木之下 博

Improving the wear resistance of polvmer-based materials can lead to high energy efficiency' of transport machineries owing to the higher strength-to-weight ratio. Oxidized wood-utilized synthesized copper-based particles (OWCu) was incorporated into epoxv resin to investigate its effect on the wear resistance of OWCu-incorporated epoxy with the steel counterpart using a ball-on-plate tribometer. OWCu was mainly composed of CuO with a small amount of graphitic carbon, and the average partide size was approximately∗ 0.5 um. A higher wear resistance was observed for the OWCu-incorporated epoxv at more than 0.6 mass% compared to the neat epoxv. The mechanism for the improvement of the wear resistance property was discussed, and it was revealed that the surface roughness of the steel counterpart was maintained at a low level for the OWCu-incorporated epoxy', which played a dominant role in reducing the wear of the OWCu-incorporated epoxv. The polishing effect of OWCu could reduce the surface roughness of the steel counterpart in the friction process. In addition, at higher concentrations of more than 5.0 mass%, OWCu adhered to the steel surface, which decreased the wear of the steel surface. OWCu is a promising material to enhance the wear resistance of polvmer-based materials, especially with low elongation.

A substantial quantity of carbon onions in a durable film state is indispensable for its applications. In this study, large area fabrication of closely packed homogeneous carbon onion nanoparticle film using plasma-based ion implantation was demonstrated. Ag film deposited on a Si substrate was used as the implantation target for the hydrocarbon ions accelerated at 20 kV. Nanoparticles with the mean diameter of 7.5 nm were formed at the grain boundary of the Ag film. Carbon onions with the mean diameter of 17.4 nm were synthesized and arranged to a closely packed nanoparticle film with the thickness of around 200 nm by gradual thermal vaporization of the Ag. The closely packed configuration was achieved due to the isolated growth of carbon onion nanoparticle and high uniformity of the diameter. This process can be used in principle large area formation compered to typical ion implantation technique of carbon onion nanoparticle film, which can be applicable for the practical use in mechanical and electrochemical applications.

Formation of smooth low friction carbon onion nanoparticle film was carried out using vacuum arc deposition. Carbon onions were synthesized by the arc discharge of carbon rod as a cathode and deposited directly onto the substrate in a vacuum. The process of carbon onion synthesis and nanoparticle film growth was investigated using transmission electron microscopy (TEM), atomic force microscopy (AFM), and quadrupole mass spectrometer (QMS). It was observed that isolated carbon onions were successfully synthesized by pulsed arc discharge of the carbon rod as a cathode under relatively low pressure of 10−7 Pa. The synthesized isolated carbon onions around the cathode were in flight in vacuum and deposited onto the substrate. A smooth carbon onion nanoparticle film with surface roughness (Ra) of 0.37 nm was gradually formed on a graphite substrate by 100 pulse shots of the arc discharge. A smooth nanoparticle film was achieved due to the mixture of the deposition of carbon onions and amorphous carbon in this process, where amorphous carbons were filled between carbon onions interparticle. AFM friction measurements in the vacuum revealed that the synthesized nanoparticle film possessed lower friction coefficient than graphite, which was attributed to the low adhesive force and smooth surface roughness of the carbon onion nanoparticle film.

A storage capacity of hydrogen in multi-wall carbon nanotubes (MWCNTs) forest has been investigated experimentally using a langasite oscillator from vacuum to 100 kPa at room temperature. MWCNTs were directionally grown on the langasite oscillator using chemical vapor deposition at 750 °C, where langasite retains its oscillating property. Modification of MWCNTs on the langasite oscillator were conducted by atomic oxygen irradiation to induce the open-ended structure of the MWCNTs. The hydrogen storage capacities of MWCNTs directly grown on the oscillator were successfully evaluated, and the maximum hydrogen storage capacity was improved 60% with the modification of MWCNTs by atomic oxygen irradiation.