Diamond coatings on femtosecond-laser-textured stainless steel 316 surfaces for enhanced adherence

At a Glance

Metadata	Details
Publication Date	2023-12-17
Journal	Diamond and Related Materials
Authors	Zhipeng Wu, Wanting Sun, Aofei Mao, Qiuchi Zhu, Xin Chen
Institutions	Centre National de la Recherche Scientifique, Institut Polytechnique de Bordeaux
Citations	6
Analysis	Full AI Review Included

Technical Documentation & Analysis: Enhanced Diamond Adherence on Textured SS 316

Executive Summary

This research successfully addresses the critical challenge of poor diamond adherence on metallic substrates (Stainless Steel 316) caused by the large coefficient of thermal expansion (CTE) mismatch. The key findings and methodology are highly relevant for industrial applications requiring robust diamond coatings on steel components (e.g., cutting tools, bearings).

Adhesion Solution: Femtosecond (fs)-laser texturing was employed to create periodic microgrids on SS 316, providing stress relief and enhanced mechanical interlocking at the diamond-metal interface.
Stress Mitigation: The residual stress in the diamond coating was successfully transitioned from high compressive stress (on bare SS) to low tensile stress, decreasing to a minimum of 0.46 GPa at the optimal microgrid depth.
High Quality Growth: The texturing process accelerated diamond growth kinetics, yielding a maximum coating thickness of 19 µm and an exceptional diamond quality factor of up to 96% (analyzed via Raman spectroscopy).
Optimized Morphology: Optimized fs-laser parameters resulted in microgrids up to 40 µm deep, facilitating the growth of large diamond crystals with an average grain size of 9 µm.
Methodology: Diamond films were deposited using Laser-Assisted Combustion Flame Chemical Vapor Deposition (LACF-CVD) at a substrate temperature of approximately 720 °C.
Industrial Relevance: This work provides a scalable strategy for producing highly adherent, high-quality polycrystalline diamond (PCD) coatings on complex ferrous alloys, crucial for extreme environment applications.

Technical Specifications

The following hard data points were extracted from the experimental results, focusing on optimized parameters (40 µm microgrid depth, 30 min deposition).

Parameter	Value	Unit	Context
Maximum Diamond Thickness	19	µm	Achieved at 40 µm microgrid depth
Maximum Diamond Quality Factor	96	%	Evaluated by Raman spectroscopy
Average Diamond Grain Size	9	µm	Optimized on 40 µm microgrids
Deposition Temperature	720	°C	Maintained during LACF-CVD
Optimized Microgrid Depth	40	µm	Achieved using 75 fs-laser scanning passes
Minimum Residual Stress (Tensile)	0.46	GPa	Achieved at 40 µm microgrid depth (30 min)
Diamond CTE (Mean)	3.5 x 10^-6	/K	Polycrystalline CVD diamond
Steel CTE (Mean)	10.7 x 10^-6	/K	Austenite-ferrite transforming steel
fs-Laser Pulse Duration	408	fs	Used for surface texturing
fs-Laser Frequency	330	kHz	Used for surface texturing

Key Methodologies

The experiment combined advanced laser texturing with specialized CVD techniques to achieve superior interfacial properties.

Substrate Pretreatment:
- Substrate Material: Commercial Stainless Steel 316 plates (10x10x1 mm³).
- Cleaning: Ultrasonically cleaned in acetone for 10 min.
- Seeding: Substrates were seeded in a nanodiamond slurry (particle size < 10 nm).
fs-Laser Surface Texturing:
- Laser Type: Femtosecond (fs) laser (Amplitude Inc, Tangor) at 1030 nm wavelength.
- Laser Parameters: 14 W power, 30 µm spot diameter, 1 m/s scanning speed.
- Microgrid Geometry: Periodic patterns achieved by scanning in two perpendicular directions.
- Grid Pitch Distance: 60 µm (maintained constant).
- Depth Control: Varied by scanning passes (25, 45, 75 passes) to achieve depths of 10, 25, and 40 µm.
Diamond Deposition (LACF-CVD):
- Method: Laser-Assisted Combustion Flame Chemical Vapor Deposition (CVD).
- Gas Precursors: Acetylene (C₂H₂), Ethylene (C₂H₄), and Oxygen (O₂).
- Flow Ratio (C₂H₂:C₂H₄:O₂): 910:400:1200 standard cubic centimeter per minute (sccm).
- Substrate Temperature: Maintained at approximately 720 °C using an infrared pyrometer and water-cooling system.
Characterization:
- Morphology/Thickness: SEM (cross-sectional analysis using electrical discharge machining).
- Phase Constitution: XRD (PANalytical Empyrean, Cu Kα source).
- Quality/Stress: Raman spectroscopy (514.5 nm argon-ion laser) to measure the diamond peak shift and quality factor.

6CCVD Solutions & Capabilities

6CCVD specializes in delivering high-performance MPCVD diamond materials tailored for complex engineering challenges, such as the CTE mismatch addressed in this research. We provide the necessary materials and customization services to replicate, scale, and enhance this technology for commercial deployment.

Applicable Materials

To replicate or extend this research, the ideal material is high-quality Polycrystalline Diamond (PCD) grown via MPCVD, offering superior control over grain size and purity compared to combustion flame methods.

6CCVD Material Recommendation	Key Features & Relevance
High-Purity Polycrystalline Diamond (PCD)	Provides the required hardness, thermal conductivity, and chemical inertness for harsh environments (e.g., cutting tools, sensors). Our MPCVD process ensures the high quality factor (> 96%) demonstrated in the paper.
Custom Substrates (Diamond on Metal)	While the paper focused on SS 316, 6CCVD can grow PCD directly onto various customer-supplied substrates, or provide the PCD layer for subsequent bonding/integration.

Customization Potential

6CCVD’s in-house capabilities directly address the critical requirements for scaling this technology: custom dimensions, precise thickness control, and advanced interface engineering.

Research Requirement	6CCVD Customization Service	Technical Advantage
Large Area Substrates	Plates/wafers up to 125 mm (PCD)	Enables industrial scaling far beyond the 10x10 mm² samples used in the study.
Precision Thickness	SCD/PCD films available from 0.1 µm up to 500 µm	Offers precise control over coating thickness, crucial for optimizing stress relief and mechanical bonding on textured surfaces.
Surface Interface Engineering	Custom Laser Cutting & Etching: We offer services to pre-pattern or texture substrates, ensuring optimal mechanical interlocking and stress distribution, mirroring the fs-laser effect.	Provides a streamlined supply chain for complex, pre-treated substrates ready for diamond deposition.
Functional Integration	Internal Metalization Capability: We apply custom metal layers (Au, Pt, Pd, Ti, W, Cu) for electrical contacts or diffusion barriers, essential for sensor or electronic applications.	Ensures robust, high-adhesion metal contacts on the high-quality diamond surface.

Engineering Support

6CCVD understands that successful diamond integration on metallic substrates requires precise control over interfacial stress. Our in-house PhD team specializes in material selection and growth parameter optimization for projects involving large CTE mismatches.

Stress Mitigation Consultation: We offer expert consultation on optimizing diamond growth recipes (e.g., gas ratios, temperature profiles) to manage residual stress, building upon the stress relief principles demonstrated in this paper.
Application Focus: Our team can assist engineers and scientists in selecting the appropriate PCD grain size and quality for similar wear-resistant coatings and harsh environment sensor projects.

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

Tech Support

Original Source

DOI: https://doi.org/10.1016/j.diamond.2023.110744

References

2021 - Progress in semiconductor diamond photodetectors and MEMS sensors [Crossref]
2021 - Quantum computer based on color centers in diamond [Crossref]
2021 - Diamond as the heat spreader for the thermal dissipation of GaN-based electronic devices [Crossref]
2022 - Deposition of an adherent diamond film on stainless steel using Cr/CrAlN as an interlayer [Crossref]
2020 - Diamond deposition on iron and steel substrates: a review [Crossref]
2011 - Influence of WC-Co substrate pretreatment on diamond film deposition by laser-assisted combustion synthesis [Crossref]
2018 - Ultraviolet laser photolysis of hydrocarbons for nondiamond carbon suppression in chemical vapor deposition of diamond films [Crossref]
2019 - Catalytic graphite mechanism during CVD diamond film on iron and cobalt alloys in CH4-H2 atmospheres [Crossref]
2015 - Metal dusting, carburization and diamond deposition on Fe-Cr alloys in CH4-H2 plasma atmospheres [Crossref]
2013 - Direct coating adherent diamond films on Fe-based alloy substrate: the roles of Al, Cr in enhancing interfacial adhesion and promoting diamond growth [Crossref]