Präsentation
Filtern
Erscheinungsjahr
- 2017 (3) (entfernen)
Dokumenttyp
- Vortrag (2)
- Posterpräsentation (1)
Referierte Publikation
- nein (3)
Schlagworte
- Vickers (3) (entfernen)
Eingeladener Vortrag
- nein (2)
185 cracks were initiated in a soda-lime-silica glass by Vickers indentation and grown under controlled dry nitrogen atmosphere. Direct observation of subcritical crack growth (SCCG) upon indentation was performed using a video camera with an image acquisition rate of 3 ms. The results show that the validity of K(c) relations used to determine the indentation fracture toughness from a single imprint is questionable. It seems that correlation of crack length to stress intensity necessitate the use of statistical significant data of multiple crack events.
Um das Risswachstum in Gläsern zu untersuchen, sind in einer Glovebox 185 Risse ausgehen von Vickers-Eindrücken in Kalk-Natron-Glas initiiert und gewachsen. Die direkte Beobachtung des unterkritischen Risswachstums erfolgte mit einer Hochgeschwindigkeitskamera. Die Ergebnisse zeigen, dass die statistische Auswertung vieler radialer Risse von multiplen Rissevents notwendig ist, um eine Korrelation zum Spannungsintensitätsfaktor ziehen zu können.
Fundamental understanding of crack healing in glassy crystalline materials is very important for many applications, especially for solid oxide fuel cells (SOFC) sealants since cracks caused by mechanical stress or thermal cycling still remain a substantial bottleneck in developing durable SOFC.
Previous studies on soda lime silicate glass published by Singh showed that crack healing is driven by viscous flow. He postulated that the healing progress is proportional to time, t, and the inverse viscosity. For a given glass, this finding would allow to present data of crack healing measured at different temperatures in a master curve, if the healing progress is plotted versus t/. Such master curves would be a helpful tool in understanding crack healing kinetics.
To verify the applicability of such master curves, crack healing in non-crystallizing soda-lime-silicate (NCS) and sodium-borosilicate glasses (NBS) was studied. Cracks were generated by Vickers indention and healed isothermally at different temperatures. Crack healing progress was monitored by optical and electron microscopy. The results show that the above mentioned proportionality applies to the two glasses and the afore developed master curve could be obtained in both cases.