Influence of N2 Gas Flow Ratio and Working Pressure on Amorphous Mo–Si–N Coating during Magnetron Sputtering

Ki Seong Lim,Young Seok Kim,Gian Song,Ki Buem Kim,Sung Hwan Hong

doi:10.3390/coatings10010034

Abstract

In this study, Mo–Si–N coatings were deposited on Si wafers and tungsten carbide substrates using a reactive direct current magnetron sputtering system with a MoSi powder target. The influence of sputtering parameters, such as the N2 gas flow ratio and working pressure, on the microstructure and mechanical properties (hardness (H), elastic modulus (E), and H/E ratio) of the Mo–Si–N coatings was systematically investigated using X-ray diffractometry (XRD), scanning electron microscopy (SEM), nanoindentation, and transmission electron microscopy (TEM). The gas flow rate was a significant parameter for determining the crystallinity and microstructure of the coatings. A Mo2N crystalline coating could be obtained by a high N2 gas flow ratio of more than 35% in the gas mixture, whereas an amorphous coating could be formed by a low N2 gas flow ratio of less than 25%. Furthermore, the working pressure played an important role in controlling the smooth surface and densified structure of the Mo–Si–N coating. For the amorphous Mo–Si–N coating deposited with the lowest working pressure (1 mTorr), the hardness, elastic modulus, and H/E ratio reached from 9.9 GPa, 158.8 GPa, and 0.062 up to 17.9 GPa, 216.1 GPa, and 0.083, respectively.

Highlights

Molybdenum nitride coatings have been found to have high hardness, excellent wear resistance, and a low friction coefficient compared with TiN and CrN coatings, which allows their use in various applications [1,2,3,4,5,6,7,8]
Mo3Si, Mo5Si3, MoSi2, and Si3N4, were observed in the X-ray diffractometry (XRD) results [3,11]. These results clearly indicate amorphous coatings can be made on working pressures ranging from 1 to 10 mTorr
Mo–Si–N coatings were deposited by adjusting the N2 gas flow ratios from 10% to 35% at room temperature using a reactive magnetron sputtering system

Summary

Introduction

Molybdenum nitride coatings have been found to have high hardness, excellent wear resistance, and a low friction coefficient compared with TiN and CrN coatings, which allows their use in various applications (i.e., hard coating, diffusion barrier, and tribological coating) [1,2,3,4,5,6,7,8]. It was reported that the microstructure of Mo–Si–N coatings (for example, formation of crystalline or amorphous phases) is influenced by the composition and sputtering parameters [3,10,11]. Controlling the sputtering parameters, such as the working pressure, can improve the density of the coating structure and reduce the roughness of the Coatings 2020, 10, 34; doi:10.3390/coatings10010034 www.mdpi.com/journal/coatings. The mechanical properties of Mo–Si–N amorphous coatings have not been studied in comparison with crystalline coatings [17]. The N2 gas flow ratio and the working pressure were systemically adjusted to understand the effect of the gas flow ratio and working pressure on the microstructure, crystallinity, and mechanical properties of Mo–Si–N coatings. X-ray spectroscopy (EDS), nanoindentation, and transmission electron microscopy (TEM)

Experimental

Results and Discussion

Deposition

It was that a higher

Conclusions