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Tetrahedral amorphous carbon (ta-C) films were prepared on cutters which are used for engraving. Engraving tests were performed on metal plates using non-coated and ta-C-coated cutters, under dry machining conditions, without oil. Generally, the metal plate is engraved using a cemented carbide (WC-Co) cutter, which uses oil for the cutting process, to fabricate a nameplate. The oil causes a high environmental load and complicates the machining process. Therefore, from an industrial viewpoint, there is a need for a dry machining process. The ta-C film is a hydrogen-free diamond-like carbon film with a high mechanical hardness. In this study, droplet-free ta-C films were prepared on WC-Co cutters using a T-shape filtered arc deposition method. The work materials used in the engraving tests were aluminum, copper, and brass. The results of the engraving tests demonstrated suppression of metal adhesion to the cutting edge, prevention of chipping of the cutting edge, and a decrease in cutting resistance during engraving when a ta-C film had been coated onto the cutting edge. In addition, burr and residue on engraved grooves were also suppressed by using a ta-C-coated cutter. The ta-C film coating offered a remarkable improvement in the engraving performance of a WC-Co cutter in the dry machining process.

PtRu or Pt catalysts were supported on four types of carbon nanomaterials with different shapes, sizes, and graphitic and electrical properties, and their resulting catalytic activities were evaluated by electrochemical methods. The carbon nanomaterials used included two types of particles: Arc Black (AcB) and Vulcan XC-72R (Vulcan), and two types of nanofibers: carbon nanocoils (CNC) and VGCF-X. Pt and Ru were loaded onto the nanomaterials by a reduction method using sodium borohydride. Transmission electron microscopy and X-ray diffraction (XRD) revealed the PtRu catalyst particles to be 4–6 nm in diameters. The shifts in the Pt(1 1 1) XRD peak of the catalysts on CNC and VGCF-X were larger than those on AcB and Vulcan, indicating a higher degree of alloying between Pt and Ru. The diameters of the CNC-supported Pt and PtRu catalyst particles had the narrowest distributions and were constant within the range of catalyst loadings investigated. Electrochemical studies of the catalysts during methanol oxidation were carried out using cyclic voltammetry. The catalyst particles supported on CNC and VGCF-X exhibited higher catalytic activity than those on AcB and Vulcan. The effect of the surface area of the carbon nanomaterials on the catalytic activity is discussed.

Tensile tests were performed on nine carbon nanocoils (CNCs) using a focused-ion-beam (FIB) technique. In each experiment, an individual CNC was picked up using an FIB, and a CNC bridge formed between a tungsten probe and the spring-table substrate. Real-time observations of the CNC elongation and subsequent fracture under prolonged stretching enabled us to estimate the elastic limit, the spring constant, the shear modulus, and the ultimate strength of each CNC and their mean values. The mechanics of CNCs was also compared to that of macroscopic springs.

A transformerless multicellular dc-dc converter has been newly proposed. The capacitively isolated dc-dc cell converters have been applied to develop the multicellular converter without using high frequency transformers. The high voltage transformation ratio is achieved by the ISOP (Input Series Output Parallel) connection topology of the cell converters and the realization of the highly efficient cell converter is expected because of no transformers. A 144 V-24 V, 200 W prototype of the multicellular dc-dc converter using 3 cell converters based on the capacitive isolation has been developed, and the feasibility of the transformerless multicellular converter has been confirmed.

Carbon nanomaterials are used as an electrode of electric double layer capacitors (EDLCs). In this research, we used arc black (AcB) and carbon nanoballoon (CNB) as the electrode material. AcB was produced by an arc discharge of graphite in N 2 atmosphere, and CNB was formed by a heat treatment of AcB. CNB is graphitic, and the particle shape is hollow. CNB has a higher specific capacitance than AcB at a high scan rate. In order to increase the specific capacitance of EDLC, CNB was oxidized at 625 °C in the air. By oxidization, the outer shell of CNB forms wrinkle. We call this material oxidized CNB (Ox-CNB). AcB, CNB, and Ox-CNB were used for the EDLC electrodes and were compared with commercially available activated carbon (AC). Cyclic voltammetry and electrochemical impedance spectroscopy of the EDLC electrodes were measured by an electrochemical measurement system. The specific capacitance of Ox-CNB (29 F/g) was larger than that of AC (16 F/g) at a scan rate of 500 mV/s. Furthermore, Ox-CNB had a high conductivity as a result of impedance measurement. Ox-CNB is an excellent electrode material of EDLC when using at a high charge/discharge rate.

Dielectric barrier discharge (DBD) treatment is one of the methods used to make carbon nanofibers stand up on substrates. Upright carbon nanofibers are used as field emission materials. We have used twisted carbon nanofibers (CNTws) as field emission materials and treated printed CNTws on substrates using DBD. In this report, we examine the effects of DBD conditions on the uprightness of the CNTws. The DBD experimental parameters were as follows: 1) N2/He gas mixture ratio, 2) pulse frequency, and 3) Pt coating on the CNTw surface. The lengths of upright CNTws from the substrate surface and from the surface of a printed CNTw dot were measured using scanning electron microscopy. N2 gas was shown to be crucial for generating streamer discharges and making the CNTw stand up on the substrate. As the pulse frequency increased, the lengths of the upright CNTws and their number density increased. This is explained by an increase in the number of streamers; the streamers move about over the substrate surface. Pt coating lowered the onset voltage for field emission from the CNTws although the number of upright CNTws was less than that without the Pt coating.

Plasma is a useful tool to synthesize carbon nanomaterials, including diamonds, fullerenes, nanotubes, and graphenes. This review gives an overview of these carbon nanomaterials produced by thermal or nonthermal plasmas and of the authors' work related to plasma-enhanced chemical vapor deposition of carbon nanotubes, along with an analysis and numerical simulation of CH4/H2 feedstock gas plasmas. The amount of carbon atoms in the grown carbon nanotubes and that calculated by simulation showed good agreement. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(6): 1–8, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11504

Electromagnetically pulled-out gas plasma (EPOP) gun was developed, which will be applied to the filtered arc deposition system in order to enhance the nitriding of preparing thin film under medium vacuum. A hot cathode of tungsten (W) filament was employed and DC discharge was generated between the cathode and anode (SUS304). The distance of electrodes was 100 mm. Electromagnetic coils were placed around the cathode, anode and plasma pulled-out duct, separately. Experimental pressure was 0.1 Pa. The following results were obtained. Ignition voltage became lower when the same direction magnetic field was axially applied to the cathode and anode. Minimum voltage for sustaining the discharge became lower when the magnetic filed was applied to the anode. With increasing discharge voltage, the discharge current increased dramatically for the discharge voltage less than 50 V and increased gradually for the voltage more than that. The plasma between the cathode and anode was able to be pulled out to the process chamber by applying magnetic field perpendicular to the discharge axis. The amount of pulled-out plasma increased with increasing the filament current and magnetic flux density for plasma pulling-out.

Substrate etching by means of Ar-mixed graphite-cathodic-arc plasma beam was investigated in a newly-developed compact-type μT-FAD. The surface level and roughness change were measured as a function of the Ar gas flow rate, when Ar gas was introduced into the arc generation zone and in the vicinity of the substrate. When Ar gas was introduced to the arc generation zone, the etching rate was lower but the surface was relatively not roughened. When Ar gas was introduced in the vicinity of the substrate, the etching rate was higher but the surface was roughened. At the same gas flow rate (and pressure), the substrate was etched more than three times faster when Ar gas was introduced into the arc generation zone than to the vicinity of the substrate. After measuring the discharge and plasma conditions, the results were considered to be caused by the difference in the amount of plasma transported to the substrate.

In recent years, multielement films have been required for high-performance cutting tools. In this paper, a Y-shaped filtered-arc-deposition (Y-FAD) system with two vacuum-arc sources was developed. First, an optimum magnetic coil arrangement was experimentally established to transport two plasma beams through the Y-shaped duct at the same time. Since the two plasma beams have the same electrical polarity, they naturally tend to repel each other. Therefore, in the second step, the two plasma beams were combined into one plasma beam through a mixer part by vibrating the plasma beams with a laterally oscillating magnetic field. Third, the electrical bias applied to the duct was optimized to obtain a higher transportation rate of plasma and deposition rate. After these design developments and tuning, titanium-aluminum (Ti-Al) film with a combined deposition pattern was finally obtained with Al and Ti cathodes. The controllability of the composition ratio by the arc current was verified.

A new technique to etch a substrate as a pre-treatment prior to functional film deposition was developed using a filtered vacuum arc plasma. An Ar-dominated plasma beam was generated from filtered carbon arc plasma by introducing appropriate flow rate of Ar gas in a T-shape filtered arc deposition (T-FAD) system. The radiation spectra emitted from the filtered plasma beam in front of a substrate table were measured. The substrate was etched by the Ar-dominated plasma beam. The principal results are summarized as follows. At a high flow rate of Ar gas (50 ml/min), when the bias was applied to the substrate, the plasma was attracted toward the substrate table and the substrate was well etched without film formation on the substrate. Super hard alloy (WC), bearing steel (SUJ2), and Si wafer were etched by the Ar-dominated plasma beam. The etching rate was dependent on the kind of substrate. The roughness of the substrate increased, when the etching rate was high. A pulse bias etched the substrate without roughening the substrate surface excessively.

Different types of diamond-like carbon (DLC) films (ta-C, a-C, ta-C:H and a-C:H) were prepared on super hard alloy (WC-Co) substrate using a T-shape filtered arc deposition (T-FAD) system. At first, the film properties, such as structure, hydrogen content, density, hardness, elastic modulus, were measured. Ta-C prepared with a DC bias of −100 V showed the highest density (3.1 g/cm3) and hardness (70–80 GPa), and the lowest hydrogen content (less than 0.1 at. %). It was found that the hardness of the DLC film is proportional to approximately the third power of film density. The DLC films were then heated for 60 min in an electric furnace at 550 °C in N2. Only the ta-C film hardly change its structure, although other films were graphitized. The 200-nm thick ta-C film was then heated for 60 min through the temperature range from 400 to 800 °C in N2 with 2 vol.% of O2 and the film structure found to be stable up to 700 °C. The substrate was oxidized at 800 °C, indicating the ta-C film had a thermal barrier function up to that temperature.

A Y-shape filtered-arc-deposition system, which has two arc sources and a common plasma-transport-duct, was operated under nitrogen gas, and a titanium aluminum nitride (TiAlN) thin film was prepared with Ti and Al cathodes. Two filtered-arc plasma beams were not completely combined into one beam even at the exit of the common duct. Thus, TiAlN film with composition-uniform distribution was not obtained at the fixed substrate position. However, different composition films were easily obtained at one time. Then various-composition films of TiAlN with different arc currents were prepared and film properties were measured. The surface roughness in arithmetical mean roughness was less than 3 nm on a 1.5-nm roughness substrate. The density of TiAlN increased with the Ti-content ratio, and its hardness tended to weakly increase with Al-content ratio. The maximum hardness was 36 GPa. Ti-rich film has internal compression stress and Al-rich film has internal tensile stress.

In recent years, greenhouse automatic-control, based on the measurement of solar irradiance, has been attracting attention. This control is an effective method for improving crop production. In the agricultural field, it is necessary to measure Photon Flux Density (PFD), which is an important parameter in the promotion of plant growth. In particular, the PFD of Photosynthetically Active Radiation (PAR, 400-700 nm) and Plant Biologically Active Radiation (PBAR, 300-800 nm) have been discussed in agricultural plant science. The commercial quantum meter (QM, PAR meter) can only measure Photosynthetically Photon Flux Density (PPFD) which is the integrated PFD quantity on the PAR wavelength.In this research, a band-spectral pyranometer or quantum meter using PVs with optical bandpass filters for dividing the PBAR wavelength into 100 nm bands (five independent channels) was developed. Before field testing, calibration of the instruments was carried out using a solar simulator. Next, a field test was conducted in three differing weather conditions such as clear, partly cloudy and cloudy skies. As a result, it was found that the response rate of the developed pyranometer was faster by four seconds compared with the response rate of the commercial pyranometer. Moreover, the outputs of each channel in the developed pyranometer were very similar to the integrated outputs of the commercial spectroradiometer. It was confirmed that the solar irradiance could be measured in each band separately using the developed band-spectral pyranometer. It was indicated that the developed band-spectral pyranometer could also be used as a PV band-spectral quantum meter which is obtained by converting the band irradiance into band PFD.

An X-shaped filtered-arc-deposition (X-FAD) apparatus was developed in order to prepare hydrogen-free tetrahedral amorphous carbon (ta-C), which is a kind of diamond-like carbon (DLC), and metal film as a binding interlayer on the superhard alloy using a plasma beam irradiated from the same direction. First of all, the droplet-reduction performance was verified, and then, the appropriate duct-bias voltages and deposition rate were measured. Optima of duct biases for chromium (Cr) and DLC were found to be 25 and 15 V, respectively. From the result of X-ray diffraction analysis, it was found that Cr film that is prepared at a higher substrate-bias voltage was well crystallized and has less internal stress. The appropriate substrate bias for preparing ta-C was -100 to -200 V. DLC film was also prepared with substrate heating. It was found that ta-C could be prepared at a substrate temperature of less than 200degC, and the film was graphitized at higher temperature. By following these results, 2.5-mum-thick ta-C film was prepared on a superhard alloy with an interlayer by X-FAD.

Cathodic arc plasma is one of the potential ion plating physical vapor deposition methods to prepare protective coatings on cutting tools, metal mold, etc. In particular, TiN, CrN, and TiAlN films are coated on industrial cutting tools using cathodic arc plasma. However, the cathode spot of the vacuum arc generates macrodroplets as coproducts of cathodic arc plasma containing high-energy ions. These macrodroplets may pose problems with smooth-surface films that are used for advanced high-precision applications. This paper reviews cathode phenomena particularly for a graphite cathode, the techniques for reduction of macrodroplet generation, and the techniques for macrodroplet removal from the processing plasma. The reduction technique includes steered arc, pulsed arcs, etc. The removal technique includes shielded arcs and filtered arcs. Recent filtered arc deposition systems are referred.

The Young’s modulus of buckypaper (BP) was improved via the addition of carbon nanocoils (CNCs). The Young’s modulus was the highest when the added amount of CNCs of the mass of the bucky paper was 11.9%. It is likely that the improved Young’s modulus was due to the higher Young’s modulus of the CNCs, compared with the multi-walled carbon nanotube (MWCNT) bundles. The helical structure of the CNCs also contributed to the improvement in the Young’s modulus. In the BP containing CNCs, the CNCs were anchored in the MWCNT matrix with superior entanglement, and this effect improved the Young’s modulus of the BP.

When carbon nanocoils (CNCs) are used in fuel cell electrodes, the diffusion of fuel and gas, and the removal of reaction products, becomes considerably smoother. In this paper, we used CNC as an anode or cathode catalyst support material in direct methanol fuel cells (DMFCs). Other carbon nanoparticles, Arc-Black (AcB) and Vulcan, were also used as catalyst supports to compare with the CNCs. Catalysts were loaded onto nanocarbon materials using the polyol method. We measured the methanol oxidation current of PtRu catalysts loaded on the carbon nanomaterials and the catalyst on CNC showed the highest current. Compared with the catalyst layers of AcB and Vulcan, the catalyst layer of CNCs was confirmed to have several voids. As for the cathode catalysts, the power density of Pt/CNC was 1.2 times higher than that of Pt/Vulcan and 1.6 times higher than that of Pt/AcB.

As an application to the nanoemitter, we investigated the nanofabrication of diamond-like carbon (DLC)-dot arrays by room-temperature curing imprint-liftoff (RTCIL) method using aluminum mask. The DLC film which has excellent properties similar to diamond properties was used as the patterning material. A polished glass like carbon (GC) was used as a mold material. The polysiloxane in the state of sticky liquid at room temperature and stable in air exhibits a negative-exposure characteristics. Therefore, the polysiloxane was used as electron beam (EB) resist and oxide mask material in EB lithography, and also used as RTC-imprint resist material. An aluminum was used as oxide metal mask material of liftoff. We have fabricated the GC mold of dot arrays with 5 µm-square and 500 nm-height. We carried out the RTCIL process using the GC mold under the following optimum imprint conditions: 0.5 MPa-imprinting pressure and 5 min- holding time. Aluminum film on the imprinted polysiloxane was prepared by vacuum evaporation method and its thickness is 20 nm. Finally, the polysiloxane patterns were removed with acetone and aluminum mask patterns were fabricated. We found that the maximum etching selectivity of aluminum film against DLC film was as high as 35, which was obtained under an ion energy of 400 eV. Then we processed the patterned aluminum on DLC film with an ECR oxygen ion shower. We fabricated DLC-dot arrays with 5 µm-square and 400 nm-height with an aspect ratio of 0.08.

The fabrication of diamond-like carbon (DLC) micro-gear by room temperature curing nanoimprint lithography (RTC-NIL) using glass-like carbon (GC) molds as applications to the DLC-based medical MEMS (Micro Electronic Mechanical Systems) was investigated. The DLC film which has excellent properties similar to chemical vapor deposited (CVD) diamond films was used as the patterning material. We propose GC as mold material because GC has higher etching selectivity than a diamond film. The etching selectivity of polysiloxane film against a GC substrate is about 5 times as high as that of a diamond film. Therefore we fabricated the GC molds that have micro-gear patterns with 30 µm-tip diameter and 500 nm-tooth thickness. We carried out the RTC-NIL process using the GC micro-gear molds under the following optimum conditions. 1 min-time from spin-coating to imprint: t1, 0.5 MPa-imprinting pressure: P and 5 min-holding time: t2, and then the imprinted polysiloxane pattern on DLC film was processed with an electron cyclotron resonance (ECR) oxygen ion shower. However, we were not able to fabricate micro-gear patterns in high accuracy because of a remaining residual layer on the DLC film. Therefore we propose the removing process for the residual layer with trifluoromethane (CHF3) ion shower under the optimum conditions of 300 eV-ion energy and 4 min-etching time. As a result, we succeeded to fabricate concave DLC-based micro-gear patterns in high accuracy which has 30 µm-tip diameter and 1 µm-depth.

The microfabrication technologiesfor organic light-emitting devices (OLEDs) are essential to the fabrication of the next generation of light-emitting devices. The micro-OLEDs fabricated by room-temperature curing nanoimprint lithography (RTC-NIL) using diamond molds have been investigated. However, light emissions from 10 μm-square-dot OLEDs fabricated by the RTC-NIL method have not been uniform. Therefore, we proposed the fabrication of micro-OLEDs by room-temperature curing nanocontact-print lithography (RTC-NCL) using the diamond-like carbon (DLC) mold. The DLC molds used in RTC-NCL were fabricated by an electron cyclotron resonance (ECR) oxygen ion shower with polysiloxane oxide mask in electron beam (EB) lithography technology. The mold patterns are square and rectangle dots which has 10 µm-width, 10 µm-width and50 µm-length, respectively. The height of the patterns is 500 nm. The DLC molds were used to form the insulating layer of polysiloxane in RTC-NCL. We carried out the RTC-NCL process using the DLC mold under the following optimum conditions: 0.1 MPa-pressure for coating DLC mold with polysiloxane film, 2.1 MPa-pressure for transferring polysiloxane from DLC mold pattern to indium tin oxide (ITO) glass substrate. We deposited N, N'-Diphenyl -N, N'-di (m-tolyl)benzidine (TPD) [40 nm-thickness] as hole transport layer / Tris(8-quinolinolato)aluminum (Alq3) [40 nm-thickness] as electron transport layer / Al [200 nm-thickness] as cathode on ITO glass substrateas anode in this order. We succeeded in formation of the insulating layer with square and rectangle dots which has 10 µm-width,10 µm-width and 50 µm-length, and operation of micro-OLEDs by RTC-NIL using DLC molds.

Helical carbon nanofibre (HCNF) is spiral-shaped carbon nanofibre (CNF) with coil and fibre diameters in the range of 20—1000 nm and 5—400 nm, respectively. The unique three-dimensional structure of HCNFs induces a lot of researches to apply HNCFs to electrical and electronic engineering as well as mechanical engineering. Carbon nanotubes (CNTs) were first discovered in the soot produced by an arc discharge and laser ablation has been one of the most reliable methods to prepare high-quality CNTs. On the other hand, HCNFs has been almost entirely grown by chemical vapour deposition (CVD) using hydrocarbon feedstock gases. In this chapter, we describe the history, classification, synthesis, and application of HCNFs. We mainly introduce our research results including the latest topics, comparing with the other group’s work. The problems that still remain in the CVD growth and the future researches of HCNFs we intend are also discussed.

Tetrahedral amorphous-carbon (ta-C) without hydrogen is the hardest in diamond-like carbon (DLC), and expected of the application to coating on dry cutting tool for aluminum. The only method to prepare ta-C on an industrial scale is cathodic vacuum arc deposition. The authors have been developed T-shape filtered arc deposition (T-FAD) system with efficient droplet reduction. However, ta-C usually requires a binding interlayer between the workpiece and film, since the internal stress of the film is very high and adhesion to the substrate is not good. In the present study, in order to prepare DLC and metal film on the superhard alloy depositing from same direction, the authors developed on X-shape filtered arc deposition (X-FAD) apparatus. First of all, the authors verified the droplet reduction function, and then the appropriate duct bias voltages and deposition rate. DLC was also prepared with substrate heating. By considering and following these results, 1 a thick ta-C film was prepared on a superhard alloy with interlayer by X-FAD

A lipid bilayer is a basic structure of the cell membrane and is stable in liquid solution. In this study, we analyzed dielectric barrier discharge (DBD) containing water on a quartz substrate using a one-dimensional fluid model. To simulate atmospheric pressure plasma for practical use, a tiny amount of N2 gas (0.5 ppm) was added to He gas ambient as an impure gas. The calculated current–voltage (I–V) characteristics reproduced the measured ones qualitatively. We focused on the behavior of DBD at the plasma–liquid interface and analyzed the temporal behavior of the electric field strength and incident fluxes of charged, excited, and radical species on the water surface. By varying the gap length, it was shown that the maximum electric field strength in an AC cycle saturated at gap lengths ≥0.15 cm. The incident fluxes of N2+ and He2+ on the water surface are almost the same and show strong correlations with the electric field in the vicinity of the water surface.

We provide direct evidence of plasma-induced pore formation in a cell membrane model system. We irradiated plasma on the basis of the dielectric barrier discharge onto a supported lipid bilayer (SLB). Observation with a fluorescence microscope and atomic force microscope revealed the formation of pores on the order of 10 nm–1 µm in size. Capturing these micropores in a fluid lipid membrane is a significant advantage of the SLB system, and quantitative analysis of the pores was performed. Stimulation with equilibrium chemicals (HNO3 and H2O2) indicated that other transient active species play critical roles during the poration in the SLB.

Multi walled carbon nanocoils (MWCNCs) were synthesized by chemical vapor deposition (CVD) and the experimental parameters were optimized to reduce their fiber diameter. The conditions for the synthesis of the thinnest MWCNC in this experiment were as follows: reaction temperature, 700 °C; C2H2/N2 pressure, 0.67 kPa; and C2H2/N2 ratio, 0.01. A low C2H2 gas flow rate and a low partial gas pressure were important in reducing the fiber diameter. The reaction temperature affected both the MWCNC fiber diameter and purity, which depends on the content of MWCNCs and multi walled carbon nanotubes (MWCNTs). At high temperatures (≥750 °C), MWCNTs were predominant and their crystallinity increased, which was confirmed by the detection of the radial breathing mode and high intensity ratios of the G peak to the D peak in the Raman spectra. By contrast, MWCNCs were produced preferentially at low temperatures (approximately 700 °C). Transmission electron microscopy showed that the fiber diameter of the thinnest MWCNC was less than 5 nm at both the helix and tip and that the thinnest MWCNC had a triple walled structure. Under optimized conditions, the vacuum deposition of a thin film of Sn on a Si substrate and the mounting of Fe catalyst supported zeolite on a Sn/Si substrate effectively increased MWCNC purity. MWCNC purity was improved by up to 30%, which is the highest purity we have observed thus far.

Carbon nanomaterials with different structures were mixed for an electric double layer capacitor (EDLC) electrode. We used two kinds of carbon nanomaterial: arc black (AcB) and a carbon nanoballoon (CNB). Arc black was synthesized by arc discharge. CNB was produced by heating the prepared AcB at 2400 °C. AcB mostly consists of an amorphous component and has a large specific surface area. On the other hand, CNB has a graphitic surface and a high conductivity. To utilize their characteristics, AcB and CNB were used as the main materials of the EDLC electrode in weight ratios of 1:1, 2:1, and 1:2. The obtained EDLC electrode was filled with 1 M H2SO4 as the electrolyte. As a result, by mixing AcB and CNB, both the power and energy densities became higher than those of AcB or CNB alone. The EDLC mixed in 1:1 weight ratio of AcB and CNB showed the highest performance, with a higher electric power density than activated carbon (AC).

PtRu catalysts were supported on five types of carbon nanomaterials of various shapes, sizes, and graphitic properties and the catalyst supports evaluated. The carbon nanomaterial used included three types of nanoparticles: Arc Black (AcB), Vulcan XC-72 (Vulcan) and graphene oxide (GO), and two types of nanofibers: carbon nanocoil (CNC) and carbon nanotube (CNT). Pt and Ru were supported by the reduction method using sodium borohydride. The metal catalyst loading was confirmed by thermo-gravimetric analysis (TGA), electron microscopy, and X-ray diffraction (XRD). Transmission electron microscopy (TEM) and XRD revealed that the diameter of PtRu catalyst nanoparticles loaded on reduced GO (rGO) and AcB were ~2 nm and was the smallest among all the samples. Shifts in Pt (111) XRD peaks of CNC and CNT were larger than those of AcB, Vulcan, and rGO. These results suggest that the diameters of catalyst nanoparticles became smaller by loading on the carbon nanoparticles with a large surface area including rGO, AcB, and Vulcan. Loading onto the carbon nanofibers enhanced the degree of PtRu alloying.

We fix a carbon nanocoil (CNC) on a substrate in a focused ion beam instrument and then fracture the CNC with a tensile load. Using the CNC spring index, we estimate the maximum to average stress ratio on the fractured surface to range from 1.3 to 1.7, indicating stress concentration on the coil wire inner edge. Scanning electron microscopy confirms a hollow region on the inner edge of all fractured surfaces.

In this study, we used two types of carbon nanomaterials, arc-black (AcB) which has an amorphous structure and carbon nano-balloon (CNB) which has a graphitic structure as electrochemical capacitor electrodes. We made a coin electrode from these carbon materials and fabricated an electric double-layer capacitor (EDLC) that sandwiches a separator between the coin electrodes. On the other hand, RuO2 was loaded on these carbon materials, and we fabricated a pseudo-capacitor that has an ion insertion mechanism into RuO2. For comparison with these carbon materials, activated carbon (AC) was also used for a capacitor electrode. The electrochemical properties of all the capacitors were evaluated in 1M H2SO4 aqueous solution. As a result of EDLC performance, AcB electrode had a higher specific capacitance than AC electrode at a high scan rate (≥ 100 mV/s). In the evaluation of pseudo-capacitor performance, RuO2-loaded CNB electrode showed a high specific capacitance of 734 F/g per RuO2 weight.

Making carbon nanofibers stand up in a field electron emitter to obtain a good field emission property when emitters are fabricated by printing on a substrate has been proposed. In the fabrication process of carbon nanotwist (CNTw) field emitters, paste composed of an ethyl cellulose binder and carbon nanotwists (CNTws) is printed on the substrate. Filament discharge (FD) treatment is an excellent technique that makes CNTws stand up because large-area treatment is possible at a low cost. To solve the problems of weak adhesion between CNTws and the substrate and the generation of fragments during FD treatment, we added a silicone binder to the paste at 0.83–0.97%. The variations in the silicone binder content were compared by the scanning electron microscopy (SEM) observation of CNTw emitter surfaces. As the content decreased, the number of upright CNTws increased and the height of upright CNTws became uniform. We confirmed that the crystalline property of CNTws was not changed by the FD treatment when the silicone binder was added. Also, spark from the CNTw emitter was inhibited with the addition of the silicone binder and the field emission current density in the case with the binder was 200 µA/cm2 higher than that in the case without the binder.

Diamond-like carbon (DLC) films were prepared on steel substrates by eleven suppliers using different types of equipment utilized in each company's own coating formation process. The deposition methods include sputtering, electron cyclotron resonance chemical vapor deposition (ECR-CVD), plasma enhanced chemical vapor deposition (PECVD), arc ion plating (Arc), filtered arc deposition (FAD), and plasma-based ion implantation (PBII). Some correlation of mechanical properties seems to be valid in a narrow range of parameters produced by a particular deposition method. In order to investigate general correlations in a wide range of parameters, various DLC films were prepared by different suppliers on the same substrate, and were evaluated in exactly the same manner. Independent of deposition methods, there existed correlations of the hardness, elastic modulus and Raman shift with a wide range of mass density.

Diamond-like carbon (DLC) film is sometimes removed using oxygen plasma in order to reuse workpieces such as cutting tools and press molds. In this study, an oxygen-dominated plasma beam was generated by converting the cathodic carbon arc plasma beam formed in T-shaped filtered-arc-deposition (T-FAD) in order to investigate the feasibility of using the plasma beam for the removal of DLC film. When the oxygen (O2) gas flow rate was relatively high (50 ml/min) and the substrate was biased (DC -500 V), the plasma beam in front of the substrate was confirmed to contain a considerable amount of excited oxygen atoms, since an atomic oxygen spectral line (777 nm) emitted from the plasma beam had relatively strong radiation intensity. The plasma beam was irradiated on a tetrahedral amorphous carbon film, a hydrogen-free sp3-rich DLC film, prepared on a hard alloy (WC with 6 wt % Co binder) substrate. It was found that a plasma beam generated with an appropriate O2 gas flow rate and applied substrate bias was able to etch the DLC film proportionally to the treatment time. The surface was not roughened when the treatment time was 1.5 times longer than the intended time to remove a given thickness of DLC film.

Arc black (AcB) was prepared in N2 gas using the twin-torch arc discharge apparatus, and a hollow capsule with graphite layers named a carbon nano balloon (CNB) was obtained by heat treatment of the AcB in Ar gas at 2400 °C. Transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and compressive resistivity measurement confirmed that the CNB was well graphitized. In the direct methanol fuel cell (DMFC) application of these carbon nanomaterials, catalyst metal nanoparticles were supported on the AcB, and a membrane-electrode assembly (MEA) was formed from the catalyst-supported AcB and the CNB by hotpressing them on an electrolyte film. The MEA containing the CNB resulted in a higher DMFC performance than that without the CNB, indicating that the CNB with lower compressive resistivity than the AcB works as a material for the improvement of electric conductivity in an MEA.