In a previous paper, it was reported that when the critical load (Lc) obtained by scratch testing in TiN-PVD and TiC-CVD films differed according to the charge, the surface residual stress (σr) measured by X-ray technique also differed. This implied that it might be possible to evaluate non-destructively differences in hard film characteristics between charges by measuring the surface residual stress by X-ray technique. This paper reports on the correlation between Lc and σr for two charges of TiN-PVD and TiC-PVD films in which the thickness was varied by varying the number of coatings. A linear relation between Lc and σr was observed in both films, and it was therefore concluded that the measurement of residual stress by X-ray technique is effective in evaluating nondestructively the differences in hard film characteristics between charges.
It was found that a two-step anodizing process to form porous oxide films on aluminum, consisting of cathodic deposition of Mo (V)-Mo (VI) mixed oxyhydroxide films on aluminum from an ammonium molybdate solution followed by anodizing of the aluminum in acid solutions, results in films having improved mechanical properties. Anodic oxide films formed in a sulfosuccinic acid solution by the present process showed an increase in Vickers hardness of about 20% and the best results were Hv50=690±23 (±1σ) for cross section. The process is being extended using chromate treatment in the first step, and further improvements in physicochemical properties are expected.
At low pH in the electroplating of silver using a sulfite salts system, the polarization decreased at higher temperatures. Cathodic current efficiency was reduced, and the deposited crystals were larger. At low pH and low temperature, a bright deposited film was obtained. At higher pH and higher temperature, the polarization was reduced slightly, and the change in cathodic current efficiency was reduced slightly. Even at high pH and high temperature, crystals were microcrystalized and films of high brightness were obtained. At all values of pH, the preferred orientation of all the electroplated crystals tended toward (220) with changes in temperature, and this tendency became stronger the higher the pH and temperature.
Co-B alloy films with B contents of 1wt% and 3wt% were electroless-deposited and their corrosion resistance was evaluated in comparison with polycrystalline Co by measuring the cathodic and anodic polarization curves in deaerated 0.2mol·dm-3 HCl. Values of corrosion current icorr and corrosion potential Ecorr suggested that the corrosion resistance of the Co-B alloy films with 1wt% B was markedly low and that of the Co-B alloy films with 3wt% B was similar to polycrystalline Co. The dissolution mechanisms of the Co and Co-B alloy films were also investigated by surface analysis using XPS, by analysis of the electrolite near the alloy electode during polarization using ICP and by values of Tafel slope b derived from polarization curves.
Polarization characteristics were investigated in electroless palladium-phosphorous alloy plating baths consisting of palladium chloride, ethylenediamine, thiodiglycollic acid and hypophosphite. Experimental results confirmed the mixed potential theory including local potential-current relationships for palladium deposition. A rise in pH brought about a substantial decrease in local current for both hypophosphite oxidation and palladium deposition. The thiodiglycollic acid had no effect on local anodic and cathodic current near mixed potential.
Solderable electrogalvanized steels have been developed as alternatives to Sn and Pb-Sn steels. This paper reports the effects of plating solution additives on solderabilitiy-specifically solder spreadability, solder wettability measured by Meniscograph and solder peeling strength. Various additives, including buffer agents, alloying additives, surfactants, brighteners and impurities that might be expected to enter during the plating process, were studied. Additives that were codeposited with or contained in the Zn layers influenced not only their appearance and crystalline structure, but also their solderability. The addition of Mo and Cr codeposited as oxides, and of brighteners such as gelatine and acrylamide, decreased solderability greatly. It was found that solder wettability was the most sensitive property to the presence of additives, and codeposition of Fe, Ni and Co tended to decrease wettability. It is inferred that the decrease in solderability due to the additives is caused not by change in the crystalline structure of the Zn layers, but rather by the additive elements and oxides codeposited or included therein.
To elucidate the stain mechanism for precoated metal (PCM), the effects of surface melamine concentration and stain temperature on the stain resistance of polyester-melamine films were investigated by characterizing the surface structure using the FTIR-ATR method and by measuring the crosslinking density of the bulk of the film. The following results were obtained (1) Melamine resin was concentrated in the surface layer of the film when an acid catalyst was used. The surface melamine concentration and the hardness value of the surface (0.2μm in depth) increased with increasing acid catalyst content. On the other hand, these films had a layer that showed a lower hardness value at depths of more than 3μm. (2) Stain resistance at room temperature was improved by increasing the surface melamine concentration. (3) The effect of surface melamine concentration on stain resistance decreased with increasing stain temperature, consequently stain materials permeated deeply into the film as stain temperature increased. The stain temperature at which the effect of surface melamine concentration on stain resistance disappeared increased with increasing film glass transition temperature Tg. (4) The stain resistance at temperatures of 140°C and above was controlled by the crosslinking density of the bulk of the film.
Aluminum foil of 99.99% purity was etched in an aqueous solution of 2mol dm-3 hydrochloric acid, 0.01mol dm-3 sulfuric acid, and 0.2mol dm-3 aluminum chloride at 303K by 5Hz AC wave with controlled anodic potential, Ea, and cathodic potential, Ec. The etched porous layer was evaluated by SEM observation, optical observation, electrostatic capacity measurement and CV behavior. Electrostatic capacity and porous structure were grcatly influenced by Ea and Eo values. To make etched pits, it was necessary to set potential Ea higher than the breakdown potential Ebd appearing in the CV curves. At Ea potentials only slightly higher than Ebd, the etched porous layer was thin and the thickness of the foil decreased at an anodic electric charge of 50C cm-2, while when Ea was too high, the pits showed local interconnection and the surface of the porous layer dissolved and lacked smoothness. The aluminum hydroxide film formed in the etched pits during the cathodic cycles played an important role in the characteristics of pit formation. The thickness of the aluminum hydroxide film increased at low Ec, when etching took place locally with several large pits on the foil. This might be caused by the non-uniformity of the hydroxide film on the bottoms of the pits. At high Ec, on the other hand, film protection was weak, leading to thinning of the porous layer and dissolution of the foil. In this study, the optimum etching conditions that provided high electrostatic capacity and a deep and uniform pit morphology were Ea=0.1V, Ec=-2.4V vs. SCE at an anodic charge C=50C cm-2
Studies have been made of the effects of the application of ultrasonic waves to ammonium alkaline solutions on the Pt-Mo alloy films electrodeposited therefore. Ultrasonic application was found to increase the Mo content in the deposits and the total current efficiency, and to result in finer grains.