Papers by Author: Petr Glogar

Abstract: Composite materials based on polysiloxane matrix reinforced by basalt fibres were prepared in laboratories of the IRSM ASCR. The composite samples were pyrolysed at 400 ÷ 750 °C after moulding and curing at 250 °C. Measurement of several mechanical characteristics (flexural strength, fracture toughness, impact strength, and measurement of elasticity) demonstrates a favourable influence of pyrolysis in comparison with the cured-only composite material. Fracture toughness was measured by chevron-notch technique and fracture surfaces were investigated using a scanning electron microscopy.

Abstract: Mechanical and fracture properties of unidirectional composites reinforced with R-glass fibres and utilizing various commercially available polysiloxane resins as matrix precursors were investigated. As the matrix becomes more brittle after the pyrolysis the impact toughness and flexural strength of the composites fall. On the other hand, the shear modulus rises after the pyrolysis as the matrix becomes stiffer in shear. The appearance of fracture surfaces generated during the flexural strength at room temperature (RT) and elevated temperatures is discussed.

Abstract: Unidirectionally reinforced ceramic matrix composites (CMC) with matrix derived by pyrolysis of polymethylsiloxane or polymethylphenylsiloxane resins and reinforced with Nicalon or Nextel fibres were investigated. In order to assess and mutually compare their mechanical properties and stability when exposed to hot air up to 1200°C their elasticity moduli were measured prior to and after this exposure. The oxidation - induced damage of the material was monitored also in terms of microstructural features. Moreover, an attempt was undertaken to assess the bonding level by monitoring the push - through of macroscopic bundles of fibres using a flat indentor.