Effect Of Water On Radial Crack Healing Of Indentation On Soda Lime Glass

The wide application of soda lime glass not only greatly improves people’s quality of life,but also promotes the development of modern industry and technology.Nowadays,soda lime glass has become one of the most important materials for human beings,and the surface of the glass will often be damaged in the practical application process,which will affect the service life of the whole glass,so it is necessary to repair the glass at high temperature to restore its properties.Therefore,it is important to study the crack repair law of soda lime glass under different conditions to improve the repair mechanism of soda lime glass.Based on the existing research literature,it is found that the current research only considers the influence of environmental water molecules,temperature and load on the high-temperature repair of soda lime glass,but does not consider the influence of the surface structure change of glass matrix on the high-temperature thermal healing mechanism of glass cracks.In this thesis,the high-temperature thermal mechanism of air-side and tin-side of float soda lime glass under chemical corrosion will be systematically studied.By using high-temperature annealing furnace,optical microscope,AFM atomic force microscope,nano-indentation instrument and Vickers hardness tester,the influence of surface water and environmental water on macro-crack morphology and micro-morphology of soda lime glass at high temperature will be analyzed,and the related crack healing model will be established.Based on the above research,the main conclusions of this academic dissertation are as follows:(1)Based on the research on the thermal healing of the“air-side”of soda lime glass corroded by hydrochloric acid in high temperature and humidity environment,it is found that the original soda lime glass can’t be repaired in dry environment(0%RH),but the highest high-temperature crack repair rate of soda lime glass corroded by hydrochloric acid for 24 h is 52%,and the crack repair length in high temperature and humidity environment(60%RH)is longer than that of non-eroded glass,and the repair rate reaches 89%under 2 N load,and in dry environment.The change of water content in the surface layer of eroded glass with erosion time was characterized by infrared spectrometer.Using Vickers microhardness tester,the influence of water inside the surface on the macro-mechanical properties of soda lime glass at room temperature after being treated with strong acid(p H=1,HCl solution)was investigated.By analyzing the influence of internal water on the surface structure of glass,it is found that the influence of internal water on the morphology of high-temperature cracks is related to the water-containing erosion layer formed on the glass surface after Na~+precipitation.The high-temperature diffusion of internal water and Na~+in the glass surface will accelerate the viscous flow of the glass surface,promote the softening of the glass surface,bridge the crack surface,accelerate the crack repair rate and repair the crack.(2)Based on the research of the thermal healing of the“tin-side”of float soda lime glass in a high-temperature and humid environment.The results show that compared with the repair of the“air-side”of the same glass,the oxidation of tin ions on the glass surface has a great influence on the crack morphology change.Moreover,under different humidity environments,the crack morphology of the“tin-side”of soda lime glass is different from that observed on the“air-side”.During the heat treatment in dry environment(0%RH),tin ions are not oxidized,and there is no obvious difference between the crack morphology changes of the“air-side”and the“tin-side”of the glass,and no crack spheroidization will occur.In humid air(60%RH),the-side viscosity of glass increases due to tin ion oxidation,which hinders the process of crack spheroidization and cracks close each other.It is also found that the crack on the“tin side”of glass is corroded by hydrochloric acid,and the crack closure will be accelerated due to the adhesion below the crack at high temperature.At the same time,the four-point bending test shows that the oxidation of the tin-side can effectively hinder the effect of stress on the crack.