ZIRCONIUM DIBORIDE BASED COATINGS FOR THERMAL PROTECTION OF RE ENTRY VEHICLES: EFFECT OF MoSi2 ADDITION

AUTHOR/S:M. TULUI, S. LIONETTII (CSM) G. PULCI, F. MARRA, J. TIRILLÒ, T. VALENTE (Univ. RM 1) PAPER PRESENTED TO: Surface & Coating Technologies DATE: February 2010

The present work is focused on ZrB2 based coatings deposited by plasma spray, containing SiC and MoSi2 in different ratios: the work aimed at understanding the role of MoSi2 addition in the oxidation resistance. XRD  analysis were carried out on starting powders and plasma sprayed coatings, in order to evaluate the transformations of crystalline phases induced by thermal deposition and to analyze the possible presence of amorphous phase; XPS was also used to study the coatings surface composition and to obtain information about chemical bonds in the materials.

 

Oxidation behaviour was studied carrying out  exposure tests up to 1800°C in static air to compare and model the oxidation kinetics of the different compositions: results show the better behaviour of materials containing MoSi2. Microstructure of as sprayed and oxidized samples was observed by means of SEM and analyzed by EDS to understand the link between dispersion of Mo containing phases and the improved oxidation resistance.

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