Papers by Author: A. Fabrizi

Abstract: This paper is a review of the thermal stability of nanostructured nitride coatings synthesised by reactive magnetron sputtering technique. In the last three decade, nitride based coatings have been widely applied as hard wear-protective coatings in mechanical components. More recently, a larger interest has been addressed to evaluate the thermal stability of such coatings, as their mechanical and tribological properties are deteriorated at high working temperatures. This study describes the microstructural, mechanical and compositional stability of nano-crystalline Cr-N and nano-composited Ti-N based coatings (Ti-Al-Si-B-N and Ti-Cr-B-N) after air and vacuum annealing. For Cr-N coatings annealing in vacuum induces phase transformation from CrN to Cr2N, while after annealing in air only Cr2O3 phase is present. For Ti-N based coatings, a well-definite multilayered structure was shown after air annealing. Degradation of mechanical properties was observed for all the nitride coatings after thermal annealing in air.

Abstract: Thin nanostructured Ti-B-N-based films are known for their excellent mechanical properties and their stability at high temperature in oxidizing atmosphere. In the present work, nanostructured Ti-Al-Si-B-N and Ti-Cr-B-N coatings deposited on AISI 304 stainless steel by ion implantation have been characterized. To evaluate the oxidation resistance and thermal stability, the coatings were annealed at 900°C in vacuum and in air for 4 hours. The mechanical properties, phase composition and micro-structure of as-deposited and annealed coatings were addressed. The coatings showed a complex multilayered structure and a substantial change of their mechanical properties, due to the new structure and to the phases formed after air annealing.