Enhanced tensile strength and thermal conductivity in copper diamond composites with B4C coating

At a Glance

Metadata	Details
Publication Date	2017-08-31
Journal	Scientific Reports
Authors	Youhong Sun, Linkai He, Chi Zhang, Qingnan Meng, Баочанг Лиу
Institutions	State Key Laboratory of Superhard Materials, Jilin University
Citations	65
Analysis	Full AI Review Included

Diamond Composite Interfacial Engineering: Enhanced Thermal and Mechanical Performance using B₄C Coatings

Technical Analysis and Solutions Brief from 6CCVD Materials Science Team

Executive Summary

This documentation analyzes the research demonstrating significant enhancements in copper-diamond (Cu-D) composite properties through surface functionalization using a Boron Carbide (B₄C) coating on the diamond particles.

Core Achievement: B₄C coating on diamond particles dramatically improved the interfacial bonding with the copper matrix in powder metallurgy composites.
Performance Uplift: Thermal conductivity (TC) increased by over 3.2 times, rising from 210 W/mK (uncoated) to 687 W/mK (6-hour coated).
Mechanical Enhancement: Tensile strength nearly doubled, increasing from 60 MPa (uncoated) to a maximum of 115 MPa.
Mechanism of Improvement: The B₄C coating reduced the interfacial gap width from 8.40 µm to a tight 0.36 µm, leading to a high composite relative density (99.52%).
Methodology: B₄C synthesis was achieved by heating diamond powder in a mixture of Boron (B) and Boric Acid (H₃BO₃) under Argon (Ar) atmosphere, followed by vacuum hot-pressing sintering with copper powder.
6CCVD Relevance: This work highlights the critical role of diamond particle surface preparation and controlled composite manufacturing, directly aligning with 6CCVD’s capability to provide custom, high-purity Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) materials and tailored metalization/surface engineering services.

Technical Specifications

Parameter	Value	Unit	Context
Maximum Thermal Conductivity (TC)	687	W/mK	Six-hours B₄C coated composite (C3)
Uncoated TC (Baseline)	210	W/mK	Uncoated composite (C0)
Maximum Tensile Strength (TS)	115	MPa	Six-hours B₄C coated composite (C3)
Uncoated TS (Baseline)	60	MPa	Uncoated composite (C0)
Diamond Volume Fraction (V_D)	50	vol.%	Reinforcement concentration
Optimal B₄C Coating Time	6	hours	Achieved complete surface coverage (D3)
B₄C Coating Thickness (D3)	1.0	µm	Average thickness on six-hours coated particles
Optimal Relative Density	99.52	%	Six-hours coated composite (C3)
Interfacial Gap Width (Optimal)	0.36	µm	Six-hours coated composite (C3)
Sintering Temperature	950	°C	Vacuum Hot-Pressing Sintering
Sintering Pressure	60	MPa	Applied during consolidation

Key Methodologies

The composite fabrication process involved two major stages: B₄C coating synthesis and subsequent vacuum hot-pressing sintering.

B₄C Coating Synthesis Parameters (Using HPHT Diamond Powder)

Diamond Precursor: Synthetic HPHT diamond particles (HSD90), 180-212 µm size range.
Powder Mix: Diamond particles immersed in a mixture of Boron (B) and Boric Acid (H₃BO₃) powders (B:H₃BO₃ ratio not explicitly stated, but 33g B and 23g H₃BO₃ were used for 25g D powder).
Mechanical Mixing: Vigorously mixed at room temperature.
Reaction Environment: Tube furnace heated in Argon (Ar) atmosphere.
Coating Temperature: 1200 °C.
Coating Time Variation (D1, D2, D3): 2, 4, and 6 hours.
Post-Process Cleaning: Dilute nitric acid treatment to remove Boron Oxide (B₂O₃).

Composite Consolidation Parameters (Vacuum Hot-Pressing)

Matrix Material: Copper powder (99.9% purity).
Mixing Ratio: Coated diamond powder mixed with Cu powder (50 vol.% diamond reinforcement).
Sintering Method: Vacuum hot-pressing sintering.
Sintering Temperature: 950 °C.
Holding Time: 20 minutes.
Applied Pressure: Approximately 60 MPa.

6CCVD Solutions & Capabilities

The successful replication and expansion of this research rely on high-quality diamond material with precise surface engineering capabilities. 6CCVD provides the expert materials and technical support necessary for advanced diamond composite development.

Applicable Materials

To achieve optimal interface formation and high-density consolidation for Cu-D or similar metal matrix composites, 6CCVD recommends the following specialized materials:

Optical/Electronic Grade SCD: For research requiring ultimate purity, low defect density, and controlled crystal faces. While the paper used powder, starting with high-quality SCD allows for detailed studies of B₄C growth kinetics on specific facets (e.g., preference for (100) vs. (111) surfaces observed in the paper).
- Dimensions: SCD substrates available from 0.1 µm up to 500 µm thickness.
Polycrystalline Diamond (PCD) Plates (Custom Sizing): For large-scale composite fabrication or scaling up the hot-pressing process. Our PCD wafers ensure consistent properties across large areas.
- Dimensions: Plates/wafers up to 125mm in diameter (PCD).
- Thickness: 0.1 µm up to 500 µm.
Boron-Doped Diamond (BDD): Though not required for the B₄C coating method studied, BDD materials are available for comparative studies involving electrochemically active diamond composites.

Customization Potential for Replication and Extension

The vacuum hot-pressing method necessitates carefully dimensioned samples. 6CCVD offers end-to-end customization to fit specific process requirements:

Custom Dimensions and Geometry: We provide precision laser cutting and shaping of both SCD and PCD materials to match specific mold or hot-pressing die geometries used in powder metallurgy (e.g., custom discs or rings required for the 60 MPa pressing step).
Advanced Surface Preparation: The paper highlights the necessity of minimizing interfacial gaps (< 1 µm). While the researchers created the B₄C coating separately, 6CCVD offers precision polishing (Ra < 5nm for inch-size PCD) to ensure the smoothest possible starting surface, which is crucial for uniform pre-treatment or direct application of subsequent matrix layers.
Custom Metalization Services (Interface Engineering): For extending this research to other metal matrix systems (e.g., Al, Ti, or W-based matrices where direct carbide formation is desired), 6CCVD offers in-house metalization capabilities:
- Available Metals: Au, Pt, Pd, Ti, W, Cu.
- Relevance: Titanium (Ti) and Tungsten (W) coatings are highly relevant for enhancing bonding via direct carbide formation (TiC, WC) during high-temperature sintering, providing alternative routes to stress relief and density control compared to B₄C.

Engineering Support

6CCVD’s in-house team of PhD material scientists specializes in CVD diamond interfaces and thermal management applications. We offer consultation services to assist researchers and engineers in:

Selecting the optimal diamond grade (SCD vs. PCD) based on required particle size distribution and purity goals.
Designing and implementing advanced interface layers, including optimization of thin-film metal layers for enhanced chemical wetting and stress mitigation in high-performance thermal management and structural projects.
Tailoring custom material specifications for similar Diamond/Metal Matrix Composite projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Original Source

DOI: https://doi.org/10.1038/s41598-017-11142-y