PRODUCTION AND CHARACTERIZATION OF CARBON-PHENOLIC ABLATIVE MATERIALS MODIFIED WITH NANO-FILLERS

Concept: Ablative materials represent the traditional approach to protect space vehicles from the severe heating during hypersonic flight through a planet’s or the Earth’s atmosphere. The Materials and Surface Engineering Lab (LIMS) of Sapienza-University of Rome has developed carbon-phenolic ablative materials with several densities and compositions. This work presents a new methodology for their manufacture adding functionalized nanofillers. In particular acetic, decanoic and methacrylic acid were chosen as functionalizing group of nano-zirconia. Mechanical (bending and compression tests) and thermal characterization (TGA/DSC) are carried out in order to understand the effect of nano-fillers on the material properties. Motivations and objectives: Ablative materials consist of a rigid felt impregnated with phenolic resin. During the process the resin is diluted and nanoparticles are added to this solution. Nano-filler are introduced in order to improve mechanical and thermo-physical properties of virgin and charred material, but their efficiency is strictly connected to the homogenous dispersion of the particles. An acid surface modification were conducted to avoid the agglomeration of particles according to Chiang et al. The efficiency of the method was proved by FE-SEM photographs, mechanical and thermal tests will enlighten the properties improvement. Results and discussion: The FE-SEM photograph (Fig. 1) of a cured carbonphenolic ablative material shows that addition of nano-fillers does not decrease the goodness of the distribution of the resin in the sample without density variation. Figure 2 shows that the surface modification and the impregnation procedure does not change the dimension of the nanoparticles (as shown in the inset). Although the particles are well dispersed in the resin. Bending and compression tests will provide a comparison between samples manufactured with and without nano-zirconia.