Deposição e caracterização microestrutural, dureza e corrosão de filmes finos de BbN/AIN depositados por magnetron sputtering reativo

Abstract

The objective of the present work was the Nb1-xAlxN thin films deposition in order to verify the Al concentration influence on microstructure, phase transitions evaluating, mechanical properties and corrosion resistance of these coatings in comparison to NbN. Thin films were obtained by reactive magnetron sputtering technique, and investigated with the following characterizations: Energy dispersive spectrometry (EDS) and Rutherford backscattering spectroscopy (RBS); Grazing Incidence X-ray Diffraction (GIXRD); X-ray photoelectron spectroscopy (XPS); Field Emission Gun Microscopy (SEM-FEG); nanohardness tests; high temperature oxidation tests; Electrochemical tests; Scanning Electron Microscope (SEM). Nb1-xAlxN thin films were obtained with 0 ≤ x ≤ 60. From GIXRD analyzes it was possible to observe that the cubic phase B1 of NbN is remains until 55 at.% Al concentration, suggesting a solid solution substitutional formation, from this concentration it is possible to observe a reduction in the material crystallinity, the critical content of AlN being verified for samples with Al contents greater than 60 at.%. The AlN phase nucleation on higher Al contents samples was also verified through calculations of crystallite size and parameter lattice. XPS analyzes suggest a solid solution formation up to a concentration of 40 at.% Al, from the micrographs obtained by SEM - FEG it was possible to verify the columnar grains formation on samples up to 40 at.% Al, a more microstructure dense was verified for Nb0.45Al0.55N and Nb0.40Al0.60N samples. The highest hardness values were found for Nb0.45Al0.55N and Nb0.40Al0.60N samples. Regarding the H3/E2 ratio, Nb0.45Al0.55N and Nb0.40Al0.60N samples were the ones with the highest values, 0.55 and 0.58 GPa, respectively. Electrochemical analyzes showed that NbN sample showed better behavior xi against corrosion when compared to samples of Nb1-xAlxN, with x ≤ 0.4. After SEM analysis of the surface, it was possible to verify that after the electrochemical tests all samples showed surface flaws, leading to pitting corrosion of the coatings. Oxidation tests on samples Nb0.45Al0.55N and Nb0.40Al0.60N were performed at temperatures of 700, 800 and 900° C, it was found that an increase in Al concentration did not improve the oxidation resistance of the studied samples.