Revestimentos protetores de nitreto de silício para aplicações tribológicas extremas

Abstract

The performance of engineering components is closely tied to surface phenomena, because it acts as an interface between the component and the environment that surrounds it. The choice of a suitable material with surface properties is critical to its functionality. In this study the physicochemical, structural and mechanical properties of silicon nitride films deposited by radio frequency reactive magnetron sputtering before and after thermal annealing in 18O2 were analyzed using different methods, such as nanohardness, X-ray diffraction, profilometry resonant nuclear reaction, nanoindentation, Rutherford backscattering spectrometry, photoelectron spectroscopy and X-ray induced X-ray reflectometry The Si3N4 films deposited are essentially amorphous, stoichiometric and free of contaminants for various deposition parameters, with hardness values ranging from 16.5 GPa 22 GPa, depending mainly on the deposition temperature of films. After 18O2 annealing at 1000°C, films hardness converged to 21 GPa, independently of the deposition temperature, which is explained on the basis of crystallization of the films at this annealing temperature. Furthermore, oxygen is incorporated only in the 7.5 nm film of Si3N4, forming silicon oxynitride on the surface of the film, indicating good oxidation resistance at high temperature. Finally, the elastic strain to failure H3/E2, which mimics the wear resistance of the film, doubles after the 1000°C annealing. These observations show the great potential of silicon nitride as a hard coating for high temperature applications.