Effect of Nanoscale W Coating on Corrosion Behavior of Diamond/Aluminum Composites

At a Glance

Metadata	Details
Publication Date	2023-01-11
Journal	Nanomaterials
Authors	Ping Zhu, Qiang Zhang, Yixiao Xia, Kai Sun, Xiu Lin
Institutions	Harbin Institute of Technology, National Academy of Sciences of Belarus
Citations	9
Analysis	Full AI Review Included

Executive Summary

This research focuses on enhancing the corrosion resistance and stability of diamond/aluminum (D/Al) composites for high-performance thermal management applications by modifying the diamond-aluminum interface with a nanoscale Tungsten (W) coating.

Core Value Proposition: Introduction of a 100 nm W nanoscale coating effectively suppresses the formation of brittle, hydrolyzable aluminum carbide (Al₄C₃), which is the primary cause of performance degradation and corrosion in D/Al composites.
Corrosion Resistance: W-coated D/Al exhibited a corrosion rate of only 0.09 mm/a in 3.5 wt.% NaCl solution, drastically lower than the 1.21 mm/a rate measured for uncoated D/Al composites.
Thermal Stability: The W coating significantly improved thermal conductivity stability, limiting degradation to 4.2% after full immersion corrosion, compared to a 12.7% loss for uncoated D/Al.
Mechanical Stability: Post-corrosion bending strength of W-coated D/Al (195 MPa) remained superior to that of uncoated D/Al (180 MPa), confirming enhanced interface integrity.
Mechanism Clarification: Corrosion in uncoated D/Al is dominated by preferential pitting and interface denudation resulting from the hydrolysis of Al₄C₃, while W coating promotes aluminum matrix galvanic corrosion due to low Al₄C₃ content and good W resistance.
Interface Phase Control: The W coating reacted with the aluminum matrix to form Al₁₂W, which improved interface bonding and reduced the contact time between diamond and aluminum, inhibiting Al₄C₃ generation.

Technical Specifications

Parameter	Value	Unit	Context
Diamond Particle Size	~100	µm	Synthetic monocrystalline (MBD4-grade)
W Coating Thickness	100	nm	Deposited via magnetron sputtering
Sputtering Temperature	400	°C	W coating deposition
Infiltration Temperature	700	°C	Gas assisted pressure infiltration
Infiltration Pressure	15	MPa	Composite fabrication
Diamond Volume Fraction	60	%	Final composite composition
Corrosion Medium	3.5	wt.%	NaCl solution (marine atmosphere simulation)
Uncoated D/Al Corrosion Rate (24h)	1.21	mm/a	Full immersion test
W-Coated D/Al Corrosion Rate (24h)	0.09	mm/a	Full immersion test
Uncoated D/Al Thermal Conductivity (Initial)	604	W/(m·K)	Before corrosion
W-Coated D/Al Thermal Conductivity (Initial)	579	W/(m·K)	Before corrosion
Uncoated D/Al Thermal Conductivity Loss	12.7	%	After full immersion corrosion
W-Coated D/Al Thermal Conductivity Loss	4.2	%	After full immersion corrosion
W-Coated D/Al Bending Strength (Initial)	319	MPa	Before corrosion
W-Coated D/Al Bending Strength (Post-Corrosion)	195	MPa	After full immersion corrosion

Key Methodologies

Diamond Surface Coating:
- A 100 nm W coating (99.99% purity target) was deposited onto 100 µm diamond particles using magnetron sputtering (MSP-5100B system).
- Sputtering was conducted at 400 °C for 180 min, maintaining a pressure range of 5 x 10^-3 to 9 x 10^-3 Pa.
Composite Fabrication:
- W-coated and uncoated diamond/aluminum (99.99 wt.% Al) composites (60% diamond volume fraction) were fabricated using the gas-assisted pressure infiltration method.
- Infiltration parameters were set at 700 °C for 30 min, followed by pressurization to 15 MPa.
Corrosion Testing (Full Immersion):
- Cylinder specimens were immersed in 3.5 wt.% NaCl solution. The solution was replaced every seven days.
- Corrosion weight loss was measured periodically, determining total test times of 144 h (uncoated) and 264 h (W-coated).
Electrochemical Analysis:
- Potentiodynamic polarization curves were measured using a PARCM332 system to compare the corrosion potential (E_corr) and corrosion current density (I_corr) of the two composite types.
Characterization:
- Phase composition (including Al₄C₃ and Al₁₂W) was analyzed using X-ray Diffraction (XRD) before and after corrosion.
- Microstructure and corrosion morphology were examined using Field-Emission Scanning Electron Microscopy (FE-SEM).
- Thermal conductivity was determined by measuring thermal diffusion coefficient (k) using Netzsch LFA 467 Nanoflash and calculating Λ = k · ρ · c.

Commercial Applications

The enhanced corrosion resistance and stability of W-coated diamond/aluminum composites make them highly suitable for demanding applications in thermal management and electronics:

High-Power Electronic Packaging: Ideal for substrates and heat sinks in high-power density devices (e.g., CPUs, GPUs, IGBTs) where reliable heat dissipation is critical, especially in humid or corrosive operating environments.
Aerospace and Defense Systems: Use in electronic components requiring stable thermal and mechanical properties under exposure to marine or high-humidity conditions, preventing performance failure due to interface degradation.
Automotive Power Electronics: Application in electric vehicle (EV) battery management systems and power converters that require robust, lightweight thermal management materials resistant to environmental factors.
Metal-Matrix Composite (MMC) Development: The W coating strategy provides a proven method for interfacial modification to improve the long-term reliability of ceramic-reinforced aluminum MMCs, extending their practical application range.
Industrial Heat Exchangers: Components where high thermal flux must be managed while maintaining structural integrity and corrosion resistance against industrial coolants or atmospheric exposure.

View Original Abstract

The stability of diamond/aluminum composite is of significant importance for its extensive application. In this paper, the interface of diamond/aluminum composite was modified by adding nanoscale W coating on diamond surface. We evaluated the corrosion rate of nanoscale W-coated and uncoated diamond/aluminum composite by a full immersion test and polarization curve test and clarified the corrosion products and corrosion mechanism of the composite. The introduction of W nanoscale coating effectively reduces the corrosion rate of the diamond/aluminum composite. After corrosion, the bending strength and thermal conductivity of the nanoscale W-coated diamond/aluminum composite are considerably higher than those of the uncoated diamond/aluminum composite. The corrosion loss of the material is mainly related to the hydrolysis of the interface product Al4C3, accompanied by the corrosion of the matrix aluminum. Our work provides guidance for improving the life of electronic devices in corrosive environments.

Tech Support

Original Source

DOI: https://doi.org/10.3390/nano13020307

References

2020 - Diamond in medical devices and sensors: An overview of diamond surfaces [Crossref]
2018 - Thermal conductivity of high purity synthetic single crystal diamonds [Crossref]
2014 - Optimisation of high thermal conductivity Al/diamond composites produced by gas pressure infiltration by controlling infiltration temperature and pressure [Crossref]
2021 - Improvement of thermal conductivity of diamond/Al composites by optimization of liquid-solid separation process [Crossref]
2018 - Enhanced thermal conductivity of diamond/aluminum composites through tuning diamond particle dispersion [Crossref]
2020 - Characterization of interfacial bonding strength at Al(Si)/diamond interfaces by neutron diffraction: Effect of diamond surface termination and processing conditions [Crossref]
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]
2022 - Research progress of diamond/aluminum composite interface design [Crossref]