Carbon ions were implanted into hardened high-speed tool steel by means of a plasma immersion ion implantation (PIII) technique with methane gas. Various process times were used in order to investigate the relationship between mechanical properties and depth distribution of carbon, and to examine whether it is possible to apply PIII for practical use for commercialized high-speed tool steel substrate. The implanted surface was characterized by X-ray diffractmeter (XRD) for investigation of surface structure. Auger electron spectroscopy (AES) was used to determine the depth distribution profile of the elements in substrate. Raman spectroscopy was also utilized for the characterization of carbon film deposited on the substrate. Substrate temperature was estimated from the hardness of a tool steel substrate treated simultaneously. Substrate temperature did not exceed the tempering temperature of high-speed tool steel, and was below 532K. Short term implantation with −20kV of negative bias caused a high concentration of carbon at the steel surface. On the other hand, carbon film was deposited on the carbon enriched surface by long term implantation. Raman spectrum for the deposited carbon film showed that for a typical DLC film. Friction test with a bearing steel ball as a counter material was similar to that the friction coefficient of deposited DLC film, carbon implanted layer, and steel substrate were 0.2, 0.3 and over 0.5, respectively. These results suggest that PIII with methane is feasible for the surface treatment of high-speed tool steel as both the implanted carbon and the DLC film reduce its friction coefficient in dry conditions.
Microcapsules containing benzotriazole, which is a corrosion inhibitor of copper, were incorporated with copper electrodeposition. Spherical microcapsules were fabricated by the polymerization between terephthalic dichloride and diethylenetriamine. The average diameter of the microcapsules was 7.3μm. The microcapsule composite copper coating was carried out at 10mA cm−2 in a copper sulfate bath. The incorporation of the microcapsules in copper film was confirmed by surface observation with a confocal laser scanning microscope and scanning electron microscope. From the result of the observation, it was found that microcapsules were incorporated in the copper films. A corrosion test was investigated for the microcapsule composite copper coating films in 100ppm sulfuric acid solution containing 100ppm chloride ion for 1month. Local corrosion was not observed on the surface of the coating films after the corrosion test. The weight of the coating film did not change. From these results, it was found that the copper film incorporated with microcapsules has good corrosion resistance.
The dissolution rate and the dissolution factor of copper immersed in a dilute anodically electrolyzed water of sodium sulfate aqueous solution (Na2SO4-acidic electrolyzed water) and in a sulfuric acid aqueous solution of the same pH were studied. As a result, it was found that the dissolution rate of copper in the former was about 3 times higher than that in the latter. The phenomenon of the dissolution of copper being enhanced in the Na2SO4-acidic electrolyzed water is considered to be attributable to the existence of high concentrations of dissolved oxygen and hydroxyl radical precursor that it is most likely synergistically produced by electrolysis. Furthermore, it was suggested that Na2SO4-acidic electrolyzed water is capable of functioning as an etchant and roughening agent for copper instead of a sulfuric acid/hydrogen peroxide mixture.
A resistance-wire type strain gauge assembly affixed to the reverse side of a copper plating substrate was used to measure the real-time variation in the internal strain developed during the deposition and dissolution of zinc-cobalt alloy films by single cycle voltammetric sweeping. An internal tensile strain developed during the cobalt deposition that began near −0.65V (vs. Ag/AgCl sat. KCl). However, in the potential region of −0.85V to −0.98V, the tensile strain stagnated due to the suppression of the cobalt deposition caused by the adsorption of zinc hydroxide produced on the electrode. On the other hand, in the potential region of −0.98V to −1.06V, the tensile strain again increased due to the cobalt deposition occurred with the onset of the electrochemical reduction of zinc ions. However, in the subsequent more negative potential region of −1.06V to −1.20V, the internal strain changed from tensile to compressive with the formation of a zinc-rich γ-phase of the Co-Zn alloy. After the electrode potential was reversed at −1.20V, the compressive strain was maintained by the alloy deposition in the potential region of −0.98V to −1.20V. However, with the cessation of the electrochemical reduction of zinc ions in the potential region more noble than −0.98V, the strain changed from compressive to tensile with selective electrolytic-leaching of zinc from the alloy deposits.