Characterisation of Niobium Carbide Coating Obtained by Chemical Vapour Deposition

Abstract

The experiments conducted to obtain thin layer of carbide by the vapour chemical deposition method have followed an original path to make NbC directly in the working room thus avoiding the import of these hazardous substances. The NbCl₄ vapoursare obtained in a heat treatment chamber by adding chloride acid vapours passed over the incandescent ferro-niobium.
Characterisation of coating deposed by CVD method was done using scanning electron microscopy (SEM), X-ray diffraction (XRD) and microhardness measurements. The thickness of the NbC layer was determined using an optical microscope and the Kalotest device. The thickness of the CVD deposit layer increases with the time of exposure to the working temperature. The values of the NbC thin layers measured by the Kalotest device are in good agreement with the values measured by microscopic analysis but slightly lower. SEM measurements were used to investigate the coating morphology and interface structure. X-ray mapping was also performed to identify the chemical elements in a semi-quantitative analysis. Dron X-ray diffractometer with Mo K_α radiation operating was used for phase(s) identification.