Concepción y preparación de un recubrimiento protector en forma de película compósito a base de carburo de titanio

Abstract

Transition metal nitrides and carbides have widely been used as refractory materials due to their high melting point, high hardness and high Young's modulus. However, its fragility induces a low cracking resistance, mainly when these materials are deposited on substrates with a very different thermal expansion coefficient. Several techniques have been widely used for depositing nitride and titanium carbide coatings. In order to obtain a hard refractory coating for protecting a tungsten device exposed to an aggressive liquid metal, in this study we report the design and synthesis of TiC coatings obtained by CVD at 1000$^\circ$C, and TiC-based coatings and Ti$_{1 - x}$W$_{x}$/TiC$_{x}$ composite films obtained by activated reactive evaporation process (ARE) at 250 and 500$^\circ$C respectively. The effect of different experimental parameters was correlated with crystalline structure, texture, morphology and chemical composition of the deposits. The microstructure, crystal size and morphology of the films were evaluated by x-ray diffraction (XRD) technique and scanning electron microscopy (SEM) respectively. The chemical composition of the films was evaluated by Auger electron spectroscopy (AES) and electron probe microanalysis (EPMA). Finally, cracking behavior of the films prepared by the ARE technique was evaluated by a heat treatment at 1000 $^\circ$C during 30 min in an He atmosphere.