Diamond Films on Stainless Steel Substrates with an Interlayer Applied by Laser Cladding

At a Glance

Metadata	Details
Publication Date	2017-03-06
Journal	Materials Research
Authors	André Contin, Kenya Aparecida Alves, Raonei Alves Campos, Getúlio de Vasconcelos, Djoille Denner Damm
Institutions	Universidade Federal do Sul e Sudeste do Pará, National Institute for Space Research
Citations	10
Analysis	Full AI Review Included

Diamond Films on Stainless Steel Substrates via Laser Cladding Interlayers: A 6CCVD Technical Analysis

This documentation analyzes the research regarding the deposition of adherent CVD diamond films on stainless steel using an intermediate silicon carbide (SiC) barrier applied via laser cladding. The findings are contextualized against 6CCVD’s advanced MPCVD capabilities, specifically highlighting solutions for challenging substrate adhesion requirements.

Executive Summary

This research successfully demonstrates a novel approach for depositing highly adherent diamond films on AISI 304L stainless steel, a substrate traditionally plagued by poor adhesion due to chemical incompatibility and thermal mismatch.

Core Achievement: Highly adherent MPCVD diamond films were achieved on AISI 304L steel by utilizing a SiC intermediate layer created through an innovative laser cladding process.
Adhesion Mechanism: The SiC layer (approx. 30 µm thick) served as a dual-function barrier, effectively blocking the catalytic diffusion of iron (Fe) from the substrate and the high diffusion rate of carbon from the gas phase.
Thermal Stress Mitigation: Deposition was performed at a lowered substrate temperature of 630 °C, combined with the intermediate thermal expansion coefficient of SiC, to successfully reduce residual stress and inhibit diamond film fragmentation.
Film Quality: The resulting films exhibited excellent adhesion, confirmed by a high critical load failure force of 41 N during scratch testing and inhibition of radial crack formation during high-load Rockwell indentation (up to 1470 N).
Growth Methodology: Diamond nucleation utilized the Electrostatic Self-Assembly (ESA) process with 4 nm diamond powders. Growth employed Hot Filament CVD (HFCVD) enhanced by Time Modulated Chemical Vapor Deposition (TMCVD) to control microstructure.
Material Compatibility: The SiC barrier enabled a strong metallurgical bond, mitigating the severe thermal expansion mismatch between diamond (0.8x 10^-6 K^-1) and AISI 304L steel (17.3x 10^-6 K^-1).

Technical Specifications

The following hard data points detail the preparation and performance metrics of the SiC interlayer and the resulting diamond film.

Parameter	Value	Unit	Context
Substrate Material	AISI 304L	Steel	Disks (25.4 mm diameter x 3 mm thickness)
SiC Interlayer Thickness	~30	µm	Formed by Laser Cladding
SiC Powder Grain Size	4	µm	Used for Laser Cladding
HFCVD Filament Temperature	~2200	°C	6 Tungsten filaments (125 µm diameter)
Substrate Deposition Temperature	630	°C	Optimized to lessen thermal stress
Total Deposition Time	3	h	Using Time Modulated CVD (TMCVD)
Working Pressure	50	Torr	Constant during HFCVD process
Methane Concentration (Modulated)	2 to 6	%	Used for TMCVD growth
SiC Surface Roughness (Ra)	1.80	µm	After laser cladding and sintering
Critical Load (First Failure)	41	N	Scratch Test result for SiC/Steel adhesion
Diamond Raman Peak (SCD)	1334	cm^-1	Characteristic diamond peak (Indicates high quality)
Graphite D-Band Peak	1350	cm^-1	Found on control sample (bare steel)
Steel Thermal Expansion Coeff.	17.3x 10^-6	K^-1	High mismatch relative to diamond

Key Methodologies

The experiment combined innovative laser cladding for interface engineering with a time-modulated HFCVD recipe.

Intermediate Layer Fabrication (Laser Cladding):
- AISI 304L steel substrates were prepared.
- SiC powder (4 µm grain size) was applied to the substrate surface.
- A CO₂ laser beam (70 kW/cm² intensity) irradiated the powder/substrate interface.
- Processing utilized 1 to 3 SiC layers, with parameters including 600 dots per square inch (dpi) resolution and scanning speeds ranging from 50 to 100 mm/s under a N₂ atmosphere (5 l/min flow).
Diamond Seeding (Electrostatic Self-Assembly - ESA):
- Samples were immersed in an aqueous solution of PDDA {- Poly(diallyldimethylamonium chloride)} for 30 minutes.
- Samples were then immersed for 30 minutes in an aqueous solution containing 4 nm dispersed diamond powder and the anionic polymer PSS - (Poly(sodium 4 - styrenesulfonate)).
Diamond Growth (HFCVD with TMCVD):
- Activation: Six tungsten filaments (125 µm diameter) were heated to ~2200 °C.
- Substrate Control: Substrate surface temperature was maintained at 630 °C, essential for mitigating thermal stress effects.
- TMCVD Recipe: The standard HFCVD process was augmented by Time Modulated CVD (TMCVD) to intentionally alter methane concentration during the 3-hour run (50 Torr pressure, 100 sccm total flow):
  - Stabilization: 20 minutes at 2% CH₄ in H₂.
  - Modulation 1: 15 minutes at 6% CH₄ in H₂.
  - Modulation 2: Repeated 15 minutes at 6% CH₄ in H₂ after a 2-hour period of the initial concentration.

6CCVD Solutions & Capabilities

This research successfully demonstrates the potential of CVD diamond for highly demanding applications, such as wear resistance on industrial steel components, provided the material interface is rigorously engineered. 6CCVD is uniquely positioned to supply the high-quality diamond material required to replicate and extend this type of interface engineering research.

Applicable Materials

The application demands a durable, stress-resistant, high-coverage coating, aligning perfectly with 6CCVD’s Polycrystalline Diamond (PCD) offerings.

6CCVD Material	Relevance to Application	Specification Advantage
Industrial Grade PCD	Ideal for high-wear environments and complex geometries (like tool inserts or large protective coatings on steel).	Provides high structural integrity needed to withstand the 41 N critical load achieved via the SiC interlayer.
Thin Film SCD/PCD	The research focuses on an intermediate layer (30 µm) and a thin diamond film.	6CCVD can precisely control film thickness from 0.1 µm up to 500 µm to match specific residual stress requirements.
Heavy Boron Doped Diamond (BDD)	While not used here, BDD films offer unique electrochemical functionality.	For engineers looking to integrate sensing or electrochemical functions onto steel components, BDD on an appropriate interlayer can be supplied.

Customization Potential

The experiment used small, circular steel disks. Scaling this technology for industrial application requires large-area capability and specialized interface handling, which is a 6CCVD core strength.

Large Area and Custom Dimensions: 6CCVD can manufacture Polycrystalline Diamond (PCD) plates/wafers up to 125mm in diameter. This significantly exceeds the 25.4 mm disks used in the study, facilitating scale-up for industrial component coating.
Interlayer Preparation Support: While laser cladding is a specialized external service, 6CCVD can supply diamond layers tailored for integration with various pre-treated substrates. We can provide surfaces with controlled roughness (e.g., matching the 1.80 µm Ra of the sintered SiC) optimized for final chemical or mechanical interlocking.
Alternative Interlayer Metalization: The literature review cited alternative interlayers like Ti/CrN/Ni. 6CCVD possesses in-house metalization capability (including Au, Pt, Pd, Ti, W, and Cu). This allows for rapid prototyping and testing of alternative adhesive transition layers directly onto high-quality diamond films.
High-Quality Polishing: If the resulting component requires low friction (a key benefit of diamond noted in the paper), 6CCVD can achieve surface roughness of Ra < 5nm on inch-size PCD plates.

Engineering Support

The successful execution of this research relied on precise control of HFCVD parameters (TMCVD, 630 °C substrate temperature) and complex surface physics.

6CCVD’s in-house PhD engineering team specializes in MPCVD process optimization and interface material science. We can assist researchers and engineers in selecting the optimal diamond type, thickness, and morphology necessary to leverage existing intermediate barriers (like SiC) for similar high-adhesion, wear-resistant coating projects.
We offer DDU default global shipping, with DDP available, ensuring efficient material supply worldwide for critical, timeline-driven research projects.

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

View Original Abstract

The objective of this work is the Hot Filament Chemical Vapor Deposition (HFCVD) of diamond films on stainless steel substrates using a new technique for intermediate barrier forming, made by laser cladding process. In this technique, a powder layer is irradiated by a laser beam to melt the powder layer and the substrate surface layer to create the interlayer. The control of the laser beam parameters allows creating homogeneous coating layers, in rather large area in few seconds. In this work, the silicon carbide powder (SiC) was used to create an intermediate layer. Before the diamond growth, the samples were subjected to the seeding process with diamond powder. The diamond deposition was performed using Hot-Filament CVD reactor and the characterizations were Scanning Electron Microscopy, X-ray diffraction, Raman Scattering Spectroscopy and Scratch Test.

Tech Support

Original Source

DOI: https://doi.org/10.1590/1980-5373-mr-2016-0346

References

2006 - CVD diamond coating of steel on a CVD-TiBN interlayer [Crossref]
2006 - Diamond coating of steel at high temperatures in hot filament chemical vapour deposition (HFCVD) employing chromium interlayers [Crossref]
2000 - Preparation and performance of diamond coatings on cemented carbide inserts with cobalt boride interlayers [Crossref]
2009 - Diamond deposition on steel substrates with an Al interlayer [Crossref]
2007 - Critical parameters in hot filament chemical vapor deposition of diamond films on tool steel substrates with CrN interlayers [Crossref]
2003 - The applicability of ultra thin silicon films as interlayers for CVD diamond deposition on steels [Crossref]
2006 - Diamond deposition on steel substrates using intermediate layers [Crossref]
2006 - Raman spectroscopy characterization of diamond films on steel substrates with titanium carbide arc-plated interlayer [Crossref]
1998 - High adhesion and quality diamond films on steel substrate [Crossref]
1998 - Diamond coating on steel with a titanium interlayer [Crossref]