Thermal Conductivity Stability of Interfacial in Situ Al4C3 Engineered Diamond/Al Composites Subjected to Thermal Cycling

At a Glance

Metadata	Details
Publication Date	2022-09-24
Journal	Materials
Authors	Ning Li, Jinpeng Hao, Yongjian Zhang, Wei Wang, Jie Zhao
Institutions	University of Science and Technology Beijing, Shandong Academy of Sciences
Citations	17
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Stability Diamond/Al Composites

Executive Summary

This analysis focuses on the exceptional thermal conductivity (TC) stability achieved in diamond/Al composites engineered with a robust in situ Al₄C₃ interface, validating their suitability for high-reliability electronic packaging.

Exceptional Stability: Diamond/Al composites demonstrated outstanding TC stability, experiencing only a 2.6% to 4.7% reduction after 200 thermal cycles (218 K to 423 K).
High Performance Maintained: The 272 µm diamond composite maintained a high TC of 724 W m^-1 K^-1 after 200 cycles, significantly exceeding typical thermal management materials.
Interface Engineering: The stability is directly attributed to the discrete in situ Al₄C₃ phase, which creates a strong chemical bond and interlock structure, effectively mitigating thermal stress concentration at the interface.
Failure Mechanism Identified: The minor TC decline observed is primarily due to the accumulation of residual plastic strain and increased dislocation density within the softer Al matrix, rather than degradation of the diamond/Al interface.
Material Purity Critical: The use of high-purity, low-nitrogen single-crystal diamond (TC up to 1778 W m^-1 K^-1) was essential to achieving the high initial composite TC values.
Application Validation: The results confirm that diamond/Al composites fabricated via gas pressure infiltration, utilizing a chemically stable interface, are highly promising candidates for demanding thermal management applications in aerospace and high-power electronics.

Technical Specifications

Data extracted from the research paper detailing material properties and performance under thermal cycling.

Parameter	Value	Unit	Context
Initial TC (272 µm Composite)	743	W m^-1 K^-1	Diamond/Al Composite (0 cycles)
Final TC (272 µm Composite)	724	W m^-1 K^-1	After 200 thermal cycles
TC Reduction Percentage (272 µm)	2.6	%	Excellent stability
Initial TC (66 µm Composite)	491	W m^-1 K^-1	Diamond/Al Composite (0 cycles)
TC Reduction Percentage (66 µm)	4.7	%	After 200 thermal cycles
Thermal Cycling Range	218 to 423	K	JESD22-A104C H test condition
Diamond Source TC (272 µm)	1778	W m^-1 K^-1	Calculated based on [N] = 129 ppm
Diamond Source TC (66 µm)	1582	W m^-1 K^-1	Calculated based on [N] = 189 ppm
Diamond Volume Fraction (272 µm)	59.2	%	Reinforcement density
Al Matrix TC (Calculated, 272 µm)	222	W m^-1 K^-1	After 200 thermal cycles (12.2% reduction from 237 W m^-1 K^-1)
Al₄C₃ CTE	8.0 x 10^-6	K^-1	Intermediate CTE between Diamond (1.0 x 10^-6 K^-1) and Al (23.4 x 10^-6 K^-1)

Key Methodologies

The diamond/Al composites were fabricated using Gas Pressure Infiltration (GPI) to ensure high density and strong interfacial bonding, followed by rigorous thermal cycling testing.

Reinforcement Selection: Synthetic single-crystal diamond particles (66 µm and 272 µm) with high purity (low nitrogen concentration) were used to maximize intrinsic thermal conductivity.
Preform Fabrication: Diamond particles were densely vibrated into a graphite mold to achieve high packing density (volume fractions of 58.2% and 59.2%).
Gas Pressure Infiltration (GPI):
- Al bulk (99.99 wt%) was heated to 1073 K (800 °C).
- The system was maintained at 1073 K for 30 minutes.
- An Argon (Ar) gas pressure of 1.0 MPa was applied for 20 minutes to infiltrate the molten Al into the diamond preform.
Interface Formation: The high temperature facilitated the in situ reaction between diamond and Al, generating the discrete Al₄C₃ phase necessary for chemical bonding and stress reduction.
Thermal Cycling Test:
- Testing was conducted in a thermal shock chamber (ESPEC TSD-101-W) under an Ar atmosphere to prevent oxidation.
- The temperature range was 218 K to 423 K.
- Samples were subjected to 200 thermal cycles (10 min dwell time at each extreme).
Characterization: Thermal conductivity was measured using Laser Flash Analysis (LFA467). Interfacial structure stability was confirmed via X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Scanning Transmission Electron Microscopy (STEM) after cycling.

6CCVD Solutions & Capabilities

6CCVD specializes in providing the high-purity, high-TC diamond materials and custom processing required to replicate and advance the performance demonstrated in this thermal management research. Our capabilities directly address the need for superior diamond quality and robust interface engineering.

Research Requirement (Diamond/Al Composites)	6CCVD Material Solution & Capability	Technical Advantage
High Thermal Conductivity Diamond Source (TC up to 1778 W m^-1 K^-1)	Optical Grade SCD & High-Purity PCD	Our MPCVD process delivers diamond with ultra-low defect density, ensuring intrinsic TC values exceeding 2000 W m^-1 K^-1. Using 6CCVD material guarantees a higher starting TC for the composite, potentially pushing performance beyond 743 W m^-1 K^-1.
Specific Particle Size/High Volume Fraction (66 µm and 272 µm single crystals)	Custom SCD/PCD Substrates and Processing	We supply SCD plates (up to 500 µm thick) and PCD wafers (up to 125mm) that can be precision laser-cut or processed into custom particle sizes and morphologies required for optimal preform packing density (58%-60% volume fraction).
Robust Interfacial Bonding (Need for stable Al₄C₃ interface)	Advanced Metalization Services (Ti, W, Cu)	While in situ reaction was used, 6CCVD offers custom metalization (e.g., Ti, W, Pt, Cu) to pre-treat diamond surfaces. This guarantees superior wettability and chemical bonding, providing an alternative, highly controlled method for interface engineering in Liquid Metal Infiltration (LMI) or Gas Pressure Infiltration (GPI).
High-Density Electronic Packaging (Need for large, smooth heat spreaders)	Inch-Size PCD Wafers (Ra < 5nm)	For direct integration into high-power modules, our large-area PCD wafers (up to 125mm) can be polished to an ultra-low surface roughness (Ra < 5nm), minimizing Thermal Boundary Resistance (TBR) when bonded to semiconductor devices or heat sinks.
Global Supply Chain	Global Shipping (DDU/DDP)	We ensure reliable, timely delivery of custom diamond materials worldwide, supporting international research and manufacturing schedules.

Engineering Support

The stability of diamond/metal matrix composites is highly dependent on the quality of the diamond source and precise interface control. 6CCVD’s in-house PhD team specializes in material selection and interface optimization for high-reliability thermal management and electronic packaging projects. We provide consultation on:

Selecting the optimal diamond grade (SCD vs. PCD) based on required TC and cost targets.
Designing custom metalization schemes (e.g., Ti/Pt/Au stacks) to enhance chemical reactivity and reduce interfacial thermal resistance (ITR).
Providing custom dimensions and thicknesses (SCD from 0.1 µm to 500 µm; PCD up to 125mm).

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

View Original Abstract

The stability of the thermal properties of diamond/Al composites during thermal cycling is crucial to their thermal management applications. In this study, we realize a well-bonded interface in diamond/Al composites by interfacial in situ Al4C3 engineering. As a result, the excellent stability of thermal conductivity in the diamond/Al composites is presented after 200 thermal cycles from 218 to 423 K. The thermal conductivity is decreased by only 2-5%, mainly in the first 50-100 thermal cycles. The reduction of thermal conductivity is ascribed to the residual plastic strain in the Al matrix after thermal cycling. Significantly, the 272 μm-diamond/Al composite maintains a thermal conductivity over 700 W m−1 K−1 after 200 thermal cycles, much higher than the reported values. The discrete in situ Al4C3 phase strengthens the diamond/Al interface and reduces the thermal stress during thermal cycling, which is responsible for the high thermal conductivity stability in the composites. The diamond/Al composites show a promising prospect for electronic packaging applications.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma15196640

References

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2021 - A review on transient thermal management of electronic devices
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2016 - Effect of (0-40) wt.% Si addition to Al on the thermal conductivity and thermal expansion of diamond/Al composites by pressure infiltration [Crossref]
2017 - Interfacial structure evolution of Ti-coated diamond particle reinforced Al matrix composite produced by gas pressure infiltration [Crossref]