Doc. Ing. Miloslav Bartuska, CSc. and co-authors GLASS DEFECTS PRAH

Transcription

1 Doc. Ing. Miloslav Bartuska, CSc. and co-authors GLASS DEFECTS PRAH

2 CONTENTS 1. Introductory chapter {Miloslav Bartuska) Methods used for the identification of defects Introduction (MiloslavBartuska) Basic identification methods Optical microscopy (Miloslav Bartuska) Polarising microscope and its accessories Working procedures 31 A. Measurement in transmitted polarised light 32 A a. Microstructure and morphological properties 32 A b. Optical properties 34 B. Measurement under crossed polars 36 В a. Morphological properties 36 В b. Optical properties 37 С Measurement in reflected light Sampling and specimens for the microscopic identification of defects Assessment of the optical microscopy References to Chapter X-ray micro-analysis (Vaclav Hulinsky) Description of the method Principle of the apparatus Comparison of the WDS and EDS x-ray micro-analysers Sensitivity limits of WDS and EDS spectrometers Preparation of specimens for measurements References to Chapter Methods applied to the analysis of gases contained in bubbles (J/7/ Ullrich) 61 11

3 Introduction Mass spectrometry Principle of the method Instrumentation Gas chromatography References to Chapter Complementary identification methods X-ray diffraction analysis (Petr Exnar) X-ray fluorescence analysis (Petr Exnar) Methods of atomic optical spectrometry (Leos Bauer) Principle and classification of the methods of atomic optical spectroscopy Atomic absorption spectrometry Atomic emission spectrometry Atomic fluorescence spectrometry Conclusion Polarimetry {Petr Exner) Method applied to the determination of gases dissolved in glasses (Jaroslav Klouzek) Measurement of the concentration of dissolved oxygen (Jaroslav Klouzek) Reference to Chapters Electron microscopy (ESCA) (Martin Maryska) Principle of the method Spectra measurement and evaluation References to Chapter Visualisation of the cords in the glass by 3-dimensional filtration of their images (Miloslav Ohlfdal) Introduction Experimental assembly Principle of the method References to Chapter Crystalline inclusions - stones Introduction (including Table 3 - I and 3 - II) (Miloslav Bartuska) 112

4 Tab. 3-1 Optical and physical properties of crystalline phases forming and accompanying stones 114 Tab. 3-2 Formation of crystalline phases in stones Stones from refractories (Miloslav Bartuska) Contribution of refractory to the stone formation Stones originated in contact with the glass melt and above the glass level. Primary and secondary phases Stones from silicate materials Silica 136 Phase composition and microstructure of silica 136 Changes in the phase composition and microstructure of silica as a consequence of its use 138 Stones originated from the silica refractories and silica mortars Fused silica products and stones originating from such materials Stones from alumino-silicate materials Fireclay refractory 169 Phase composition and microstructure of fireclay refractory 169 Changes in the phase composition and microstructure of firebricks due to corrosion Stones from fireclay refractory 176 Stones from ceramic rings and pot inserts High-alumina refractories 212 High-alumina refractory materials composed of clay raw materials enriched with corundum 213 Stones from high-alumina refractories composed of clay raw materials enriched with corundum 216

5 High-alumina refractories composed of natural raw materials of the sillimanite type 216 Stones from sillimanite refractories 219 High-alumina refractories composed of man-made mullite 219 Stones from refractories composed of man-made mullite Stones from materials composed of Al Refractories composed of granular corundum Sintered corundum ceramics Fused cast refractories containing corundum and ß-AI produced by melt crystallisation Stones from alumina-zirconia-silicate refractory (AZS) Sintered AZS refractories 270 Stones from sintered AZS refractories Fused-cast corundum-baddeleyite refractories 289 Stones from fused-cast corundum-baddeleyite refractories Stones from zirconia-silicate (zircon) refractories Stones from refractories composed of Zr Stones from Cr containing refractories Sintered chrome-corundum refractories Sintered materials composed of Cr Fused-cast chrome-corundum-baddeleyite refractories (CAZS) Fused-cast chrome-corundum-spinel refractories Stones originated from the batch (Miloslav Bartuska) Stones from imperfectly melted sand Stones from accessory minerals in sand Stones from aluminium hydrate Stones from contaminated batch Stones caused by an inhomogeneous distribution of raw materials containing components characterised by a low solubility in molten glass

6 3.4 Stones caused by glass crystallisation (devitrification products) (Mlloslav Bartuska) ß-cristobalite y-tridymite Devitrite ß-wollastonite Diopside Other products of glass crystallisation 405 a-wollastonite 405 Di-sodium-di-calcium tri-silicat 405 Anorthite 406 Sanbornite 406 Alamosite Condensates in inclusions References to Chapters 3.1 to Inclusions caused by metals and reduced glass components (Jiff Mate}) Inclusions containing molybdenum and elemental metals formed on molybdenum by reduction Inclusions caused by platinum components Inclusions created by the reduction of glass components by batch impurities Survey of inclusions caused by metallic materials and reduced glass components. Identification of possible causes of their origin References to Chapter Glassy inhomogeneities - cords and layers (Vaclav Hullnsky) Cord definition and sources Spectral methods Origin of various types of cords Cords originating in the batch Cords originating from refractory Cords originating from the furnace crown Cords generated by stones Cords due to a layered structure of the glass melt

7 4.3.6 Cords due to temperature fluctuations in the furnace Cords released from the furnace bottom Cords due to local changes in temperature Inhomogeneities in the glass melt Definition of the term "glass homogeneity" Batch homogeneity Furnace atmosphere as a cause of cords Glass evaporation as a possible source of cords Cullet behaviour in the glass melt Refractory dissolution and tank wall corrosion Corrosion of the furnace superstructure Corrosion of the furnace crown Hidden cords (JiriBubenik) References to Chapter Gaseous inhomogeneities in the glass - bubbles (Lubomir Nemec) Introduction Gas equilibria in the glasses Origin of gases and the type of their solubility in the glass melts Physical solubility of gases in the glasses Chemical solubility of gases in the glass melts Chemical solubility of water vapour Chemical solubility of hydrogen Chemical solubility of carbon dioxide Chemical solubility of sulfur dioxide Chemical solubility of nitrogen Chemical solubility of oxygen Gas diffusion in glasses Kinetics of bubble behaviour in glasses Ascendance speed of a single bubble in a static isothermal glass melt Bubble growth and dissolution in glass melts Effect of temperature, pressure and glass composition on the rate of bubble elimination

8 Effect of temperature Effect of pressure Effect of composition Effect of the concentration of the fining agent Effect of major glass components Effect of the redox state of the glass melt Bubble behaviour in a very viscous and solid glass Results of the mathematical and experimental investigation of bubbles in molten glasses Development in the bubble dimension Development in the bubble composition Influence of the glass melting factors on the time needed for bubbles to rise to the surface Kinetics of the bubble behaviour in glasses. Summary Typical properties of the sources and bubbles generated by them Bubbles generated by decomposition and other reactions of raw materials Bubbles generated by the nucleation or by growth of the nuclei as a result of melt oversaturation with gases Bubbles produced by chemical reactions Reactions of molten glass with solid impurities Reactions of molten glass with liquid impurities Bubbles generated by electrochemical reactions Bubbles generated in a mechanical way Bubbles due to the entrapment or introduction of the surrounding atmosphere Bubbles generated by refractories Bubbles resulting from the use of cooling water 555

9 5.5 Systemic approach to the identification of bubble sources in the melting process Conditions required for modelling bubble sources and bubble history during glass melting General features characterising the behaviour of multi-component bubbles important for the identification of their sources Characteristic features of bubble analyses Qualitative knowledge base of most current bubble sources based on their analyses Identification of bubble sources with the aid of analyses of bubble sets Application of other features to the identification of bubble sources Application of the bubble features within the framework of an experimental automatic identification system Application of the mathematical modelling within the automatic identification system Conclusion List of symbols References to Chapter Strategy adopted during the fight against glass defects (Jiri Bubenfk, Hana Noväkovä, Antonin Smrcek) 600 Index 637