Study On Surface Indentation Damage And Corrosion Behavior Of Float Glasses

Glass materials are widely used in the field of aerospace due to their excellent optical properties and mechanical properties,such as aircraft windshields,spacecraft porthole,etc.However,glass is one kind of brittle materials,which are extremely sensitive to surface damage.In the actual service environment,glass will inevitably be impacted by external forces and cause surface damage,which conbines with the external environment?acid,alkali,wet,hot,etc.?,making the glass material earlier failure.Therefore,it is of great importance to study the resistance of glass material to surface damage and of damaged glass material to corrosion behavior.In this paper,cracking behavior and cracking type of the float glass are investigated through three different structure indenters,corrosion behavior of indent with no cracks in alkali solution and of indent with cracks in acid,alkali solution and deionized water are studied.The results show that the Radial-type cracks are generated in the Vickers and Berkovitch indentation,and the cracking loads are 97 ± 3 and 330 ± 10 mN,respectively.The Rockwell indentation first produces Cone-type cracks,and then generates Radial-type cracks.The recovery ratio of the Berkovitch,Vickers and Rockwell indent are 0.419,0.450 and 0.948 respectively.Considering the geometrical structure of the indenter,it is found that the blunter the indenter is,the higher the recovery ratio is and the less damage the glass has.Experiments show that uncracking indentation in the alkaline solution corrosion process enhanced corrosion phenomenon.The Vickers and Berkovitch indentation morphology change with the extension of the etching time.The indentation depth reachs the maximum at about 12 and 11 h,respectively,and then remained stable.The simulation results show that the closer to the central region of indentation,the higher the corrosion rate is.The maximum corrosion rates in both Vickers and Berkovitch indentation regions is 161 nm/h,and the enhanced corrosion zone extends to 2000 and 2100 nm below the indentation surface.The cracking indentation does not change significantly in deionized water and sulfuricacid solution,and only the crack length increases slightly in the first 1 h of corrosion.While in the sodium hydroxide solution,the crack length increases rapidly in the first 1h of corrosion,then the growth rate slows down,the crack width continues to increase with the average rate of 0.159 ?m/h,which is 3 times of that of crack length.After 426 h of corrosion,the flaky crack area is completely corroded and is connected with the crack to form a cave-type pits.In the sodium hydroxide solution,the fracture toughness of the float glass continues to decrease with the prolongation of the corrosion time,with an average reduction of 370 Pa·m^1/2/h.