Fabrication of Titanium and Copper-Coated Diamond/Copper Composites via Selective Laser Melting

At a Glance

Metadata	Details
Publication Date	2022-04-30
Journal	Micromachines
Authors	Lu Zhang, Yan Li, Simeng Li, Ping Gong, Qiaoyu Chen
Institutions	China University of Geosciences
Citations	16
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond/Copper Composites via SLM

Executive Summary

This analysis focuses on the successful fabrication of high-performance diamond/copper Metal Matrix Composites (MMCs) using Selective Laser Melting (SLM), demonstrating critical advancements in thermal management materials.

Core Achievement: SLM was validated as a manufacturing route for dense, complex diamond/copper composites, overcoming traditional challenges related to poor diamond-copper wettability.
Interface Engineering: Copper coating (via electroless plating) on diamond particles proved superior to titanium coating, resulting in excellent interfacial bonding and eliminating micro-cracking in optimal samples.
Peak Thermal Performance: A maximum Thermal Conductivity (TC) of 336 W/mK was achieved in 1 vol.% copper-coated diamond/copper composites.
Mechanical Strength: Copper-coated composites exhibited significantly higher bending strength (up to 150 MPa) and lower Coefficients of Thermal Expansion (CTE) compared to titanium-coated materials.
Process Optimization: Optimal SLM parameters were identified, utilizing a volumetric laser energy density of 300 J/mm³ (180 W laser power, 200 mm/s scanning rate) and a thin layer thickness (0.025 mm).
Application Potential: The methodology opens new avenues for 3D printing a wide range of diamond-particle-reinforced MMCs for high-density electronic packaging and advanced heat dissipation systems.

Technical Specifications

The following hard data points were extracted from the research detailing the optimal performance and processing parameters:

Parameter	Value	Unit	Context
Peak Thermal Conductivity (TC)	336	W/mK	1 vol.% Cu-coated composite (300 J/mm³)
Volumetric Laser Energy Density (D)	300	J/mm³	Optimal for peak TC
Laser Power (P)	180	W	Used for peak TC
Scanning Rate (v)	200	mm/s	Used for peak TC
Maximum Bending Strength	150	MPa	1 vol.% Cu-coated composite
Minimum Surface Roughness (S_a)	5.751	µm	Achieved at 180 W, 200 mm/s
Optimal SLM Layer Thickness (t)	0.025	mm	To prevent rubbing/failure
Diamond Particle Size (Average)	25	µm	Used as reinforcement filler
Copper Powder Particle Size (Average)	18.856 ± 15	µm	Used as matrix material
Relative Density (Max)	96	%	1 vol.% Ti-coated composite

Key Methodologies

The fabrication process relied on precise material preparation and optimized Selective Laser Melting (SLM) parameters:

Material Sourcing:
- Micron-level pure gas atomized copper powders (99.99% purity).
- Diamond particles (average size 25 µm).
Surface Modification (Coating):
- Copper Coating: Applied via electroless plating process to enhance wettability.
- Titanium Coating: Applied via evaporation method for comparative testing.
Powder Preparation:
- Coated diamond particles were mixed with copper powder (1, 3, or 5 vol.%) in a ball mill at 100 rpm for 3 hours.
- Mixtures were dried at 60 °C and sifted through a 400 mesh.
Selective Laser Melting (SLM):
- Equipment: SISMA MYSINT100 system utilizing a neodymium-doped yttrium aluminum garnet fiber laser (wavelength: 1060 nm).
- Atmosphere: High-purity N₂ atmosphere (residual oxygen content < 0.5 vol.%) to prevent oxidation.
- Key Parameters:
  - Laser Spot Size: 30 µm.
  - Optimal Layer Thickness (t): 0.025 mm.
  - Hatch Distance (h): Approximately 100 µm (calculated for 60% melt pool overlap).
- Scanning Strategy: Chessboard scan strategy was used for cubic samples (5 × 5 × 5 mm³) to ensure perpendicular scanning directions between adjacent squares.

6CCVD Solutions & Capabilities

The research demonstrates the critical role of high-quality diamond material and precise interface engineering in achieving superior thermal management composites. 6CCVD is uniquely positioned to supply the foundational diamond materials and advanced processing required to replicate and extend this research.

Applicable Materials

To replicate or advance this research, 6CCVD recommends the following MPCVD diamond materials:

High-Purity Polycrystalline Diamond (PCD): Ideal for use as the reinforcement filler in large-volume Metal Matrix Composites (MMCs). 6CCVD can supply PCD plates/wafers up to 125mm in size, which can be processed into high-purity micro-sized particles (like the 25 µm particles used) with controlled defect density.
Optical Grade Single Crystal Diamond (SCD): For high-fidelity interface studies and benchmarking. SCD offers the highest intrinsic thermal properties, providing a perfect baseline for evaluating the effectiveness of various coating and SLM strategies. We offer SCD thicknesses from 0.1µm to 500µm.
Boron-Doped Diamond (BDD): For applications requiring integrated thermal and electrical management, BDD substrates can be used to create composites with tailored electrical conductivity.

Customization Potential

The paper utilized specific rectangular contour (1 × 3 mm²) and cubic (5 × 5 × 5 mm³) samples. 6CCVD’s custom manufacturing capabilities directly support the needs of advanced additive manufacturing research:

Custom Dimensions: We provide diamond plates and wafers in custom dimensions up to 125mm (PCD) and substrates up to 10mm thick, suitable for use as SLM base plates or large-scale heat spreaders.
Precision Polishing: The SLM parts achieved a minimum surface roughness (S_a) of 5.751 µm. For final device integration, 6CCVD offers industry-leading polishing services, achieving surface roughness of Ra < 1nm (SCD) and Ra < 5nm (Inch-size PCD), crucial for minimizing Thermal Boundary Resistance (TBR) in high-power electronic devices.

Metalization and Interface Engineering

The research confirms that the success of diamond/copper MMCs hinges on the quality of the interface coating (Cu vs. Ti). 6CCVD offers comprehensive, in-house metalization services to support interface engineering:

Metalization Service	Relevance to SLM Composites
Titanium (Ti)	Used in the paper for carbide-forming interface layers. 6CCVD offers precise Ti deposition.
Copper (Cu)	Used in the paper’s most successful composites (336 W/mK). We provide high-purity Cu deposition.
Gold (Au), Platinum (Pt), Palladium (Pd)	Essential for subsequent bonding, soldering, or creating robust electrical contacts on the final composite structure.
Tungsten (W)	Alternative carbide-forming element (as cited in related literature) for interface optimization.

Engineering Support

6CCVD’s in-house PhD team specializes in MPCVD growth, material characterization, and interface physics. We provide expert consultation on material selection, pre-treatment, and optimization of diamond properties for similar Thermal Management Materials (TMM) and electronic packaging projects. We can assist researchers in selecting the optimal diamond morphology and purity to maximize the effectiveness of their SLM coating recipes.

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

View Original Abstract

The poor wettability and weak interfacial bonding of diamond/copper composites are due to the incompatibility between diamond and copper which are inorganic nonmetallic and metallic material, respectively, which limit their further application in next-generation heat management materials. Coating copper and titanium on the diamond particle surface could effectively modify and improve the wettability of the diamond/copper interface via electroless plating and evaporation methods, respectively. Here, these dense and complex composites were successfully three-dimensionally printed via selective laser melting. A high thermal conductivity (TC, 336 W/mK) was produced by 3D printing 1 vol.% copper-coated diamond/copper mixed powders at an energy density of 300 J/mm3 (laser power = 180 W and scanning rate = 200 mm/s). 1 and 3 vol.% copper-coated diamond/copper composites had lower coefficients of thermal expansions and higher TCs. They also had stronger bending strengths than the corresponding titanium-coated diamond/copper composites. The interface between copper matrix and diamond reinforcement was well bonded, and there was no cracking in the 1 vol.% copper-coated diamond/copper composite sample. The optimization of the printing parameters and strategy herein is beneficial to develop new approaches for the further construction of a wider range of micro-sized diamond particles reinforced metal matrix composites.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi13050724

References

2020 - Manufacturing of metal matrix composites: A state of review [Crossref]
2020 - A review of processing of Cu/C base plate composites for interfacial control and improved properties [Crossref]
2019 - Pore elimination mechanisms during 3D printing of metals [Crossref]
2010 - Selective laser melting W-10 wt% Cu composite powders [Crossref]
2017 - Microstructural and mechanical characterization of aluminum matrix composites produced by laser powder bed fusion [Crossref]
2011 - Nanocrystalline TiC reinforced Ti matrix bulk-form nanocomposites by selective laser melting (SLM): Densification, growth mechanism and wear behavior [Crossref]
2020 - Selective laser melting of TiN nanoparticle-reinforced AlSi10Mg composite: Microstructural, interfacial, and mechanical properties [Crossref]
2014 - Densification behavior, microstructure evolution, and wear property of TiC nanoparticle reinforced AlSi10Mg bulk-form nanocomposites prepared by selective laser melting [Crossref]
2002 - In-situ formation of copper matrix composites by laser sintering [Crossref]
2001 - Selective laser sintering of TiC-Al2O3 composite with selfpropagating high-temperature synthesis [Crossref]