Short-fibre-reinforced reaction-bonded silicon nitride (RBSN) by precursor route: Processing and properties

A new approach to manufacture short-fibre-reinforced ceramic matrix composites (CMC) by mixing carbon fibres, ceramic fillers and a viscous ceramic precursor by means of a plastic forming technique is introduced. To transform the composite from the polymer into a nitride ceramic state, a two-step process consisting of pyrolysis and nitridation is applied. Transformations of the polymer-modified RBSN (PMRBSN) during this process are examined in terms of dimensional changes, porosity and phase composition. The role of the precursor during the processing and nitridation sequence, aspects concerning fibre shortening and packing and the effects on the material properties as Young's modulus, strength, hardness, porosity, crack deflection and fibre pullout are discussed.