Manufacture of glass composites reinforced with long and short fibres by extrusion

Abstract

In the case of fibre-reinforced glass composites the glass matrix is the property-determining component, i.e., in the first place the composite possesses the characteristic properties of the glass. The embedded fibres serve for increasing the strength, the work of fracture and thus, the toughness of the glass. In contrast to the manufacture of composites by hot pressing, the extrusion method produces samples with high length-to-diameter ratios. The continuous flowing of the glass melt within the deformation zone and within the die channel leads to a preferential orientation of the fibres parallel to the direction of extrusion. Since the processing temperature is rather low compared with hot pressing, a thermal damage of the fibres can nearly be avoided. The manufacture of the glass composites is shown exemplarily for the embedding of continuous and discontinuous SiC fibres. The desizing, the impregnation of the long fibres and the homogeneous mixing of the short fibres with the glass powder are introduced and explained. This is followed by a schematic description of the extrusion method for both kinds of reinforcement. By means of some composite rods produced in this way the principal suitability of this processing for the unidirectional aligning of the reinforcing component is shown. The improvement of properties achieved by embedding the fibres into the samples is demonstrated by measured impact strength values.