研究目的
To study the stress corrosion behavior of silica aerogels to better understand the crack propagation rate as a function of stress under different environmental conditions.
研究成果
The study evidenced a corrosion domain in silica aerogels with two parts, suggesting the involvement of two silica reactive species: 3 fold and 2 fold silica rings. Oxidation treatment highlighted the importance of silanol groups content on stress corrosion. Unexpected behaviors, such as crack velocities decreasing with temperature and water vapor pressure, were observed, possibly due to structural changes and capillary condensation effects.
研究不足
The study focuses on silica aerogels, and the findings may not be directly applicable to other materials. The mechanisms proposed for the observed behaviors are hypotheses that require further validation.
1：Experimental Design and Method Selection:
The study used Dynamic fatigue experiments and the Double-Cleavage-Drilled-Compression test (DCDC) to investigate sub-critical crack growth in silica aerogels.
2：Sample Selection and Data Sources:
Samples were prepared from standard hydrolysis and polycondensation reactions of tetramethoxysilane diluted in ethanol, with some samples oxidized to remove surface organic radicals.
3：List of Experimental Equipment and Materials:
Universal testing machine (Instron 1196), balance for force measurement, sensor based on Foucault currents for sample deflection measurement, infra-red heater elements for temperature control.
4：Experimental Procedures and Operational Workflow:
Samples were outgassed and stored under controlled atmosphere before experiments. Dynamic fatigue and DCDC tests were conducted under varying temperatures and relative humidity levels.
5：Data Analysis Methods:
Crack growth velocities were plotted as a function of stress intensity factor (KI), and chemical susceptibility factors were calculated from the slope of the curve V = f(KI).
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
