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The aim of this work is to determine the tribological behaviour of various materials on an ice surface. For preliminary investigations a pin-on-disc tribometer was placed into a cooling chamber. The dependence of the coefficient of friction on the normal force, the ice temperature, the sliding velocity and the heat conductivity of the sample pin as well as the surface topography were measured. It was difficult to obtain clear results, because of the manual preparation method of the ice surface. There was no electronical collection of the data. As this experimental set-up presents these disadvantages, a new low-temperature tribometer was developed. It is a computer aided low-temperature tribometer with a fixed ice disk and a rotary measuring system including the specimen. The spin can be moved on a spiral path, thus guaranteeing a new ice surface for measurement. A minimum temperature of -30 C, a normal force up to 10 N and a maximum sliding velocity of 9,4 m/s can be achieved. The important influence of a rough ice surface will be minimized by applying a careful mechanical preparation method.Some first measuring results obtained in friction-on-ice tests using the novel tribometer will be presented.

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Das Ziel der Untersuchungen ist die Entwicklung von transparenten Glasmatrix-Kompositen. Neben den mechanischen müssen dazu auch die optischen Eigenschaften der Komponenten aneinander angepaßt werden. Der Einfluß unterschiedlicher Faserbeschichtungen (Bornitrid-, Titandioxid-Einzelbeschichtung oder Bornitrid/ Titandioxid-Doppelbeschichtung) auf die mechanischen und optischen Eigenschaften von Nextel 440-Faser verstärktem Glas wird untersucht. Mikromechanische Untersuchungen (push-in Tests) und 3-Punktbiegeversuche erbrachten die größte Verbesserung der Bruchzähigkeit für die Verbunde mit Bornitrid/Titandioxiddoppelbeschichteten Fasern. Die Verbunde mit Bornitrid bzw. Titandioxid Einzelschichten wurden durch Transmissionsmessungen im sichtbaren Spektralbereich charakterisiert.Schlagworte: Verbundwerkstoff, Glas, Faserbeschichtung, RasterkraftmikroskopieThe aim of the work is the developement of transparent glass matrix composites. Therefore besides the mechanical properties also the optical properties of the components have to be adapted. In this study the influence of different fiber coatings (boron nitride, titanium oxide and a boron nitride/titanium oxide double coating) on the mechanical and optical properties of Nextel 440-fiber reinforced glass was investigated. Micromechanical investigations (push-in-tests) and 3-point-bending tests have shown the best improvement of the fracture toughness for the binary boron nitride/ titanium oxide coating. For single coatings of boron nitride or titanium oxide the transparency was characterized by the transmission spectra.

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