Control of Tribological Characteristics of Wear-Resistant AlCrBN Coatings by Nanoscratch Testing
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-07-02 |
| Journal | Devices and Methods of Measurements |
| Authors | V. A. Lapitskaya, T. A. Kuznetsova, B. WarcholiĆski, Anastasiya Khabarava, T. V. Hamzeleva |
| Institutions | Belarusian National Technical University, A.V. Luikov Heat and Mass Transfer Institute |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Fidelity Tribology using MPCVD Diamond
Section titled âTechnical Documentation & Analysis: High-Fidelity Tribology using MPCVD DiamondâExecutive Summary
Section titled âExecutive SummaryâThis research validates the nanoscratch testing method as a superior control technique for evaluating the intrinsic tribological characteristics of wear-resistant coatings, specifically AlCrBN. The findings underscore the critical need for ultra-smooth, defect-free surfacesâa core strength of 6CCVDâs MPCVD diamond materials.
- Method Validation: Nanoscratch testing, utilizing a 226 nm spherical diamond indenter, successfully isolated the true micro-level friction coefficient (CoFmicro) of AlCrBN coatings.
- Defect Elimination: The method effectively eliminated the influence of microparticles (characteristic defects of Cathodic Arc Evaporation, CAE) which severely skewed macro-tribological results.
- Friction Reduction: Optimized deposition parameters (increased N2 pressure from 2 to 5 Pa, or bias voltage from -50 V to -150 V) reduced the CoFmicro from 0.087 to a minimum of 0.036.
- Roughness Discrepancy: Standard profilometer roughness (Ra up to 0.361 ”m) was drastically higher than the AFM roughness measured on microparticle-free areas (Ra down to 14.8 nm), highlighting the surface quality challenge inherent in CAE methods.
- 6CCVD Value Proposition: The requirement for defect-free, ultra-smooth surfaces for accurate nano-tribology directly aligns with 6CCVDâs capabilities in producing high-purity, low-roughness MPCVD Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD).
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the study detailing the deposition parameters and tribological results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Indenter Radius | 226 | nm | Spherical diamond indenter used for nanoscratch |
| Indenter Apex Angle | 60 | ° | Conical diamond indenter geometry |
| Nanoscratch Load | 500 | ”N | Applied load during multi-cycle testing |
| Test Cycles | 100 | cycles | Reciprocating motion duration |
| Scratch Length | 5 | ”m | Length of single scratch track |
| Deposition Temperature | 350 | °C | AlCrBN coating deposition temperature |
| N2 Pressure Range | 2 to 5 | Pa | Parameter varied to optimize CoF |
| Substrate Bias Voltage Range | -50 to -150 | V | Parameter varied to optimize CoF |
| Lowest Micro Friction CoF (CoFmicro) | 0.036 ± 0.004 | N/A | Achieved at 5 Pa N2 pressure |
| Highest Macro Friction CoF (CoFmacro) | 0.77 ± 0.01 | N/A | Macrotest result (-150 V bias) |
| Lowest AFM Roughness (Ra) | 14.8 ± 0.7 | nm | Measured on microparticle-free 3x3 ”m2 area |
| Highest Profilometer Roughness (Ra) | 0.361 ± 0.044 | ”m | Standard surface roughness measurement |
Key Methodologies
Section titled âKey MethodologiesâThe study utilized advanced physical vapor deposition (PVD) and high-resolution metrology techniques to characterize the coatings:
- Coating Deposition: AlCrBN coatings (4.4 ± 0.1 ”m thickness) were deposited via the Cathodic Arc Evaporation (CAE) method using Al50Cr30B20 alloy cathodes in a TINA 900 M setup.
- Substrate Preparation: Martensitic stainless steel 4H13 (X39Cr13) substrates (28 mm and 32 mm diameter, 3 mm thick) were polished to an initial roughness of Ra 0.02 ”m.
- Parameter Variation: Coatings were produced by systematically varying three key parameters: Nitrogen pressure (2 Pa to 5 Pa), Substrate Bias Voltage (-50 V to -150 V), and Cathode Arc Current (80 A to 100 A).
- Surface Metrology: Surface morphology was analyzed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM, Dimension FastScan) in Peak-Force QNM mode, utilizing NSC-11 silicon cantilevers (tip radius 10 nm).
- Tribological Testing: Microtribological properties were determined using a Hysitron 750Ubi nanoindenter. Tests employed a spherical diamond conical indenter (R=226 nm, 60° apex).
- Nanoscratch Procedure: Multi-cycle reciprocating tests (100 cycles, 5 ”m scratch length, 500 ”N load) were performed exclusively on small, microparticle-free surface areas (3x3 ”m2) identified via SEM/AFM.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research demonstrates that achieving reliable, intrinsic tribological data requires surfaces with roughness far below the microparticle-induced defects common in PVD coatings. 6CCVDâs expertise in high-purity MPCVD diamond growth and ultra-precision polishing directly addresses this need, offering superior platforms for advanced tribology and wear applications.
| Research Requirement/Challenge | 6CCVD Solution & Capability | Technical Advantage for Engineers |
|---|---|---|
| Challenge: Microdroplets/Defects skewing results (Ra up to 0.361 ”m). | Applicable Materials: Optical Grade Single Crystal Diamond (SCD) or Ultra-Smooth Polycrystalline Diamond (PCD). | MPCVD diamond growth is inherently cleaner than CAE, eliminating the microdroplet phase and providing a truly defect-free surface for fundamental tribology studies. |
| Requirement: Ultra-low roughness for accurate nano-tribology (AFM Ra down to 14.8 nm). | Polishing Capability: Standard SCD polishing achieves Ra < 1 nm. Inch-size PCD polishing achieves Ra < 5 nm. | 6CCVD provides surfaces significantly smoother than those achieved in the study, enabling higher fidelity measurements and minimizing topographical influence on CoF. |
| Requirement: High-precision diamond tooling (Indenters, AFM tips) and reference standards. | Custom Dimensions & Materials: 6CCVD supplies high-purity SCD wafers and custom-cut diamond components for indenter fabrication and calibration standards. | SCD offers the highest hardness and thermal stability, ensuring longevity and accuracy for critical nano-mechanical tooling (e.g., R=226 nm indenters). |
| Requirement: Integration of coatings onto complex substrates requiring electrical control. | Metalization Services: Internal capability for custom metalization (Au, Pt, Pd, Ti, W, Cu) on diamond plates/wafers. | Allows researchers to integrate diamond films onto complex systems requiring precise electrical biasing (similar to the -50 V to -150 V bias used here) or specialized bonding layers. |
| Need: Large-area, uniform wear-resistant surfaces for industrial scale-up. | Custom Dimensions: PCD plates/wafers available up to 125 mm diameter. Thicknesses up to 500 ”m. | Supports scaling up of tribological studies or industrial application of diamond coatings on large components where uniformity is critical. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the material science of diamond films and can assist engineers and scientists in selecting the optimal diamond grade (SCD, PCD, or BDD) and surface finish required for high-precision nano-mechanical and tribological projects, such as advanced wear-resistant coating characterization.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. Global shipping (DDU default, DDP available) ensures rapid delivery worldwide.
View Original Abstract
In recent years, high-precision probe methods have been increasingly used to control the surface microstructure, mechanical and tribological properties of coatings instead of standard methods. The aim of the work was to study the tribological characteristics of the wear-resistant coatings (using the example of AlCrBN coatings deposited with changes in nitrogen pressure, substrate bias voltage and cathode current) at the microand nanolevel using the nanoscratch testing (nano-scratching) method. The nanoscratch testing method is a non-standard method of tribotesting the wear-resistant coatings and is based on the reciprocating movement of a spherical diamond indenter with a curvature radius of 226 nm on the surface (under a certain load). It was found that the friction coefficient decreases from 0.087 to 0.036 for coatings deposited with an increase in pressure from 2 to 5 Pa. When the bias voltage on the substrate changes from -50 to -150 V, the friction coefficient decreases from 0.077 to 0.041 and when the cathode current changes from 80 to 100 A, the friction coefficient remains virtually unchanged. The use of this method made it possible to perform multi-cycle tribotesting of the AlCrBN coatings, determine the average values of the friction coefficient, and completely eliminate the influence of microparticles (the characteristic defects for coatings deposited by the cathodic arc method) on the measurements. Thus, the effectiveness of the nanoscratch testing (nanoscratching) as a method for the control wear-resistant coatings is demonstrated.