Effects of the In Situ Growth of CNTs on Ti-Coated Diamond Surfaces on the Mechanical Properties of Diamond/Aluminum Composites

At a Glance

Metadata	Details
Publication Date	2024-04-07
Journal	Nanomaterials
Authors	Hao Wu, Ping Zhu, Yixiao Xia, Yifu Ma, Junyao Ding
Institutions	Harbin Institute of Technology, Nanjing University of Science and Technology
Citations	2
Analysis	Full AI Review Included

Technical Documentation & Analysis: Multi-Scale Diamond Interface Engineering

Executive Summary

This research successfully demonstrates a multi-scale interface modification strategy for enhancing the mechanical reliability of diamond/aluminum (D/Al) composites, critical for advanced thermal management applications.

Core Achievement: In situ growth of Carbon Nanotubes (CNTs) on Ti-coated diamond particles significantly improved the bending strength of the resulting D/Al composite by approximately 9%.
Performance Metrics: The CNT-modified composite achieved a maximum bending strength of 275 ± 6 MPa, compared to 252 ± 9 MPa for uncoated D/Al.
Interface Mechanism: The CNT layer facilitated robust chemical bonding by promoting the formation of bridging phases (TiC and Al₄C₃) during the Gas-Assisted Pressure Infiltration (GPI) process.
Methodology: Monocrystalline diamond particles (355 µm) were coated with 300 nm of Ti via magnetron sputtering, followed by Fe catalyst application and subsequent CNT growth (approx. 1 µm length) using Plasma-Enhanced Chemical Vapor Deposition (PECVD) at 650 °C.
Trade-off: While mechanical strength was maximized, the thermal conductivity was reduced (577 W·m^-1·K^-1) compared to the uncoated composite (726 W·m^-1·K^-1), attributed to increased interface thermal resistance from thicker interfacial phases (TiC, Al₃Ti).
Strategic Value: This work provides a proven pathway for designing high-reliability diamond/metal composites where mechanical integrity is paramount alongside acceptable thermal performance.

Technical Specifications

The following hard data points were extracted from the experimental results and preparation parameters:

Parameter	Value	Unit	Context
Diamond Particle Type	MBD4	N/A	Monocrystalline Diamond (SCD precursor)
Diamond Particle Size	355	µm	Reinforcement average size
Diamond Volume Fraction	60	%	Composite composition
Ti Coating Thickness	300	nm	Applied via magnetron sputtering
CNT Length (In Situ Growth)	~1	µm	Grown via PECVD
PECVD Growth Temperature	650	°C	Held for 30 min
PECVD RF Frequency	13.56	MHz	Used to generate plasma
PECVD Pressure	140-160	Pa	Total pressure during CNT growth
GPI Infiltration Temperature	800	°C	Aluminum heating temperature
GPI Infiltration Pressure	15	MPa	Gas pressure applied
Max Bending Strength	275 ± 6	MPa	CNT-modified Ti-coated D/Al composite
Max Thermal Conductivity	726	W·m^-1·K^-1	Uncoated D/Al composite
CNT-Modified Thermal Conductivity	577	W·m^-1·K^-1	Demonstrates mechanical/thermal balance

Key Methodologies

The preparation of the multi-scale CNT-modified Ti-coated diamond reinforcement involved precise sequential steps:

Ti Coating: Monocrystalline diamond particles were coated with a 300 nm Ti layer using magnetron sputtering.
Catalyst Precursor Application: The Ti-coated diamond was immersed in a 0.05 mol/L Fe(NO₃)₃·9H₂O solution for 12 hours (solution impregnation method) to encapsulate the Fe catalyst precursor.
PECVD Setup: The particles were transferred to a PECVD reactor chamber. Methane (CH₄) served as the carbon source, and Hydrogen (H₂) served as the reducing and carrier gas.
Fe Reduction: The system was heated to 650 °C (10 °C/min rate) and held for 30 min under H₂ flow (20 sccm) to reduce Fe³⁺ to metallic Fe catalyst particles.
CNT Growth: RF power (13.56 MHz) was applied for 20 minutes to generate plasma. CH₄/H₂ mixture (20/5 sccm flow rate) was introduced at 140-160 Pa pressure to grow CNTs in situ.
Composite Fabrication: CNT-modified diamond particles (60 vol.%) were infiltrated with molten 1060 bulk aluminum using the Gas-Assisted Pressure Infiltration (GPI) method at 800 °C and 15 MPa pressure.

6CCVD Solutions & Capabilities

6CCVD specializes in providing the high-quality MPCVD diamond materials and precision engineering services required to replicate and advance this critical research in high-reliability diamond/metal composites.

Applicable Materials

To replicate or extend this research, high-purity diamond material is essential for consistent interface chemistry and thermal performance:

Optical Grade SCD (Single Crystal Diamond): The MBD4 particles used are precursors to high-quality SCD. 6CCVD provides high-purity, low-defect SCD plates and wafers (0.1 µm to 500 µm thick) ideal for thermal management research requiring superior intrinsic properties and consistent crystallographic orientation.
PCD (Polycrystalline Diamond): For scaling up composite production or applications requiring larger reinforcement sizes, 6CCVD offers high-quality PCD plates up to 125mm in diameter, suitable for large-area heat spreaders.

Customization Potential

The success of this study hinges on precise material modification, a core competency of 6CCVD:

Research Requirement	6CCVD Capability	Technical Advantage
Ti Coating (300 nm)	Internal Metalization Services	6CCVD offers precise, internal metalization via sputtering, routinely handling Ti, W, Au, Pt, Pd, and Cu layers, ensuring exact thickness control (e.g., 300 nm ± 10 nm).
Particle Surface Quality	Advanced Polishing	We provide ultra-smooth polishing (Ra < 1nm for SCD, < 5nm for inch-size PCD), ensuring optimal surface preparation for subsequent catalyst deposition and PECVD growth.
Custom Dimensions	Large Format & Custom Thickness	We supply diamond substrates in custom dimensions up to 125mm (PCD) and thicknesses up to 10mm, enabling direct integration into advanced electronic packaging designs, moving beyond particle-based composites.
Interface Chemistry Control	Boron-Doped Diamond (BDD)	For research extending into electrochemical or sensing applications related to the interface, 6CCVD offers BDD materials, providing tunable electrical properties alongside thermal performance.

Engineering Support

6CCVD’s in-house PhD team specializes in MPCVD growth parameters and interface modification strategies. We can assist researchers in optimizing material selection and pre-treatment protocols (e.g., surface termination, metalization thickness, and catalyst preparation) for similar Diamond/Metal Composite projects. Our expertise ensures the desired balance between mechanical reliability (as achieved in this study) and thermal performance for specific application requirements.

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

View Original Abstract

Diamond/aluminum composites have attracted significant attention as novel thermal management materials, with their interfacial bonding state and configuration playing a crucial role in determining their thermal conductivity and mechanical properties. The present work aims to evaluate the bending strength and thermal conductivity of CNT-modified Ti-coated diamond/aluminum composites with multi-scale structures. The Fe catalyst was encapsulated on the surface of Ti-coated diamond particles using the solution impregnation method, and CNTs were grown in situ on the surface of Ti-coated diamond particles using the plasma-enhanced chemical vapor deposition (PECVD) method. We investigated the influence of interface structure on the thermal conductivity and mechanical properties of diamond/aluminum composites. The results show that the CNT-modified Ti-coated diamond/aluminum composite exhibits excellent bending strength, reaching up to 281 MPa, compared to uncoated diamond/aluminum composites and Ti-coated diamond/aluminum composites. The selective bonding between diamond and aluminum was improved by the interfacial reaction between Ti and diamond particles, as well as between CNT and Al. This led to the enhanced mechanical properties of Ti-coated diamond/aluminum composites while maintaining acceptable thermal conductivity. This work provides insights into the interface’s configuration design and the performance optimization of diamond/metal composites for thermal management.

Tech Support

Original Source

DOI: https://doi.org/10.3390/nano14070640

References

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2022 - Realizing ultrahigh thermal conductivity in bimodal-diamond/Al composites via interface engineering
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2018 - Thermal conductivity of metal matrix composites with coated inclusions: A new modelling approach for interface engineering design in thermal management [Crossref]
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