TiNbN Hard Coating Deposited at Varied Substrate Temperature by Cathodic Arc: Tribological Performance under...

Area of Science:

• Materials Science
• Surface Engineering
• Tribology

Background:

• Titanium nitride (TiN) coatings are widely used due to their excellent properties.
• Doping TiN with niobium (Nb) can further enhance its mechanical and tribological performance.
• Understanding the effect of substrate temperature on TiNbN coatings is crucial for optimizing their application.

Purpose of the Study:

• To investigate the influence of substrate temperature (Ts) on the adhesion, mechanical, and tribological properties of niobium-doped titanium nitride (TiNbN) coatings.
• To correlate coating microstructure and surface morphology with observed properties.
• To evaluate the performance of TiNbN coatings under simulated cutting conditions.

Main Methods:

• Deposition of TiNbN coatings on D2 steel substrates at varying Ts (200, 400, 600 °C).
• X-ray diffraction (XRD) for structural analysis.
• Nanoindentation for mechanical properties (hardness, elastic modulus).
• Adhesion testing (critical load).
• Pin-on-disk tribometry for friction and wear analysis.

Main Results:

• XRD confirmed FCC structure with Nb substituting Ti. Lattice parameter decreased with increasing Ts.
• Hardness increased, while elastic modulus decreased with Ts, improving H/E and H³ /E² ratios.
• Adhesion critical load was higher at 200 and 400 °C (~50 N) compared to 600 °C (~38 N).
• Friction coefficients increased with Ts but remained lower than the substrate.
• Wear tracks showed no coating detachment, indicating good wear resistance.

Conclusions:

• Substrate temperature significantly affects the microstructure, mechanical, and tribological properties of TiNbN coatings.
• Optimizing Ts can enhance hardness, elastic strain limit, and adhesion.
• TiNbN coatings exhibit promising adhesion and wear resistance for cutting applications, even at elevated temperatures.