CERAMICS INTERNATIONAL ELSEVIER Ceramics International 33(2007)385-388 www.elsevier.com/locate/ceramint Improvement of mechanical properties of Al2O3/Ti3 SiC2 multilayer ceramics by adding Sic whiskers into alo la 3 ayers Zan Qingfeng. D, Dong Limin, Wang Chena Institute of Nuclear and New Energy Technology Tsinghua University, Beijing 100084, PR China b State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering Tsinghua University, Beijing 100084, PR China Received 3 August 2005: received in revised form 18 August 2005: accepted 4 October 2005 Available online 28 February 2006 Abstract Al2O, /Ti3 SiC2 multilayer materials with high mechanical properties in terms of bending strength and work of fracture have been prepared by in situ hot-pressing at 1600C for 4 h In order to further improving the mechanical properties, SiC whiskers were added to Al2O3 layers as the 2nd level toughening agent with the content of Sic whisker increasing the bending strength and work of fracture showed a similar trend of increasing firstly and then decreasing. Hence, the optimal mechanical properties of 688 MPa for bending strength and 2583 J/m2 for work of fracture were btained when the added content of Sic whisker was 20 wt%. These excellent properties should be attributed to 1st-level toughening mechanism multilayer structural toughening ), 2nd-level toughening mechanism(whisker toughening), and the synergy effect between them. Hence, adding Sic whiskers was an effective approach to improving the mechanical properties C 2005 Elsevier Ltd and Techna Group S.r.L. All rights reserved. Keywords: B. Whisker; D Al2O3; Ti3SiC2; Toughening mechanism; Multilayer ceramics 1. Introduction Si3N,/BN [10, 11], SiC/C [9, 12, Al,, [13], etc. and several 10-folds of fracture toughness and several 100-folds of Ceramics are brittle and sometimes they fail catastrophically. work of fracture were achieved compared to the monolithic This limits theirapplications in engineering. In to overcome ceramics. Al2O3/Ti3SiC2 multilayer ceramics is a typical the problem, studying of toughening becomes a very important multilayer material, which possess good mechanical properties research area in ceramics, especially structural ceramics. As a of 659 MPa for bending strength and 2159 J/m- for work of result, many toughening methods had been devised, researched fracture [14] and used in ceramics, such as whisker toughening[ 1-3, long-and In recent years, synergy mechanism between two or more short-fiber toughening [4,5], dispersed rigid particle toughening toughening methods was reported [15]. By this toughening [61, ZrO2 phase transformation toughening [7, 8], andso on. These mechanism, the toughness effect was usually larger than the toughening methods were all effective for some ceramics, additional effect brought by the individual toughening hereinto whiskers were used very widely mechanisms. The all fore-mentioned toughening mechanisms Otherwise, multilayer structural toughening was proved as could be used in synergy toughening design of ceramics by an effective toughening mechanism [9-12]. Since the SiC/c appropriate methods. multilayer ceramics was first developed by Clegg et al. [9], this In this paper, the SiC whiskers as 2nd-level toughening agent toughening approach has been used in many systems, such as were added into Al2O3 layers in Al2O3/Ti3 SiC2 multilayer ceramics. The 2nd-level toughening mechanism in the multi layer ceramics, the synergy effect between the multilevel Corresponding author. Tel. +86 10 897961 12: fax: +86 10 89796118 toughening mechanisms and the fractural behavior of the whole materials will be described in this paper. 2-8842/$32.00 2005 Elsevier Ltd and Techna Group S.r.L. All rights reserved 10.1016 1. ceramist.2005.10.007Improvement of mechanical properties of Al2O3/Ti3SiC2 multilayer ceramics by adding SiC whiskers into Al2O3 layers Zan Qingfeng a,b, *, Dong Limin a , Wang Chen a , Wang Chang-an b , Huang Yong b a Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, PR China b State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China Received 3 August 2005; received in revised form 18 August 2005; accepted 4 October 2005 Available online 28 February 2006 Abstract Al2O3/Ti3SiC2 multilayer materials with high mechanical properties in terms of bending strength and work of fracture have been prepared by in situ hot-pressing at 1600 8C for 4 h. In order to further improving the mechanical properties, SiC whiskers were added to Al2O3 layers as the 2nd￾level toughening agent. With the content of SiC whisker increasing, the bending strength and work of fracture showed a similar trend of increasing firstly and then decreasing. Hence, the optimal mechanical properties of 688 MPa for bending strength and 2583 J/m2 for work of fracture were obtained when the added content of SiC whisker was 20 wt%. These excellent properties should be attributed to 1st-level toughening mechanism (multilayer structural toughening), 2nd-level toughening mechanism (whisker toughening), and the synergy effect between them. Hence, adding SiC whiskers was an effective approach to improving the mechanical properties. # 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: B. Whisker; D. Al2O3; Ti3SiC2; Toughening mechanism; Multilayer ceramics 1. Introduction Ceramics are brittle and sometimes they fail catastrophically. Thislimitstheir applicationsin engineering. In orderto overcome the problem, studying of toughening becomes a very important research area in ceramics, especially structural ceramics. As a result, many toughening methods had been devised, researched and usedin ceramics, such aswhiskertoughening[1–3],long- and short-fiber toughening [4,5], dispersed rigid particle toughening [6], ZrO2 phasetransformationtoughening [7,8], and so on.These toughening methods were all effective for some ceramics, hereinto whiskers were used very widely. Otherwise, multilayer structural toughening was proved as an effective toughening mechanism [9–12]. Since the SiC/C multilayer ceramics was first developed by Clegg et al. [9], this toughening approach has been used in many systems, such as Si3N4/BN [10,11], SiC/C [9,12], Al2O3/ZrO2 [13], etc. and several 10-folds of fracture toughness and several 100-folds of work of fracture were achieved compared to the monolithic ceramics. Al2O3/Ti3SiC2 multilayer ceramics is a typical multilayer material, which possess good mechanical properties of 659 MPa for bending strength and 2159 J/m2 for work of fracture [14]. In recent years, synergy mechanism between two or more toughening methods was reported [15]. By this toughening mechanism, the toughness effect was usually larger than the additional effect brought by the individual toughening mechanisms. The all fore-mentioned toughening mechanisms could be used in synergy toughening design of ceramics by appropriate methods. In this paper, the SiC whiskers as 2nd-level toughening agent were added into Al2O3 layers in Al2O3/Ti3SiC2 multilayer ceramics. The 2nd-level toughening mechanism in the multi￾layer ceramics, the synergy effect between the multilevel toughening mechanisms and the fractural behavior of the whole materials will be described in this paper. www.elsevier.com/locate/ceramint Ceramics International 33 (2007) 385–388 * Corresponding author. Tel.: +86 10 89796112; fax: +86 10 89796118. E-mail address: Zanqingfeng@tsinghua.org.cn (Zan Qingfeng). 0272-8842/$32.00 # 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved. doi:10.1016/j.ceramint.2005.10.007