To improve the water repellency of inorganic materials, silica glass substrates treated with ion irradiation and organic monomer gas adsorption were evaluated using the contact angle to distilled water. Changes of the contact angle by cleaning in solvents on standing after aging in air and after rubbing were measured. Samples that adsorbed monomer gas immediately after ion irradiation showed the largest contact angle and had the highest water repellency. The contact angle of samples became smaller in the order of ion irradiation only, monomer gas adsorption only, untreated. Samples that adsorbed monomer gas immediately after ion irradiation showed small dispersion in the contact angle. These samples thus had small change on standing and showed water repellency even after cleaning in solvents and after rubbing. Surface analyses by X-ray photoelectron spectroscopy (XPS) revealed that ion irradiation enhanced monomer gas adsorption, in addition to carbon deposition for samples which adsorbed organic monomer gas immediately after ion irradiation. The result also suggested the formation of a low-surface-energy layer by the reaction of the silica glass surface and organic monomer gas.
The influence of Ar ion bombardment of Si (100) substrates on adhesion between Ti thin films and Si substrates was investigated. To evaluate adhesion, the internal stress in overcoated films was used. TEM, AES, and RBS observation were used to observe the interface between Ti and Si. In the low power density of Ar ions, adhesion was not high enough because of insufficient substrates cleaning. When power density was too high, adhesion was not high enough, either. This is due to the incorporation of Ar atoms at the interface during Ar ion bombardment. To enhance adhesion, it is important to optimize the power density of Ar ion bombardment.
Porous fiber sintered metal consists of sintered short metal fibers that produce chattering. The metal is widely used in audio and domestic electrification, and in such mechanical parts as bearings, filters, and vibration suppressors. It is difficult, however, to calculate the hardness of porous fiber sintered metals from dent dimensions because they are characteristically viscoelastic. In the present paper, carbon steels are tested and the relationship between the porosity ratio and the depth of indentations are clarified in experiments. The shapes of indentations are observed and analyzed in scanning electron microscopy, indicating the following: 1) The hardness value, depth of an indentation caused by indenter pressure, and elastic recovery are all related to the metal porosity ratio. 2) The depth of indentations increases with incremented porosity ratio. 3) The Rockwell superficial hardness value is negative.
The electrodeposition of Zn-Cr alloys from sulfate baths was conducted to investigate the codeposition mechanism of Cr with Zn. Results are as follows: (1) Cr was codeposited with Zn at high current densities in both polyethylene glycol (PEG)-free and PEG-containing baths. However, PEG made it possible to reduce Cr3+ to metallic state and Cr existed in the form of Cr3+ hydroxide in the deposits obtained in PEG-free bath. (2) Partial polarization curves of Zn shifted when PEG was added to the baths. (3) The pH in the cathode layer was found to rise from bulk pH 2.0 to about 4. Zn and Cr hydroxides seemed to form simultaneously in the cathode layer. (4) It was estimated that alloys were electrodeposited from the composite Zn and Cr oxides formed due to the pH rise in the cathode layer and that the PEG acted as a polarizer to shift the cathode potential toward the reduction potential of Cr.
A method for evaluating the rust resistance of stainless steels by applying the ferroxyl test was investigated. Filter paper is moistened with test solution containing Fe(CN)63- and Cl- ions. The paper is then superimposed on a sample for 3 to 10 minutes. This induces pitting corrosion on the sample's surface. Iron ions generated by corrosion react with Fe(CN)63- ions to produce blue precipitates of prussian blue, Fe4[Fe(CN)6]3, which form blue spots on the filter paper. After the filter paper is rinsed and dried, rust resistance is evaluated based on the ratio of the total area of blue spots. The time required for this test is only 15 to 20 minutes and the method is very simple. It also has strong correlativity with the atmospheric exposure test on the evaluation of rust resistance of bright annealed ferritic stainless steels. It should also be noted, however that the method cannot predict the deterioration of rust resistance in every steel having a different surface film and roughness induced by atmospheric exposure. In conclusion, the method is most useful for quality control in a manufacturing process or the product inspection.
A Pb thin layer was prepared at an air/solution interface using a monomolecular layer as a supporting substrate in electroless deposition. Procedure of the Pb thin film formation and the morphology of the SEM-observed films are described.