Crack growth behavior of zinc tellurite glass with or without sodium oxide

The crack growth behavior was investigated for zinc tellurite glasses with or without sodium oxide by using a small-size double cleavage drilled compression (DCDC) specimen, which was a rectangular bar with a small hole in the middle. The sample dimensions used were about a half or less than those of the previous studies, and comparable with those of JIS specimen for flexural strength testing. The validity of applying such a small specimen for test was examined on a commercial soda-lime silicate glass, and it was found feasible to obtain the data and to discuss crack growth behavior of glass. By using this small-size DCDC specimen, KI−v curves for tellurite glasses were successfully obtained for the first time. It was found that KI−v curves showed three characteristic regions similar to silicate glasses, but they shifted considerably toward the low KI side, reflecting much weaker bond-strength of tellurite glass than silicate glass. The fatigue parameter for tellurite glass was much larger than that for commercial silicate glass. This large fatigue parameter of tellurite glass was considered to result from a relatively small contribution of stress corrosion reaction to the subcritical crack growth because of the narrow distribution of bond-strength caused by the lack of ring structures in tellurite glass.