Microstructure and finite element analysis of Mo2C-diamond/Cu composites by spark plasma sintering
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-01-01 |
| Journal | Science and Engineering of Composite Materials |
| Authors | Changrui Wang, Hongzhao Li, Wei Tian, Wenhe Liao |
| Institutions | Nanjing University of Aeronautics and Astronautics |
| Citations | 1 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research focuses on developing high thermal conductivity (TC) diamond/Cu composites for advanced heat sink applications by modifying the interface using a molybdenum carbide (Mo2C) interlayer.
- Core Achievement: Successfully fabricated Mo2C-coated diamond/Cu composites via Spark Plasma Sintering (SPS), achieving a peak TC of 511 W/(m K) and a relative density (RD) of 96.13%.
- Interface Strategy: A Mo2C interlayer was generated on 100 ”m diamond particles using vacuum micro-evaporation to enhance wettability and bonding with the copper matrix.
- Optimal Coating Parameters: The best Mo2C coating quality (uniform and dense) was achieved at 1000 °C for 60 min, resulting in a theoretical coating thickness of 267.30 nm.
- Optimal Sintering Parameters: The highest performance was obtained using SPS at 900 °C, 80 MPa, with a short holding time of 10 min.
- Sintering Time Sensitivity: Prolonged SPS holding times (20 min and 40 min) severely damaged the Mo2C interlayer, leading to weakened bonding, increased porosity, and a significant drop in TC (down to 302 W/(m K)).
- Predictive Modeling: Finite Element Analysis (FEA) incorporating low-conduction gaps and air within the porosity provided TC predictions closely matching experimental results, validating the model for future design optimization.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Peak Thermal Conductivity (TC) | 511 | W/(m K) | Experimental, 10 min SPS hold time |
| Peak Relative Density (RD) | 96.13 | % | Experimental, 10 min SPS hold time |
| Diamond Volume Fraction | 50 | vol% | Composite composition |
| Diamond Particle Size (Average) | 100 | ”m | Reinforcement material |
| Optimal Mo2C Coating Temperature | 1000 | °C | Vacuum micro-evaporating |
| Optimal Mo2C Coating Time | 60 | min | Vacuum micro-evaporating |
| Theoretical Mo2C Thickness | 267.30 | nm | Calculated for 60 min deposition |
| Optimal SPS Sintering Temperature | 900 | °C | Consolidation process |
| Optimal SPS Loading Pressure | 80 | MPa | Consolidation process |
| Optimal SPS Holding Time | 10 | min | Consolidation process |
| Mo2C TC (FEA Input) | 21 | W/(m K) | Thermal resistance layer |
| Porosity TC (FEA Input) | 0.026 | W/(m K) | Air/gap thermal resistance |
| Diamond Density (FEA Input) | 3.52 | g/cm3 | Simulation parameter |
| Copper Density (FEA Input) | 8.96 | g/cm3 | Simulation parameter |
| Lowest Experimental TC | 302 | W/(m K) | 40 min SPS hold time |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication involved two primary stages: Mo2C coating via vacuum micro-evaporation and composite consolidation via Spark Plasma Sintering (SPS).
I. Mo2C Coating Preparation
Section titled âI. Mo2C Coating Preparationâ- Pre-treatment: Commercially synthesized MBD-8 diamond particles (100 ”m) were cleaned using 10 wt% NaOH and 20 wt% HCl to remove oil and coarsen the surface.
- Mixing: Diamond particles and Mo powder (2 ”m) were mixed at a 10:1 molar ratio using a planetary ball mill (300 rpm for 2h).
- Vacuum Micro-Evaporation:
- The mixed powder was placed in a ceramic crucible inside a tube furnace (TL1200).
- The system was vacuumed to a pressure of <10-3 Pa.
- The temperature was ramped up to the optimal 1000 °C and held for 60 min to facilitate the reaction: 2Mo(s) + C(diamond) â Mo2C(s).
- Post-treatment: Coated particles were cleaned ultrasonically in distilled water to remove residual Mo powder and then dried.
II. Composite Fabrication and Analysis
Section titled âII. Composite Fabrication and Analysisâ- SPS Consolidation: 50 vol% Mo2C-coated diamond was mixed with Cu powder and sintered using the following optimal parameters:
- Temperature: 900 °C
- Pressure: 80 MPa
- Holding Time: 10 min (also tested at 20 min and 40 min).
- Microstructural Analysis:
- Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to observe coating morphology and roughness.
- X-Ray Diffraction (XRD) confirmed the presence of Mo2C, Cu, and Diamond phases, and verified the absence of graphite formation.
- Thermal Performance Measurement: Thermal conductivity (TC) was measured using a laser flash TC measurement apparatus (TC-7000H).
- Finite Element Analysis (FEA):
- A Representative Volume Element (RVE) model was established using Digimat and ABAQUS software.
- The model incorporated the Mo2C coating thickness (267 nm) and varying porosities (4.87%, 9.45%, 14.68%) derived from experimental relative densities.
- Crucially, the simulation included the low thermal conductivity of air/gaps within the porosity (TC = 0.026 W/(m K)) to accurately predict real-world heat conduction behavior.
Commercial Applications
Section titled âCommercial ApplicationsâThe Mo2C-diamond/Cu composites are specifically engineered for high-performance thermal management, targeting industries where high heat flux and miniaturization are critical.
- Advanced Electronics Packaging: Used as high-efficiency heat sinks for highly integrated microchips, CPUs, and GPUs, where traditional materials fail to meet dissipation demands (>300 W/(m K)).
- High-Power Communication Systems: Thermal management in 5G/6G base stations, high-frequency transmitters, and satellite communication components.
- Aerospace and Defense: Applications requiring lightweight, high-reliability thermal dissipation components for avionics and specialized transmission systems (consistent with the authorsâ institutional focus).
- Power Electronics: Heat spreaders and substrates for high-power semiconductor devices (e.g., IGBT modules) used in electric vehicles and industrial machinery.
View Original Abstract
Abstract Mo 2 C layer was generated on the diamond surface via vacuum micro-evaporating, which was used as the reinforcement particles to fabricate diamond/Cu composites by spark plasma sintering (SPS). The effect of evaporation parameters on the forming of Mo 2 C, and the holding time on diamond/Cu composites fabrication is studied. Combined with the experiment and finite element analysis (FEA), the holding time on diamond/Cu composites influence on the thermal conductivity (TC) of composites is further discussed. The results show that the Mo 2 C area on the diamond surface would gradually enlarge and cover the diamond surface evenly with the increment in evaporation time and temperature, better vacuum micro-evaporating parameters were given as 1,000°C for 60 min. The fractures in the diamond/Cu composites are mainly ductile fractures on copper and diamond falling out from the Mo 2 C interface. It was found that sintering time would significantly influence the dissipation property of diamond/Cu composites. A comprehensive parameter for SPS was obtained at 900°C, 80 MPa for 10 min, the relative density (RD) and TC of the composites obtained under the parameter were 96.13% and 511 W/(m K). A longer sintering time would damage the Mo 2 C interlayer and further decrease the bonding between copper matrix and diamond particles, which would lower the RD and TC of composites. It can be obtained from the comparison of simulation results and experimental results that the FEA result is closer to the experimental results due to the gaps with low heat conduction, and the air in the gaps is added in the simulation process.