Faculty Profiles - UMEHARA, Noritsugu

Papers - UMEHARA, Noritsugu

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The 1 μm wear particles entrainment in situ observation via fluorescent staining silica particles by silane coupling with Rhodamine B Reviewed

Tokoroyama, T; Okashita, M; Fusetani, N; Murashima, M; Hashizume, N; Tsuboi, R; Shiomi, H; Umehara, N

FRONTIERS IN MECHANICAL ENGINEERING-SWITZERLAND Vol. 10 2024.2

Super hardening of Fe-W alloy plating by phase transformation of amorphous to metal carbides-dispersed nanocrystalline alloys and application as promising alternative for hard chromium plating Reviewed International coauthorship International journal

SURFACE & COATINGS TECHNOLOGY Vol. 477 2024.2

Development of an Electrocautery Surface Coating Method to Suppress Surgical Smoke Reviewed

Takayuki Tokoroyama, Motoyuki Murashima, Koki Ogawa, Noritsugu Umehara,

Journal of Surgery and Research 2024.1

Nitrogen-containing diamond-like carbon deposited on glass substrate via filtered cathodic vacuum arc with high-frequency pulsed DC substrate bias Reviewed International coauthorship International journal

Kim, JI; Lee, WY; Tanaka, K; Tokoroyama, T; Murashima, M; Umehara, N

SURFACES AND INTERFACES Vol. 44 2024.1

Creation of anti-frost micro-plastic texture surfaces enhancing thermal conductivity by carbon black containing in polyvinyl chloride Reviewed

TOKOROYAMA Takayuki, ZHANG Liying, WU Wenjun, MURASHIMA Motoyuki, UMEHARA Noritsugu

Journal of Advanced Mechanical Design, Systems, and Manufacturing Vol. 18 ( 3 ) page： JAMDSM0032 - JAMDSM0032 2024

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Mechanical Engineers

Frost formation poses challenges in various sectors, impacting efficiency and safety. Active methods involve energy-consuming processes like heating, while passive approaches utilize protective coatings or hydrophobic surfaces to minimize frost aggregation. However, low thermal conductivity remains a concern. In previous research, lotus leaves inspired micro-meter-sized asperities were effective in controlling frost growth. Applying this concept to plastic, particularly low-cost PVC, raised challenges due to its low thermal conductivity. The study explores utilizing carbon black (CB) waste from hard coating processes to enhance PVC's thermal conductivity, forming a micro-plastic texture (MPT). The research investigates the influence of CB amount and AC voltage frequency on MPT features and thermal conductivity, aiming for a sustainable solution to address frost-related issues. Incorporating 0.9 vol.% CB into PVC solution under a 2 kV AC electric field (6 Hz) resulted in an extensively distributed MPT on the surface. This MPT, formed under the 6 Hz condition, exhibited no in-plane bias, making it an ideal surface for preventing frost formation. Adding CB to PVC within the range of 0 to 2.1 vol.% and applying a 2 kV, 6 Hz AC electric field led to independent MPT formation at concentrations between 0.4 to 1.2 vol.%. Conducting cooling tests in atmospheric and vacuum conditions, we found that MPT with 0.9 vol.% CB displayed a thermal conductivity of approximately 0.19 kW/mK in atmospheric conditions, similar to aluminum alloy. However, with 1.2 vol.% or more CB, it decreased to about 0.15 kW/mK. In vacuum conditions, MPT with 1.2 vol.% CB exhibited a higher thermal conductivity of 0.063 kW/mK compared to the 0.055 kW/mK observed in MPT with 0 vol.% CB.

DOI： 10.1299/jamdsm.2024jamdsm0032

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CiNii Research

Active control of Lubricant Flow Using Dielectrophoresis and Its Effect on Friction Reduction Reviewed

Murashima Motoyuki, Aono Kazuma, Umehara Noritsugu, Tokoroyama Takayuki, Lee Woo-Young

Tribology Online Vol. 18 ( 6 ) page： 292 - 301 2023.10

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society of Tribologists

With the increasing demand for active friction control, we newly proposed to use dielectrophoresis to change the flow of PG-droplet-containing PAO4 to reduce the friction coefficient. The friction result with a 1-mm roller shows 20% reduction in friction coefficient (from 0.065 to 0.052) at AC 100 V, and in situ observation exhibits that PG tracks are formed over the contact area. On the other hand, at a high bias of 1000 V, the friction coefficient increases to 0.065. In this situation, in situ observation exhibits that PG forms a horseshoe-shaped track covering only the roller edges. Controlled friction tests and FEM analysis using 5-mm rollers revealed a unique behavior; a balanced bias effectively attracts the PG to the roller surface, and surface forces can resist mild dielectrophoretic forces to spread the PG across the roller surface. The present study strongly suggests the importance that the bias strength should be controlled to achieve a balance between surface force and dielectrophoretic force in order to obtain excellent lubrication conditions.

DOI： 10.2474/trol.18.292

CiNii Research

Clarification of the effects of adsorption films of ester-blended oil on friction by in situ reflectance spectroscopy Reviewed International coauthorship International journal

Kodai Hirata, Motoyuki Murashima, Noritsugu Umehara, Takayuki Tokoroyama, Naoya Hashizume, Woo Young Lee, Daisuke Takekawa, Keiichi Narita

Tribology International Vol. 187 2023.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

In recent years, the demand for friction reduction in oil lubrication systems has become increasingly important due to the need to improve fuel economy and achieve carbon neutrality. Ester-based lubricants are known to show low friction and environmentally friendly, and they have high viscosity indexes. In the present paper, first, in situ reflectance spectroscopy was used to clarify the behavior of the oil-film thickness increase during sliding. The results showed that as the number of ester bonds increased from 1 to 4, the ester oil film thickened and the friction coefficient decreased from 0.10 to 0.06. In addition, oleic-acid-type lubricants were found to have superior ability to form a thicker oil film than the isostearic acid type.

DOI： 10.1016/j.triboint.2023.108718

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Synthesis and characterisation of oil palm fibre-based graphene deposited on copper particles for superlubricity oil additive Reviewed International coauthorship International journal

Rahman Nurul Liyana, Amiruddin Hilmi, Bin Abdollah Mohd Fadzli, Umehara Noritsugu

JURNAL TRIBOLOGI Vol. 37 page： 128 - 141 2023.6

Effects of Phosphonate Additives with Hydroxy Groups on the Tribological Properties of ta-C Coatings Under Boundary Lubrication Reviewed International journal

Kento Tanaka, Takayuki Tokoroyama, Noritsugu Umehara, Motoyuki Murashima, Tadashi Oshio, Kazuhiro Yagishita

Tribology Letters Vol. 71 ( 2 ) 2023.6

Language：English Publishing type：Research paper (scientific journal)

Additives that are optimized for diamond-like carbon (DLC) coatings are highly demanded as their applications have expanded recently. In this study, friction tests were conducted on a tetrahedral amorphous carbon (ta-C)/ta-C tribopair using a phosphonate additive with hydroxy groups, which comprises glycerol monooleate (an additive that reduces the friction of DLC) and zinc dialkyl dithiophosphate (an additive that reduces wear), and the obtained tribolayers were analyzed using AFM, XPS, and ToF–SIMS. We found that the phosphonate additive with hydroxy groups tribochemically reacted with the ta-C coating to form a low-shear, hard tribolayer on the surface, thereby reducing the friction and wear of the ta-C coating. Our results indicate that additives with phosphonate structures and hydroxy groups are effective for DLC coatings. Graphical abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s11249-023-01734-3

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An effective strategy for improving the performance of electrodeposited Fe-W alloy plating: Tailoring microstructure by graphene incorporation Reviewed International coauthorship International journal

Shinohara Yu, Park Jae-Hyeok, Hagio Takeshi, Kim Jae-Il, Lee Woo-Young, Umehara Noritsugu, Ichino Ryoichi

MATERIALS & DESIGN Vol. 230 2023.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials and Design

Despite the excellent performance of hard Cr plating using hexavalent chromium (Cr6+), its use is being restricted owing to recent environmental regulations. Electrodeposited Fe-W alloy is considered a possible alternative, but its high coefficient of friction (COF), high wear rate owing to tribo-oxidation, and high corrosion rate hinder its practical application. In this study, we attempted to solve these problems by modifying the microstructure of Fe-W alloy by incorporating 2D-structured graphene. The effect of graphene incorporation on the structure of the Fe-W alloy and its properties, especially microhardness, wear, and corrosion resistance, were investigated. The results showed the graphene effectively modified the columnar structure of the Fe-W alloy by inhibiting the vertical growth of clusters during electrodeposition, leading to fragmentation of the vertical cluster boundaries. This improved the hardness by as much as 17 % up to 9.1 GPa, and the corrosion resistance by changing the corrosion mechanism from localized corrosion to uniform corrosion. In addition, the graphene reduced the COF and wear rate by reducing the Fe2O3 formed by tribo-oxidation to a lower oxidation state. The structural modification of the plating by graphene incorporation thus provides an effective solution to improving the performance of Fe-W alloys.

DOI： 10.1016/j.matdes.2023.111938

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Synthesis and characterisation of oil palm fibre-based graphene deposited on copper particles for superlubricity oil additive Reviewed International coauthorship International journal

Rahman N.L., Amiruddin H., Abdollah M.F.B., Umehara N.

Jurnal Tribologi Vol. 37 page： 128 - 141 2023.6

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Jurnal Tribologi

This paper presents the synthesis and characterisation of oil palm fibre-based graphene deposited on copper (Cu) particles for superlubricity oil additive. Oil palm fibre (OPF) is employed as a renewable carbon feedstock to grow graphene on Cu particles during Chemical Vapor Deposition (CVD) process. The surface morphology was observed using Scanning Electron Microscopy (SEM) embedded with Energy Dispersive X-Ray Analysis (EDX), and Transmission Electron Microscopy (TEM). Meanwhile, the presence and quality of graphene were validated and examined using Gaussian analysis of Raman spectroscopy. The results show that decreasing the peak D to peak G intensity ratio (ID/IG) tends to improve graphene quality with less number density of structural defects. The I2D/IG value greater than 1 is indicative of multilayer graphene growth. Increasing the full width at half maximum (FWHM) ratio of peak D to peak G (FWHMD/FWHMG) suggests a better dispersion of graphene. The uniform spread of surface ‘wrinkles’ observed by SEM and TEM implies that the distribution of graphene is more homogeneous on the surface of Cu particles. Further investigation into the synergistic effect of graphene as an oil additive can be performed to achieve superlubricity properties.

Scopus

Superlubricity with Graphitization in Ti-Doped DLC/Steel Tribopair: Response on Humidity and Temperature Reviewed International coauthorship International journal

Kim Jae-Il, Lee Woo-Young, Tokoroyama Takayuki, Umehara Noritsugu

ACS APPLIED MATERIALS & INTERFACES Vol. 15 ( 15 ) page： 19715 - 19729 2023.4

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Applied Materials and Interfaces

The anti-friction of diamond-like carbon (DLC) is achieved by a well-developed carbonaceous transfer layer, and Ti-doped DLC is developed into a robustly built-up carbonaceous transfer layer. The friction performance of DLC depends on the operating environment, e.g., ambient gas, humidity, temperature, lubricants, and mating material. In this study, we aimed to reveal the environmental sensitivities of Ti-DLC on friction characteristics. To this end, a Ti-DLC was rubbed against a steel ball, and friction behaviors were evaluated with different gas compositions, humidity, and temperature. Finally, we identified that fractional coverage of water on surfaces affected the anti-graphitization on Ti-DLC, leading to avoiding friction reduction.

DOI： 10.1021/acsami.3c01704

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Novel friction stabilization technology for surface damage conditions using machine learning Reviewed International coauthorship International journal

Motoyuki Murashima, Takazumi Yamada, Noritsugu Umehara, Takayuki Tokoroyama, Woo Young Lee

Tribology International Vol. 180 2023.2

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

The surface damage is a serious cause of failure in tribosystems. In the present paper, we propose a new damage avoidance method that combines a contact position control system (e.g., morphing surface) and artificial-intelligence-based control (e.g., genetic algorithm: GA) to achieve stable friction and long life of sliding surfaces. In the case of the single-damage condition, the GA sequentially avoided contact with the damaged position, and finally complete damage avoidance was achieved. In the multiple-damage condition, we confirmed that learning by GA effectively stabilized friction, although the learning time was longer. In summary, the contact-position control method should provide new capabilities on real machine surfaces where unexpected damage occurs.

DOI： 10.1016/j.triboint.2023.108280

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Long-term low-friction of Ti-overcoated and-doped DLCs: Robustly developed carbonous transfer layer with titanium Reviewed International coauthorship International journal

Kim Jae-Il, Lee Woo-Young, Tokoroyama Takayuki, Umehara Noritsugu

CARBON Vol. 204 page： 268 - 283 2023.2

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon

Diamond-like carbon (DLC) has been under the research spotlight as an exceptional solid lubricant. Its friction performance is depending on a well-developed transfer layer upon its counterparts. Nowadays, iron-and brass-based metals have been utilized as the counterpart against DLC, however, it is reported their friction behaviors are somewhat inferior compared to titanium alloys. In this study, we tried to improve their friction behaviors and modified the contact interface from Fe/C to C/C by Ti addition in DLC. It was revealed that Ti, which has good adhesion for Fe and C, promoted the development of carbon transfer on Fe-based counterpart. Furthermore, Ti built-up a thick carbonous transfer layer and make better the friction performance of DLC sliding against Fe.

DOI： 10.1016/j.carbon.2022.12.012

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Influence of Defects in Graphene-Like Network of Diamond-Like Carbon on Silica Scale Adhesion Reviewed International journal

Y. Nakashima, N. Umehara, H. Kousaka, T. Tokoroyama, M. Murashima, K. Murakami

Tribology Letters Vol. 71 ( 1 ) 2023.2

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

Silica scale adhesion onto geothermal power plant equipment reduces the power efficiency. In our previous study, diamond-like carbon (DLC) coatings with low sp2 fractions and high hydrogen contents were found to suppress silica adhesion. Therefore, the present study was aimed at clarifying the mechanism of silica adhesion onto the graphene-like network of DLC. In-lens scanning electron microscopic imaging of silica adhered onto defective graphene indicated that the adhesion occurred on defects in the graphene-like network. First-principles calculations revealed that the graphene with hydrogen-terminated defects exhibited reduced adsorption energy between silica and the graphene-like network. Overall, the simulations and experiments helped establish a silica adhesion model in which defects in the graphene-like network of DLC behave as silica adhesion sites. Graphical Abstract: [Figure not available: see fulltext.].

DOI： 10.1007/s11249-022-01690-4

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Mechanical properties of maze-like carbon nanowalls synthesized by the radial injection plasma enhanced chemical vapor deposition method Reviewed International coauthorship International journal

Swapnil Ghodke, Motoyuki Murashima, Dennis Christy, Ngo Van Nong, Kenji Ishikawa, Osamu Oda, Noritsugu Umehara, Masaru Hori

Materials Science and Engineering: A Vol. 862 2023.1

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

The unique structural properties of vertically aligned graphene sheets or Carbon Nanowalls (CNWs) have attracted great interests for their potential for various applications in microelectronic devices, energy storage, and catalyst support materials. During the handling or operation of the devices, tension and/or pressure are often needed. Under such conditions, CNWs must undergo compression and stress. Therefore, the deformation mechanism and evolution behavior of the CNW structures under load play a critical role in the performance and reliability of the devices. In this study, the mechanical properties of a typical maze-like CNW structure synthesized by a Radial Injection Plasma Enhanced Chemical Vapor Deposition (RI-PECVD) technique were analyzed by employing the nanoindentation method. The measured compressive strength of the CNW structure was 50 MPa with an average modulus E value of ∼28 GPa, which is significantly higher than that of pyrolytic graphite and other graphene-based materials such as 3D graphene-derived carbon, commercial graphene, and reduced graphene oxide films. An elastoplastic behavior of a soft material was observed in high-resolution microscopy and a mechanism of deformation for CNWs is elucidated.

DOI： 10.1016/j.msea.2022.144428

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Tribo-chemical wear of various 3d-transition metals against DLC: Influence of tribo-oxidation and low-shear transferred layer Reviewed International coauthorship International journal

Jae-Il Kim, Woo-Young Lee, Takayuki Tokoroyama, Motoyuki Murashima, Noritsugu Umehara

Tribology International Vol. 177 page： 107938 - 107938 2023.1

Carbon-based coatings for suppression of silica adhesion in geothermal power generation Reviewed International journal

Y. Nakashima, N. Umehara, H. Kousaka, T. Tokoroyama, M. Murashima, D. Mori

Tribology International Vol. 177 page： 107956 - 107956 2023.1

Essence of Tribology and Its Future Invited

UMEHARA Noritsugu

JOURNAL OF JAPANESE SOCIETY OF TRIBOLOGISTS Vol. 67 ( 12 ) page： 813 - 813 2022.12

The Tribological Property of a-C:H Coating with Tribolayer by Additive Having Glycerol and Phosphate Oxide Structure Reviewed International coauthorship International journal

Tokoroyama T., Tanaka K., Kani T., Murashima M., Lee W-Y, Umehara N., Oshio T., Yagishita K.

TRIBOLOGY LETTERS Vol. 70 ( 4 ) 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Tribology Letters

The tribological properties of a-C:H coating sliding against a SUJ2 ball, a SUJ2 roller, and an a-C:H coated roller were investigated under temperatures ranging from 20 to 80 °C in PAO with different additives. The additives had a glycerol and hydroxyl functional group in one molecule to enhance additive adsorption for mating with the a-C:H coating disk material and to build a phosphorus oxide tribolayer. Additives with different numbers of hydroxyl groups and primary or secondary-type C6H13O structures were also prepared. The tribolayer derived from each additive was analyzed via EDS, XPS, and ToF-SIMS. XPS depth analysis for the tribolayers revealed that additives were dissociated by friction and suggested C–O bond cleavage occurred. Graphical Abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s11249-022-01659-3

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Papers - UMEHARA, Noritsugu