Spectroscopic evaluation of tungsten carbide-titanium carbide composite prepared by arc plasma melting

Abstract

Tungsten carbide-titanium carbide composite of six different compositions (in the range 1-15 wt% TiC) prepared by arc plasma melting has been evaluated for the first time by spectroscopic methods such as X-ray photoelectron spectroscopy (XPS), micro Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. From XPS, the presence of elements like W, Ti, C and O were identified unambiguously. The de-convoluted spectra of binding energy for W4f and Cls levels in XPS showed occurrence of different carbide phases of W. Raman spectra recorded in the range 100-3200 cm(-1) identified various phases of tungsten carbide and titanium carbide, titanium sub-carbide, different phases of carbon (G, D, 2D) and oxide of tungsten (W=O). FTIR, besides identifying TiC phase, detected the presence of aromatic carbon (C=C) and O-H stretching. Taking into account the findings from the three spectroscopic methods and comparing them with the XRD (X-ray diffraction) results, one concludes that WC phase totally disappears in the composite at higher TiC compositions (10-15 wt%). C as an independent phase ceases to appear in XRD in the 5-15 wt% TiC range of the composite. This happens due to change of graphitic C to sp(2)-rich amorphous C in the respective samples, as confirmed from XPS.