High Temperature Observation Of High Aluminosilicate Glass Fining Process And Study Of Fining Agent

Bubble is one of the most common defects in glass melting process,which affects the appearance,transparency,mechanical strength and optical homogeneity of glassworks.To eliminate bubbles in the glass,glass fining agents play an important role.In recent years,with the improvement of glass types and properties as well as increasingly stringent environmental requirements,some traditional glass fining agents have been unable to meet the requirements.Therefore,new non-toxic,environmental and compound fining agents with good fining effect have became one of the current research focus.At present,with the wide use of touch screen electronic equipment,the cover glass become popular direction.Because of its many excellent properties,high aluminosilicate glass become the first material of cover glass.At the same time,due to its physical characteristics of high melting point,high viscosity and large surface tension,make it very difficult for industrial production.Especially the problem of bubbles eliminate in the process of clarification has been a great concern for many glass manufacturers.In this paper,for high aluminosilicate glass,using the CelSianhigh temperature observation system,explore the effects of adding no,single and multi-compound fining agent on the generation,growth and elimination of bubbles in the glass melts,analyze the change of bubbles in the process of melting and fining.The main research results are as follows:(1)Using the DSC-TG analytical method,glass transition of the batch happen at 861.3℃,Between 855.9 and 876.3℃,the reaction of carbonate and silicon dioxide absorb a lot of heat.As temperatures continue to rise,the rest of silicon dioxide fuse and diffuse in the carbonate which release a large amount of heat.(2)For high aluminosilicate glass,when different kind and dosage of single fining agent added,the best fining effect is the sample with 0.5wt%SnO2 added;when different kind and dosage of multi-compound fining agent added,the best fining effect is the sample with 0.4wt%SnO2+0.60wt%Na2SO4 added;(3)In virtue of CelSian high temperature observation system,the changes of high aluminosilicate glass batch in the process of melting and fining and various kinds of fining agent effect temperature are fully observed.At the same time,calculate average bubbles escape rate and absorption rate by the software system.Synthesize every group data shows SnO2+Na2SO4 multi-compound fining agent added,due to the large difference of effect temperature between SnO2 and Na2SO4,can release gas in different stages of fining,making bubbles escape rate faster and get the effect of gradient fining.(4)By the CelSian high temperature observation system,record the changes of different diameter range of bubble numbers with temperature variation:when fining agent did not start to work,bubble numbers within the diameter scope of 0.3 to 0.9 mm accounts for 70%to 80%of the total.Once fining agent begin to work,the total number of bubbles rise rapidly and reach the peak after 10min.The bubble numbers more than 0.9 mm in diameter have risen sharply.The bubble escape rate increase significantly.