No abstract

The effects of impact energy on damage characteristics and tensile properties of 2D C/SiC-ZrC composites were studied by low-speed impact, post-impact tensile tests and the CT scanning methods. The results indicated that C/SiC-ZrC composites had a high impact damage tolerance. The damage state of the composites in the energy range of 15-24 J was mainly shown as penetrating damage. When the impact energy increased within the range of 15-24 J, the nominal tensile strength of C/SiC-ZrC composites reduced slowly, with a maximum decrease of around 25%. The impact mainly caused lamination and fiber fracture damage near the impact areas. However, the impact damage was not observed out of the impact areas.

No abstract

In this paper, effect of in situ grown boron nitride nanotubes (BNNTs) and preparation temperature on mechanical behavior of PIP (Precursor Infiltration and Pyrolysis) SiC/SiC minicomposites under monotonic and compliance tensile is investigated. In situ BNNTs are grown on the surface of SiC fibers using ball milling – annealing process. Composite elastic modulus, tensile strength, fracture strain, tangent modulus, and loading/unloading inverse tangent modulus (ITM) are obtained and adopted to characterize the mechanical properties of the composites. Microstructures of in situ grown BNNTs and tensile fracture surfaces are observed under scanning electronic microscopic (SEM). For SiC/SiC minicomposites with BNNTs, the elastic modulus, tensile strength, and fracture strain are all lower than those of SiC/SiC minicomposites without BNNTs, mainly due to high preparation temperature and the oxidation of the PyC interphase during the annealing process. Tensile stress-strain curves of SiC/SiC minicomposites with and without BNNTs are predicted using the developed micromechanical constitutive model. The predicted results agreed with experimental data. This work will provide guidance for predicting the service life of SiCf/SiC composite materials and may enable these materials to become a backbone for thermal structure systems in aerospace applications.