1. Investigation of parameters influence on optical properties of silicon glasses Paróczai Csilla 1, Dr Gömze A. László 2 undergraduate, senior lecturer University of Miskolc, Department of Ceramic and Silicate Engineering microCAD 2004

2. Goals Our goal is reduce the number of these defects The quick and exact determination of the defects

3. Glass Amorf Phisically homogeneous Raw materials Quarts sand SiO 2 LimestoneCaCO 3 Dolomit CaCO 3 *MgCO 3 Feldspar R 2 O*Al 2 O 3 *SiO 2 AluminaAl 2 O 3 SodaNa 2 CO 3 Natrium-szulfatNa 2 SO 4 Coke Cullet

4. Glass defects Glassy unhomogeniticy (cord, knot) Crystal or opaque bubble (stone, metal, crystal) Air bubble (blister, bubble) Cranny

5. Cause of the defects Inadequate rawmaterial Inadequate melting parameters Substantial evaporation Irregularity in the flowing glass Contact of glass with the wall of the furnace

6. Methods are adopted to identify stones in glass. Visual or magnifier observation Methods using an electron-ray probe micro analyzer Identification by chemical analysis Identification by spectro analysis

7. SiO 2 stones in the glass Cause: –Cristallization –The silica brick corrodes and refractory material get into the glass –Unmelted quarts sand in the melting

8. Tridimit Forceful stress lines Cause: –Inadequate melting of the quarts sand

9. Kristobalit Cause: –The silica brick corrodes and refractory material get into the glass

10. Al 2 O 3 -SiO 2 stones The defect puport a lot of Al Cause: –Polluted cullet Korrundum

11. Al 2 O 3 -ZrO 2 -SiO 2 stones Cirkon Cause –Corrosion of the furnace

12. Other defects BubblesTop tin

13. Experiment Method Identification by polarization microscope When defect is reduced by glass, it loses O 2. Thus this O 2 meets with carbon and CO 2 formes

14. Identification by EDX- microanalyses Electron microprobe X- ray analyzer Jeol Superprobe 733 Thin carbon film High vacuum We examined two different zone of glass which are the metallic silica and the surrounding glass.

15. Measurements and results This zone contains metallic pollutant such as Fe, Ti, Mn, Cu. Probably the cause of this defect is the polluted basic material. These defects could be reduced by using metal detector. 1. Zone

16. Mass and atomic percent of the elements of the glass

17. Measurements and results Pure glass can be seen because the examined material contained only Si 2. zone

18. Conclusion It is important to particle daily training for the eye to distinguish characteristics and optical properties peculiar to each kind of stone minerals may lead to the implementation of irrelevant countermeasures, and it is therefore essential to correctly identify stone minerals and of surmising the causes of their occurrence.

19. Thank you for attention.