Improvement of the Wear and Corrosion Behaviors of DLC/oxynitriding Duplex-treated PM60 High-speed Steel <i>via</i> Various Power Densities of DC-pulsed Plasma Enhanced CVD
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2016-01-01 |
| Journal | ISIJ International |
| Authors | Shih‐Hsien Chang, Chi-Long Huang, Kuo-Tsung Huang, Chung‐Ming Liu |
| Institutions | Lunghwa University of Science and Technology, National Taipei University of Technology |
| Citations | 6 |
| Analysis | Full AI Review Included |
Technical Analysis and Documentation: MPCVD Diamond for Extreme Tribological and Corrosion Applications
Section titled “Technical Analysis and Documentation: MPCVD Diamond for Extreme Tribological and Corrosion Applications”Source Paper: Improvement of the Wear and Corrosion Behaviors of DLC/oxynitriding Duplex-treated PM60 High-speed Steel via Various Power Densities of DC-pulsed Plasma Enhanced CVD
Executive Summary
Section titled “Executive Summary”This research successfully optimized the tribological and corrosion performance of PM60 high-speed steel using a duplex treatment combining oxynitriding and Diamond-Like Carbon (DLC) films deposited via DC-pulsed Plasma Enhanced Chemical Vapor Deposition (PECVD).
- Core Achievement: Identification of the optimal PECVD power density (400 mW·cm-2) required to maximize stable sp3 bonding in the DLC film, leading to superior mechanical properties.
- Tribological Performance: The optimal 400 mW·cm-2 treatment yielded the highest surface hardness (Hv0.2 2516.4) and the lowest wear volume loss (2.36 x 10-3 mm3 at 2 N load).
- Corrosion Resistance: Optimal corrosion resistance (Rp 6.26 x 102 Ω·cm2) was achieved at a slightly lower power density (200 mW·cm-2), demonstrating a trade-off between mechanical strength and surface defect minimization.
- Material Structure: The duplex layer consisted of stable Fe3O4 and Fe3N (ε phase) layers beneath the DLC film, acting as an effective intermediate layer to improve adhesion.
- Mechanism: High power densities (> 400 mW·cm-2) increased ion bombardment energy, causing the desirable sp3 bonds to transform into softer sp2 (graphitic) bonds, thereby degrading wear resistance.
- 6CCVD Value Proposition: While DLC films offer enhancement, 6CCVD’s bulk MPCVD diamond (SCD/PCD) provides intrinsic hardness (Hv > 8000) and chemical inertness far superior to optimized DLC coatings, offering a pathway to next-generation extreme environment tooling.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Optimal PECVD Power Density (Wear) | 400 | mW·cm-2 | Achieved lowest wear loss and highest hardness |
| Optimal PECVD Power Density (Corrosion) | 200 | mW·cm-2 | Achieved lowest Icorr and highest Rp |
| Highest Surface Hardness (Hv0.2) | 2516.4 | N/A | Result of 400 mW·cm-2 treatment |
| Lowest Wear Volume Loss (2 N Load) | 2.36 x 10-3 | mm3 | Result of 400 mW·cm-2 treatment |
| Lowest Corrosion Current (Icorr) | 7.24 x 10-5 | A·cm-2 | Measured at 200 mW·cm-2 in 3.5 wt.% NaCl |
| Highest Polarization Resistance (Rp) | 6.26 x 102 | Ω·cm2 | Measured at 200 mW·cm-2 in 3.5 wt.% NaCl |
| Optimal DLC sp3 Bonding Indicator (ID/IG) | 2.38 | N/A | Lowest ratio, indicating highest sp3 content (400 mW·cm-2) |
| G-Peak Offset (Optimal) | 1540.8 | cm-1 | Greatest offset, indicating stable sp3 structure (400 mW·cm-2) |
| Substrate Hardness (PM60 HSS) | 67 ± 1 | HRC | Prior to surface treatment |
| DLC Deposition Time | 90 | min | Constant parameter for all PECVD runs |
| Pulsed Voltage / Frequency | -1.5 kV / 10 kHz | N/A | Constant PECVD parameters |
| Corrosive Medium | 3.5 | wt.% NaCl | Standardized corrosion test solution |
Key Methodologies
Section titled “Key Methodologies”The study employed a multi-stage surface engineering approach, utilizing controlled thermal and plasma processes to create a high-performance duplex coating on PM60 high-speed steel.
- Substrate Heat Treatment:
- PM60 HSS was quenched at 1180 °C and tempered at 550 °C (repeated 3 times) to achieve a base hardness of 67 ± 1 HRC.
- Oxynitriding Duplex Pre-Treatment:
- Nitriding: Performed at 550 °C for 8 h.
- Oxidation: Performed via steam at 525 °C for 60 min, forming stable Fe3O4 and Fe3N layers.
- DLC Film Deposition (DC-Pulsed PECVD):
- System: DC-pulsed PECVD utilizing a unipolar negative-pulsed voltage.
- Gas Mixture: CH4 gas (volumetric flow 8.3 x 10-8 m3·s-1) supplied at < 1.33 Pa.
- Electrical Parameters: Pulsed voltage fixed at -1.5 kV, frequency at 10 kHz, and duty cycle at 11%.
- Variable: Power density was varied across five levels: 200, 400, 600, 800, and 1000 mW·cm-2.
- Performance Evaluation:
- Tribology: Ball-on-Disk Wear Test (ASTM G99) using a WC ball, 0.25 m·s-1 sliding speed, and axial loads of 2 N and 5 N.
- Mechanical: Rockwell C Indentation (1.47 kN load) and Micro-hardness testing (Hv0.05).
- Corrosion: Tafel polarization analysis using a three-electrode method in 3.5 wt.% NaCl solution.
- Structural Analysis: Raman spectroscopy (to determine sp3/sp2 ratio via ID/IG), XRD, and SEM.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”The research demonstrates the critical role of carbon-based coatings in enhancing the life of high-speed steel tools. While the optimized DLC film provides significant improvement, 6CCVD specializes in high-purity, bulk MPCVD diamond, which offers intrinsic properties (hardness, chemical inertness, thermal conductivity) that fundamentally surpass the performance limits of amorphous DLC films.
For engineers and scientists seeking to replicate or extend this research into ultra-high-performance tooling, sensors, or extreme environment components, 6CCVD provides tailored diamond solutions:
| Research Requirement/Challenge | 6CCVD Solution & Value Proposition | Applicable 6CCVD Material |
|---|---|---|
| Need for Extreme Hardness & Wear Resistance | Superior Intrinsic Hardness: DLC films are limited (Hv ~2500). 6CCVD’s Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) offer Vickers hardness exceeding 8000, providing maximum resistance to abrasion and erosion for cutting and forming tools. | Optical Grade SCD or High-Purity PCD |
| Requirement for Chemical Inertness & Corrosion Barrier | Ultimate Chemical Stability: Crystalline MPCVD diamond is chemically inert and highly resistant to aggressive media (like the 3.5 wt.% NaCl used). This eliminates the risk of sp2 graphitization and surface defects observed in high-energy DLC deposition. | High-Purity PCD |
| Custom Dimensions for Tooling/Wafers | Large Area & Custom Processing: 6CCVD supplies PCD plates/wafers up to 125mm in diameter, easily accommodating the Ø36 x D5 mm dimensions used in the study, along with custom laser cutting services. | PCD (up to 125mm) |
| Minimizing Surface Defects (Pitting Corrosion) | Ultra-Low Roughness Polishing: Surface defects are a primary cause of corrosion initiation. 6CCVD offers precision polishing down to Ra < 1nm (SCD) and Ra < 5nm (PCD), ensuring a defect-free barrier layer. | Polished SCD or Polished PCD |
| Extending Research to Electrochemical Sensing | Conductive Diamond Electrodes: For applications requiring both extreme corrosion resistance and electrochemical activity (e.g., advanced Tafel analysis or sensing), 6CCVD provides highly stable Boron-Doped Diamond (BDD). | Heavy Boron Doped PCD or BDD Thin Films |
| Metalization Requirements | Integrated Metalization Services: If the final component requires electrical contacts or bonding layers, 6CCVD offers in-house deposition of standard metal stacks including Au, Pt, Pd, Ti, W, and Cu. | SCD, PCD, or BDD with custom metalization |
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD engineering team specializes in material selection and optimization for extreme tribology, high-power electronics, and electrochemical projects. We can assist researchers in transitioning from DLC films to bulk CVD diamond solutions for superior performance in similar high-speed steel or tooling applications.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In this study, diamond-like carbon (DLC) films are prepared by DC-pulsed plasma-enhanced chemical vapor deposition (PECVD) after the oxynitriding treatment of PM60 high-speed steel. The chief study of the parameters of a DC-pulsed PECVD process includes various power densities (200, 400, 600, 800 and 1000 mW·cm−2) with unipolar negative-pulsed voltage. In order to evaluate the properties of the DLC films for DLC/oxynitriding-treated PM60 high-speed steel, Raman spectroscopy analysis, wear tests, hardness tests, Rockwell indentation and corrosion resistance inspections are performed. The experimental results show the duplex coating layers to have the ideal properties when the DLC films are treated by the unipolar negative-pulsed voltage, a deposition time of 90 min and duty cycles maintained at 11%, with an appropriate power density (400 mW·cm−2), respectively. The DLC/oxynitriding duplex treatment results in the highest surface hardness (Hv0.2 2516.4) and lowest wear volume loss (when the load of 2 N and 5 N is 2.36 × 10−3 mm3 and 5.67 × 10−3 mm3, respectively). In addition, when the DLC/oxynitriding duplex film is treated by a power density of 200 mW·cm−2, it possesses the lowest corrosion current (Icorr = 7.24 × 10−5 A·cm−2) and highest polarization resistance (Rp = 6.26 × 102 Ω·cm2) in 3.5 wt% NaCl solutions. The test results confirm that the optimal wear and corrosion resistance can be acquired by the DLC/oxynitriding duplex treatments.