The Effects of Nitrogen Content on the Mechanical and Tribological Properties of CrTaWNx Thin Films

In the study described herein, CrTaWNx thin films were deposited on Si and 304 stainless-steel (SUS304) substrates through magnetron co-sputtering using CrW and Ta targets. The nitrogen flow ratio (fN2 = [N2/(N2 + Ar)]) was adjusted to 0.05, 0.2, 0.4, and 0.5 to fabricate CrTaWNx films with various N contents. The CrTaWNx films prepared at a low fN2 of 0.05 exhibited a low stoichiometric ratio x of 0.16 and a nanocrystalline structure. In contrast, the CrTaWNx films fabricated at an fN2 of 0.2–0.5 exhibited x values of 0.42–0.62 and formed a face-centered cubic phase. The nanocrystalline (Cr0.34Ta0.20W0.46)N0.16 film exhibited mechanical properties and wear resistances that were inferior to those of the crystalline CrTaWNx thin films. A (Cr0.38Ta0.15W0.47)N0.55 film exhibited a hardness of 25.2 GPa, an elastic modulus of 289 GPa, and a low wear rate of 0.51 × 10−5 mm3/Nm.