Nanocompressive Properties of Carbon Microballoons andMechanical Properties of Carbon Based Syntactic FoamComposites

摘要

A novel technique for compressive testing of individual carbon microballoons, CMB, hasbeen developed, utilizing a specially equipped nanoindentation apparatus. The CMB range in sizefrom 10 to 100 μm and are an integral component in carbon based syntactic foams.Polished cross sections of the foams and electron microscopy revealed complicated structuresin many of the CMB, rather than simple hollow spheres. Stereological techniques were used toevaluate variations in CMB wall thickness.Because syntactic foam composites have low density, approximately 0.3 g/cm3, they have awide range of applications and potential applications in aerospace and other transportation fields. Thefoam composites consist of CMB, bismaleimide resin and voids. Cylinders of syntactic foams weretested in compression. Unconfined compression strength was between 4.5 and 7 Mpa. The stressstraincurves showed an elastic region followed by a plateau at or near the ultimate compressivestrength and then failure of the sample by exfoliating flakes from the edges of the cylinders. Dynamicmodulus measurements were performed by impulse excitation and the dynamic flexural modulus wasapproximately 737 Mpa.