Read Consulting Failure Analysis Services include first article testing for various importers. In this case, borosilicate glass carafes were to be imported, and the consultants at Read Consulting were asked to perform thermal shock durability tests. In this case, the carafe bottoms were scrubbed with a wet sponge embedded with 400 grit aluminum oxide (alumina). These carafes were then heated to 160°C and then rapidly quenched in 10°C water. This procedure was repeated till the carafe cracked. This carafe cracked on the fifty first cycle. Glass failure analysis was performed. The carafe bottom cracked from thermal fatigue. The crack originated at one of the scratches created by the scrubbing. The surprise is that glass can experience fatigue cracking. In this case, the outside bottom was put into tension during the rapid quench into the cold water. The initial defect (i.e.crack) grew incrementally until it reached a critical length where it was able to traverse the entire carafe bottom.
