CERAMICS INTERNATIONAL ELSEVIER Ceramics International 27(2001)565-570 www.elsevier.com/locate/ceramint High performance 3d textile Hi-Nicalon SiC/SiC composites by chemical vapor infiltration Yongdong Xu*, Aifei Cheng, Litong Zhang, Xiaowei Yin, Hongfeng Yin State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xian, Shaanxi 710072, China Received Il September 2000: received in revised form 30 October 2000: accepted 18 December 2000 Abstract Three dimensional textile Hi-Nicalon silicon carbide fiber reinforced silicon carbide composites with high toughness and relia- bending, shear, and impact loading. bor infiltration. The mechanical properties of the composite materials were investigated under b lity were fabricated by chemical val ne density of the composites was 2.5 g cm-3 after the three dimension silicon carbide perform has been infiltrated for 30 h. The values of flexural strength were 860 MPa at room temperature and 1010 MPa at 1300C in vacuum. Above the infiltration temperature, the failure behavior of the composites became brittle because of the strong interfacial bonding and the mis-match of thermal expansion coefficients between fiber and matrix. The obtained value of shear strength was 67.5 MPa. The composites exhibited excellent impact resistance and the value of dynamic fracture toughness is 36.0 kJ m-2 was measured with Charpy impact tests. C 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved Keywords: C. Mechanical properties; 3D SiC/SiC composites; Chemical vapor infiltration 1. Introduction tration and examined the mechanical properties over the temperature range from room temperature to 1300C. Continuous fiber reinforced ceramic matrix compo- The aims of the current contribution are to develop an sites(CFCCs) show superior performance when super- understanding of the architecture on the mechanical lloy at elevated temperatures and higher toughness properties and the damage behavior of the 3D Hi-Nica- wheen compared with monolithic ceramics [1-4]. For lon SiC/Sic composites and to expand the experimental these reasons, CFCCs have the most potential to be used knowledge for the three dimensional textile composite in advanced aero-engines, space, and fusion power reac materials tors [1-4]. Among these CFCCs, silicon carbide fiber reinforced silicon carbide composites(SiC/SiC)are pro- mising and have received considerable attention. Many 2. Materials and experimental procedures investigations have been conducted on one dimension (ID)and two-dimension(2D)woven SiC/SiC composite 2.1. Fabrication of the composites materials [5-12]. Recently, attention has been focused on three-dimension woven or braided ceramic matrix Hi-Nicalon SiC fiber was employed and each ya aIn composite materials in order to meet mechanical and contained 500 filaments. The three dimensional(3D) thermal properties requirements under most complex fabric perform was braided by four-step processing and loads [13-18. supplied by Nanjing Institute of Glass Fiber in China The present research involved 3D textile Hi-Nicalon The structure of the preform is illustrated in Fig. 1. The SiC/SiC composites prepared by chemical vapor infil- fiber volume fraction was 40%. In the present experi ment, chemical vapor infiltration was employed to deposit a pyrolytic carbon layer and silicon carbide, 4 Corresponding author which has been described previously in detail [ 14, 15].A 8491000. +86-29-8491427:fax: 86-29. thin carbon layer as the interfacial layer was deposited E-mailaddress:ydxu(@nwpu.edu.cn(Y.Xu). on the surface of the hi-Nicalon sic fiber with butane 0272-8842/01/S2000C 2001 Elsevier Science Ltd and Techna S.r. I All rights reserved. PII:S0272-8842(01)00002-5High performance 3D textile Hi-Nicalon SiC/SiC composites by chemical vapor infiltration Yongdong Xu*, Laifei Cheng, Litong Zhang, Xiaowei Yin, Hongfeng Yin State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi, an, Shaanxi 710072, China Received 11 September 2000; received in revised form 30 October 2000; accepted 18 December 2000 Abstract Three dimensional textile Hi-Nicalon silicon carbide fiber reinforced silicon carbide composites with high toughness and relia￾bility were fabricated by chemical vapor infiltration. The mechanical properties of the composite materials were investigated under bending, shear, and impact loading. The density of the composites was 2.5 g cm
3 after the three dimension silicon carbide perform has been infiltrated for 30 h. The values of flexural strength were 860 MPa at room temperature and 1010 MPa at 1300C in vacuum. Above the infiltration temperature, the failure behavior of the composites became brittle because of the strong interfacial bonding and the mis-match of thermal expansion coefficients between fiber and matrix. The obtained value of shear strength was 67.5 MPa. The composites exhibited excellent impact resistance and the value of dynamic fracture toughness is 36.0 kJ m
2 was measured with Charpy impact tests. # 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved. Keywords: C. Mechanical properties; 3D SiC/SiC composites; Chemical vapor infiltration 1. Introduction Continuous fiber reinforced ceramic matrix compo￾sites (CFCCs) show superior performance when super￾alloy at elevated temperatures and higher toughness wheen compared with monolithic ceramics [1–4]. For these reasons, CFCCs have the most potential to be used in advanced aero-engines, space, and fusion power reac￾tors [1–4]. Among these CFCCs, silicon carbide fiber reinforced silicon carbide composites (SiC/SiC) are pro￾mising and have received considerable attention. Many investigations have been conducted on one dimension (1D) and two-dimension (2D) woven SiC/SiC composite materials [5–12]. Recently, attention has been focused on three-dimension woven or braided ceramic matrix composite materials in order to meet mechanical and thermal properties requirements under most complex loads [13–18]. The present research involved 3D textile Hi-Nicalon SiC/SiC composites prepared by chemical vapor infil￾tration and examined the mechanical properties over the temperature range from room temperature to 1300C. The aims of the current contribution are to develop an understanding of the architecture on the mechanical properties and the damage behavior of the 3D Hi-Nica￾lon SiC/SiC composites and to expand the experimental knowledge for the three dimensional textile composite materials. 2. Materials and experimental procedures 2.1. Fabrication of the composites Hi-Nicalon SiC fiber was employed and each yarn contained 500 filaments. The three dimensional (3D) fabric perform was braided by four-step processing and supplied by Nanjing Institute of Glass Fiber in China. The structure of the preform is illustrated in Fig. 1. The fiber volume fraction was 40%. In the present experi￾ment, chemical vapor infiltration was employed to deposit a pyrolytic carbon 1ayer and silicon carbide, which has been described previously in detail [14,15]. A thin carbon layer as the interfacial layer was deposited on the surface of the Hi-Nicalon SiC fiber with butane 0272-8842/01/$20.00 # 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved. PII: S0272-8842(01)00002-5 Ceramics International 27 (2001) 565–570 www.elsevier.com/locate/ceramint * Corresponding author. Tel.: +86-29-8491427; fax: 86-29- 8491000. E-mail address: ydxu@nwpu.edu.cn (Y. Xu).