J Mater Sci(2007)42:763-771 DOI10.1007/s10853-006-1443-3 Effect of heat treatment in air on the thermal properties of siC fibre-reinforced composite. Part 1: a barium osumilite (BMas) matrix glass ceramic composite R. Yilmaz·R. Taylor October 2003/ Accepted: 13 April 2006/Published online: 12 January 2007 Springer Science+Business Media, LLC 2007 Abstract The thermal properties have been studied Introduction on a glass ceramic composite comprised of a barium umilite(BMAS)matrix reinforced with SiC (Tyran- SiC fibres have been developed and used in a variety of no) fibres which has been subjected to a heat treatment reinforced glass ceramic composites over the last two in air in the range of 700-1, 200C. Microstructural decades. They are intended to provide reinforcement studies were carried out especially on of the interface and to improve the performance of structural ceramics between fibre and matrix. The presence of a carbon for high temperature applications [1] thin layer in the interface is a typical observation in Sic Ceramics are brittle, have low fracture toughness fibre-reinforced glass ceramic matrix composite sys- and they fail in a catastrophic manner. The brittleness tems. The microstructural evaluation and thermal of the material results from sudden propagation of a properties showed a degradation of interfacial layer crack under the applied stress. Thus, for the future ccurred at low heat treatment temperatures, (700- application of ceramics at high temperatures it is 800C)this was attributed to the fact that, at those necessary to develop ceramic fibres as reinforcement in heat treatment temperatures the carbon rich layer suitable matrices. It is also necessary to understand the formed during processing was oxidised away leaving fracture behaviour of these composites and behaviour voids between fibre and matrix, which were linked by of the interface for design matters in order to optimise isolated silicon-rich bridges. After heat treatment at their mechanical properties higher temperatures of 1,000-1, 200C, the thermal One of the most promising glass ceramic matrix properties were retained or even enhanced by leaving a systems is barium osumilite(BMAS), first developed thick interfacial layer. by Brennan et al. [2]. Thermal properties of BMAS glass ceramic matrix composites have been studied by Johnson et al. 3]. Although the use of such materials ill be governed by the development of the suitable mechanical properties, the accurate thermo-physical properties are also needed such as thermal expansion, thermal diffusivity and conductivity During manufacturing stage, due to fibr R. Yilmaz(凶) reaction, a carbon layer is formed [4, 5] in SiC fibre- Technical Education Faculty. Metal Education Division Sakarya University, Esentepe Campus, 54187 Sakarya reinforced glass ceramic composites. This carbon rich Turkey layer has been observed in MAS, calcium aluminium e-mail: ryilmaz@sakarya. edu.tr silicate (CAS), barium aluminium silicate (BAS) barium magnesium aluminium silicate(BMAs)glass R. Pavlo Manchester Materials Science Centre, University of ceramic matrix composites 6-12 Manchester Institute of Science and Technology. Grosvenor The in-service performance of these composites Street, Manchester M1 7HS. England depends on the environmental conditions. The thermalEffect of heat treatment in air on the thermal properties of SiC fibre-reinforced composite. Part 1: a barium osumilite (BMAS) matrix glass ceramic composite R. Yilmaz Æ R. Taylor Received: 13 October 2003 / Accepted: 13 April 2006 / Published online: 12 January 2007
Springer Science+Business Media, LLC 2007 Abstract The thermal properties have been studied on a glass ceramic composite comprised of a barium osumilite (BMAS) matrix reinforced with SiC (Tyran￾no) fibres which has been subjected to a heat treatment in air in the range of 700–1,200 C. Microstructural studies were carried out especially on of the interface between fibre and matrix. The presence of a carbon thin layer in the interface is a typical observation in SiC fibre-reinforced glass ceramic matrix composite sys￾tems. The microstructural evaluation and thermal properties showed a degradation of interfacial layer occurred at low heat treatment temperatures, (700– 800 C) this was attributed to the fact that, at those heat treatment temperatures the carbon rich layer formed during processing was oxidised away leaving voids between fibre and matrix, which were linked by isolated silicon-rich bridges. After heat treatment at higher temperatures of 1,000–1,200 C, the thermal properties were retained or even enhanced by leaving a thick interfacial layer. Introduction SiC fibres have been developed and used in a variety of reinforced glass ceramic composites over the last two decades. They are intended to provide reinforcement and to improve the performance of structural ceramics for high temperature applications [1]. Ceramics are brittle, have low fracture toughness and they fail in a catastrophic manner. The brittleness of the material results from sudden propagation of a crack under the applied stress. Thus, for the future application of ceramics at high temperatures it is necessary to develop ceramic fibres as reinforcement in suitable matrices. It is also necessary to understand the fracture behaviour of these composites and behaviour of the interface for design matters in order to optimise their mechanical properties. One of the most promising glass ceramic matrix systems is barium osumilite (BMAS), first developed by Brennan et al. [2]. Thermal properties of BMAS glass ceramic matrix composites have been studied by Johnson et al. [3]. Although the use of such materials will be governed by the development of the suitable mechanical properties, the accurate thermo-physical properties are also needed such as thermal expansion, thermal diffusivity and conductivity. During manufacturing stage, due to fibre and matrix reaction, a carbon layer is formed [4, 5] in SiC fibre￾reinforced glass ceramic composites. This carbon rich layer has been observed in MAS, calcium aluminium silicate (CAS), barium aluminium silicate (BAS), barium magnesium aluminium silicate (BMAS) glass ceramic matrix composites [6–12]. The in-service performance of these composites depends on the environmental conditions. The thermal, R. Yilmaz (&) Technical Education Faculty, Metal Education Division, Sakarya University, Esentepe Campus, 54187 Sakarya, Turkey e-mail: ryilmaz@sakarya.edu.tr R. Taylor Manchester Materials Science Centre, University of Manchester Institute of Science and Technology, Grosvenor Street, Manchester M1 7HS, England J Mater Sci (2007) 42:763–771 DOI 10.1007/s10853-006-1443-3 123