Influence of Intrinsic Hydroxyl Content on Subcritical Crack Growth and Mechanical Reliability of Silica Glass

ABSTRACT The role of internal hydroxyl (OH) content on subcritical crack growth (SCG) in silica glass was investigated using static fatigue testing combined with fracture‐mechanics‐based crack length analysis and Weibull statistical evaluation. Fourier‐transform infrared spectroscopy confirmed distinct OH concentrations in the investigated silica grades. Static fatigue results showed a systematic decrease in fracture stress with increasing OH content, with high‐OH silica exhibiting significantly lower strength under stepwise loading conditions. Crack length calculations revealed larger initial and final crack sizes in high‐OH samples, indicating enhanced crack extension during sustained loading. The estimated flaw dimensions remain within micrometer‐scale ranges reported for bulk silica glass. Weibull analysis demonstrated a substantial shift in characteristic strength due to subcritical crack growth, while variations in the Weibull modulus remained within experimental uncertainty. These findings demonstrate that intrinsic hydroxyl content significantly influences crack propagation behavior and mechanical performance of silica glass under static fatigue conditions.