Tribology Online
Online ISSN : 1881-2198
ISSN-L : 1881-218X
最新号
選択された号の論文の5件中1~5を表示しています
Article
  • Kentaro Yamada, Masabumi Masuko, Yukio Tamura, Masao Kikuchi, Shinji T ...
    2024 年 19 巻 6 号 p. 464-477
    発行日: 2024/10/15
    公開日: 2024/10/15
    ジャーナル オープンアクセス

    This study examines the wear characteristics of case-carburized steel surfaces with manganese phosphate (MnPh) coating under commercial fully formulated oil (FFO). This combination can improve the steel’s tribological properties and rolling contact fatigue strength. The role of oil additives in FFO, which affect the wear characteristics through the formation of a wear-resistant tribofilm, on the MnPh coated steel was analyzed in detail. The process of chemical etching during the MnPh coating application makes the steel substrate rougher. Consequently, both MnPh-coated and MnPh-removed disks were analyzed to ensure comparability in terms of surface roughness and morphology. Under FFO lubrication, the MnPh-coated disks exhibited continuous wear of the steel peaks during the initial friction period, similar to that observed under base oil lubrication. This continuous wear occurs because the residual MnPh coating in the valleys of the roughness primarily supports the contact load during the initial friction period, preventing the formation of a wear-resistant tribofilm on the exposed steel peaks. The proposed wear mechanism for MnPh-coated steel aims to further improve the rolling contact fatigue strength.

  • Mohammad Arif Parray, Suhail Shahzad, M. Jebran Khan, Fatima Farooq Bi ...
    2024 年 19 巻 6 号 p. 478-485
    発行日: 2024/10/15
    公開日: 2024/10/15
    ジャーナル オープンアクセス

    This study explores the remarkable potential of garlic oil as a green, high-performance lubricant in machining, aiming to elevate wear resistance, reduce cutting temperatures, and improve surface finishes, all in contrast to conventional dry cutting methods. Through Scanning Electron Microscopy (SEM), intricate wear patterns on tungsten carbide (WC) tool inserts were meticulously analyzed, while Energy Dispersive X-ray Spectroscopy (EDS) unveiled the adhesive behavior influenced by the garlic oil-based lubrication. Surface roughness, following the turning operation, was elegantly measured using stylus profilometry. The results reveal that garlic oil-based Minimum Quantity Lubrication (MQL) achieved a 43.8% reduction in flank wear, a 69.3% decrease in cutting temperatures, and an impressive 79.3% improvement in surface finish. These findings illuminate garlic oil’s ability to maintain cooler cutting zones, significantly extending tool life while preserving the precision of machined parts. This research underscores the promise of garlic oil as a natural, eco-friendly lubricant, paving the way for sustainable machining practices that not only protect the environment but also ensure unparalleled performance in the processing of EN24 steel.

Short Communication
  • Kiyoshi Mabuchi, Hiroko Iwashita, Rina Sakai, Ryusuke Nakaoka
    2024 年 19 巻 6 号 p. 486-489
    発行日: 2024/10/31
    公開日: 2024/10/31
    ジャーナル オープンアクセス

    Pendulum friction-tester is specifically useful for experiments in biotribological field because that is good at the measure on circular sliding surfaces, like as synovial joints, joint prostheses, eye balls, or contact lenses. Stanton’s formula has been generally used for the data processing as the calculation of friction coefficient from the amplitude decay during a pendulum libration. Because Stanton used the balance of moment to analyze the pendulum motion, his analysis must inevitably include an approximation of sin θ as angle θ. However, the error in the formula has not been evaluated because the strict analysis was thought to be impossible. In the present study, the strict analysis was clarified by energy balance in a pendulum. As the result, error in Stanton’s formula was able to be evaluated.

Article
  • Takayuki Tomokiyo, Hitoshi Washizu
    2024 年 19 巻 6 号 p. 490-498
    発行日: 2024/10/31
    公開日: 2024/10/31
    ジャーナル オープンアクセス

    Carbon-based nanomaterials have been employed as lubricants in industrial settings due to their low-friction properties. Among them, graphene oxide (GO) has been employed in a variety of applications because it is more hydrophilic than graphene and disperses easily in polar solvents. Furthermore, it has low production costs and low environmental impact. These properties render it a promising new lubricant additive with the potential to supplant long-used organometallic lubricant additives. It has been reported that GO exhibits low friction not only in water lubrication, but also in oil lubrication with GO-modified alkyl groups. In this study, a hierarchical GO model was constructed by molecular dynamics simulations using the reactive force field (ReaxFF) and compared with friction experiments. The analysis revealed that GO is stable in water but sensitive to pressure in oil. Sheets in contact with oil showed instability, moving from side to side. Furthermore, the alkyl-modified GO appeared to be integrated with the oil, suggesting that the alkyl groups contribute to the observed low-friction properties. These results are in qualitative agreement with the experimental data and indicate that the behavior of GO is solvent dependent.

  • Tatsunori Tomota, Mamoru Tohyama, Kazuyuki Yagi
    2024 年 19 巻 6 号 p. 499-507
    発行日: 2024/10/31
    公開日: 2024/10/31
    ジャーナル オープンアクセス

    A contact between surfaces with low roughness (approximately 0.01–0.1 μm) and relatively large nominal contact area (mm2 order) is a complex phenomenon that requires consideration of deformation behavior at various scales, and is an important subject in contact mechanics. Contact simulation using the elastoplastic boundary element method is considered to be effective for this analysis. However, only a few studies have examined such contacts with a detailed comparison to measurement data, meaning that the simulation accuracy has not been sufficiently verified. Therefore, in this study, to verify their accuracy, simulations for low roughness and large area contact were performed using actual roughness shape data, and were compared with optical interferometry data of the contact surface shapes obtained in a previous study. The calculated distribution of the gap between two surfaces was similar to the measured data. Furthermore, nominal contact areas were determined from each distribution based on the statistical theory. The simulation results for nominal contact area sizes and average gaps were in good agreement with experimental results. Our findings demonstrate the utility of the elastoplastic boundary element method for the multi-scale contact analysis of surfaces with low roughness and large nominal contact area.

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