Abstract
The aim of the present contribution is to study the dynamic fracture properties of brittle materials MoSi₂, Si₃N₄ and WC-Co. Dynamic tests at different loading rates ( ν = 0.992, 1.916, 3.677 m/s) were carried out using an instrumented Charpy impact pendulum. The force signals were recorded as a function of time by a digital oscilloscope. The stored data were analysed with a spreadsheet procedure. Microstructure analysis was realised by optical microscope and SEM using plasma or chemical etched samples. Fracture surfaces were investigated by SEM. The impact energies for MoSi₂ and Si₃N₄ are about 0.02 - 0.06 J, respectively. The results revealed that the most brittle material is MoSi₂ and the systems of WC-Co are the toughest ones. The impact energies of WC-Co systems are between 0.06 - 1 J, their value depends on the microstructure and increases with increasing volume fraction of Co and grain size of WC grains.

Key words
instrumented impact testing, brittle materials, fractography

Full text (178 KB)