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6CCVD Research

Preparation of Diamond Nanofluids and Study of Lubrication Properties

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2025-04-30
JournalMaterials
AuthorsJiamin Yu, Junhao Wu, Chengcheng Jiao, Huanyi Chen, Xinxin Ruan
InstitutionsTaiyuan University of Science and Technology, Kogakuin University
Citations2
AnalysisFull AI Review Included

Preparation of Diamond Nanofluids and Study of Lubrication Properties

Section titled “Preparation of Diamond Nanofluids and Study of Lubrication Properties”

Executive Summary

Section titled “Executive Summary”

This research successfully developed a highly stable, solvent-free, two-dimensional (2D) diamond nanofluid (SCND-KH560-M2070, or SKM) designed to overcome the poor dispersion and low mechanical strength issues common to conventional 2D lubricant additives (e.g., graphene, MoS2).

  • Core Innovation: Covalent grafting of organosilane (KH560) and polyether amine (M2070) onto 2D diamond nanosheets, creating a stable organic-inorganic hybrid material.
  • Material Advantage: The nanofluid combines the extreme hardness and chemical stability of the diamond core with the flexibility and excellent dispersion properties of the polymer shell.
  • Benchmark Performance (Dry Friction): The optimal 185 nm SKM nanofluid reduced the Coefficient of Friction (COF) by 94.7% (to 0.025) and decreased the wear rate by 96% compared to unlubricated steel.
  • Additive Performance (Aqueous Glycol): When used as an additive in H2O-C2H6O2, a 3 wt% concentration of SKM achieved a 66.9% reduction in COF (to 0.16) and an 81.8% reduction in wear rate compared to the pure base fluid.
  • Lubrication Mechanism: The functionalized nanosheets rapidly form a strong, elastic, and continuous protective wear film on the friction interface, confirmed by XPS and Raman analysis showing the transfer of Si and N elements to the steel surface.
  • Thermal Stability: TGA confirmed the nanofluid exhibits high thermal stability, with the organic shell remaining stable up to 300 °C.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Optimal Nanofluid Size185nmAchieved lowest COF (0.025) in dry friction
Optimal Additive Concentration3wt%Achieved lowest COF (0.16) in H2O-C2H6O2
COF Reduction (Dry)94.7%185 nm SKM vs. unlubricated AISI 52100
Wear Rate Reduction (Dry)96%185 nm SKM vs. unlubricated AISI 52100
COF Reduction (Additive)66.9%3 wt% SKM in aqueous glycol vs. pure base fluid
Wear Rate Reduction (Additive)81.8%3 wt% SKM in aqueous glycol vs. pure base fluid
Steady-State COF (Dry, 185 nm)0.025-Lowest friction coefficient observed
Organic Shell Mass Fraction11.05wt%Determined by TGA analysis
Thermal Stability (Onset of Decomp.)300°CTemperature where organic shell decomposition begins
Fixed Load (Tribological Test)5NApplied load (Ball-on-plate UMT tester)
Fixed Sliding Speed50mm/sSliding velocity during friction test
Steel Ball Material/RoughnessGCr15 / 6- / nmFriction pair material
Steel Plate Material/RoughnessAISI 52100 / 12.9- / nmFriction pair material
Diamond Characteristic Peak (Modified)1328cm-1Raman spectroscopy confirmation of diamond structure
Lattice Spacing (Diamond)0.206nmHRTEM measurement of (111) lattice plane

Key Methodologies

Section titled “Key Methodologies”

The solvent-free 2D diamond nanofluid (SKM) was prepared via a two-step covalent grafting process, followed by rigorous tribological evaluation.

  1. Intermediate Synthesis (KH560-M2070):

    • 5 wt% KH560 (organosilane) solution was mixed with 10 wt% M2070 (polyether amine) solution in ethanol.
    • The mixture was stirred continuously at 50 °C for 12 hours to form the KH560-M2070 organic shell intermediate via covalent bonding.

  2. Grafting onto Diamond Nanosheets (SCND):

    • 0.5 g of pre-dispersed SCND (70, 120, or 185 nm) was added to the intermediate solution.
    • A grafting reaction was carried out at 45 °C for 6 hours.

  3. Purification and Drying:

    • The mixture was purified for 3 days using dialysis (8 kDa MWCO membrane) to remove unreacted M2070.
    • Solvent was removed via rotary evaporation.
    • The final SKM sample was vacuum-dried at 60 °C for 72 hours to yield the solvent-free nanofluid.

  4. Structural and Chemical Characterization:

    • FTIR and Raman: Confirmed the formation of covalent bonds between the organic shell and the diamond surface (peak shift from 1325 cm-1 to 1328 cm-1).
    • TGA/DSC: Determined the organic shell content (11.05 wt%) and thermal stability (stable up to 300 °C).
    • HRTEM/EDS: Confirmed the sheet structure, the presence of the organic shell, and the high crystallinity of the diamond lattice.
    • Rheology: Demonstrated typical fluidic behavior (Loss Modulus G” > Storage Modulus G’) and temperature-sensitive viscosity decrease, confirming good flow properties.

  5. Tribological Testing:

    • Friction tests were conducted using a UMT-3 tester in ball-on-plate mode (GCr15 ball vs. AISI 52100 plate).
    • Tests evaluated SKM as a pure lubricant (dry friction comparison) and as an additive (0.5 wt% to 5 wt%) in an aqueous ethylene glycol (H2O-C2H6O2) base fluid.
    • Wear tracks were quantified using 3D optical profilometry and surface chemistry was analyzed via XPS and SEM/EDS to confirm the lubrication mechanism.

Commercial Applications

Section titled “Commercial Applications”

The functionalized 2D diamond nanofluids developed in this study offer superior tribological performance, stability, and wear resistance, making them highly valuable for demanding engineering applications.

  • High-Load Gearboxes and Transmissions: Ideal for reducing friction and wear in heavy-duty machinery and automotive components where high contact pressures are common.
  • Metal Processing and Hot Rolling: The excellent performance in aqueous glycol base fluids makes SKM suitable for water-based coolants and lubricants used in metal forming and rolling processes, especially where high temperatures are encountered (due to 300 °C thermal stability).
  • Precision Machining (MQL): Suitable for Minimal Quantity Lubrication (MQL) systems in grinding and cutting operations, providing superior anti-wear properties and surface finish compared to conventional fluids.
  • Advanced Diamond Materials: The core material, 2D diamond nanosheets, is a high-value carbon material. This research validates the use of functionalized diamond materials for advanced tribological coatings and composites.
  • Hydraulic Systems: The demonstrated ability to maintain stable COF and flow properties under varying temperatures makes SKM a candidate for high-performance hydraulic fluids.
View Original Abstract

As an emerging two-dimensional nanomaterial, diamond nanosheets have the advantages of high hardness and chemical stability; exhibiting good tribological properties when used as lubricant additives. However, the dispersion stability of nanomaterials as additives in lubricants remains a significant challenge. In this study, fluidized and functionalized diamond nanofluids were prepared by grafting polyether amine on the surface of diamond nanosheets. By changing the state of diamond nanosheets, this material not only improved its own lubrication property, but also improved its dispersion in the lubricant. The friction test results demonstrated that the friction coefficient was reduced by 66.9% and the wear rate was reduced by 81.8% with the addition of 3 wt% of diamond nanofluid in water-glycol solution. This enhancement of lubricating properties is related to the excellent film-forming properties of diamond nanofluids during the tribology. This indicates that fluidized 2D diamond nanosheets have excellent lubricating properties and can significantly improve the friction properties of lubricants as additives.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2017 - Influence of tribology on global energy consumption, costs and emissions [Crossref]
  2. 2019 - Tribology of two-dimensional materials: From mechanisms to modulating strategies [Crossref]
  3. 2022 - Nanodiamond plates as macroscale solid lubricant: A “non-layered” two-dimension material [Crossref]
  4. 2020 - Optimization of groove texture profile to improve hydrodynamic lubrication performance: Theory and experiments [Crossref]
  5. 2023 - Functionalized carbon nanostructures as lubricant additives—A review [Crossref]
  6. 2011 - Effect of aggregation on the viscosity of copper oxide-gear oil nanofluids [Crossref]
  7. 2021 - Mechanical properties and wear resistance of industrial bearing liners in concentrated boundary-lubricated sliding [Crossref]
  8. 2024 - The tribological properties of nano-lubricants and their application on bearings: Recent research progress
  9. 2023 - Molecular dynamics simulation of the Stribeck curve: Boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level [Crossref]
  10. 2021 - Numerical and Experimental Studies on Performance Enhancement of Journal Bearings Using Nanoparticles Based Lubricants [Crossref]

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