Strength of annealed soda-lime float glass at elevated temperatures up to the glass transition range

本研究项目的目的是在从环境温度到玻璃化转变温度范围内对退火钠钙硅浮法玻璃的弯曲强度的温度依赖性进行实验研究。为了预测玻璃热钢化过程和玻璃增材制造过程中的玻璃失效，玻璃在相关温度范围内的弯曲强度，必须知道冷却过程的相关应力速率以及先前生产过程导致的典型表面损伤。对钠钙玻璃和硼硅酸盐玻璃的一些实验结果可用。以前的工作集中在温度依赖性的断裂韧性（钠钙玻璃）和温度依赖性的弯曲强度（硼硅酸盐玻璃）。此外，测试大多在高达320 MPa/s的非常高的应力速率下进行。根据热回火工艺的冷却过程的持续时间和玻璃增材制造过程中的冷却速率，应力速率应较低，以使结果在土木工程中适用。因此，在本研究项目中，特别是在升高的温度下的弯曲强度高达玻璃化转变范围和两个应力速率（2 MPa/s，20 MPa/s）应进行调查。应研究温度和应力率对试样的影响，这些试样因玻璃加工而具有典型的表面损伤（定义的划痕、金刚石钻孔机的圆柱形钻孔）。由于在土木工程中主要使用钠钙玻璃，因此应主要使用钠钙硅浮法玻璃进行研究，其中一个试验系列与硼硅酸盐玻璃进行比较。

The objective of this research project is the experimental investigation of the temperature dependency of the flexural strength of annealed soda-lime-silica float glass in a temperature range from the ambient temperature up to the glass transition range.In order to make predictions on the glass failure during the thermal tempering process of glass and during the additive manufacturing with glass, the flexural strength of glass in the relevant temperature range, the related stress rate from the cooling process as well as typical surface damages resulting from the prior production processes have to be known.Regarding the temperature dependency of the flexural strength up to the glass transition range there are only a few experimental results available for soda-lime glass and borosilicate glass. The previous works focus on the temperature dependency of the fracture toughness (soda-lime glass) and the temperature dependency of the flexural strength (borosilicate glass). In addition, the tests mostly were carried out at very high stress rates with up to 320 MPa/s. According to the duration of the cooling process of the thermal tempering process and the cooling rate during additive manufacturing of glass, the stress rate should be lower for the applicability of the results in civil engineering. Accordingly, in this research project particularly the flexural strength at elevated temperatures up to the glass transition range and with two stress rates (2 MPa/s, 20 MPa/s) shall be investigated. The influence of the temperature and the stress rate shall be investigated on specimens with a typical surface damaging resulting from the glass processing (defined scratches, cylindrical drill holes from a diamond driller).Since in civil engineering primarily soda-lime glass is used, the investigations shall mainly be carried out with soda-lime-silica float glass, one test series with borosilicate glass for a comparison.