Borides and carbides of early transition metals are considered a class of promising materials for several applications, the most appealing ones being in the aerospace and energy sectors. The present work is focused on toughening of UHTCs, which is a crucial issue that needs to be addressed for application in aerospace engineering. Common strategies to increase the fracture toughness include either incorporation of elongated reinforcement (SiC chopped fibers, SiC whiskers) or in-situ development of SiC platelet-reinforced materials. Addition of fibers or whiskers allows toughness to be increased from 3-4 MPa?m1/2 (for unreinforced materials) to 5.0-6.3 MPa?m1/2. On the other hand, quite often, the improvement of fracture toughness is accompanied by a decrease of strength, due to a change of the defects population. The high temperature behavior of fiber-reinforced materials is investigated, including mechanical properties and oxidation behavior in conventional furnaces up to 1700°C. Finally, the dynamic response to oxidation of sharp profile demonstrators is studied in plasma wind tunnel at temperatures around 1800°C.

Potential and limits of SiC chopped fiber-reinforced Ultra High Temperature Ceramics

D Sciti;L Silvestroni;A Bellosi
2012

Abstract

Borides and carbides of early transition metals are considered a class of promising materials for several applications, the most appealing ones being in the aerospace and energy sectors. The present work is focused on toughening of UHTCs, which is a crucial issue that needs to be addressed for application in aerospace engineering. Common strategies to increase the fracture toughness include either incorporation of elongated reinforcement (SiC chopped fibers, SiC whiskers) or in-situ development of SiC platelet-reinforced materials. Addition of fibers or whiskers allows toughness to be increased from 3-4 MPa?m1/2 (for unreinforced materials) to 5.0-6.3 MPa?m1/2. On the other hand, quite often, the improvement of fracture toughness is accompanied by a decrease of strength, due to a change of the defects population. The high temperature behavior of fiber-reinforced materials is investigated, including mechanical properties and oxidation behavior in conventional furnaces up to 1700°C. Finally, the dynamic response to oxidation of sharp profile demonstrators is studied in plasma wind tunnel at temperatures around 1800°C.
2012
Istituto di Scienza, Tecnologia e Sostenibilità per lo Sviluppo dei Materiali Ceramici - ISSMC (ex ISTEC)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/269108
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