Mechanical properties and mechanical behavior of (SiO2 ) f /SiO2 composites with 3D six-directional braided quartz fi ber preform

Abstract

(SiO2 ) f /SiO2 composites reinforced with three-dimensional (3D) six-directional preform were fabricated by the silicasolinfi ltration-sintering method. The nominal fi ber volume fraction was 47 % . To characterize the mechanical properties of the composites, mechanical testing was carried out under various loading conditions, including tensile, fl exural, and shear loading. The composite exhibited highly nonlinear stress-strain behavior under all the three types of loading. The results indicated that the 3D six-directional braided (SiO2 ) f /SiO 2 composites exhibited superior fl exural properties and good shear resistant as compared with other types of preform (2.5D and 3D four-directional)-reinforced (SiO2 ) f /SiO2 composites. 3D six-directional braided (SiO2 ) f /SiO2 composite exhibited graceful failure behavior under loading. The addition of 5th and 6th yarns resulted in controlled fracture and hence these 3D six-directional braided composites could possibly be suitable for thermal structure components. © 2012 by Walter de Gruyter.© 2012 by Walter de Gruyter.