Thermal behaviour of thick TiC layers made by plasma spraying

Abstract

Abstract In this work the production of thick (greater than 500 μm) TiC coatings by plasma spraying and their behaviour under high thermal load is presented. Potential applications of such thick TiC coatings are in the field of first-wall protection or emissivity enhancement in fusion devices or as wear-resistant coatings for forging devices. The influence of different spraying conditions on coating structure was studied by light and scanning electron microscopy. The content of the elements carbon, nitrogen, oxygen and hydrogen in the sprayed TiC coatings was determined as well. Phase identification was done by X-ray diffraction. The thermal shock behaviour of the coatings under transient heat loads similar to plasma disruptions in fusion devices was determined by applying a heat flux using a pulsed neodymium-doped yttrium aluminium garnet laser. The investigations have shown that the chemical composition as well as the structure of the TiC coatings influence the behaviour of the coatings exposed to a high thermal load. A correlation was also noticed between the porosity and the stoichiometric ratio (carbon to titanium) and the thermal behaviour of such coatings.