The optical emission intensities of the species N2 +, H, C, NH, N2, Ar e CN in a carbonitriding plasma (using Ar+N2+CH4 gases) were studied with optical emission spectroscopy in an atmosphere of constant pressure and temperature, changing the CH4 flow. Afterwards a commercially pure Ti was exposed to a carbonitriding plasma in similar conditions. The objective of this work is to evaluate the influence of the gaseous species on the superficial properties (chemical composition, topography, and microhardness profile) of the TiCN layer. When the CH4 flow was increased, the species H, N2 +, C, NH, and CN were observed. The continuous increase of CN and a progressive reduction of N2 + were detected. Grazing incidence X-ray diffraction revealed titanium nitride and carbonitride with variable chemical compositions, related to the changes observed in the emission patterns of the species CN and N2 +. The topography, evaluated by atomic force microscopy, showed that the roughness increased when CN increased and N2 + decreased. Micro-Raman spectroscopy showed unreacted carbon on the surface that developed with de increase of the CN emission. This carbon film may be responsible for the progressive decrease of surface hardness.
titanium; plasma carbonitriding; OES; GIXRD; Raman spectroscopy; microhardness
