Please cite this article in press as: P. Makurunje, et al., Self-generating oxidation protective high-temperature glass-ceramic coatings for C f /C-SiC-TiC-TaC UHTC matrix composites, J Eur Ceram Soc (2017), http://dx.doi.org/10.1016/j.jeurceramsoc.2017.03.068 ARTICLE IN PRESS G Model JECS-11169; No. of Pages 13 Journal of the European Ceramic Society xxx (2017) xxx–xxx Contents lists available at www.sciencedirect.com Journal of the European Ceramic Society journal homepage: www.elsevier.com/locate/jeurceramsoc Feature article Self-generating oxidation protective high-temperature glass-ceramic coatings for C f /C-SiC-TiC-TaC UHTC matrix composites Phylis Makurunje a,b , Frédéric Monteverde c,∗ , Iakovos Sigalas a,b a DST-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Johannesburg, South Africa b School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, South Africa c CNR-ISTEC, National Research Council of Italy, Institute of Science and Technology for Ceramics, Faenza, Italy a r t i c l e i n f o Article history: Received 8 November 2016 Received in revised form 9 March 2017 Accepted 29 March 2017 Available online xxx Keywords: Ceramic-matrix composite Microstructure Oxidation/ablation resistance Self-repairing mechanisms a b s t r a c t The ablation/oxidation resistance of a carbon fibre (C f )/carbon matrix (C)-SiC-TiC-TaC ceramic matrix composite (CMC) produced by melt infiltration of alloy into a C f /C preform and tested in severely oxi- dising conditions was quantitatively determined and discussed. An oxyacetylene flame shot of 7.5 s (4 MW/m 2 nominal heat flux), as well as oxidising conditions imposed by a radiant furnace in air at 1873 K up to 480 s were the selected testing conditions. Detailed post-test microstructure investigations of the oxidised/ablated infiltrated CMC samples, compared to unprotected CMCs tested in nominally identical conditions, enabled to establish an increase in ablation/oxidation resistance of one order of magnitude. The occurrence of a self-generating protective high-temperature glass-ceramic, disclosed by microstructure analyses, played a substantial role for that performance jump during oxidation/ablation. The C f /C-SiC-TiC-TaC composite herein tested can be a valuable candidate for uses in severe aerospace applications (propulsion and hypersonic flight). © 2017 Elsevier Ltd. All rights reserved. 1. Introduction The ability of a non-oxide ceramic matrix composite (CMC) to withstand ultra-high temperatures (i.e above 2273 K) with minor damage in a strongly oxidative and ablative environment qualifies it to operate for extreme applications like the propulsion of rockets or hypersonic flight. The possibility of combining the advantages of CMCs and monolithic forms of ceramics in a single hybrid design to obtain a strong damage tolerant material was explored using modelling [1]. The necessity of externally protecting carbon fibres (C f ), or their bundles, constituting C f /C composites by the use of a ceramic matrix which forms oxides with high melting points during application is widely acknowledged [2]. Opeka et al., [3] empha- sised that it is actually the ability of these materials to form oxides with high melting points during service which qualifies them as ultra-high temperature ceramics (UHTCs). A number of dense ceramic coatings have been developed that are applied on top of C f /C composites for oxidation/ablation resis- tance. Very recently Xu et al., [4] successfully tested a UHTC double layered and porous modified carbon bonded/carbon fibre compos- ∗ Corresponding author at: CNR-ISTEC, National Research Council of Italy, Institute of Science and Technology for Ceramics, Faenza, Italy. E-mail address: frederic.monteverde@istec.cnr.it (F. Monteverde). ite under simulated atmospheric re-entry conditions of 1.3 MW/m 2 heat flux and 1673 K peak stagnation point temperature. However, the underlying C f /C composite experienced severe oxidation and erosion when the protective coating was compromised. Oxide glass coatings, usually introduced as SiC-based coatings, on C f /C composites have been extensively used. SiC is preferred as protective barrier for C f /C composites against oxidation, or as internal buffer layer, due to its favourable intrinsic chemical- physical compatibility with carbon. In an oxidising environment, SiC typically yields glassy silica which affords effective protection to C f /C composites depending on the operational envelope. However, above 2273 K, massive volatilisation of silica glass takes place [5], and protection for the underlying C f /C composites is definitely lost because of the occurrence of gaseous carbon oxides from reactions. The desired combination of excellent thermo-chemical, thermo- mechanical and thermo-physical stability in harsh operational environment requires the development of fibre reinforced UHTC composites to enable viable application development beyond 2273 K. For such hybrid components, the choice of carbon fibres remains superior owing to their favourable density-to-strength ratio, ready availability and opportunity to be formed into complex shapes. UHTC additions to C f /C composites are of great technological appeal because they possess outstanding thermal stability and, properly selected, can yield glassy oxides able not only to impede http://dx.doi.org/10.1016/j.jeurceramsoc.2017.03.068 0955-2219/© 2017 Elsevier Ltd. All rights reserved.