Effect of components on viscosities and coefficients of thermal expansion of borosilicate glasses

The effect of components on viscosities and coefficients of thermal expansion of borosilicate glasses were studied.With the increasing of n(B2O3)/n(SiO2) ratio,the viscosities of borosilicate glasses decrease,and their coefficients of thermal expansion increase.When Al2O3 replaces SiO2,the viscosities of borosilicate glasses enhance,but their coefficients of thermal expansion have little change.The viscosities rapidly decrease and coefficients of thermal expansion increase if Li2O was adopted.ZnO can also improve the melting of borosilicate glasses,but its influence is less than Li2O's.When CaO replaces Na2O,the viscosity change of high temperature is little,but that of low temperature is much.The coefficients of thermal expansion decrease when ZnO and CaO were adopted.If a few TiO2,ZrO2 and La2O3 were introduced,the viscosities of borosilicate glasses decrease and their coefficients of thermal expansion have little increase.The coefficient of thermal expansion of E glass was matched excellently with that of Kovar alloy,indicating that E glass has a great potential application.