Investigation of parameters influence on optical properties

of silicon glasses

Paróczai Csilla1, Dr Gömze A. László2

undergraduate, senior lecturer

University of Miskolc, Department of Ceramic and Silicate

Engineering

microCAD 2004

Goals

• Our goal is reduce the number of these defects

• The quick and exact determination of the defects

Glass

• Amorf• Phisically homogeneous• Raw materials

• Quarts sand SiO2

• Limestone CaCO3

• Dolomit CaCO3*MgCO3

• Feldspar R2O*Al2O3*SiO2

• Alumina Al2O3

• Soda Na2CO3

• Natrium-szulfat Na2SO4

• Coke• Cullet

Glass defects

• Glassy unhomogeniticy

(cord, knot)

• Crystal or opaque bubble

(stone, metal, crystal)

• Air bubble

(blister, bubble)

• Cranny

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

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

SiO2 stones in the glass

• Cause:– Cristallization– The silica brick corrodes and refractory

material get into the glass– Unmelted quarts sand in the melting

Tridimit

• Forceful stress lines• Cause:

– Inadequate melting of the quarts sand

Kristobalit

• Cause:– The silica brick

corrodes and refractory material get into the glass

Al2O3-SiO2 stones

• The defect puport a lot of Al

• Cause:– Polluted cullet

• Korrundum

Al2O3-ZrO2-SiO2 stones

• Cirkon

• Cause– Corrosion of the

furnace

Other defects

• Bubbles • Top tin

Experiment Method

• Identification by polarization microscope

• When defect is reduced by glass, it loses O2. Thus this

O2 meets

with carbon and CO2

formes

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.

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

Mass and atomic percent of the elements of the glass

Measurements and results

• Pure glass can be seen because the examined material contained only Si

•2. zone

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.

Thank you for attention.