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

Abstract

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.