基础材料和有机材料 (20).pdf

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1、 Melt and Glass QUESTIONS 1.Known the composition of the glass is 13wt%Na2O,13wt%CaO and 74wt%SiO2,calculate the fraction of non-bridging oxygens.2.3673.6273.613.812.6SiO+RZ4 X2RZ22.3640.72 YZX40.723.28 fraction of non-bridging oxygens:30.5%3.28/20.720.72Y/2+XXSolution：Na2O CaO SiO2 wt%13 13 74 mol

2、0.21 0.23 1.23 mol%12.6 13.8 73.6 2.Given the compositions of two kinds of glass:Na2O(wt%)Al2O3(wt%)SiO2(wt%)1 8 12 80 2 12 8 80 Try to compare the viscosities of glass at high temperature according to their structure parameters.Na2O Al2O3 SiO2 wt%mol%wt%mol%wt%mol%1 8 8.18 12 7.48 80 84.3 2 12 12.1

3、 8 4.87 80 83.03 Solution：Y1 3.986;Y2 3.844 Y1 Y2 Therefore,the viscosity at high temperature of 1 is higher than that of 2.1 ：Na2O/Al2O38.18/7.481 Al3+should be taken as glass network forming ion.007.284.37.482284.33.4878.18=+RY=2Z2R2(42.007)3.986 Z=4 2：Na2O/Al2O312.1/4.87 1 Al3+should be taken as

4、glass network forming ion.078.2287.483.03283.03387.412.1=+RY=2Z2R2(42.078)3.844 Z=4 3.In order to keep O/Si2.5,try to analyze the amount of Na2O in the glass of SiO2-Na2O.The crystallization ability of the system is enhanced or weakened?31x 5.21)1(2=+=解得xxxSiORSolution：If the content of Na2O is x mo

5、l,the content of SiO2 would be 1-x mol.The crystallization ability would be enhanced.4.The diagram shows the T dependent formation rate of nucleation and T dependent growth rate of silicate melt.Try to explain which curve represents nucleation rate,and which curve represents growth rate.速速 率率 T Solu

6、tion：On the whole,viscosity of melt is high at low temperatures,particles are hard to move and tend to agglomerate and form crystal nucleus.That is to say,low temperature avails nucleation.Viscosity of melt is low at high temperatures,migration rate of particles is high,crystal nucleus tends to grow

7、th and forms larger ones.That is to say,high temperature avails growth of crystal nucleus.0.4 Na2O 0.6 CaO 0.3 Al2O3 SiO2 (Na2O+CaO)/Al2O31/0.3 1 Al3+should be taken as glass network forming ion.According to Random network theory:network modifying ions(Na+and Ca2+)are in the center of polyhedrons;ne

8、twork forming ions(Al3+and Si4+)are statistically distributed in the network space.5.The structure of porcelain glaze is similar with that of glass.Try to analyze the position of the ions in the porcelain glaze of using Random network theory.Solution：6.In the silicate glass and borate glass,how will

9、 the viscosity of melt change with the adding of alkali metal oxides(25mol)?Try to explain using polymer theory of the melt structure.Solution：In the silicate glass,the role of R2O is degradation.With the increase of R2O content,the viscosity of melt decreases.In the borate glass,“Boron anomaly”should be considered.With the increase of R2O content,the viscosity of melt increases firstly and then decreases.