DENSIFICATION PROCESS AND PROPERTIES OF DIAMOND/SiC COMPOSITES BY PRESSURELESS VAPOUR INFILTRATION
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-04-04 |
| Journal | Ceramics - Silikaty |
| Authors | Xulei Wang |
| Institutions | University of Science and Technology Beijing, Zhengzhou University of Aeronautics |
| Citations | 1 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond/SiC Composites via Pressureless Vapour Infiltration
Section titled âTechnical Documentation & Analysis: Diamond/SiC Composites via Pressureless Vapour InfiltrationâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the fabrication of high-performance Diamond/Silicon Carbide (SiC) composites using Pressureless Si Vapour Infiltration (PVI), yielding materials highly suitable for advanced electronic thermal management.
- Peak Thermal Performance: Achieved a maximum Thermal Conductivity (TC) of 536 W·m-1·K-1 at an optimal diamond content of 60 vol. %.
- Mechanical Superiority: The composite exhibited high mechanical strength, reaching a maximum bending strength of 348.67 MPa.
- Thermal Matching: Demonstrated a low and well-matched Thermal Expansion Coefficient (TEC) ranging from 1.0 to 3.25 ppm·K-1 (50-500 °C), crucial for electronic packaging reliability.
- Densification Mechanism: The process involves three stages: Si-C reaction on the diamond surface, pore filling, and SiC nanowire accumulation, determined primarily by Si vapor concentration.
- Structural Integrity: The SiC skeleton embedded with high-quality diamond forms the preferred three-dimensional path for efficient heat conduction.
- Material Requirement: The process relies on high-purity, high-thermal-conductivity single crystal diamond powder (TC 1738 W·m-1·K-1).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the analysis of the optimal D60-SiC composite:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Peak Thermal Conductivity (TC) | 536 | W·m-1·K-1 | At 60 vol. % diamond content |
| Maximum Bending Strength | 348.67 | MPa | At 60 vol. % diamond content |
| Thermal Expansion Coefficient (TEC) Range | 1.0 to 3.25 | ppm·K-1 | Measured between 50 °C and 500 °C |
| Optimal Diamond Volume Fraction | 60 | vol. % | Yields highest TC and strength |
| Diamond Raw Material TC | 1738 | W·m-1·K-1 | Corresponds to 140 ppm N concentration |
| Diamond Particle Size (Raw Material) | 148 | ”m | Single crystal, -100 mesh |
| Si Infiltration Temperature | 1650 | °C | Required for Si-C reaction and densification |
| Si Infiltration Time (Densification) | 60 | minutes | Required for complete infiltration |
| Ultimate Vacuum Pressure | 1 | Pa | Used during pressureless Si vapour infiltration |
| Si Diffusion Coefficient in SiC (1600 °C) | 4.2 x 10-10 | cmÂČ·s-1 | Indicates extremely slow diffusion process |
Key Methodologies
Section titled âKey MethodologiesâThe Diamond/SiC composites were prepared using a multi-step process centered on Pressureless Si Vapour Infiltration (PVI):
- Raw Material Mixing: Single crystal diamond powder (148 ”m), phenolic resin (binder/carbon source), silicon powder (< 10 ”m), and graphite powder (< 50 ”m) were calculated based on volume fraction and wet-mixed.
- Green Body Compaction: Composite green bodies (40-80 vol. % diamond) were formed under 30 MPa pressure (forming size: Ί = 30 x 3 mmÂČ).
- Pre-Treatment/Pyrolysis: Green bodies were heat-treated at a high temperature (1100 °C) under high-purity argon protection to pyrolyze the resin and prepare the carbon source.
- Pressureless Vapour Infiltration (PVI): Si infiltration was conducted in a vacuum furnace at 1650 °C, maintaining an ultimate vacuum of 1 Pa.
- Densification Control: Infiltration time was optimized to 60 minutes to ensure complete densification and minimize residual free Si.
- Characterization: Microstructure was analyzed using SEM/EDS. Thermophysical properties (TC, TEC) were measured using the Archimedes method, Netzsch LFA 467 HyperFlashÂź, and TA Instruments DIL 802.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the foundational diamond materials and advanced processing services necessary to replicate, optimize, and scale the production of high-performance Diamond/SiC composites for thermal management applications.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve the high thermal conductivity demonstrated in this research (TC 536 W·m-1·K-1), the starting diamond material must be of exceptional quality.
- High Thermal Grade SCD Powder: The paper utilized diamond powder with a TC of 1738 W·m-1·K-1. 6CCVD specializes in producing High-Purity Single Crystal Diamond (SCD) materials with TCs routinely exceeding 2000 W·m-1·K-1, ensuring the highest possible thermal performance for the composite matrix.
- High-Purity PCD Substrates: For applications requiring large-area thermal spreaders, 6CCVD offers High-Purity Polycrystalline Diamond (PCD) wafers, which can serve as robust, pre-sintered substrates or components for similar infiltration processes.
- Boron-Doped Diamond (BDD): For researchers extending this work into electrically functional composites (e.g., integrated heating elements or sensors), 6CCVD provides Boron-Doped Diamond (BDD) materials, offering tunable conductivity within the diamond phase.
Customization Potential
Section titled âCustomization PotentialâThe research utilized small, laboratory-scale samples (30 x 3 mmÂČ). 6CCVDâs capabilities enable immediate industrial scaling and advanced integration:
| Research Requirement | 6CCVD Customization Capability | Benefit to Client |
|---|---|---|
| Small Sample Size (30 x 3 mmÂČ) | Large Area Wafers: Custom PCD plates and wafers available up to 125mm in diameter. | Enables industrial production of inch-size thermal management substrates. |
| Specific Thickness (3 mm) | Substrate Thickness Control: SCD/PCD layers from 0.1 ”m to 500 ”m; Substrates up to 10mm thick. | Provides flexibility for both thin-film packaging and robust, high-power heat sinks. |
| Interface Integration (SiC/Si) | Advanced Metalization: In-house deposition of Au, Pt, Pd, Ti, W, and Cu. | Facilitates reliable soldering, bonding, and electrical contact for direct integration into electronic circuits. |
| Surface Finish (Post-Processing) | Precision Polishing: Achievable surface roughness (Ra) < 1nm for SCD and < 5nm for inch-size PCD. | Ensures optimal thermal contact resistance when bonding the composite to high-power chips. |
Engineering Support
Section titled âEngineering SupportâThe successful preparation of high-performance Diamond/SiC composites requires precise control over raw material quality, particle size distribution, and infiltration parameters (temperature, pressure, time).
- Material Selection Expertise: 6CCVDâs in-house PhD team offers consultation on optimizing diamond particle morphology and purity for similar High-Power Electronic Packaging projects.
- Process Optimization: We provide technical support to help engineers select the ideal diamond grade and volume fraction to achieve specific TC and TEC matching targets, minimizing the detrimental effects of free Si residue observed in the high-volume fraction composites.
- Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) of high-value diamond materials directly to your research or production facility.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Diamond/silicon carbide (SiC) composites with different diamond contents were prepared by pressureless silicon (Si) vapour infiltration. The densification process of the Si infiltration of the composites was analysed. Three densification process were put forward. The densification degree of the composites was determined by the concentration of the Si vapour. The three-dimensional skeleton of the SiC composite embedded with diamond constitutes the best path for the heat conduction of composites. With an increase of diamond content, the thermal conductivity (TC) of the composites increases at first and then decreases, reaching a maximum value at a diamond 60 vol.%, with the TC of 536 W/(m·K). In the temperature range of 50~500 °C, the thermal expansion coefficient of the composite varies from 1.0 to 3.25 ppm/K. The bending strength of the composite reached a maximum value of 334.52 MPa. The composite has a low thermal expansion coefficient, superior thermal conductivity and bending strength, and can be used as an alternative thermal management material.