Available online at www.sciencedirect.com Journal of the European Ceramic Society 33 (2013) 2901–2908 Flexural creep of zirconium diboride–silicon carbide up to 2200 ◦ C in minutes with non-contact electromagnetic testing Sindhura Gangireddy a , John W. Halloran a,∗ , Zachary N. Wing b a Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2136, United States b Advanced Ceramics Manufacturing, Tucson, AZ 85706-9645, United States Received 12 March 2013; received in revised form 17 May 2013; accepted 24 May 2013 Available online 5 July 2013 Abstract Flexural creep of ZrB 2 –30 vol% SiC ultra high temperature ceramic composite was studied at 1700–2200 ◦ C and 20–50 MPa using the novel method of electromagnetic Lorentz force loading of electrically heated specimens. Experiments were conducted in air and in non-oxidizing atmospheres. The apparent activation energy for creep was 344 ± 35 kJ/mol for non-oxidizing conditions. The stress exponent was 1.4 ± 0.4. The creep rate was slightly higher in air due to a decrease in the size of the load bearing substrate because of oxidation. There was no evidence of electric field effects. Creep experiments could be performed up to 2200 ◦ C very quickly, with experiments conducted in a few minutes. © 2013 Elsevier Ltd. All rights reserved. Keywords: Creep; Zirconium diboride; Ultra high temperature ceramics; Silicon carbide 1. Introduction Ultra high temperature ceramics (UHTCs) are candidates for structural components in hypersonic and supersonic vehicles 1 where temperatures can go higher than 2000 ◦ C. Zirconium diboride, ZrB 2 , is a prominent candidate due to its high melt- ing temperature, thermal and electrical conductivity, low density and retained high temperature strength. 2 Zirconium diboridie is often combined with 20–30 volume percent SiC to improve the oxidation resistance. 3–5 Creep deformation will be impor- tant at such high temperatures. 6 High temperature behaviors in ZrB 2 –SiC include a transition from brittle to plastic behavior 7 and nonlinear stress strain curves. 8 There are a number of papers concerned with oxidation and mechanical behavior at high temperature. 9–13 Talmy et al. 14 extensively studied the creep of ZrB 2 –SiC systems as a function of temperature, stress, mate- rial composition and particle sizes, but at temperatures limited to 1300–1500 ◦ C. There is a need for creep data near the appli- cation temperature range of 2000 ◦ C. This paper reports creep up to 2200 ◦ C. Our data is obtained with a novel non-contact method to avoid contamination and reaction with the loading fixtures used in ∗ Corresponding author. Tel.: +1 734 763 1051; fax: +1 734 763 4788. E-mail address: peterjon@umich.edu (J.W. Halloran). conventional mechanical testing techniques. We seek a method that is relatively fast and easy. Here we report the use of a novel mechanical testing technique 15 – electro magnetic mechanical apparatus (EMMA) – to measure the ultra high temperature creep of ZrB 2 –30 vol% SiC for temperatures from 1600 ◦ C to 2200 ◦ C, over a stress range of 20–50 MPa. This technique used specimens in the form of self-heated thin ribbons. Small total creep strains cause large, easily measured creep deformations in long thin ribbons. This enables creep measurements for quite small strains. Sensitivity to small strains, combined with rapid heating and cooling, enables complete creep experiments can be conducted in only a few minutes. Creep experiments were performed both in a relatively non-oxidizing atmosphere (N 2 with 0.25% O 2 ) and in air to compare the effect of oxidation on creep. The EMMA technique uses direct Joule heating of the specimen, so no external furnace is required to achieve ultrahigh temperatures. The mechanical load is applied as an electro- magnetic Lorentz force, so no physical contact is involved. The complete EMMA system is a simple tabletop apparatus. 2. Experimental procedure 2.1. Material Advanced Ceramic Manufacturing (ACM Inc., Tucson, AZ) prepared the ZrB 2 –30 vol% SiC composite by hot pressing. 0955-2219/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jeurceramsoc.2013.05.031