Martina Halasová

Fracture response of SiOC-based composites on dynamic loading:

The fracture resistance to the dynamic loading of composites based on partially pyrolysed SiOC glass reinforced with basalt fibres was investigated using an instrumented impact test. The three-point bend loading configuration of the specimen bars prepared from the composite plate was used. Evolution of the matrix during the pyrolysis plays a key role in creation of bonding between the matrix and fibres, which was in the form of woven fabrics. Different temperatures of pyrolysis were applied in order to determine their influence on the fracture behaviour during impact tests. The high speed camera was employed to observe fracture response to impact loading during the fracture process. The temperature range for pyrolysis was chosen from 600 to 800℃ with the step of 50℃. The partial melting of basalt fibres occurred at temperatures above 800℃. Observation of fractographic features on the fracture surfaces was performed using scanning electron microscopy.

Fibre-Matrix Interface Development during High Temperature Exposition of Long Fibre Reinforced SiOC Matrix

The fracture behaviour of long fibre reinforced composites is predetermined mainly by properties of fibre-matrix interface. The matrix prepared by pyrolysis of polysiloxane resin possesses ability to resist high temperatures without significant damage under oxidising atmosphere. The application is therefore limited by fibres and possible changes in the fibre matrix interface. The study of development of interface during high temperature exposition is the main aim of this contribution. Application of various techniques as FIB, GIS, TEM, XRD allowed to monitor microstructural changes in the interface of selected places without additional damage caused by preparation. Additionally, it was possible to obtain information about damage, the crack formation, caused by the heat treatment from the fracture mechanics point of view.