Carbon nanotubes (CNT) are generally obtained using vapor phase methods such as CVD, for which catalytic metals are necessary for carbon deposition. Recently, a liquid phase method was also developed for preparing CNTs. This method is simpler than usual vapor phase methods. We studied preparation of CNTs using this liquid phase method with an alcohol solution and non-catalytic substrates, and observed CNT production. In this study, we investigated CNT preparation using liquid phase method with ohmic heating of substrates in an alcohol solution. Mainly, Ti was used as the substrate and CH3OH was used as the reactant. The substrate was chemically polished and washed with acetone before the experiments. After the substrate was soaked in the alcohol solution, the CNT preparation experiments were started. Fiber-shaped deposits were observed on the Ti substrate using SEM. Evaluation by Raman spectroscopy revealed spectra attributable to single-wall carbon nanotubes [SWCNTs] on Ti and Zr substrates. Fiber-shaped deposits in the SEM image were identified as CNTs using Raman spectroscopy. Results show that the Ti substrate was the most effective for preparation of CNT using a liquid phase method by ohmic heating of substrates in an alcohol solution.
Amorphous WO3·nH2O thin films were deposited at room temperature on Si and ITO/glass substrates. After mixing Na2WO4 solution and HCl solution, they were dripped immediately on a rotating substrate to produce a deposited film. This process is simple and applicable to a non-heat resistant substrate. Furthermore, it might be preferable for producing electrochromic (EC) properties of WO3 thin film because the film obtained at room temperature contains OH group. The optimum film deposition parameters are as follows: Na2WO4 solution, 1.0 mol·dm−3; HCl solution, 1.0 mol·dm−3; flow rate, 2.0 mL·min−1; pH: 0.2. The films obtained under the optimum parameters had a composition of WO3·(2.6-2.7)H2O and displayed good adhesion and scratch hardness (pencil method > 9H). The thin films obtained using this method exhibit excellent EC properties of color efficiency (45-50 cm2·C−1), and response time (3 V, 2 s, ΔT = 50%).
Because automobile bodies are so large and complicated, in the analyses of film thickness of electrodeposition coating undertaken to date, only the portion with thin coating film was calculable. Therefore, to study matters such as the electrode arrangement, bath structure, body size, coating voltage, coating time, and so on, analyses of the whole body structure are necessary. In this report of our study, a virtual surface with a simplified shape is introduced and analyses of the whole body are described. The area ratio of the actual coating surface and the virtual surface are defined as a surface coefficient, that is used in the governing equation of thickness analyses of coating by electrodeposition. A computer experiment based on the virtual surface was conducted. The calculated results showed good agreement with those from the asperity surface model. Results demonstrated that analyses of the whole body, including the solution of the thickness distribution of the side sill with a bad coating film distribution, are obtainable using the virtual surface model. Results show that the study of bath structure, operating conditions, and so on can be realized through analyses of the whole body using a virtual surface.
Using atomic force microscopy (AFM), nanoindentation, nanowear, and viscoelastic testing were performed to elucidate nanomechanical properties of lubricant-coated magnetic disks. The surface deformation resistance of an ultraviolet (UV)-irradiated disk is superior to those of heat-treated or untreated disks. Evaluation of viscoelastic change using nanowear tests revealed that, for the UV-irradiated and untreated magnetic disks, tanδ does not decrease with friction. However, for the heat-treated disk, tanδ decreases with sliding. This result demonstrates the resupply capability of the UV-irradiated and untreated lubricant-coated disks during sliding. The lubricant-coated magnetic disks’ friction properties are evaluated using the ball-on disk friction test. The UV-irradiated magnetic disk exhibits stable friction coefficients, and less friction damage than the other. These superior properties of the UV-irradiated magnetic disk can be understood in terms of nanomechanical properties evaluated using AFM. The UV-irradiated disk has suitable bonding strength between the lubricant and DLC, in addition to the resupply capability of the free lubricant.
Hydroxyapatite fine particles (HAp) were loaded on an anodized titanium plate in an alkaline electrolytic bath under spark discharge. Bioactivity was investigated by immersion of the materials into the simulated body fluid for a predetermined period. Bioactivity was remarkably improved by loading of HAp on the anodized titanium surface.