Depositi CVD per Accrescere la Resistenza alla Corrosione delle Barriere Termiche

Abstract

Silicon dioxide (SiO2) films were deposited on thermal barrier coatings (TBC) by means of metal-organnic chemical vapour deposition (MOCVD) in an attempt to reduce the external porosity. The thermal barrier coatings were fabricated by plasma spray method and consisted of an outer yttria-stabilized zirconia layer, an intermediate bonding layer of a CoNiCrAlY (AMDRY 995) and a nickel superalloy substrate (UD520). The SiO2 layers were deposited using tetraethylorthosilicate (TEOS) as a precursor and with nitrogen and oxygen as carrier gas and reactant gases respectively. Following the thin film deposition the effectiveness of sealing was evaluated, firstly by porosity measurements at room temperature and secondly by testing the oxidation resistance at 1000 C.