The effects of pressure on the carbonization of pitch and pitch/carbon fibre composites

Abstract

Three pitches which give carbons of varying optical texture have been carbonized singly and with different carbon fibres at pressures in the range 0.1 to 200 MPa. The effect of pressure on the carbonization system is to retard growth and coalescence of the growth units of mesophase, thus reducing the size of the optical texture of the resultant carbon. With increasing pressure botryoidal (spherical) structures are formed. On co-carbonization of pitches with carbon fibres the alignment of the basal planes of the matrix carbon parallel to the fibre length at the fibre/matrix interface is improved within a given pressure range. This range is dependent upon the parent pitch used and is experimentally determined. This effect is seen for all fibre types.