Pt-Ir and Pt-Rh alloy films were deposited on a cemented carbide substrate by RF magnetron sputtering and film characteristics were examined to determined a candidate for the molds used for molding optical glass elements. XRD showed a highly oriented (111) texture for both the Pt-Ir and Pt-Rh films. Tensile stress existed in pure Pt films deposited in the present experiment. In Pt-Ir films, tensile stress decreased with increases in Ir content up to 20wt%. Film stress changed in sign from tension to compression, and the compressive stress increased with increases in Ir content. In Pt-Rh films, on the contrary, tensile stress increased only slightly with increases in Rh content up to approximately 40wt%. The Vickers hardness of the alloy films increased with increases in either Ir or Rh content, and this tendency is marked in the Pt-Ir alloy system Pt-80wt% Ir films shows a Vickers hardness of approximately 1200. Molds coated with pure Pt film or alloy films containing a small amount of Ir or Rh were degrated markedly by heat treatment at 600°C for 5hrs. Molds coated with Pt-Ir alloy films containing more than 30wt% of Ir, however, exhibited excellent performance despite heat treatment. No degradation was observed for molds coated with Pt-Ir alloy films containing more than 30wt% Ir.
Thin films of Pt-Mn-Sb alloy prepared by RF sputtering were deposited onto glass and silica substrates at room temperature and at 573K under argon pressures of 1.33∼26.6Pa, and the targets were altered by changing the number of Pt and Mn chips on Pt-Mn-Sb alloys. The composition and structure of the deposited films were determined by EPMA and X-ray diffraction. In order to prepare PtMnSb Heusler alloy, the target composition should be about 21Pt-53Mn-26Sb. The compositional range making the PtMnSb phase was in the vicinity of the stoichiometric composition. Films prepared at low argon pressures and low substrate temperatures were nearly amorphous, but they crystallized when heated above 573K.
Diamond was deposited in both film and particle form by microwave plasma CVD from a CO-H2 system at a power input of 220W, an H2 flow of 100cm3/min., and a pressure of 3.3kPa. O2 and CO2 were used as additive gases. In deposition without additives, the rate reached a maximun at 50cm3 CO/min., while idiomorphism was apparent at CO concs<15cm3/min.; for the same CO flow with the O2 additive, the maximum occurred at 1cm3 O2/min. and the idiomorphism appeared at O2 cones>4cm3/min.; and for the same CO flow with CO2, the maximum occurred at 4cm3 CO2/min, and the idiomorphism appeared at CO2 cones>6 cm3/min. The highest deposition rates obtained in this study were 2.8 and 9.2μm/min, for the film and particles, respectively, with a CO-CO2-H2 system. The favorable results make this appear to be the most promising combination for diamond synthesis by microwave CVD. Addition of either O2 or CO2 to this system can form diamond of higher crystallinity comparable to that of naturally occurring type II a. A possible mechanism of deposition from those gases is also suggested.
Electrochemical polarization experiments were carried out on liquid and solid Gallium electrodes in alkaline gallate solution. The cathodic polarization curves for the electrodeposition of gallium exhibited a Tafel line with, a slope of 0.16V/decade in a limited range of current densities, and was slightly dependent on the phase change of the electrode. The exchange current densities were of the order of 10-1∼100A m-2, depending on the concentration. No dramatic changes in the kinetics were observed with phase change. The electrodeposition of Gallium from alkaline gallate solution is probably controlled by the charge transfer step. The electrodeposits on the Pt and Fe electrodes were pure Gallium, but those on the Ni and Cu electrodes were found to be Ga36Ni64, (GaNi2) and CuGa2 respectively. 100% current efficiency was obtained at an intermediate current density.
The effect of additives such as selenious acid, sodium thiosulfate and thiourea on the electrodeposition behavior of Zn-Mn alloys from sulfate baths containing sodium citrate was investigated. The additives were found to improve the current efficiency, especially in the deposition of alloys. of high Mn content, but showed little effect on the Mn content of the alloys. Polarization curve for Zn-Mn alloys electrodeposition revealed that the additives affected hydrogen evolution in addition to Zn and Mn deposition, i.e., the partial current for hydrogen evolution was suppressed to modify current efficiency at potentials less noble than -1.5V (vs. Ag/AgCl). X-ray diffraction patterns for the Zn-Mn alloys also showed that these additives readily changed the alloy phase from epsilon to gamma.
Laser Raman spectra were investigated for hopeite crystal films formed on galvannealed steel. Four clear peaks due to PO43- for the crystalline state of hopeite were found at 800-1300cm-1. Orthophosphate (PO43-), which is a regular tetrahedron, has four basic vibration modes-ν1, ν2, ν3 and ν4-, of which, ν1 and ν3 are observed at 800-1300cm-1. Here, the main peak corresponds to ν1 and the other peaks correspond to ν3 untied and split. A reference sample of 85%-H3PO4 showed two peaks in the same region, the main peak corresponding to ν1 and the sub-peak corresponding to ν3 degenerated. It was found that a basic vibration mode of ν3 appears at 1150cm-1. Raman spectra were observed for hopeite dissolved in HCI solution. Three peaks were found in the region, but the spectral pattern was quite different from that of crystalline hopeite, and was similar to that of H3PO4 aq. soln.. The peak intensity ratio of I1075/I890 differed between liquid-state hopeite and H3PO4 aq. soln., but the band frequencies of the three peaks were consistent with each other. It was confirmed that the three peaks correspond to the P(OH)3 and PO stretching vibrations of [H3PO4] and the PO2 stretching vibration of [H2PO4-] formed by the dissociation of H3PO4. The PO2 stretching vibration observed at 1075cm-1 depends on the dissociation state of H3PO4.
A colored surface film can be formed on SUS 430 stainless steel in 0.5∼10kmol m-3 H2SO4 from 298K to 353K using the potential-pulse method. It was showed that the rate of formation of the colored film increased as sulphuric acid concentrations or solution temperature increased. The pulse potential range for getting a fine color film on SUS 430 was 0∼0.95V (vs. SCE), and the pulse time was 10s∼3-0.2s. The rate of formation of the film decreased as the pulse time decreased from 10-3s, and no color film was formed at pulse times≥0.5s. The surface film tended to be nonadherent at anodic pulse potentials above 1.0V. This can be explained by considering that the film be dissolved into solution at the more anodic potential. AES analysis showed that the film formed was Cr-rich and Fe-deficient comparing with the matrix. It is suggested that Cr2O72- ions were formed at the anodic pulse-time, and Cr oxide was deposited by reduction of Cr2O72- at the cathodic pulse-time.