We investigated the relation between the contents of hydrogen absorbed and compressive stress in nickel deposits during electrolysis of H2O corresponding to electric charges of 0.20 C at cathodic current density of 2 mA/cm2. Using an electric balance, the amounts of hydrogen absorbed in nickel deposits and evolved during electrolysis of H2O were evaluated quantitatively based on the buoyancy produced by the hydrogen gas bubble. Variation of the internal strain with the absorption and desorption of hydrogen was also measured in situ using a resistance wire-type strain gauge placed on the reverse side of the copper substrate. Compressive strain with absorption of hydrogen occurred immediately after electrolysis of H2O began. Then it relaxed spontaneously with desorption of hydrogen from the nickel deposits when current was off. However, the buoyancy caused by the hydrogen gas bubble started after the elapsed time of a quarter a minute or more from application of electrolysis of H2O. Gas bubble formation continued for a while after the current was turned off. The former resulted from hydrogen absorption into nickel deposits. The latter was associated with hydrogen leaking out of the deposits. The variation of compressive stress with increasing hydrogen contents was described as Δσ/Δn (Hab), which was ca. −28 kgfmm−2 mol%−1 in nickel deposits electroplated from a Watts-type bath containing brightener 2-butyne-1,4-diol at electric charges of 10 C/cm2 and current density of 30–120 mA/cm2.
The coating process was conducted using an inline-type plasma deposition system. Thin and thick films containing SnO2 were prepared from the starting material sintered ITO pellets (0–15 wt% SnO2). The thin film (<0.6 μm thick) showed an amorphous-like structure. The thick film (>1 μm thick) showed a well-ordered crystalline structure. The crystalline and electrical properties of the films were dependent on the deposition temperature and were closely related to the SnO2 contents. Films deposited on substrates at temperatures of 50–180°C comprised a mixture of amorphous and polycrystalline phases and had a hazy appearance because of light scattering at the rough surface. That appearance was not observed in films with 0 wt% SnO2 content, but it was observed with increasing SnO2 content and substrate temperature. In films with thickness greater than 0.6 μm, the hazy appearance was more pronounced than in films with thickness of less than 0.6 μm. Polycrystalline ITO films with a clean and transparent appearance, as well as minimum resistivity of 1.7×10−4 Ω cm, were obtained on substrates at 180 °C (4 wt%, 7.5 wt% SnO2). Transparent and uniform ITO films with sheet resistance of 1.7 Ω/□ were obtained at 2.1 μm thickness at a high deposition rate (ca. 0.5 μm/min).
DC reactive sputtering of SiO2 films is performed using a new rotary cathode. The cathode is positioned at the center of the vacuum chamber used for deposition, so that the chamber is partitioned into a pre-sputtering zone and a deposition zone assisted by a partition block. When this new rotary cathode is used, the insulating film formed at the boundary between the eroded and uneroded areas on the target surface is removed. The insulating film mentioned above causes arcing during sputtering, but the new method suppresses arcing, and the electrical conductivity of the metallic cathode is increased. Consequently, the deposition rate is increased considerably during DC reactive sputtering. This new method necessitates two separate zones in the vacuum chamber: a pre-sputtering zone and a deposition zone. Plasma of two types must be introduced into the two zones simultaneously. The ignition voltage and sputtering voltage in each zone are controlled according to the discharge gas pressure in each zone. Using this method, the deposition rate for SiO2 films can be increased to 4 nm/s, which is 2.5 times the conventional deposition rate.
We propose a novel procedure for estimating coating–substrate adhesion energy using a knife-cutting method. This method presented the problem that the force exerted by a cutting blade to a specimen during coating removal is not fixed. That issue associated with the method has been resolved by detecting the “critical normal load.” The value of this load and that of the parallel load are used to ascertain the adhesion energy and the energy for the deformation of the removed part of the coating. The adhesion energy between an electro-deposited acrylic resin coating and a cold-rolled steel substrate was obtained using this procedure.