Preparation and properties of an oxide fiber-reinforced silica matrix composite

摘要

Oxide (Nextel 440) fiber-reinforced silica composites, with the density and porosity of 1.97 g/cm(3) and 21.8, were prepared through sol-gel. Their average flexure strength, elastic modulus, shear strength, and fracture toughness at room temperature were 119.7 MPa, 25.6 GPa, 10.8 MPa, and 4.0 MPam1/2, respectively. The composites showed typical toughened fracture behavior, and distinct pullout fibers were observed at the fracture surface. Their mechanical properties were performant up to 1000 degrees C, with the maximum flexural strength of 132.2 MPa at 900 degrees C. Moreover, the composites showed good thermal stability, even after thermal aging and thermal shock at elevated temperatures.