MIATERIALS SENE S ENGEERING ELSEVIER Materials Science and Engineering A354(2003)58-66 Kinetics of oxidation in oxide ceramic matrix composites P. Mogilevsky a, b, * A. Zangvil Air Force Research Laboratory/MLLN, Wright-Patterson Air Base. OH 45433. USA UES Inc.. 4401 Dayton-Xenia Rd, Dayton, OH 45432. US.A Ceramic Shield Ltd. Misgar Carmiel Technology Incubator, M. P. Misgav 20179, Israel Received 25 June 2002. received in revised form 4 Novem ber 2002 Oxidation of sic reinforcement is or factor affecting the environmental stability of Sic reinforced ceramic matrix omposites(CMCs) for high temperature applications. a new quantitative model for the oxidation of oxide CMCs with non-oxide reinforcements is described. The proposed model is applied to the experimental results from the literature on oxidation of Al2O3/Sic composites. C 2003 Elsevier Science B V. All rights reserved. Keywords: Kinetics: Oxidation; Oxide ceramic matrix 1. Introduction situated deeper into composite would occur. This mode results in a sharp interface separating the surface layer Ceramic matrix composite (CMC) materials rein- of completely oxidized material from the underlying forced with Sic particles, whiskers, fibers, or platelets virgin composite Mode II is the case where oxygen can have high fracture toughness and strength [1-5]. In deeply penetrate into the matrix before reinforcement oxide matrix CMCs, high temperature oxidation of Sic particles in the outer region are completely oxidized, reinforcement affects the environmental stability of the leaving behind a region of partially oxidized reinforce- CMC. Alumina and mullite have been considered as ment Mode I was experimentally found in alumina/Sic matrix materials for oxide CMCs due to their excellent and mullite/SiC composites [6, 8, 14], while mode II was high-temperature stability and, in particular, slow oxy- observed in mullite/Zro2/SiC composites [7, 10, 12-14 gen permeation, minimizing the oxidation of the re- A semi-quantitative model was proposed by the present inforcement authors for the oxidation mode ii of sic reinforced Oxidation of sic reinforced alumina. mullite, and oxide CMCs[17]. Based on this model, a qualitative link mullite/zirconia matrix composites has been studied between the diffusion characteristics of the components both microscopically and via conventional weight gain ind structural characteristics of the composite(such as method [6-16]. Two oxidation modes of Sic reinforced the volume fraction of the non-oxide reinforcement) nd the oxidation mode of the composite, was estab- [7. 8, 10, 11, 14. Mode I was defined as the case when Sic lished. a quantitative model describing the oxidation icles at a particular depth become completely mode I was first suggested by Luthra and Park [8]. In he present study the approach of [17] is extended and ized before any observable oxidation of particles used as a basis to develop a new model for the oxidation mode i of oxide Cmcs. that allows to examine the s Corresponding author. Tel: +1-937-255-9855: fax: +1-937-656- oxidation kinetics in detail. The proposed model is plied to the expe E-mail address: pavel mogilevsky @wpafb af mil(P Mogilevsky) AlO3/SiC composites available in the literatureKinetics of oxidation in oxide ceramic matrix composites P. Mogilevsky a,b,*, A. Zangvil c a Air Force Research Laboratory/MLLN, Wright-Patterson Air Force Base, OH 45433, USA b UES Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432, USA c Ceramic Shield Ltd. Misgav Carmiel Technology Incubator, M.P. Misgav 20179, Israel Received 25 June 2002; received in revised form 4 November 2002 Abstract Oxidation of SiC reinforcement is a major factor affecting the environmental stability of SiC reinforced ceramic matrix composites (CMCs) for high temperature applications. A new quantitative model for the oxidation of oxide CMCs with non-oxide reinforcements is described. The proposed model is applied to the experimental results from the literature on oxidation of Al2O3/SiC composites. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Kinetics; Oxidation; Oxide ceramic matrix 1. Introduction Ceramic matrix composite (CMC) materials rein￾forced with SiC particles, whiskers, fibers, or platelets have high fracture toughness and strength [1
/5]. In oxide matrix CMCs, high temperature oxidation of SiC reinforcement affects the environmental stability of the CMC. Alumina and mullite have been considered as matrix materials for oxide CMCs due to their excellent high-temperature stability and, in particular, slow oxy￾gen permeation, minimizing the oxidation of the re￾inforcement. Oxidation of SiC reinforced alumina, mullite, and mullite/zirconia matrix composites has been studied both microscopically and via conventional weight gain method [6
/16]. Two oxidation modes of SiC reinforced oxide matrix composite materials have been reported [7,8,10,11,14]. Mode I was defined as the case when SiC particles at a particular depth become completely oxidized before any observable oxidation of particles situated deeper into composite would occur. This mode results in a sharp interface separating the surface layer of completely oxidized material from the underlying virgin composite. Mode II is the case where oxygen can deeply penetrate into the matrix before reinforcement particles in the outer region are completely oxidized, leaving behind a region of partially oxidized reinforce￾ment. Mode I was experimentally found in alumina/SiC and mullite/SiC composites [6,8,14], while mode II was observed in mullite/ZrO2/SiC composites [7,10,12
/14]. A semi-quantitative model was proposed by the present authors for the oxidation mode II of SiC reinforced oxide CMCs [17]. Based on this model, a qualitative link between the diffusion characteristics of the components and structural characteristics of the composite (such as the volume fraction of the non-oxide reinforcement), and the oxidation mode of the composite, was estab￾lished. A quantitative model describing the oxidation mode I was first suggested by Luthra and Park [8]. In the present study the approach of [17] is extended and used as a basis to develop a new model for the oxidation mode I of oxide CMCs, that allows to examine the oxidation kinetics in detail. The proposed model is applied to the experimental results on oxidation of Al2O3/SiC composites available in the literature. * Corresponding author. Tel.: /1-937-255-9855; fax: /1-937-656- 4296. E-mail address: pavel.mogilevsky@wpafb.af.mil (P. Mogilevsky). Materials Science and Engineering A354 (2003) 58
/66 www.elsevier.com/locate/msea 0921-5093/02/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0921-5093(02)00872-9