Availableonlineatwww.sciencedirectcom ScienceDirect E噩≈RS ELSEVIER Joumal of the European Ceramic Society 27(2007)4603-4611 www.elsevier.comlocate/jeurceramsoc Creep damage resistance of ceramic-matrix composites B Wilshire MR Bache Materials Research Centre, School of Engineering, University of Wales Swansea, Singleton Park, Swansea SA2 8PP UK Received 22 November 2006: received in revised form 20 March 2007: accepted 25 March 2007 Available online 12 June 2007 The tensile creep and creep fracture properties in air at 1300C are documented for two ceramic fibre-reinforced ceran (CFCMCS). These recently developed materials were produced with woven bundles of Hi-Nicalon fibres reinforcing either SiBC matrices, allowing data comparisons to be made with similar CFCMCs having different fibre-matrix combinations. The r the longitudinal fibres govern the rates of strain accumulation and crack growth, but the fracture characteristics are determined by fibre failure aused by oxygen penetration as matrix cracks develop. The analysis then suggests that carbon fibre-reinforced doloma-matrix composites could offer a combination of creep-resistant fibres and creep damage-resistant matrices suitable for long-term load-bearing in high-temperature oxidizing environments. 2007 Elsevier ltd. all rights reserved. Keywords: Composites; Creep: Fracture; Damage resistance; Structural applications 1. ntroduction mined in air at 1300C are documented for two advanced sic fibre-reinforced products. These results are then discussed with Since the 1950s, the introduction of new metallic materi- reference to data sets reported for several related materials als and improved manufacturing technologies have supported In this way, a straightforward evaluation can be made of the major advances in the power, efficiency and reliability of creep performance improvement achieved using aeroengines, underpinning impressive increases in the range, performance and safety of civil and military aircraft. In seek-(a) different fibre types for composites with comparable matri- ing further gains in thrust-to-weight ratio and fuel economy, ces. fibre-matrix interfaces and fibre architectures and ceramic-matrix composites reinforced with continuous ceramic (b) different matrices for composites having similar fibre type fibres(CFCMCs)represent a recognized material development fibre configurations and fibre-matrix interfaces opportunity. Even so, particularly as the civil aviation sec- tor becomes increasingly cost conscious, emphasis must be By clarifying the principal creep life-limiting features of this directed towards product cost reduction as well as component product range, proposals are made for a relatively low-cost com life enhancement posite which may provide the creep damage resistance needed Although a wide variety of CFCMCs have been developed, for high-temperature load-bearing applications involving pro- special attention has been focussed on composites with either longed exposure in oxidizing environme Sic or Al2 O3 matrices, reinforced with interwoven bundles of silicon carbide fibres. However, the creep fracture char- 2. Experimental procedures acteristics of these types of composite at high temperatures are this reason, in the present sudy, creep property values deter- produced with high Hi-Nicalon TM fibrer for two C bres, adversely affected by oxidizing atmospheres,bi.ethe service To quantify the effects of changing the reinforcing fibres, conditions typically experienced by aeroengine components For creep property measurements now recorde re compared with results available for similar composites containing Nicalon M NLM202 fibres(Nippon Carbon Co., Japan). Hi-NicalonTM Corresponding author. Tel. +44 1792 295243: fax: +44 1792 295244 fibres are characterized by superior elastic moduli and creep E-mail address: b wilshire@swansea. ac uk(B. wilshire) istance, achieved through processing operations adopted to 0955-2219/S-see front matter o 2007 Elsevier Ltd. All rights reserved. doi: 10. 1016/j-jeurceramsoc. 2007.03.029Journal of the European Ceramic Society 27 (2007) 4603–4611 Creep damage resistance of ceramic–matrix composites B. Wilshire ∗, M.R. Bache Materials Research Centre, School of Engineering, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK Received 22 November 2006; received in revised form 20 March 2007; accepted 25 March 2007 Available online 12 June 2007 Abstract The tensile creep and creep fracture properties in air at 1300 ◦C are documented for two ceramic fibre-reinforced ceramic–matrix composites (CFCMCs). These recently developed materials were produced with woven bundles of Hi-NicalonTM fibres reinforcing either A12O3 or enhanced SiBC matrices, allowing data comparisons to be made with similar CFCMCs having different fibre–matrix combinations. The results confirm that the longitudinal fibres govern the rates of strain accumulation and crack growth, but the fracture characteristics are determined by fibre failure caused by oxygen penetration as matrix cracks develop. The analysis then suggests that carbon fibre-reinforced doloma–matrix composites could offer a combination of creep-resistant fibres and creep damage-resistant matrices suitable for long-term load-bearing service in high-temperature oxidizing environments. © 2007 Elsevier Ltd. All rights reserved. Keywords: Composites; Creep; Fracture; Damage resistance; Structural applications 1. Introduction Since the 1950s, the introduction of new metallic materi￾als and improved manufacturing technologies have supported major advances in the power, efficiency and reliability of aeroengines, underpinning impressive increases in the range, performance and safety of civil and military aircraft.1,2 In seek￾ing further gains in thrust-to-weight ratio and fuel economy, ceramic–matrix composites reinforced with continuous ceramic fibres (CFCMCs) represent a recognized material development opportunity. Even so, particularly as the civil aviation sec￾tor becomes increasingly cost conscious, emphasis must be directed towards product cost reduction as well as component life enhancement. Although a wide variety of CFCMCs have been developed, special attention has been focussed on composites with either SiC or A12O3 matrices, reinforced with interwoven bundles of silicon carbide fibres.2,3 However, the creep fracture char￾acteristics of these types of composite at high temperatures are adversely affected by oxidizing atmospheres,4–6 i.e. the service conditions typically experienced by aeroengine components. For this reason, in the present study, creep property values deter- ∗ Corresponding author. Tel.: +44 1792 295243; fax: +44 1792 295244. E-mail address: b.wilshire@swansea.ac.uk (B. Wilshire). mined in air at 1300 ◦C are documented for two advanced SiC fibre-reinforced products. These results are then discussed with reference to data sets reported for several related materials.7–11 In this way, a straightforward evaluation can be made of the creep performance improvement achieved using (a) different fibre types for composites with comparable matri￾ces, fibre–matrix interfaces and fibre architectures and (b) different matrices for composites having similar fibre types, fibre configurations and fibre–matrix interfaces. By clarifying the principal creep life-limiting features of this product range, proposals are made for a relatively low-cost com￾posite which may provide the creep damage resistance needed for high-temperature load-bearing applications involving pro￾longed exposure in oxidizing environments. 2. Experimental procedures To quantify the effects of changing the reinforcing fibres, creep property measurements now recorded for two CFCMCs produced with high Hi-NicalonTM fibres are compared with results available for similar composites containing NicalonTM NLM202 fibres (Nippon Carbon Co., Japan). Hi-NicalonTM fibres are characterized by superior elastic moduli and creep resistance, achieved through processing operations adopted to 0955-2219/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jeurceramsoc.2007.03.029