List of Contents ................................................ I
List of Figures .............................................. VIII
List of Tables ............................................... XVII
List of Abbreviations .......................................... XX
List of Equations ............................................. XXI
1 Introduction ................................................. 1
2 State of the Art of Doloma Carbon Refractories ............... 4
2.1 Doloma and Doloma Carbon Refractories ................... 4
2.1.1 Dolomite and Doloma .............................. 4
2.1.2 Production of Doloma Based Refractories ......... 10
2.1.3 Application of Doloma based Refractories in
Steel Making Practice ........................... 14
2.1.4 Special Properties of Lime (CaO) and Magnesia
(MgO) ........................................... 22
2.2 Carbon Polytypes and Carbon Sources of Interest in
Doloma Carbon Refractories ............................. 24
2.2.1 Phenolic Resin and Glassy Carbon ................ 25
2.2.2 Graphite ........................................ 29
2.2.3 Carbon Black .................................... 31
2.3 Background on Used Additives and Tasks ................. 32
2.3.1 Titania (TiO2) .................................. 33
2.3.2 Aluminium (Al) .................................. 43
2.3.3 Silicon (Si) .................................... 44
2.3.4 Zirconia (ZrO2) ................................. 46
2.3.5 Ceria (CeO2) .................................... 48
2.3.6 Perovskite (CaTiO3) and Ilmenite (FeTiO3) ....... 49
2.4 Concluded Tasks for the Present Work ................... 50
3 Experimental ................................................ 53
3.1 Raw Materials .......................................... 53
3.1.1 Doloma, Magnesia and Alumina .................... 53
3.1.2 Carbon .......................................... 53
3.1.3 Phenol Novolak Resin ............................ 54
3.1.4 Titania (TiO2) .................................. 55
3.1.5 Aluminium ....................................... 55
3.1.6 Silicon ......................................... 56
3.1.7 Zirconia (ZrO2) ................................. 57
3.1.8 Ceria (CeO2) .................................... 57
3.1.9 Perovskite (CaTiO3) and llmenite (FeTiO3) ....... 58
3.1.10 Lime (CaO) ...................................... 58
3.2 Sample Preparation and Experimental Design ............. 59
3.3 Test Methods ........................................... 63
3.3.1 Physical, Mechanical and Thermomechanical
Properties ...................................... 63
3.3.2 Carbon Content and Determination of Carbon
Polytypes ....................................... 64
3.3.3 Phase Analysis .................................. 65
3.4 Experimental Investigation of Titanate Formation in
the System CaO-MgO-TiO2 ................................ 66
3.5 Experimental Influence of Anatase on the Rheological
Properties of Novolak Resin ............................ 67
4 Investigation of Titanate formation in the System CaO-MgO-
TiO2 ........................................................ 69
4.1 Background ............................................. 69
4.2 Investigations on the Formation of Titanates in the
Binary System CaO-TiO2 ................................. 72
4.2.1 Combination of CaO+TiO2 in the Mole Ratio 1:1 ... 72
4.2.2 Combination of CaO+TiO2 in the Mole Ratio 3:2 ... 73
4.2.3 Combination of CaO+TiO2 in the Mole Ratio 4:3 ... 73
4.3 Investigations on the formation of titanates in the
binary system MgO-TiO2 ................................. 74
4.3.1 Combination of MgO+TiO2 in the Mole Ratio 2:1 ... 74
4.3.2 Combination of MgO+TiO2 in the Mole Ratio 1:1 ... 75
4.3.3 Combination of MgO+TiO2 in the Mole Ratio 1:2 ... 76
4.3.3 Combination of MgO+TiO2 in the Mole Ratio 1:2 ... 76
4.4 Investigations on the Stability of MgTiO3 and CaTiO3 ... 76
4.4.1 Stability of CaTiO3 in the Presence of MgO ...... 76
4.4.2 Stability of MgTiO3 in the Presence of CaO ...... 77
4.5 Conclusions on Titanate Formation in the System
CaO-MgO-TiO2 ........................................... 78
5 Influence of TiO2 ........................................... 79
5.1 Addition of TiO2 to Doloma Carbon refractories ......... 79
5.1.1 Influence of Anatase on the Mechanical and
Physical Properties of Doloma Carbon
Refractories .................................... 79
5.1.2 Influence of Rutile on the Mechanical and
Physical Properties of Doloma Carbon
Refractories .................................... 81
5.1.3 Influence of Anatase on the Refractoriness
Under Load ...................................... 82
5.1.4 Influence of TiO2 on the Carbon Content and
Carbon Phase Composition ........................ 83
5.1.5 Microstructure and Phase Composition of Doloma
Carbon System Containing TiO2 ................... 86
5.2 Influence of TiO2 Addition into Different Oxide-C
Systems ................................................ 91
5.2.1 Influence of Anatase on the Mechanical
Properties of Different Oxide Carbon Systems .... 91
5.2.2 Influence of Anatase on the Carbon Content
and Carbon Phase Composition .................... 92
5.2.3 Microstructure and Phase Composition ............ 94
5.3 Influence of Anatase on the Novolak Resin ............. 101
5.3.1 Influence of Anatase on the Rheological
Properties of Novolak Resin .................... 101
5.3.2 Influence of Anatase on the Novolak
Carbonisation .................................. 104
5.4 Summary of the TiO2 Addition .......................... 105
6 Influence of Silicon ....................................... 109
6.1 Influence of Silicon on the Properties of Doloma
Carbon Refractories ................................... 109
6.1.1 Influence of Silicon on Mechanical and
Physical Properties ............................ 109
6.1.2 Influence of silicon on the carbon phase
composition of doloma carbon refractories ...... 110
6.1.3 Microstructure and Phase Evolution ............. 112
6.2 Influence of Silicon (Grade 1a) on the Properties of
Magnesia Carbon Refractories .......................... 113
6.2.1 Influence of Grade 1a Silicon on Mechanical
and Physical Properties ........................ 113
6.2.2 Influence of Silicon Grade 1a on the Carbon
Content of Magnesia Carbon Refractories ........ 114
6.2.3 Influence of Silicon Addition on the
Microstructure and Phase Composition ........... 115
6.3 Summary of the Silicon Addition ....................... 115
7 Influence of ZrO2 .......................................... 117
7.1 Influence of ZrO2 on Mechanical Properties of Doloma
Carbon Refractories ................................... 117
7.2 Influence of ZrO2 on the Carbon Phase Composition ..... 118
7.3 Influence of ZrO2 Addition on the Phase Evolution
and Microstructure .................................... 119
7.4 Conclusions on ZrO2 Addition .......................... 121
8 Influence of CeO2 .......................................... 123
8.1 Influence of CeO2 on mechanical properties of doloma
carbon refractories ................................... 123
8.2 Influence of CeO2 on the Carbon Phase Composition ..... 124
8.3 Influence of CeO2 Addition on the Phase Evolution
and Microstructure .................................... 125
8.4 Conclusions on CeO2 Addition .......................... 126
9 Influence of Perovskite Type Titanates ..................... 127
9.1 Influence of Perovskite (CaTiO3) and Ilmenite
(FeTiO3) on Mechanical Properties of Doloma Carbon
Refractories .......................................... 127
9.2 Influence of Titanates on the Carbon Content .......... 128
9.3 Influence of Titanate Addition on the
Microstructure ........................................ 128
9.4 Conclusions ........................................... 130
10 Influence of Technical Parameters on Product Quality ....... 131
10.1 Influence of Resin Premixing Process .................. 131
10.2 Influence of Mixing Parameters, Grain Size
Distribution and Pressing Power ....................... 131
10.3 Influence of Curing Parameters ........................ 134
10.4 Influence of Powder Resin ............................. 135
11 Transfer of the Laboratory Results in the Industrial
Scale ...................................................... 136
11.1 Initial Situation ..................................... 136
11.2 Experimental Procedure ................................ 137
11.3 Results and Discussion ................................ 138
11.3.1 Physical and Mechanical Properties ............. 138
11.3.2 Refractoriness Under Load ...................... 139
11.3.1 Relaxation Test ................................ 139
11.3.4 Thermomechanical Properties .................... 140
11.3.5 Phase Composition .............................. 141
11.4 Application of Bricks into an AOD Converter ........... 142
11.5 Summary ............................................... 143
12 Summary and Outlook ........................................ 145
13 List of References ......................................... 149
14 Appendix ................................................... 167
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