The effects of the catalyst deposition on the adhesion between electroless Ni-P film and polished sapphire substrate were investigated with AFM, XPS and SEM. The adhesion strength was measured with the direct pull-off test. It was found that the adhesion strength was affected by the dispersed state of catalyst. The higher the dispersed state of the catalyst, the stronger the adhesion achieved. In order to explain the difference in adhesion strength, the fracture surfaces of samples were analyzed with XPS. This analysis showed that Sn was present on both sapphire fracture surface and NiP fracture surface. Therefore, it was considered that fracture took place through the Sn layer. It was concluded that the catalyst deposition condition was one of the most important factors in improving the adhesion strength between electroless Ni-P films and polished sapphire substrates.
The effects of ultraviolet irradiation on three-step coloring film were investigated through TEM observation and the measurement of chromaticity and of the metal content. TEM observation revealed that ultraviolet irradiation apparently decreases electrodeposits in the DC anodic oxidation film. Metals that had electrodeposited in the process for three-step coloring film were ascertained by means of neutron activation analysis, which revealed that ultraviolet irradiation does not change the amount of nickel and tin in the film as a whole. In addition, the percentage of nickel in the electrodeposits was found to be higher than that previously reported.
The recrystallization behavior of silver electrodeposits obtained from a low-cyanide silver plating solution containing selenocyanate as an additive was studied using XRD and SIM measurements. For bright deposits obtained at 120A/dm2, the as plated deposits consisted of randomly oriented small crystallites with very weak XRD patterns, deposits hardness was ca. Hv 100. Several hours after plating, the crystallites of the deposits kept at room temperature grew into large crystallites that were predominantly parallel to the substrates. The peak height of the (200) plane of the deposits increased dramatically. Accordingly, the hardness of the deposits decreased drastically to ca. Hv 50. In contrast, matt silver deposits obtained at 40A/dm2 produced no recrystallization phenomena at room temperature after plating. The difference between the deposits coincides with the amount of codeposited selenium in the deposits. Bright deposits containg lower levels of selenium than matt deposits. recrystallized easily compared with matt deposits.
By static ion beam mixing treatment using the physical vaporized deposition of the titanium followed by nitrogen ion implantation, the titanium nitride coating was formed onto the disk surface of hardening steel and tribological properties were evaluated in pin-on-disk tests under a lubricated condition. In comparison with the uncoated case, the coating increased microhardness by 1.3 times and decreased the coefficient of friction from 0.6 to 0.1 and the volumetric wear rate of pin material to 1/10. Break away of the coating was not observed. By the glancing angle X ray diffraction and the Rutherford back scattering analysis, titanium oxide and TiN were observed in the coating. It was confirmed that atomic mixing occurred at the interface between coating and substrate. This results indicate that this structure consisting of TiN including Ti oxides and atomic mixing at the interface results in superior tribological properties and stiffness of the coating.
The mechanism of electrodeposition of Cr in a Sargent bath was investigated with electrochemical impedance spectroscopy (EIS). Cr(VI)sol is reduced to Cr via two reaction intermediates, i.e., Cr(III)ad and Cr(II)ad. The current-potential curve for Cr(VI)sol reduction can be divided into three potential regions. Inductive semicircles were observed on the Nyquist plots of electrochemical impedance measured in two potential regions, where it was found that the inductive behavior originates from the actions of Cr(III)ad and Cr(II)ad. Moreover, results indicate that the hydrogen evolution influenced the Cr(VI)sol reduction rate. The simulated results on the basis of the reaction model as outlined are in agreement with the experimental results.