Influence of carbon target power on the tribological and electrochemical properties of NbMoSiC composite films in seawater

Abstract

Because the wear and corrosion of marine engineering equipment will cause huge economic losses to enterprises every year, thus it is necessary to develop advanced protective films to ensure the normal operation of marine equipment. Here NbMoSiC composite films are deposited using DC magnetron sputtering in an argon atmosphere through varying the carbon target sputtering power, and their microstructure and mechanical properties are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS)，Raman spectroscopy and dynamic ultra-micro hardness tester, respectively. The tribological properties of the films in air and artificial seawater are determined by a reciprocating ball-on-disc tester, while the electrochemical properties of the films in seawater were evaluated by an electrochemical workstation. The results demonstrate that the presence of Nb2C, MoSi2, free silicon, and amorphous carbon (a-C) in the NbMoSiC composite films. Particularly, Sample C250, featuring a carbon content of 35.02 at.%, exhibits higher hardness, elastic modulus, excellent wear resistance, and superior corrosion resistance. However, a further increase in carbon target sputtering power leads to escalated surface roughness and microchannels, ultimately resulting in reduced wear and corrosion performance. Electrochemical analysis reveal that the strong synergistic effect of amorphous carbon as well as the metal oxide phase formed on the surface significantly enhanced the corrosion resistance of the film in artificial seawater with a corrosion current density as low as 1.8 × 10−8 A/cm2.