Experimental Study On The Damage Mechanism Of Tempered Glass By Sand Erosion Under The Combined Effect Of Freeze-thaw Cycle And Ultraviolet Radiation

In northwest China,the average elevation is over 1km.The annual temperature difference is large and the frost-free period is short,deserts are widely distributed.The factors above lead to the extreme cold climate,high ultraviolet radiation and wind-sand environment in the area the long-term compound erosion of tempered glass by these environmental factors have a particularly huge impact on the durability,safety and reliability of materials and it leads to a decrease in their service life and normal service levels.Tempered glass is widely used in doors,windows,curtain walls,high-speed train and automobile windshield because of its good mechanical properties,good thermal stability and high transmittance.The special and complicated natural environment features in the midwest of Inner Mongolia is representative in northwestern China.The railway mileage is China’s first in Inner Mongolia,highway mileage ranks in the forefront of the northwest region,and countless buildings are distributed along the desert.The front windshield of trains and the automobile,building glasses are destroyed by three factors: cold climate,intensive UV irradiation and wind-sand environment.This project was supported by the National Natural Science Foundation of China " Mechanical behavior and damage mechanism of high-speed train windshield corroded by special regional environment "(No.11662012).The high and low temperature alternating test chamber is used to simulate freeze-thaw cycle under cold and heat environment,the ultraviolet aging test chamber was used to simulate plateau ultraviolet radiation,and the wind-sand erosion test was carried out by the simulated wind-sand environmental erosion experiment system.It can be used to simulate the erosion of tempered glass by three factors in Inner Mongolia:the cold climate environment,the plateau intensive ultraviolet radiation and the wind-sand environment.The main contents of this study are as follows:1.To study and the characteristics of the special natural environment in the Inner Mongolia region,and to count the meteorological parameters of the region for the past 30 years: temperature,humidity,precipitation,annual sunshine hours and ultraviolet radiation,and the origin,frequency and spatial and temporal distribution of sandstorms.2.According to the characteristics of temperature,humidity and ultraviolet radiation intensity in the midwest of Inner Mongolia in the past years,The accelerated test of composite erosion of tempered glass in freeze-thaw cycle and UV irradiation was studied.With the increase of the number of freeze-thaw cycle and UV irradiation time,The transmittance of the tempered glass decreased obviously.3.In order to study the erosion effect on the tempered glass under natural conditions an experimental study was carried out for one year of exposure and aging of tempered glass specimens under natural conditions,the surface damage is serious,and the deterioration of the optical performance of the specimen is more serious than that under freeze-thaw and irradiation conditions.4.According to the characteristics of wind-sand environment in the midwest of Inner Mongolia,a gas-solid two-phase flow erosion wear test was performed on tempered glass specimens after freeze-thaw cycle and UV irradiation composite erosion.The erosion wear law of specimens under different erosion mechanical parameters(erosion velocity,erosion angle,sand flow rate and erosion time)was studied.Specifically:(1)the erosion rate of specimen increases with the increase of erosion velocity.Between 14~22m/s erosion rate,the erosion rate grows more slowly.The decrease of light transmittance is becoming more and more serious with the increase of speed.(2)As the erosion angle increases,the erosion rate of the specimen gradually increases and reaches a maximum at 90°.At 15~45 degrees,the transmittance rate drops rapidly.(3)with the increase of dust concentration,the erosion rate of the specimen shows a decreasing trend.It has little effect on the optical properties of the tempered glass.(4)the damage of the tempered glass specimens after the freeze-thaw cycle and UV irradiation composite erosion is more serious than that of the ordinary tempered glass specimens.5.Using the Taguchi orthogonal method,the contribution rate of each erosion factor was determined.The ratio of wind-sand erosion speed and erosion angle is up to 95%.They play a key role in the impact of erosion and wear on tempered glass.6.Erosion rate,light transmittance and weight loss of tempered glass are used as evaluation indicators for multi-factor erosion damage in the area environment.The damage mechanism was analyzed from microcosmic angle by electron scanning microscope and laser confocal.The damage and failure mechanism of tempered glass is mainly caused by the cross propagation of crack and the superposition of the structure of the specimen.It shows typical damage law of brittle materials.