Laser Fusion of Aluminum Powder Coated with Diamond Particles via Selective Laser Melting - Powder Preparation and Synthesis Description

At a Glance

Metadata	Details
Publication Date	2021-10-05
Journal	Coatings
Authors	Alexander S. Shinkaryov, D. Yu. Ozherelkov, Ivan A. Pelevin, С. А. Еремин, V. N. Anikin
Institutions	National University of Science and Technology, Skolkovo Institute of Science and Technology
Citations	15
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond-Reinforced Aluminum Composites via SLM

Executive Summary

This research successfully demonstrates the fabrication of high-performance Aluminum-Carbon (Al-C) Metal Matrix Composites (MMC) using Selective Laser Melting (SLM) reinforced with nanodiamond particles. The key findings and value proposition for engineers are summarized below:

High-Performance Composite Synthesis: Al-C composites were successfully synthesized using SLM by coating AlSi10MgCu powder (43 µm) with 500 nm nanodiamond particles (0.67 wt %).
Significant Hardness Improvement: The resulting composite material achieved a microhardness of up to 172 ± 5 HV50, significantly exceeding the hardness of the base AlSi10MgCu alloy (95-105 HV).
Interfacial Bonding Confirmation: X-ray Diffraction (XRD) confirmed the formation of the desirable Al₄C₃ aluminum carbide phase, indicating strong chemical bonding between the matrix and the carbon reinforcement.
Process Optimization for Nanodiamonds: Optimal SLM parameters were determined (Laser Energy Density 1.40-2.0 J/mm²) to balance sufficient matrix melting while minimizing the graphitization of the nanodiamond reinforcement, a critical challenge in high-temperature processing.
Additive Manufacturing Potential: This work validates the feasibility of using submicron diamond particles in additive manufacturing (SLM) to create complex, high-strength, wear-resistant components for aerospace and tooling applications.
Material Challenge Addressed: The study provides crucial data on mitigating diamond graphitization and managing residual oxygen/porosity during SLM of diamond-reinforced MMCs.

Technical Specifications

Hard data extracted from the research paper detailing the composite materials and processing parameters.

Parameter	Value	Unit	Context
Reinforcement Particle Size (D_avg)	500	nm	Nanodiamond fraction used for coating
Reinforcement Thickness	20-30	nm	Thickness of lamellar diamond particles
Diamond Content	0.67	wt %	Concentration in the composite powder
Matrix Powder Median Diameter (D₅₀)	43	µm	Initial AlSi10MgCu alloy powder
Highest Microhardness Achieved	172 ± 5	HV50	SLM Sample 10 (300 W, 1650 mm/s)
Base Alloy Hardness (Reference)	95-105	HV	AlSi10MgCu alloy without reinforcement
Optimal Laser Energy Density (LED) Range	1.40 - 2.0	J/mm²	Range identified for dense, hard composite
Laser Power Range Tested	250 - 370	W	SLM fiber laser source
Scanning Speed Range Tested	850 - 1650	mm/s	SLM process parameter
Powder Layer Thickness	50	µm	SLM process parameter
Laser Spot Size	80	µm	SLM process parameter
Maximum Estimated SLM Temperature	Up to 2000	°C	Temperature during high-power laser melting
Confirmed Carbide Phase	Al₄C₃	N/A	Aluminum carbide (via XRD)

Key Methodologies

The following steps outline the preparation and synthesis methods used to create the Al-C composite via Selective Laser Melting:

Nanodiamond Synthesis and Purification:
- Nanodiamonds were synthesized via detonation of an explosive mixture (TNT/RDX ratio of 1.5).
- Purification involved a two-stage washing process: (i) mixture of nitric and sulfuric acids, followed by (ii) washing with distilled water to remove non-diamond carbon (40 wt % of initial blend).
Matrix Powder Preparation:
- Initial matrix material was gas-sprayed AlSi10MgCu alloy powder (D₅₀ = 43 µm).
- Chemical composition (wt %): 87% Al, 10.7% Si, 0.5% Mg, 0.7% Cu, 0.5% Mn, 0.2% Ti, 0.3% Fe.
Composite Powder Coating:
- AlSi10MgCu powder was mechanically coated with 500 nm diamond particles using a laboratory roller mill.
- Mixing parameters: Drum rotation speed (ω) = 48 rpm, ensuring coating without grinding.
- Final diamond content: 0.67 wt %.
Selective Laser Melting (SLM):
- Equipment: SLM Solutions 280 HL 3D printer equipped with a fiber laser.
- Atmosphere: Argon atmosphere (residual oxygen content < 0.2 vol.%).
- Build Strategy: Samples built in the Z-axis direction with 67° layer-to-layer rotation.
- Fixed Parameters: Hatch distance = 130 µm; Layer thickness = 50 µm; Laser spot size = 80 µm.
Characterization:
- Microstructure: Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
- Phase Analysis: X-ray Diffraction (XRD) and Raman Spectroscopy (confirmed diamond presence and Al₄C₃ formation).
- Surface Chemistry: X-ray Photoelectron Spectroscopy (XPS) with Ar⁺ ion etching (analyzed oxide layers and elemental composition).
- Mechanical Testing: Vickers Microhardness (HV50) using a 490.3 N loading test force.

6CCVD Solutions & Capabilities

The successful integration of diamond reinforcement into metal matrices via SLM requires materials with exceptional purity, controlled morphology, and precise surface engineering—all core competencies of 6CCVD.

Applicable Materials for Advanced MMCs

The research highlights the challenge of diamond graphitization at high SLM temperatures (up to 2000 °C). High-purity CVD diamond precursors offer superior thermal stability compared to detonation nanodiamonds, minimizing unwanted reactions and gas formation.

Material Requirement	6CCVD Solution	Technical Advantage
High Purity Reinforcement	High Purity Polycrystalline Diamond (PCD)	CVD-grown PCD powder or micronized SCD powder offers significantly higher purity than detonation nanodiamonds, increasing the graphitization threshold (typically 1500 °C in inert atmosphere) and improving composite stability.
Controlled Morphology	Custom SCD/PCD Precursors	We can supply SCD or PCD material that can be micronized or processed into specific morphologies (e.g., lamellar or sub-micron powders) to optimize mechanical interlocking and surface area for coating, replicating or improving upon the 500 nm fraction used.
Interfacial Enhancement	Boron-Doped Diamond (BDD)	While not used in this study, BDD films or powders can be explored for matrix reinforcement where specific electrical or electrochemical properties are required alongside mechanical strength.

Customization Potential for SLM Precursors

To replicate or advance the results of this study, 6CCVD offers specialized material preparation and engineering services:

Custom Metalization Services: The literature review noted that coating diamond particles (e.g., with Ti) enhances adhesion and prevents direct reaction with the Al matrix. 6CCVD offers in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu) for diamond surfaces, enabling the creation of pre-treated, reaction-barrier-coated diamond particles optimized for SLM.
Precision Sizing and Polishing: Although this study used powder, 6CCVD specializes in large-area PCD plates (up to 125mm) and SCD wafers with ultra-low roughness (Ra < 1nm for SCD, < 5nm for PCD). This capability ensures that any diamond material derived for powder applications maintains the highest structural integrity and purity.
Custom Dimensions and Thickness: For post-SLM processing or integration into larger systems, 6CCVD can supply SCD or PCD substrates up to 10mm thick, or thin films (0.1µm - 500µm) for specialized coating applications.

Engineering Support

The primary technical challenge identified in this research is the delicate balance between achieving sufficient laser energy density for matrix melting and avoiding the thermal degradation (graphitization) of the diamond reinforcement.

6CCVD’s in-house PhD team specializes in the thermal and chemical stability of CVD diamond and can assist researchers and engineers with material selection and process optimization for similar Metal Matrix Composite (MMC) Additive Manufacturing projects. We offer consultation on:

Selecting diamond grades with optimal thermal stability for high-temperature SLM.
Designing custom metalization layers (e.g., Ti/W) to promote stable carbide formation (like Al₄C₃) at the interface while inhibiting bulk graphitization.
Providing high-purity diamond materials that minimize residual impurities (like those found in detonation nanodiamonds) which act as catalysts for graphitization.

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

View Original Abstract

This work aims to study the possibility of obtaining Al-C composite from AlSi10MgCu aluminum matrix with the addition of 500 nm-sized diamond particles by selective laser melting (SLM) process. Al-C composite powder was prepared by mechanical mixing to form a uniform cover along the surface of aluminum particles. The diamond content in the resulting AlSi10MgCu-diamond composite powder was equal to 0.67 wt %. The selection of the optimal SLM parameters for the obtained composite material is presented. For materials characterization, the following methods were used: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) was applied after SLM printing for a detailed investigation of the obtained composites. The presence of carbon additives and the formation of aluminum carbides in the material after the SLM process were demonstrated.

Tech Support

Original Source

DOI: https://doi.org/10.3390/coatings11101219

References

2003 - P/M aluminum matrix composites: An overview [Crossref]
1976 - Aluminum matrix composites: Fabrication and properties [Crossref]
2014 - Investigations on mechanical properties of aluminum hybrid composites [Crossref]
2019 - Microstructure characteristics and its formation mechanism of selective laser melting SiC reinforced Al-based composites [Crossref]
2019 - Laser solid forming additive manufac-turing TiB2 reinforced 2024Al composite: Microstructure and mechanical properties [Crossref]
2015 - Nanometric TiC reinforced AlSi10Mg nanocomposites: Powder preparation by high-energy ball milling and consolidation by selective laser melting [Crossref]