The reactions occurring between a Zr2Cu melting phase and possible compounds intended for use in ultra-refractory ceramic matrix composite, i.e. SiC, TiB2 and ZrB2 are first explored through sessile drop tests, confirming a promising infiltration capability of the melt. Then, a multiphasic ultra-high temperature ceramic matrix composite was prepared by reactive melt infiltration (RMI), using a TiB2-coated carbon fiber preform infiltrated with Zr2Cu at 1500 °C which resulted in the precipitation of ZrB2 and ZrC sub-micrometric faceted grains and a general damage of both fiber and fiber coating, which were penetrated by the melt. Then, to decrease the RMI process temperature down to 1200 °C and limit the fiber damage degree, a second composite was prepared by introducing an additional ZrB2-B infiltration step. Although processing at 300 °C lower, notable alteration of the fiber occurred upon reaction with the Zr2Cu melt and developed a ZrC layer around them, but still allowing pull-out. In addition, the local B-rich environment promoted the development of a dual-phase microstructure within the matrix composed of new sub-micrometric grains and of larger ZrB2 grains, partially dissolved in the melt and re-precipitated acquiring a nano-sized lamellar eutectic structure. The combination of factors on multiple scale length, from the micro- of the fiber to the nano-of the lamella, seems to provide synergistic reinforcing phenomena and thus could be a valuable approach to develop materials for extreme environments.

Melt/solid interaction and melt super-saturation effect on the microstructure asset of ultra-refractory composites prepared by reactive melting infiltration

Silvestroni, L.
Primo
Writing – Original Draft Preparation
;
Vinci, A.
Secondo
Methodology
;
Gilli, N.
Formal Analysis
;
Zoli, L.
Membro del Collaboration Group
;
Sciti, D.
Project Administration
;
2023

Abstract

The reactions occurring between a Zr2Cu melting phase and possible compounds intended for use in ultra-refractory ceramic matrix composite, i.e. SiC, TiB2 and ZrB2 are first explored through sessile drop tests, confirming a promising infiltration capability of the melt. Then, a multiphasic ultra-high temperature ceramic matrix composite was prepared by reactive melt infiltration (RMI), using a TiB2-coated carbon fiber preform infiltrated with Zr2Cu at 1500 °C which resulted in the precipitation of ZrB2 and ZrC sub-micrometric faceted grains and a general damage of both fiber and fiber coating, which were penetrated by the melt. Then, to decrease the RMI process temperature down to 1200 °C and limit the fiber damage degree, a second composite was prepared by introducing an additional ZrB2-B infiltration step. Although processing at 300 °C lower, notable alteration of the fiber occurred upon reaction with the Zr2Cu melt and developed a ZrC layer around them, but still allowing pull-out. In addition, the local B-rich environment promoted the development of a dual-phase microstructure within the matrix composed of new sub-micrometric grains and of larger ZrB2 grains, partially dissolved in the melt and re-precipitated acquiring a nano-sized lamellar eutectic structure. The combination of factors on multiple scale length, from the micro- of the fiber to the nano-of the lamella, seems to provide synergistic reinforcing phenomena and thus could be a valuable approach to develop materials for extreme environments.
2023
Istituto di Scienza, Tecnologia e Sostenibilità per lo Sviluppo dei Materiali Ceramici - ISSMC (ex ISTEC)
Istituto per la Microelettronica e Microsistemi - IMM
Borides, Reaction melt infiltration, Dual-phase microstructure, Eutectic structure
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/511599
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