Influence of matrix densification upon structure and elastic properties ofcarbon-carbon composite shells

Carbonisation of "green" composite shells reinforced with carbon yarn braid and soaked with phenolic resin yielded carbon-carbon composite cylindrical shells. The obtained porous composite material was densified by impregnati on with various precursors of secondary carbon matrix. By measuring the lon gitudinal and tangential elastic moduli of the composite shells by a resona nt frequency technique their gradual stiffening was monitored. The roles of the braiding angle and of the processing parameters (heat treatment, densi fication, and impregnant type) upon constitution of the composite shell ela sticity are discussed.