Structural and mechanical studies of W2N embedded Si3N4 nanocomposite hard coating prepared by reactive magnetron sputtering

Abstract

Crystalline tungsten nitride embedded amorphous silicon nitride (W2N/Si3N4) coatings were prepared on Si (100) substrate using DC/RF reactive magnetron co-sputtering. Two series of coatings were prepared at 200 degrees C and 300 C substrate temperature. The deposition time was varied from 1 h to 2 h. The effect of deposition time on structural and mechanical properties of W2N/Si3N4 coatings was investigated. GIXRD results showed the formation of dominant polycrystalline cubic phase of W2N in all the coatings. The crystal growth improves with increase in deposition time of the coatings. FESEM micrographs showed the randomly oriented, well -developed, sharp edged, irregular shaped grains on surface of the coatings. The microstructure leads to denser structure with increase in deposition time. EDAX confirms the presence of W, Si and N with atomic % approximately 69.2, 173 and 13.5 respectively in the films. The mechanical property improved with increasing deposition time. The maximum Hardness (H), Elastic Modulus (E), Elastic recovery (We) and resistance to plastic deformation (H-3/E-2) achieved were 37.8 +/- 1.6 GPa, 393 +/- 11 GPa, 60.7 +/- 1.2% and 349 +/- 14 MPa respectively for 300 degrees C and 1.5 h coating. Fairly good value of H/E ratio close to 0.1 and H-3/E-2 ratio similar to 350 Mpa were obtained for above coating (300 degrees C and 1.5 h), suggesting superior wear resistance.(C) 2017 Elsevier B.V. All rights reserved.