Strength behaviour of etched Zerodur®

As a rule of thumb the average strength of Zerodur® is assumed to be around 10 MPa. The measured strength is much higher. The strength distributions showed unexpected results, especially the absence of the expected size effect. Through a thorough fractographic analysis it was shown what kind of defects were responsible for failure of etched Zerodur® and why the prerequisites for the validity of the Weibull theory were not fulfilled in the investigated specimens.