Browsing by Author "Langhans, Klaus"

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    Manufacture of glass composites reinforced with long and short fibres by extrusion
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1988) Roeder, Erwin; Klein, Norbert; Langhans, Klaus
    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.
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    Manufacture of short-fibre reinforced glasses by extrusion and examinations regarding their structure and their mechanical properties
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1992) Langhans, Klaus; Roeder, Erwin
    Technical applications of glasses are mainly limited by their well-known tendency to brittle fracture. One promising possibility to improve the mechanical properties of glasses is the embedding of high-strength reinforcement fibres for increasing the strength and, first of all, the fracture toughness of these materials. Therefore, new fields of application for these glasses can be developed, where their many favourable properties become effective. In this paper the manufacture - by extrusion - of short-fibre reinforced glasses as well as structural and mechanical examinations of the thus produced specimens are represented. Due to the manufacturing process, extrusion results in a nearly unidirectional orientation of the fibres, parallel to the axis of the rod, with a corresponding high degree of reinforcement. After the explanation of the theoretical fundamentals of short-fibre reinforcement of brittle materials, the properties of the materials used for the experiments and the manufacture of the composites are described in detail. The subsequently illustrated examinations have clearly shown improvements of the mechanical properties of the glasses as well as good accordance with the theoretical considerations.