Effect of Hot-forging Temperature on the Microstructure and Thermal Conductivity of Copper/W-coated Diamond Composites
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-03-14 |
| Journal | Journal of the Japan Society of Powder and Powder Metallurgy |
| Authors | Jingnan Ma, Rob Torrens, L. Bolzoni, Fei Yang |
| Institutions | University of Waikato |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: Copper/W-coated Diamond Composites
Section titled âTechnical Analysis and Documentation: Copper/W-coated Diamond CompositesâSource Paper: J. Jpn. Soc. Powder Powder Metallurgy, 72 (2025) S1299-S1305. Focus: Optimization of hot-forging temperature for enhanced thermal conductivity (TC) in Copper/W-coated diamond composites via interface control (WC/W2C formation).
Executive Summary
Section titled âExecutive SummaryâThis research validates the critical role of the diamond-metal interface in achieving high thermal conductivity (TC) in Copper/Diamond composites for advanced thermal management.
- Core Achievement: A peak TC of 432 W/mK was achieved in 55 vol% W-coated diamond/Copper composites fabricated via hot forging.
- Interface Solution: Tungsten (W) coating successfully reacted with diamond carbon to form tungsten carbide (WC and W2C) interfacial layers, overcoming the weak chemical affinity between pure Copper and Diamond.
- Optimal Process Parameter: Hot forging at 950 °C was identified as the optimal temperature, yielding the highest TC due to the formation of an ideal interface composed primarily of WC phase with a minor W2C phase.
- Mechanism Insight: Internal stress generated during cold compaction (600 MPa) and subsequent hot forging significantly lowered the required reaction temperature for carbide formation, allowing WC synthesis even at 800 °C.
- Material Specification: The study utilized relatively small diamond particles (~70 ”m, 230/270 mesh) with a 50nm W coating thickness, demonstrating high TC is achievable without relying solely on large particle sizes.
- 6CCVD Value: This work directly aligns with 6CCVDâs expertise in custom metalization (W, Ti, Cu) and high-quality Polycrystalline Diamond (PCD) substrates for scaling high-performance thermal solutions.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Peak Thermal Conductivity (TC) | 432 | W/mK | Achieved by 950W-D/Cu composite. |
| Optimal Hot Forging Temperature | 950 | °C | Maximizes TC and optimal WC/W2C balance. |
| Diamond Volume Fraction | 55 | vol% | Nominal composition in Copper matrix. |
| Diamond Particle Size | ~70 | ”m | 230/270 mesh (relatively small). |
| W Coating Thickness (Input) | 50 | nm | Applied to MBD8 diamond particles. |
| Optimal Interface Composition | WC (Substantial) + W2C (Minor) | N/A | Correlates with peak TC at 950 °C. |
| Relative Density (Optimal) | 95.47 | % | Density of 950W-D/Cu composite. |
| Lowest Relative Density | 92.15 | % | Density of 1050W-D/Cu composite (due to pore formation). |
| Forging Atmosphere | Argon | N/A | Oxygen content maintained below 200ppm. |
| Annealing Vacuum | 10-2 | Pa | Used for W-coated diamond particle studies. |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication and analysis focused on controlling the W-C interface reaction kinetics through precise temperature and pressure control during hot forging.
- Raw Material Selection: Utilized 99.7% purity Copper powder (< 45 ”m) and W-coated MBD8 diamond particles (55 vol%, 50nm W coating, 230/270 mesh).
- Green Compact Preparation: Mixed powders were subjected to cold compaction (pressure implied to be high, contributing to internal stress).
- Hot Forging Process: Composites were fabricated via hot forging under an Argon atmosphere at three distinct temperatures: 800 °C, 950 °C, and 1050 °C.
- Interface Annealing Study: W-coated diamond particles were separately annealed at the same three temperatures for 30 minutes under 10-2 Pa vacuum to isolate the temperature-driven reaction mechanism.
- Phase Analysis: X-ray Diffraction (XRD) was used to identify phase constitutions (Cu, Diamond, W, WC, W2C, CuO) in both hot-forged and annealed samples.
- Microstructural Analysis: Scanning Electron Microscopy (SEM) was used to characterize the surface morphology and interface coverage rate on extracted diamond particles.
- Thermal Property Measurement: Thermal diffusivity (α) was measured using a LFA 467 instrument on cylindrical samples (12.7mm diameter, 3mm thickness). Thermal Conductivity (λ) was calculated using the rule of mixture formula: λ=αÏΔp.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the critical need for precise material engineering, specifically in metal coating thickness, uniformity, and post-processing control (hot forging/annealing) to optimize the carbide interface. 6CCVD is uniquely positioned to supply the high-quality diamond materials and custom metalization services required to replicate and scale this high-performance thermal management solution.
Applicable Materials
Section titled âApplicable Materialsâ| Research Requirement | 6CCVD Material Recommendation | Rationale |
|---|---|---|
| W-Coated Diamond Particles | Polycrystalline Diamond (PCD) Substrates/Wafers | We supply high-purity PCD material suitable for composite applications, offering superior mechanical stability and thermal properties compared to natural diamond. |
| Interface Control (W-C Reaction) | Custom Metalization Services (W, Ti, Cu) | 6CCVD offers in-house W metalization (as well as Ti, Cu, Au, Pt, Pd) via advanced CVD techniques, ensuring highly uniform 50nm coatings or custom thicknesses required for precise carbide formation kinetics. |
| High Thermal Performance | Thermal Grade SCD or PCD | For applications requiring TC > 432 W/mK, our high-purity Single Crystal Diamond (SCD) or specialized Thermal Grade PCD can serve as superior starting materials for composite fabrication. |
Customization Potential
Section titled âCustomization PotentialâThe success of this research hinges on controlling the interface geometry and material dimensions. 6CCVD provides the necessary customization to transition this laboratory success into scalable engineering solutions.
- Custom Dimensions: The paper used 12.7mm diameter cylinders. 6CCVD routinely supplies PCD wafers up to 125mm in diameter and SCD plates up to 10mm thick, which can be precision laser cut or machined to any required geometry for thermal spreader integration.
- Thickness Control: We offer precise thickness control for both SCD and PCD materials, ranging from 0.1”m to 500”m, allowing engineers to optimize the diamond volume fraction and thermal path length.
- Surface Finish: While the study focused on particle interfaces, for final device integration, 6CCVD guarantees ultra-low surface roughness (Ra < 1nm for SCD, Ra < 5nm for inch-size PCD), minimizing thermal boundary resistance (TBR) when bonding the composite to semiconductor chips.
Engineering Support
Section titled âEngineering SupportâThe complex interplay between temperature, pressure, and phase composition (WC vs. W2C) requires expert material science consultation.
- 6CCVDâs in-house PhD team specializes in optimizing CVD diamond properties and post-processing techniques (including metalization and surface preparation) for extreme thermal management projects.
- We can assist researchers and engineers in selecting the optimal diamond type (SCD vs. PCD) and metalization stack (e.g., Ti/W/Cu) to achieve target TC values and Coefficient of Thermal Expansion (CTE) matching for high-power electronic devices.
- We offer global shipping (DDU default, DDP available) to ensure rapid delivery of custom-specified diamond materials worldwide.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.