Investigation of the mechanical and tribological properties of CrWN–Ru coatings with Cr, Ti, and Si interlayers on quartz glass substrates

In light of the potential application of quartz glass as a mould material for precision glass moulding (PGM), this study aims to evaluate the feasibility of employing CrWN–Ru coatings for protective purposes. Particular attention is given to the effect of Cr, Ti and Si interlayers on enhancing the service performance of the CrWN–Ru coating system. CrWN–Ru, Cr/CrWN–Ru, Ti/CrWN–Ru, and Si/CrWN–Ru coatings were deposited on quartz glass substrates using plasma-enhanced magnetron sputtering. A comparative experimental approach was adopted to investigate the mechanical and tribological properties of the four coating systems. The results demonstrate that plasma-enhanced magnetron sputtering enables the fabrication of CrWN–Ru coatings with satisfactory surface quality and structural stability on quartz glass substrates. The introduction of Cr, Ti, and Si interlayers was found to reduce the surface quality of the coatings without altering their preferred crystallographic orientation, while the phase structure remained stable. At the same time, the presence of interlayers enhanced the hardness and Young's modulus of the CrWN–Ru coatings, thereby improving their overall strength–toughness balance. Among the systems examined, the coating with a Cr interlayer exhibited the best performance, achieving the highest hardness (9.35 GPa) and Young's modulus (144.55 GPa), together with superior toughness and film–substrate adhesion. In contrast, the CrWN–Ru coating without an interlayer demonstrated excellent tribological behaviour, with the coefficient of friction and wear rate reaching as low as 0.326 and 1.14 × 10⁻⁷ mm³/N·m, respectively. However, the introduction of interlayers was observed to diminish the wear resistance of the CrWN–Ru coatings, and this adverse effect became more pronounced with increasing interlayer thickness. All four CrWN–Ru coatings were found to exhibit a similar wear damage mechanism, which proceeds through the sequence: friction - oxidation - adhesion - abrasive wear - crack formation - delamination. This study provides theoretical guidance for the design, optimisation, and performance tailoring of CrWN–Ru coatings on quartz glass substrates, thereby promoting the application of quartz glass in the field of precision glass moulding.