Copper electroplating and copper electroless plating were examined by quantitatively evaluating morphological changes of plating surfaces deposited in magnetic fields with the spatial power spectrum. From copper electroplating in 0.3moldm-3 copper sulfate and 0.1moldm-3 sulfuric acid solution, it was obtained that the intensity of the spectrum increases with increasing magnetic flux density. This result suggests that the crystal grains become larger as the magnetic flux density increases. However, for 0.03moldm-3 copper sulfate and 0.01moldm-3 sulfuric acid solution, the intensity decreased with increasing magnetic flux densities, which means, as observed by SEM, that the crystal sizes decrease and a flat surface emerges in high magnetic fields. Then, for the copper electroless plating, the surface morphological change in the magnetic field was also examined by the spatial power spectrum. In this case, a decrease of crystal grain sizes was observed, which was ascertained by the decrease of the spectrum. From these results, it was concluded that the morphological changes of plating surface deposited in magnetic fields could be quantitatively evaluated by the spatial power spectrum.
Electroless nickel initial deposition and subsequent steady state deposition process on a nonconductor and conductor were investigated. It is indicated that phosphorus contents in the deposited films during the initial nickel deposition reaction were higher than the subsequent steady state deposited films. The plating baths containing acetic acid, propionic acid, succinic acid, malic acid, citric acid, glycine and aspartic acid as a complexing agent showed higher phosphorus in the deposited films. On the conductor, lactic acid and glycolic acid added bath showed the shortest induction time and deposited films readily changed to continuous films at the initial deposition steps. Also, it is confirmed that a bath exhibiting a higher deposition rate compared with a basic bath leads to extraneous particles during the initial deposition period. On the nonconductor, the morphology of initially deposited nickel was not a layer-by-layer structure on nonconductor, it is confirmed that deposited films are composed of fine particles. Also, particle sizes of nickel-phosphorus deposits ranged from 10 to 40nm.
In the hot-dip galvanizing of steel structure, crack failures, which is well-known as Liquid Metal Embrittlement, occurs sometimes at heat affected zones after welding processes of steel structures. We found crack failures at gas cut edges, especially at inflection of straight line cuts and at concave edges of circular cut on 40mm thick steel plates. Microscopic observation on surfaces and cross sections of gas cut zones, showed changes of the micro-structure of steel at shallow sections. These structural changes cause the embrittlement of steel plates at hot-dip galvanizing. To simulate the embrittlement of steel plates in galvanizing, tensile tests were carried in a galvanizing bath using gas cut, mechanical cut and annealed after gas cut samples. Results showed clearly that structural changes of steel at gas cut edges played an important role in the embrittlement in galvanizing. Calculation of thermal stress in steel structure edges at the initial stage of dipping in the galvanizing bath was attempted. From the calculated stress level due to heat expansion at edge of steel, it is estimated that the embrittlement sensitive steel may be broken in galvanizing baths.
Thin films were prepared by reactive magnetron sputtering of polyimide (Kapton) targets using Ar-N 2 discharge gas mixtures. Mass analysis of ions in the discharge space showed that the masses indicating a monomer of polyimide or an imide base were not observed. The compositions of the films investigated by XPS were nitrogen-rich. In the spectra of FTIR, two wide spread peaks corresponding to expansion/contraction mode and angle variation mode of imide or amide base were observed. The thermal stability of the films was relatively inferior to that of bulk Kapton but the wear characteristics of the films were remarkably excellent. The relative dielectric constant of the films adjustable by controlling the N2 gas content in the discharge gas and became 3 or less.
The effect of rotation rate upon potential and etch rate of a steel was examined utilizing a rotating steel disk electrode. Being based upon these experiments, etching mechanism was discussed. The principal ingredient of etchants was FeCl3. The concentration of FeCl3, FeCl2 and free HCl were 3.7 to 4.1mol dm-3, 0.17±0.02mol dm-3 and 0.15±0.02mol dm-3, respectively. The temperature of the etchants was maintained at 70°C and rotation rate of the steel disk was set at 400∼4900rpm. The etch rate was obtained from the weight loss. The etch rate and square root of rotation rate are in proportionate relations at any concentrations of FeCl3. The anodic reaction is controlled by surface reaction process, while the catholic reaction proceeds under mass transfer control.
An electric current distribution analysis program, “Electroplating Pilot System” (EPPS), was developed, and has been sold. As an expansion of EPPS, a new program using the Finite Element Method (FEM) that allows users to calculate thickness distribution of electrodeposition coating was developed. By introducing new paint parameters for thickness calculation that considered special characteristics of electrodeposition coatings, actual thickness calculation precision was obtained. The experiment method to obtain paint parameters and parameter determination methods based on experimental measured data were indicated. Also, constant voltage coating testing on flat plates and calculated results of the testing were compared. Both total current and thickness matched well at each time frame.