Superlubricity of silicon-based ceramics realized by controlling atomic-scale interfacial phenomena and structures

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K20413
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: Osaka Metropolitan University
• Principal Investigator: Kuwahara Takuya 大阪公立大学, 大学院工学研究科, 講師 (10851917)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: セラミクス / 超潤滑 / 分子シミュレーション / 量子化学

Outline of Final Research Achievements

Superlubricity of silicon-based ceramics sliding against hydrogenated amorphous carbon (a-C:H) has been observed in ultrahigh vacuum. Combined experiments and simulations reveal that transfer of a thin hydrogenated amorphous carbon layer onto the ceramic surface and formation of the sliding interface between two carbonaceous layers are necessary.A stable passivating a-C:H film can only be transferred if, after initial cold welding of the tribological interface, the plastic shear deformation is localized within the a-C:H coating. This occurs if the yield shear stress for plastic flow of a-C:H is lower than that of the ceramic and of the shear strength of the a-C:H-ceramic interface. While the importance of a relatively high hydrogen content to achieve an efficient passivation of a-C:H surfaces in a vacuum is well-documented, this work reveals how the hydrogen content is also crucial for obtaining a stable a-C:H transfer film. These results can be extended to glass, SiC, and steel.

Free Research Field

トライボロジー

Academic Significance and Societal Importance of the Research Achievements

移着膜形成は、摩擦後の表面に一般的に観察される現象であり、低摩擦化の寄与が知られていた。一方、そのメカニズムや制御方針に関しては、ほとんど知られていなかった。そこで本研究では、シミュレーションによりその原子レベルのメカニズムを明らかにし、また水素含有量の制御により移着膜の形成及び摩擦特性を制御できることを見出した。また、得られた知見が他材料へ適用可能であることを示していることから、セラミクスに限らず、様々なトライボロジー材料の低摩擦を無潤滑環境下で引き出すことが可能になると考えられる。