The effect of silver ions electrolytically introduced into colloidal nanodiamond solution on its viscosity and thermal conductivity
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2017-03-01 |
| Journal | Colloid Journal |
| Authors | Alexey P. Puzir, А. В. Минаков, A. E. Burov, С. М. Жарков, N. G. Maksimov |
| Institutions | Russian Academy of Sciences, Institute of Chemistry and Chemical Technology |
| Citations | 3 |
| Analysis | Full AI Review Included |
Technical Analysis of Enhanced Nanodiamond Suspension for Thermal Management
Section titled “Technical Analysis of Enhanced Nanodiamond Suspension for Thermal Management”Source Paper: ВЛИЯНИЕ ЭЛЕКТРОЛИТИЧЕСКИ ВВЕДЕННЫХ ИОНОВ СЕРЕБРА НА ВЯЗКОСТЬ И ТЕПЛОПРОВОДНОСТЬ КОЛЛОИДНОГО РАСТВОРА НАНОАЛМАЗОВ (The influence of electrolytically introduced silver ions on the viscosity and thermal conductivity of colloidal nanodiamond solution.)
Prepared by: 6CCVD Material Science & Technical Sales Team
Executive Summary
Section titled “Executive Summary”This study demonstrates that the thermal and rheological properties of aqueous nanodiamond (DND) nanofluids can be significantly enhanced and controlled through electrolytic surface modification using silver ions (Ag+). This research holds immediate relevance for high-performance heat transfer applications.
- Significant Thermal Enhancement: Introduction of 0.05 mass.% silver resulted in a noticeable increase in thermal conductivity, reaching a relative coefficient ($\lambda/\lambda_0$) of 1.075 (a 7.5% enhancement over water, or 4% over pure DND nanofluid).
- Surface Chemistry Control: Electron Paramagnetic Resonance (EPR) g-factor analysis confirmed the binding of cationic silver forms (Ag+ or clusters) directly to the nanodiamond surface, which drives the property changes.
- Viscosity Modification: The surface modification caused the suspension’s relative viscosity ($\mu/\mu_0$) to sharply increase from 1.95 (pure DND) to 3.19 (DND+Ag), an increase of approximately 1.64 times.
- Mechanism Identified: The enhancement is primarily attributed not just to the silver particles themselves, but to the formation of tightly structured nanodiamond-silver clusters (approx. 108 nm effective diameter) resulting from the surface interaction.
- Non-Classical Behavior: The experimental results deviate substantially from classic hydrodynamic theories (e.g., Maxwell and Einstein models), underscoring the critical role of surface chemistry and clustering in nanoliquid properties.
- Application Potential: This research validates advanced diamond materials for use in next-generation thermal management systems (nanofluids) requiring tailored, controllable heat transfer characteristics.
Technical Specifications
Section titled “Technical Specifications”The following quantitative data points were extracted from the experimental results, focusing on the changes in transport properties after electrolytic silver introduction.
| Parameter | Value (DND Only) | Value (DND+Ag) | Unit | Context |
|---|---|---|---|---|
| Nanodiamond Concentration | 5 (1.4) | 5 (1.4) | mass.% (vol.%) | Suspension in deionized water (Milli-Q) |
| Silver Concentration | 0 | ≤ 0.05 | mass.% | Introduced electrolytically via Ag plates |
| Thermal Conductivity Ratio ($\lambda/\lambda_0$) | 1.035 | 1.075 | Ratio | Relative to water thermal conductivity |
| Relative Viscosity ($\mu/\mu_0$) | 1.95 | 3.19 | Ratio | Relative to water viscosity |
| Viscosity Increase Factor | N/A | 1.64 | Times | Increase relative to pure DND suspension |
| Effective Cluster Diameter | 114 ± 3.0 | 108 ± 1.1 | nm | Measured by Dynamic Light Scattering (DLS) |
| Measurement Temperature | 25 | 25 | °C | All viscosity and thermal measurements |
| EPR g-factor (300 K) | 2.00258 | 2.00267 | Unitless | Positive shift confirms Ag cationic binding |
| Ag Content (EDX Analysis) | 0 | 0.05 | mass.% | Silver content detected post-electrolysis |
Key Methodologies
Section titled “Key Methodologies”The research relied on advanced material preparation techniques and specialized characterization methods to accurately measure nanodiamond surface states and transport properties.
- Nanofluid Preparation: 15 g of detonation nanodiamond powder was dispersed into 300 mL of deionized water (Milli-Q system) to achieve a 5 mass.% concentration.
- Electrolytic Silver Doping: Silver ions (Ag+) were introduced using an electrolytic method, employing high-purity silver plates (Cp 999.9 GOST 3836-72) as the source electrodes in an ionizer (LK-27), with the nanodiamond suspension acting as the electrolyte.
- Microstructural and Elemental Analysis:
- Transmission Electron Microscopy (TEM, JEOL JEM-2100) was used to image particle microstructure (DND 3-8 nm, Ag 5-30 nm) and verify phase composition (Ag: Fm-3m, C: Fd-3m).
- Scanning Electron Microscopy with EDX (Hitachi TM 3000) confirmed the silver concentration (0.05 mass.%).
- Surface Chemistry Analysis (EPR): Electron Paramagnetic Resonance (Bruker ELEXYS E-580) spectra were registered at room temperature and after freezing at 85 K to confirm the existence of cationic silver forms associated with the nanodiamond surface defects.
- Thermal Conductivity Measurement: The transient hot wire method was utilized, involving a 150 mm long, 75 µm diameter copper wire placed in a temperature-controlled cell containing 200 mL of fluid. Measurement uncertainty was approximately 2%.
- Viscosity Measurement: A Brookfield DV2T rotational viscometer with a ULA(0) adapter was used to measure viscosity across a broad shear rate range (1 to 200 1/s), demonstrating non-Newtonian behavior at low shear rates.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”6CCVD provides the engineered diamond platforms necessary to scale, implement, and extend the findings of advanced thermal fluids research into functional thermal management devices.
Applicable Materials for Thermal and Electrochemical Systems
Section titled “Applicable Materials for Thermal and Electrochemical Systems”To advance research utilizing high-thermal conductivity nanostructures and specialized fluid interaction, 6CCVD offers superior materials that can function as structural components, sensors, or advanced electrodes:
- Boron-Doped Diamond (BDD): The study used electrolytic Ag introduction. BDD is the premier material for stable, highly efficient electrochemistry due to its wide potential window and extreme stability. We recommend utilizing Heavy Boron Doped PCD or SCD wafers as high-surface-area microchannel electrodes for electrolytic doping experiments, replacing the traditional Ag plates. This offers higher reproducibility and integration capability into microfluidic systems.
- High-Purity Single Crystal Diamond (SCD): For advanced microfluidic heat sinks and high-resolution sensor integration within the fluid flow, 6CCVD supplies Optical Grade SCD films (0.1 µm to 500 µm thickness) with superior thermal properties and pristine surface quality (Ra < 1 nm).
- Thermal Grade Polycrystalline Diamond (PCD): Ideal for constructing robust, scaled microchannel heat exchangers. We provide Inch-Size PCD plates up to 125 mm diameter, polished to Ra < 5 nm, enabling complex lithographic patterning for microchannels where the nanoliquid will be utilized.
Customization Potential for Nanofluid Integration
Section titled “Customization Potential for Nanofluid Integration”The successful modification of nanodiamond surfaces using silver highlights the need for precise integration of conductive elements. 6CCVD offers comprehensive services to support the fabrication of custom thermal and fluidic test structures:
| Research Requirement | 6CCVD Customization Service | Benefit to Researcher |
|---|---|---|
| Precise Silver Doping/Detection | Custom Metalization Services (Ag, Ti/Pt/Au) | Allows integration of high-purity silver contact pads or sensing structures directly onto BDD electrodes or SCD substrates for controlled electrolytic experimentation. |
| Non-standard Device Dimensions | Custom Dimensions & Laser Cutting | Plates and wafers up to 125 mm (PCD) or custom geometry substrates up to 10 mm thick, optimized for specific flow dynamics or calorimetry setups. |
| Need for Low-Noise Sensing | Polishing to Ra < 1 nm (SCD) | Ultra-smooth SCD surfaces are essential for minimizing hydrodynamic disturbance and ensuring accurate thermal boundary layer measurements in microfluidic channels. |
| High-Density Integration | Custom Layer Thickness | Provision of thin SCD (0.1 µm) for high-sensitivity thermal sensors or thick PCD (up to 500 µm) for robust microreactor walls. |
Engineering Support
Section titled “Engineering Support”The observed synergistic effects between nanodiamonds and silver ions—where surface interaction (confirmed by g-factor shift) dramatically increases viscosity and thermal conduction—are highly non-trivial. 6CCVD’s in-house PhD team specializes in CVD diamond surface termination, doping mechanisms, and application-specific thermal engineering. We can assist research teams replicating or extending this research in Nanofluid and Microchannel Cooling Systems projects, ensuring material selection and surface conditioning maximizes performance in exotic nanofluids.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Experimental data have been presented on the influence of silver on the viscosity and thermal conductivity of a dispersion of diamond nanoparticles. A stable dispersion (5 wt %) of detonation nanodiamond particles has been used in the experiments. Silver ions have been introduced electrolytically into the dispersion of diamond nanoparticles. Silver concentration was not higher than 0.05 wt %. It has been shown that the introduction of silver ions significantly affects the thermal conductivity and viscosity of the dispersion.