Preparation and Property Modulation of Multi-Grit Diamond/Aluminum Composites Based on Interfacial Strategy

At a Glance

Metadata	Details
Publication Date	2024-07-09
Journal	Metals
Authors	Hao Wu, Sen Yang, Chen Yang, Xiaoxuan He, Changrui Wang
Institutions	Nanjing Institute of Railway Technology, Nanjing University of Aeronautics and Astronautics
Citations	1
Analysis	Full AI Review Included

Executive Summary

Core Achievement: Successful preparation and optimization of multi-grit Diamond/Aluminum (D/Al) composites via Spark Plasma Sintering (SPS) for high-performance heat sink applications.
Interfacial Strategy: Performance modulation was achieved by adjusting the diamond particle size, which controls the number, area, and bonding quality of the heterogeneous diamond-aluminum interfaces.
Optimal Performance Point: The composite reinforced with 150 µm diamond particles demonstrated the best overall properties, balancing thermal and mechanical requirements.
Thermal Excellence: Achieved a high Thermal Conductivity (TC) of 660.1 W/mK, significantly utilizing the diamond phase potential.
CTE Matching: The Coefficient of Thermal Expansion (CTE) was minimized to 5.63 x 10^-6/K, providing an excellent thermal match for typical semiconductor materials, reducing thermal stress failures.
Mechanical Reliability: The optimal composite exhibited a high flexural bending strength of 304.6 MPa, ensuring reliable structural support in electronic packaging.
Process Efficiency: The SPS method enabled high heating speed and preparation efficiency, resulting in high material densification (99.5% relative density) and controlled interfacial carbide (Al₄C₃) formation.

Technical Specifications

Parameter	Value	Unit	Context
Peak Thermal Conductivity (TC)	660.1	W/mK	Achieved with 150 µm diamond particles.
Minimum Coefficient of Thermal Expansion (CTE)	5.63 x 10^-6	/K	Optimal value for semiconductor matching (150 µm).
Peak Flexural Bending Strength	304.6	MPa	Achieved with 150 µm diamond particles.
Peak Relative Density (RD)	99.5	%	Achieved with 150 µm diamond particles.
Matrix Material	Al-12wt%Si	Powder	Average particle size 10 µm.
Reinforcement Material	MBD4-type Synthetic Diamond	Powder	Particle sizes tested: 50, 100, 150, 200 µm.
Volume Ratio (Diamond:Al)	3:2	N/A	Proportioning of mixed powders.
SPS Sintering Temperature	510	°C	Constant sintering temperature.
SPS Uniaxial Pressure	50	MPa	Constant pressure maintained during sintering.
SPS Holding Time	5	min	Duration of sintering reaction.
Diamond Intrinsic TC (Reference)	1200 ~ 2000	W/mK	Ultra-high TC of the reinforcing phase.
Al Intrinsic CTE (Reference)	23.6 x 10^-6	/K	High CTE of the matrix phase.

Key Methodologies

Material Selection and Proportioning: Al-12wt%Si alloy powder (10 µm) was chosen as the matrix. MBD4-type synthetic diamond powders were used as reinforcement, testing four different average particle sizes (50, 100, 150, 200 µm). The powders were mixed at a fixed 3:2 volume ratio (Diamond:Al).
Spark Plasma Sintering (SPS): The mixed powders were loaded into graphite molds. The chamber was evacuated to below 10 Pa vacuum before heating commenced.
Sintering Parameters: The material was heated to 510 °C at a rate of 50 °C/min. A constant uniaxial pressure of 50 MPa was applied and held for 5 minutes to promote densification and interfacial bonding.
Interfacial Analysis (XRD/SEM): X-ray Diffraction (XRD) confirmed the presence of the reaction product Al₄C₃, indicating chemical bonding. Scanning Electron Microscopy (SEM) was used to visualize the fracture surfaces and the heterogeneous interface bonding state.
Thermal Property Measurement: Thermal diffusivity (α_c) and specific heat capacity (C_p) were measured using the Laser Flash Method (LINSEIS-LFA). Thermal Conductivity (TC) was calculated using the formula: λ_e = α_cρ_cC_p.
CTE and Mechanical Testing: CTE was measured between 25 °C and 100 °C using a thermal expansion coefficient tester. Flexural bending strength was tested using a computerized tensile testing machine.
Theoretical Modeling: The Acoustic Mismatch Model (AMM) was combined with the Differential Medium Model (DEM) to theoretically predict and analyze the interfacial thermal resistance and overall TC based on particle size effects.

Commercial Applications

The optimized Diamond/Aluminum composites are critical for high-reliability thermal management in demanding electronic systems:

Advanced Electronic Packaging: Used as heat spreaders and substrates where high heat flux density requires rapid and efficient heat dissipation.
5G and Telecommunications: Cooling high-power amplifiers and integrated circuits in base stations and network infrastructure.
High-Performance Computing (HPC): Thermal solutions for servers, data centers, and AI accelerators where maintaining low operating temperatures is essential for reliability and speed.
Power Electronics: Substrates for IGBTs (Insulated Gate Bipolar Transistors) and other high-power switching modules in electric vehicles and industrial control systems, requiring matched CTE to prevent solder joint failure.
Aerospace and Defense: Applications demanding lightweight materials with exceptional thermal stability and mechanical robustness under extreme temperature cycling.

View Original Abstract

The development of electronic devices has a tendency to become more complicated in structure, more integrated in function, and smaller in size. The heat flow density of components continues to escalate, which urgently requires the development of heat sink materials with high thermal conductivity and a low coefficient of expansion. Diamond/aluminum composites have become the research hotspot of thermal management materials with excellent thermophysical and mechanical properties, taking into account the advantages of light weight. In this paper, diamond/Al composites are prepared by combining aluminum as matrix and diamond reinforcement through the discharge plasma sintering (SPS) method. The micro-interfacial bonding state of diamond and aluminum is changed by adjusting the particle size of diamond, and the macroscopic morphology performance of the composites is regulated. Through this, the flexible design of diamond/Al performance can be achieved. As a result, when 150 μm diamond powder and A1-12Si powder were used for the composite, the thermal conductivity of the obtained specimens was up to 660.1 W/mK, and the coefficient of thermal expansion was 5.63 × 10−6/K, which was a good match for the semiconductor material. At the same time, the bending strength is 304.6 MPa, which can satisfy the performance requirements of heat-sinking materials in the field of electronic packaging.

Tech Support

Original Source

DOI: https://doi.org/10.3390/met14070801

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