were made on surface phenomena of evaporated gold by measuring the change in wieght, single electrode potential, and electric resistance of the thin films deposited under 1-3×10^-5 Torr. The films showed some reactivity with oxygen in the dry air, though bulky gold is chemically inactive. The temperature of the film substrate had effects on the weight increase of the films due to oxidation and adsorption. The rate of weight increase of a film prepared at 30°C was lower than that of a film prepared at 200°C, but the total amount of oxygen adsorbed on the former film was greater than that adsorbed on the latter film. A very thin film obtained on the substrate of 30°C by low rate of evaporation showed a peculiar process of weight change with time in the dry air; the process was quite different from those of ther films. That is, the weight increase of the film due to adsorption of oxygen continued for about 1hr., and then, gradually decreased. It was found by the measurement of single electrode potential that the deposit prepared by high deposition rate on the substrate at a low temperature (such as 30°C) showed a thin film having smooth continuous texture (not insular structure), which was chemically active against oxygen.

抄録全体を表示

The behavior of Cr-Ca systems in CO atmosphere was investigated. As the results, it was found that the formation of Cr⁶⁺was completely inhibited by calcining Cr³⁺-Ca systems at above 400°C and CaCrO₄ was completely reduced at above 600°C in CO atmosphere; and simultaneously, a substance, α was produced which was insoluble in water and HCl, and had the highest peak of X-ray diffraction pattern at 2θ=23.8. It was confirmed by the above facts that the calcination in reducing atmosphere would be effective for the treatment of sludge including chromium.

抄録全体を表示

Thickness of greasy layer and that of oxide film on aluminum as rolled were determined by means of ellipsometry, and the effects of surface layers on the peeling strength of polyethylene and aluminum were examined. Chemical properties of the greasy layer were also studied by Auger electron spectroscopy and infrared absorption spectroscopy. From these measurements, it was found that the greasy layer is depleted almost completely in the air at above 500°C, being replaced by the growth of oxide film. It was also found that the peeling strength of aluminum and polyethylene decreases with the increase in the oxide film thickness. This is interpreted that bond failure does not take place at the interface between aluminum and polyethylene, but is caused cohesively by the brittle fracture of the oxide film. On the other hand, the greasy layer had very little effects on the adhesion of hotmelt abhesives such as polyethylene, but a marked decrease in the peeling strength was observed, if the layer was oxidized during the heating process.

抄録全体を表示

Hexamethylenetetramine (HMT) as a vapor phase rust-inhibitor was mixed with various reducing agents and was submitted to accelerated corrosion tests in the presence of various sub-components. The results obtained were as follows: (1) When reducing agents such as cuprous chloride, sodium sulfite, stannous chloride, and sodium nitrite were mixed, the rust-inhibiting effects of these agents were no good except for those of sodium nitrite. (2) A mixture of HMT and sodium nitrite (SN) showed excellent rust-inhibiting effects for iron as a vapor phase rust-inhibitor at the molar ratio of 1:4. (3) The rust-inhibiting effects of HMT-SN system can be explained in terms of the vapor transfer mechanism as follows. Since HMT and SN are hygroscopic, they can reduce corrosion not only by thier removal of moisture, but also by their decomposition due to absorption of moisture. That is, ammonia, one of the decomposition products, neutralizes acidic atmospheres; and formaldehyde and nitrous acid, other decomposition products, give a space effect as reducing agents. In addition, when sodium hydroxide, one of the other decomposition products, directly contacts with iron surfaces, the contact rust-inhibiting effects will be given to iron.

抄録全体を表示

The optimum conditions for preparation of vapor phase rust-inhibiting papers, powders, tablets, and oils for aluminum were investigated by using hexamethylenetetramine (HMT) and various subcomponents; and the vapor transfer mechanism of rust-inhibitors was discussed together. The results obtained were as follows: (1) Among water-soluble binders for the vapor phase rust-inhibiting papers, polyvinyl alcohol, milk casein, and gum arabic showed the most remarkable effects at the contents of 5-7, 8-10, and 9-10%, respectively. As for an oil soluble binder, 4-7% of shellac solution gave good effects. (2) As for extenders for the vapor phase rust inhibiting powders, white pigments such as titanium white, talc, and kaolin showed good effects. (3) In the case of vapor phase rustinhibiting tablets, the extenders did not show direct contact effects as on the powders. However, the pigments effective for vapor phase rust-inhibiting powders were also effective for the tablets, and the addition of 20% or more of HMT in general showed good rust-inhibiting effects. (4) In the case of vapor phase rust-inhibiting oils, the addition of 0.5% or more of HMT showed good effects. (5) The discussion on the vapor phase transfer mechanism of HMT led to the following presumption on its rust-inhibition. Since HMT is hygroscopic, it reduces corrosion of aluminum by removing environment moisture; in addition, the decomposition products due to moisture absorption such as ammonia and formaldehyde give space effects such as prevention of aluminum surface from oxide formation, which will bring the rust-inhibiting effects.

抄録全体を表示