Tribological Performance of TiN–WS2 Soft–Hard Multifunctional Composite Coatings Deposited by Magnetron Sputtering

Titanium nitride (TiN) is a widely used industrial hard coating material, known for its excellent hardness and chemical stability. However, its relatively high coefficient of friction (COF) often leads to interfacial heat accumulation and adhesive wear during service, limiting its applicability in high-temperature tribological environments. To enhance its tribological performance, a TiN–WS2 soft–hard composite coating was fabricated on cemented carbide substrates using reactive co-sputtering magnetron deposition. By adjusting the sputtering parameters and target power ratio, a synergistic deposition of the hard (TiN) and lubricating (WS2) phases was achieved and compared with a pure TiN coating. The results revealed that the incorporation of WS2 significantly reduced the COF at both room temperature (25 °C) and an elevated temperature (200 °C), with the average values decreasing from 0.61 to 0.39 at 25 °C and from 0.53 to 0.36 at 200 °C. A white light interferometry analysis showed that the TiN–WS2 coating exhibited narrower wear tracks and less surface damage than TiN at elevated temperatures, demonstrating superior friction-reducing and wear-resistant capabilities. In terms of mechanical properties, the composite coating showed a reduction in the hardness, the reduced elastic modulus (Er), and the adhesion strength by 27.3%, 19.8%, and 9.5%, respectively, compared to pure TiN. These findings indicate that the introduction of a quantitatively controlled lubricating WS2 phase allows for a balance between nanoscale hardness and wear resistance, offering promising potential for engineering applications under complex working conditions.