Interfacial Characterization and Thermal Conductivity of Diamond/Cu Composites Prepared by Liquid-Solid Separation Technique

At a Glance

Metadata	Details
Publication Date	2023-02-26
Journal	Nanomaterials
Authors	Yaqiang Li, Hongyu Zhou, Chunjing Wu, Zheng Yin, Chang Liu
Institutions	University of Science and Technology Beijing, Baise University
Citations	10
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Performance Diamond/Cu Composites for Thermal Management

Executive Summary

This analysis focuses on the successful fabrication and characterization of high-thermal-conductivity Diamond/Copper (Cu) composites using a Liquid-Solid Separation (LSS) technique, highlighting the critical role of nanoscale surface modification.

Core Achievement: Diamond/Cu composites containing 40 vol.% Ti-coated diamond particles achieved a thermal conductivity (TC) of 457.22 W·m^-1·K^-1.
Performance Gain: This represents a nearly 50% increase in TC compared to uncoated diamond/Cu composites (315.19 W·m^-1·K^-1) fabricated by the same LSS method.
Mechanism: The significant TC enhancement is directly attributed to the formation of a high-integrity Titanium Carbide (TiC) layer at the diamond-Cu interface, which overcomes the intrinsic chemical incompatibility and weak physical bonding.
Material Requirement: The study utilized synthetic single-crystalline diamond (SCD) particles (~102 µm) coated with a nanoscale Ti layer (~100 nm).
Design Optimization: Differential Effective Medium (DEM) modeling established a critical TiC layer thickness of approximately ~260 nm, beyond which thermal conductivity dramatically declines due to increased phonon scattering.
Process Scalability: The Liquid-Solid Separation (LSS) technology is identified as a compact, low-cost routine suitable for large-scale production of high-volume fraction diamond composites.

Technical Specifications

The following hard data points were extracted from the research detailing the material properties and performance metrics of the optimized Diamond/Cu composites.

Parameter	Value	Unit	Context
Peak Thermal Conductivity (TC)	457.22	W·m^-1·K^-1	40 vol.% Ti-coated Diamond/Cu composite
Relative Density	98.1	%	Achieved via LSS technology
TC Relative to Theoretical (DEM)	75.3	%	Efficiency of heat transfer
Diamond Volume Fraction	40	vol.%	Optimized composite composition
Diamond Particle Size (Raw)	~102	µm	Synthetic Single-Crystalline Diamond (SCD)
Initial Ti Coating Thickness	~100	nm	Applied via vacuum ion plating
Critical TiC Layer Thickness (DEM)	~260	nm	Maximum thickness before TC decline
LSS Sintering Temperature	1376	K	Held for 30 min
LSS Squeezing Pressure	100	MPa	Applied during liquid-solid separation
Surface Roughness (Ti-coated {100} facet)	~29	nm	Root Mean Square (RMS)
Surface Roughness (Ti-coated {111} facet)	23.9	nm	Root Mean Square (RMS)
Intrinsic Diamond TC (Calculated)	1450	W·m^-1·K^-1	Based on nitrogen content (190~200) x 10^-6

Key Methodologies

The Diamond/Cu composites were prepared using an independently developed Liquid-Solid Separation (LSS) technology, focusing on precise control over the interfacial layer formation.

Diamond Surface Modification: Synthetic single-crystalline diamond (SCD) particles (~102 µm) were coated with a nanoscale Titanium (Ti) layer (approx. 100 nm) using a vacuum ion plating process.
Powder Mixing: Ti-coated diamond particles and spherical copper powder (~45 µm) were mechanically mixed in a 1:4 volume ratio for 5 hours.
Billet Preparation: The mixed powder was cold-pressed into a billet at 300 MPa for 2 minutes.
Sintering Phase: The billet was heated at 15 K·min^-1 to 1376 K and held for 30 minutes to achieve a liquid-solid mixed state.
Separation and Consolidation: The liquid-solid mixed melt slurry was squeezed at 100 MPa. The diamond particles were retained in the LSS chamber while liquid copper was separated.
Directional Solidification: Continuous pressure was maintained for 10 minutes under a water-cooling system, resulting in layer-by-layer solidification and the formation of the interfacial Titanium Carbide (TiC) layer.
Characterization: Thermal diffusivity was measured using Laser Scattering TC (LFA 427), and interfacial chemistry (TiC formation) was confirmed via XRD and XPS analysis.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-quality diamond materials and precise metalization services required to replicate and advance this high-performance thermal management research. Our capabilities ensure material purity, dimensional accuracy, and optimized interfacial chemistry.

Applicable Materials

To replicate the high intrinsic thermal conductivity required for this application (1450 W·m^-1·K^-1), the highest quality diamond is essential.

Material Recommendation: Optical Grade Single Crystal Diamond (SCD) or High-Purity Polycrystalline Diamond (PCD).
- SCD Advantage: Provides the highest intrinsic thermal conductivity and purity, ideal for small-scale, ultra-high-performance prototypes.
- PCD Advantage: Available in larger custom dimensions (up to 125mm wafers), offering a scalable solution for industrial composite fabrication.

Customization Potential

The success of this research hinges on the precise control of the nanoscale Ti interfacial layer. 6CCVD offers comprehensive services to meet these exact specifications.

Research Requirement	6CCVD Customization Capability	Engineering Advantage
Active Metal Coating (Ti, ~100 nm thickness)	Custom Metalization (Ti, W, Cu, Pt, Pd, Au). We control layer thickness from nanometers to microns.	Enables precise replication of the critical Ti layer thickness, ensuring optimal TiC formation and minimizing interfacial thermal resistance (ITC).
Diamond Dimensions (Particle size ~102 µm)	Custom SCD/PCD Substrates and Wafers. Thicknesses from 0.1 µm to 500 µm (SCD/PCD) and substrates up to 10 mm.	We supply diamond materials in custom dimensions and particle sizes suitable for LSS, Spark Plasma Sintering (SPS), or pressure infiltration techniques.
Surface Preparation (Roughness control)	Ultra-Low Roughness Polishing. SCD: Ra < 1 nm. Inch-size PCD: Ra < 5 nm.	While the paper utilized rougher surfaces for mechanical interlocking, 6CCVD can provide ultra-smooth surfaces for alternative bonding methods (e.g., direct bonding) or subsequent thin-film deposition steps.
Global Logistics	Global Shipping (DDU/DDP).	Ensures rapid, reliable delivery of high-value diamond materials worldwide, supporting international research collaborations.

Engineering Support

The paper highlights that the thermal performance is highly sensitive to the TiC layer thickness (critical value ~260 nm). 6CCVD’s in-house PhD team specializes in optimizing diamond material properties for extreme thermal and electronic applications.

Thermal Interface Optimization: Our experts can assist engineers and scientists in selecting the optimal active metal (Ti, W, etc.) and deposition parameters to achieve the desired interfacial carbide layer thickness, maximizing TC for similar Diamond/Metal Matrix Composite (MMC) projects.
Material Selection for LSS/SPS: We provide consultation on the ideal diamond morphology (SCD vs. PCD) and particle size distribution to ensure high-volume fraction loading and high relative density during composite fabrication processes like LSS.

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

View Original Abstract

Diamond/Cu composites are widely studied as a new generation of thermal management materials in the field of electronic packaging and heat sink materials. The surface modification of diamond can improve interfacial bonding between the diamond and Cu matrix. The Ti-coated diamond/Cu composites are prepared via an independently developed liquid-solid separation (LSS) technology. It is worth noting that there are obvious differences for the surface roughness between the diamond-{100} and -{111} face by AFM analysis, which may be related to the surface energy of different facets. In this work, the formation of titanium carbide (TiC) phase makes up the chemical incompatibility between the diamond and copper, and the thermal conductivities of 40 vol.% Ti-coated diamond/Cu composites can be improved to reach 457.22 W·m−1·K−1. The results estimated by the differential effective medium (DEM) model illustrate that the thermal conductivity for 40 vol.% Ti-coated diamond/Cu composites show a dramatic decline with increasing TiC layer thickness, giving a critical value of ~260 nm.

Tech Support

Original Source

DOI: https://doi.org/10.3390/nano13050878

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