Nanographite-reinforced carbon/carbon composites

Carbon/carbon composites (C/Cs) with nanographite platelets (NGP) filler in a matrix derived from phenolic resin were produced. Different weight concentration (0.5, 1.5, 3, 5 wt.%) NGP were introduced by spraying the NGP during the prepreg formation. The NGP-reinforced C/Cs were characterized for effect of NGP concentration on microstructure, porosity, interlaminar shear strength (ILSS), flexural, ultrasonic and vibration damping behavior. At 1.5 wt.% NGP C/C, the highest values of ILSS observed was 10.5 MPa (increased by 22%), flexure strength of 142.4 MPa (increased by 27%), flexural modulus of 59.2 GPa (increased by 68%) and porosity of 18.8% (reduced by 17.5%) in comparison to neat (without NGP) densified C/C. Ultrasonic testing revealed an average increase of 15% through the thickness Young's modulus of NGP-C/C; (3.12 GPa at 1.5 wt.% NGP). A 20% average decrease in the damping ratio of the first four modes of vibration was observed in 1.5 wt.% NGP densified C/C. At low concentration (<= 1.5 wt.%) the NGP filled in the pores, cracks and debonded interface but at concentration higher than 1.5 wt.% NGP lost their effectiveness due to agglomeration. The required cycles for desired density/properties are projected to be less compared to neat C/C due to less porosity observed in <= 1.5 wt.% NGP concentration C/C. (C) 2012 Elsevier Ltd. All rights reserved.