Investigation On Float Mechanism Of Borosilicate Glass

Borosilicate glass have many excellent performance ,such as its high thermal and chemical resistance, its excellent transparency and its good surface quality, allow access to new and high tech special glass applications.Especially,the flat borosilicate glass can be applied to solar cell glass,flat display glass and fireproofing glass. And the best method of flat glass manufacture is float process.It is reported little about borosilicate glass used for float process,so this paper studied on the float mechanics from the polishing, flattening and physical chemistry reaction during the float process.Determined the float process system by the testing of the high temperature viscosity and expansion coefficient. Simulated the float process in the high-purity graphite tin bath under the shielding gas N₂. Kept the glass on the tin liquor for different time under the different temperature.Measuresed the free thickness of the borosilicate glass, and the relation between the thickness and time,thickness and temperature,and comparesd with the soda-lime-silicate glass.Compared the surface tension of the both glasses ,by collecting the high temperature microcope photograph . Tested the polishing result of the borosilicate glass under different polishing time through atom force microcope, investigated and analyzed the relation between the polishing result and polishing time.Moreover, collected the micropolariscope photo and observed pattern of the lower surface of the borosilicate glass. Made use of the electronics probe microscopic analysis, and tested the distribution curve of Sn in the borosilicate glass at different reducing temperature velocity and under different pureness shielding gas. And carried on the contrast experiment with the soda-lime-silicate glass under the same condition.The results indicated that borosilicate glass entering tin bath and comeing out tin bath temperature was higher than soda-lime-silicate glass 100-200℃. The borosilicate glass freedom thickness was about 7.1mm～7.5mm,but soda-lime-silicate glass freedom thickness was lower than borosilicate glass under the same process .The borosilicate glass can attain the value of the free thickness in 2-3 min after enter the tin bath , and thickness can attain a stability after 30 min. The borosilicate glass polished 300s, and then can attain perfect polishing result. Under the lower temperature, the tin adheres to very easily the borosilicate glass to under surface, and formation is stained with tin blemish. The high temperatureinfluence glass inner part tin distributtion , reducing the heat velocity and protecting gaseous pure degrees all only influence near surface scope inside of content.