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Zro^ SYSTEM a THESIS Presented to the Faculty Of SOLIDUS TEMPERATURE DETERMINATION IN THE HIGH ZIRCONIA REGION OF THE CaO-Al^O^-ZrO^ SYSTEM A THESIS Presented to The Faculty of the Division of Graduate Studies By Baek Hee Kim In Partial Fulfillment of the Requirements for the Degree Master of Science in Ceramic Engineering Georgia Institute of Technology December, 1977 SOLIDUS TEMPERATURE DETERMINATION IN THE HIGH ZIRCONIA REGION OF THE CaO-Al^O^-ZrO^ SYSTEM Appro;w^ed: Jj^K. /Cochran, Jr., ^hairm^^ -Alan_Xa__Chapman // ^ Japfties F. Benzel^ >^ Date Approved by Chairman jLkc. / v r\~l^ 11 ACKNOWLEDGMENTS To my advisor Dr. J. K. Cochran, Jr., I cannot express my unforgettable appreciation in a short sentence, and it is regrettable that I should use a simple word "Thank You." I also appreciate Dr. A, T. Chapman and Dr. J. F. Benzel for their invaluable advice and support as part of my reading committee. My deep appreciation goes to Dr. J. L. Pentecost who allowed me to study in this department and for the confidence showed in help­ ing to arrange financial support. I would like to express my appre­ ciation to both the U. S. Bureau of Mines and Department of Health, Education, and Welfare for their contribution to the success of this work. Technical support by Mr. Tom Mackrovich, excellent translation of Spanish articles by Mr. F. Rivera L.; draft typing by Ms. Mary Ann Breazeale, and friendly discussion with Mr. J. D. Lee allowed completion of this work without delay. I appreciate Ms. Shirleye McCombs doing the final typing of this thesis on such short notice. Above all, my parent's continuous encouragement and my wife's painful support, in spite of her pregnancy, have led this work to a fruitful result. Ill mBLE OF CONTENTS Page ACKNOWLEDGMENTS ii LIST OF TABLES iv LIST OF ILLUSTRATIONS v GLOSSARY OF ABBREVIATIONS ix SUMMARY X Chapter I. INTRODUCTION 1 II. LITERATURE SURVEY 2 CaO-AUOo System Al^O -ZrO System CaO-ZrO^ System CaO-Al^O-ZrO^ System III. PROCEDURE 24 Materials Sample Preparation Microstructural Analysis Qualitative X-ray Diffraction Analysis Determination of Solidus Temperature IV. RESULTS AND DISCUSSION 32 Determination of Compatibility Triangles at 1500 C Solidus Temperature Determination V. CONCLUSIONS 75 BIBLIOGRAPHY 76 IV LIST OF TA.BLES Table Page 1 Phase Data for Binary Compounds in the CaO-Al^O System 3 2 Physical Properties of C-„A^ Depending on the Existence of Moisture 6 3 Comparison of Eutectics in the System A1«0 -ZrO„ as Determined by Various Investigators 10 4 Chemical Analysis of Raw Materials ..... 25 5 Composition of Series -1 and -2 26 6 Phase Analysis for Samples 2-10, -15 and -20, Fired at 1670°C and 1690°C 67 V LIST OF ILLUSTRATIONS Figure Page 1 CaO-Al^O System at Normal Humidity 4 2 CaO-Al^O System Under Anhydrous Conditions 8 3 Al^O -ZrO System 11 4 Al^O -ZrO System By Alper 13 5 CaO-ZrO^ System by Duwez 15 6 CaO-ZrO^ System by Noguchi 16 7 Comparison of Phase Boundaries at 1700"C 19 8 Liquidus Curve in the System CaO-ZrO„ bad MgO-ZrO^ . 19 9. CaO-Al^Oo System by Berezhnoi 20 10 CaO-Al^O -ZrO^ System by Espinosa 21 11 Location of Series -1 and -2 Compositions 22 12 X-ray Diffraction Sample Holder 30 13 Chart of Relative X-ray Diffraction Intensities of Phase Present in CaO-Al«0 -ZrO_ Series -1 and -2 Com­ positions 33 14 Phase Boundary Locations in the High Zirconia Region of the CaO-Al^O -ZrO System at 1500°C 35 15 Micros truetures of Compositions 1-3 and 1-4 After o o Firing at 1500 C and 1550 C Showing Liquid Formation at 1550°C, 600x 37 16 Micros truetures of Compositions 1-5 after Firing at Various Temperatures Showing Liquid Formation at 1530°C, 600x 38 17 Micros truetures of Composition 2-23 After Firing at Various Temperatures Showing Liquid Formation at 1550°C, 600x 39 vi 18 Microstruetures of Composition 1-1 After Firing at Various Temperatures Showing Liquid Formation at 1590°C, 600x 41 19 Micros truetures of Composition 1-2 After Firing at Various Temperatures Showing Liquid Formation at 1590°C, 600x 42 20 Micros truetures of Composition 2-22 After Firing at Various Temperatures Showing Liquid Formation at 1590°C, 600x . 43 21 Effect of CaO Contents on the Solidus Behavior of CaO- A1„0 -ZrO„ Series -1 Compositions 45 22 Micros truetures of Composition 2-16 After Firing at Various Temperatures Showing Liquid Formation at 1630°C, 600x 46 23 Microstruetures of Composition 2-17 After Firing at Various Temperatures, Solidus Temperature Was Deter­ mined as 1630°C, 600x 47 24 Microstruetures of Composition 2-23 After Firing at Various Temperatures, Solidus Temperature Was Deter­ mined as 1630°C, 600x 48 25 Micros truetures of Composition 2-1 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670°C, 600x 50 26 Micros truetures of Composition 2-4 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670 C, 600x 51 27 Microstruetures of Composition 2-6 After Firing At Various Temperatures, Solidus Temperature was Deter­ mined as 1670 C, 600x 52 28 Micros truetures of Composition 2-7 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670 C, 600x . • • 53 29 Microstruetures of Composition 2-8 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670 C, 600x 54 30 Microstruetures of Composition 2-9 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670 C, 600x 55 vll 31 Microstrueture of Composition 2-11 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670°C, 600x 56 32 Micros trueture of Composition 2-14 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670°C, 600x 57 33 Micros trueture of Composition 2-18 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670°C, 600x . 58 34 Micros trueture of Composition 2-19 After Firing at Various Temperatures, Solidus Temperature was Deter­ mined as 1670°C, 600x 59 35 Microstrueture of Composition 2-8 After Firing at 1670°C Showing Needle-like Phases, 600x 60 36 Microstrueture of Composition 2-5 After Firing at Various Temperature, Solidus Temperature was Deter­ mined as 1670°C, 600x 62 37 Microstrueture of Composition 2-10 After Firing at Various Temperature, Solidus Temperature was Deter­ mined as 1670 C, 600x. » 63 38 Microstrueture of Composition 2-15 After Firing at Various Temperature, Solidus Temperature was Deter­ mined as 1670 C, 600x 64 39 Microstructure of Composition 2-20 After Firing at Various Temperature, Solidus Temperature was Deter­ mined as 1670 C, 600x -, 65 40 Micros trueture of Composition 2-25 After Firing at Various Temperature, Solidus Temperature was Deter­ mined as 1670 C, 600x. <> o . o 66 41 Microstructure of Composition 2-17 After Firing at 1500°C Showing Local Melting, 600x 69 42 Polished Surface of Series -2 Samples After Firing at 1500°C 70 43 Solidus Temperatures of Series -1 and -2 Composition . 71 44 Solidus Isotherms in the High Zirconia Corner of the CaO-Al^O -ZrO^ System 72 viii 45 Solidus Surface in the High Zirconia Region of the CaO-Al^O -ZrO System • • • • 74 IX GLOSSARY OF ABBREVIATIONS CA Ca0-Al202 ^2 CaO-2Al202 C3A5 3CaO-5Al202 CAg CaO-6Al202 cz CaO-Zr02 S^7 3CaO-7Al20 ^12^7 12CaO-7Al202 SS Solid Solution SUMMARY Solidus temperatures in the high zirconia region of the CaO-Al« 0 -ZrO„ system were determined. For this experiment, 30 compositions which were located in the high zirconia-content region were selected. Successive firings and analyses were performed from 1500 C to 1690 C nnO m 20 C increments. The solidus temperatures were determined by carefully examining the microstrueture of each sample after firing using optical micro­ scopy. X-ray diffraction was also used to determine phase changes. This study revealed that solidus temperatures in the high zir­ conia corner of the Ca0-Al«0 -ZrO^ system are lower than one may have expected. The general trend of solidus temperatures in this region was to lower temperatures as the calcia and alumina content increased. Alumina additions of less than 5 mole % decreased solidus temperatures substantially from approximately 2500 C to 1550 C. For the selected compositions, the solidus temperatures were between 1530 C and 1690 C. Phase boundaries below the solidus in the high zirconia region were also determined at 1500 C. CHAPTER I INTRODUCTION Among all the physical properties of refractory materials, the solidus temperature is the most important decision making factor for the application as a refractory. In the CaO-A1^0„-ZrO« system, most of the physical properties, except solidus temperature, for the high ZrO^ content corner had been well established by Cochran, et.al. The purpose of this study is to determine solidus temperatures in the high zirconia corner of the system CaO-Al^O -ZrO_. 2 Berezhnoi mentioned that most compositions in this system start to melt below 1600 C. Espinosa showed in his CaO-Al^O -ZrO diagram that the invariant points of alkamade triangle CA^-CZ-Z and CA^-CAx--Z are 1565 C and 1657 C, respectively. A preliminary study of the se­ lected 30 compositions located in the high zirconia comer of the system CaO-Al„0_-ZrO„ revealed that initial melting occurs somewhere between 1500 C and 1700 C. Thus, successive firings and analyses were performed from 1530 C to 1690 C in 20 C increments. The solidus temperatures were determined by observing microstrueture changes of samples after each firing.
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