| AVS 65th International Symposium & Exhibition | |
| Advanced Surface Engineering Division | Monday Sessions |
| Session SE+NS+TF-MoM |
| Session: | Nanostructured Thin Films and Coatings |
| Presenter: | Y.G. Li, Dalian University of Technology, China |
| Authors: | Y.G. Li, Dalian University of Technology, China H. Yuan, Dalian University of Technology, China Z.T. Jiang, Dalian University of Technology, China N. Pan, Dalian University of Technology, China M.K. Lei, Dalian University of Technology, China |
| Correspondent: | Click to Email |
Isomeric NbN nanocomposite coatings on stainless steel substrate with face-centered cubic phase δ-NbN and hexagonal phase δ’-NbN were deposited by modulated pulsed power magnetron sputtering under nitrogen flow rate fN2 from 15% to 30%. It was found that the nitrogen flow rate fN2 had a significant influence on the energy delivered in each macropulse, which led to a marked change in the phase composition and mechanical properties. The peak power decreases from 54 kW to 16 kW as fN2 increases from 15% to 30% with the energy delivered in each macropulse from 23.2 J to 9.8 J. When fN2 is at 15%, NbN coatings are mainly composed of δ’-NbN phase which usually exists at high fN2 or under high compressive residual stress showing (100) and (102) preferred orientation, while δ-NbN gradually appears with the preferred orientation from (111) to (200) as fN2 increases accompanied with the decrease of δ’-NbN phase composition. The hardness and modulus of isomeric NbN nanocomposite coatings go up to 36 GPa from 30 GPa and 460 GPa from 366 GPa as fN2 increases to 20% with residual compressive stress from 0.47 GPa to 1.93 GPa, then decrease to 29 GPa and 389 GPa with residual compressive stress of 1.01 GPa showing a nonlinear response with peak power. The NbN nanocomposite coatings with more δ’-NbN phase show higher hardness and better toughness due to the composition variation of δ’-NbN and δ-NbN phases. The phase composition from δ’-NbN to δ-NbN phase should attribute to the delivered energy difference by peak power, and the anomalous increase in hardness should be originated from strengthening of the nanocomposite structure.