Please cite this article in press as: J. Yuan, et al., Preparation of dense SiHf(B)CN-based ceramic nanocomposites via rapid spark plasma sintering, J Eur Ceram Soc (2017), http://dx.doi.org/10.1016/j.jeurceramsoc.2017.04.066 ARTICLE IN PRESS G Model JECS-11239; No. of Pages 9 Journal of the European Ceramic Society xxx (2017) xxx–xxx Contents lists available at www.sciencedirect.com Journal of the European Ceramic Society jo ur nal home p ag e: www. elsevier.com/locate/jeurceramsoc Preparation of dense SiHf(B)CN-based ceramic nanocomposites via rapid spark plasma sintering Jia Yuan a,1 , Duan Li b,1,2 , Kurt Johann a , Claudia Fasel a , Karsten Durst a , Hans-Joachim Kleebe c , Zhijian Shen b , Ralf Riedel a , Emanuel Ionescu a,∗ a Technische Universität Darmstadt, Institut für Materialwissenschaft, Jovanka-Bontschits-Straße 2, D-64287, Darmstadt, Germany b Stockholm University, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, S-106 91 Stockholm, Sweden c Technische Universität Darmstadt, Institut für Angewandte Geowissenschaften, Schnittspahnstrasse 9, D-64287 Darmstadt, Germany a r t i c l e i n f o Article history: Received 31 January 2017 Received in revised form 21 April 2017 Accepted 26 April 2017 Available online xxx Keywords: High-temperature stable ceramics nanocomposites SiHfBCN Rapid sintering Mechanical properties High-temperature oxidation a b s t r a c t Dense SiHf(B)CN-based ceramic nanocomposites were prepared by spark plasma sintering (SPS) using high heating rates (∼450 ◦ C/min.) and high pressures (≥100 MPa). The obtained nanocomposites were investigated by X-ray diffraction, Raman spectroscopy and electron microscopy concerning their phase evolution and microstructure. The hardness and the elastic modulus of dense SiHfCN were found to be 26.8 and 367 GPa, respec- tively. Whereas the SiHfBCN samples exhibited a hardness of 24.6 GPa and an elastic modulus of 284 GPa. The investigation of the oxidation of the prepared dense ceramic nanocomposites at high temperature revealed that the parabolic oxidation rates of SiHfCN were comparable to those of ultra-high temperature ceramics (UHTCs, e.g. HfC-20 vol% SiC); whereas the parabolic oxidation rates of SiHfBCN were several orders of magnitude lower than those. The results obtained within this study indicate the feasibility of SPS for rapid preparation of dense though nano-scaled Hf-containing ceramic nanocomposites that are promising candidates for high-temperature applications in harsh environments. © 2017 Elsevier Ltd. All rights reserved. 1. Introduction Group IV metal carbides, borides and nitrides have been defined as Ultrahigh-Temperature Ceramics (UHTCs), due to their extremely high melting points (which exceed 3000 ◦ C) and show in addition to their high-temperature stability high hardness and good thermal shock resistance [1–3]. Thus, UHTCs-based com- posites are usually identified as potential candidates for high temperature application, e.g. utilization in high velocity flight [3,4] and future generations of reentry vehicles [5]. When considering real engineering applications, high melting point (≥3000 ◦ C) is only one of the properties relevant for materials selection. However, the presence of very high temperatures implies also exposure to very harsh environmental conditions in terms of oxidation/corrosion. ∗ Corresponding author at: Technische Universität Darmstadt, Institut für Mate- rialwissenschaft, Jovanka-Bontschits-Straße 2, D-64287, Darmstadt, Germany. E-mail address: ionescu@materials.tu-darmstadt.de (E. Ionescu). 1 These authors contributed equally to this work. 2 Current affiliation: Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, National University of Defense Technology, 410073 Chang- sha, China. Therefore, reasonable oxidation behavior of UHTCs should be pro- vided and obviously has to be addressed as a primary parameter in materials selection. However, refractory carbides, borides and nitrides show rather poor oxidation behavior when exposed to harsh chemical environments, which restricts their application. In order to improve oxidation resistance of the UHTC phases, typically silica formers are used [6–12]. Thus, HfB 2 -based composites con- taining 20 vol% SiC were shown to exhibit reasonable oxidation properties along with their excellent high-temperature stability [13]. Sintering is an essential process for obtaining UHTCs with good mechanical strength, hardness, thermal stability and oxidation resistance [14]. However, this is rather a challenging task due to the fact that they have strong covalent bonding and low self- diffusion coefficients that significantly restrict their sinterability [15–17]. Within this context, the consolidation of UHTCs by using spark plasma sintering (SPS) technique was reported [15–20]. HfB 2 - SiC [15], ZrB 2 -ZrC [17] and TaC-HfC [18] as well as SiB 0.5 C 1.5 N 0.5 [16] systems were well densified by SPS at moderate temperatures within minutes. High heating rates (up to ∼1000 ◦ C/min) and high external pressures (>100 MPa) render SPS superior to the conven- tional approaches [21–25]. Both thermal and non-thermal effects contribute to its unique features [23,24]. http://dx.doi.org/10.1016/j.jeurceramsoc.2017.04.066 0955-2219/© 2017 Elsevier Ltd. All rights reserved.