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This Dissertation Has Been 62—2136 M Icrofilm Ed Exactly As Received GIELISSE, Peter Jacob M., 1934- INVESTIGATION of PHASE EQ

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This Dissertation Has Been 62—2136 M Icrofilm Ed Exactly As Received GIELISSE, Peter Jacob M., 1934- INVESTIGATION of PHASE EQ This dissertation has been 62—2136 microfilmed exactly as received GIELISSE, Peter Jacob M., 1934- INVESTIGATION OF PHASE EQUILIBRIA IN THE SYSTEM ALUMINA-BORON OXIDE-SILICA. The Ohio State University, Ph.D., 1961 M ineralogy University Microfilms, Inc., Ann Arbor, Michigan INVESTIGATION OP PHASE EQUILIBRIA IN THE SYSTEM ALUMINA-BORON OXIDE-SILICA DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University By Peter Jacob M. Gielisse, M. S. The Ohio State University 1961 Approved by Adviser Department of Mineralogy ACKNOWLEDGMENTS The writer wishes to extend his sincere thanks to the many people without whose help the preparation of this dissertation would have been impossible. He is indebted in particular to his adviser, Dr. Wilfrid R. Foster, for his invaluable aid, advice and many kindnesses; to the other members of the faculty of the Department of Mineral ogy, Drs. Ernest G. Ehlers, Henry E. Wenden, and Rodney T Tettenhorst; and to his friend and colleague, Thomas J. Rockett. Acknowledgment is also made for financial support re­ ceived under contract No. AF 33(616)-3189, sponsored by Aeronautical Research Laboratories, Air Force Research Division, Wright Patterson Air Force Base, Ohio; as well as for aid received through a Mershon National Graduate Fellowship awarded to the writer by the Mershon Committee on Education in National Security for 1960-‘61'. It goes without saying that he is also most grate­ ful to his wife, Anna, for her excellent help and encour­ agement over the years. TABLE OF CONTENTS Page INTRODUCTION ....................................... 1 PRESENTATION OF THE PROBLEM.......................... 3 LITERATURE S U R V E Y ................................... 3 The Binary S y s t e m s ................................ 3 The Ternary S y s t e m ................................ 9 METHOD OF INVESTIGATION ........................... 11 General Remarks ................................. 11 Raw Materials..................................... 11 Preparation of Samples ........................... 14 Heat Treatment of Samples......................... 16 Phase Identification ............................ 20 PRESENTATION OF EXPERIMENTAL D A T A ................... 22 The Binary System AI2O3-B2O3 ...................... 22 The Ternary System Al2 0 3-B2 0>$-Si0 2 ................ 23 DISCUSSION OF RESULTS .............................. 40 The Binary System AI2O3-B2O3 ...................... 40 Compound stability ........................... 40 Attempted synthesis of jeremejevite ............ 49 Liquidus d a t a .................................. 36 Tentative phase diagram ........................ 37 The Ternary System Al2 0 3-B2 0 3~Si02 ............... 62 Compound formation . 62 Attempted synthesis of sillimanite with boron oxide f l u x .................................. 63 Phase compatibilities......................... 7^ Liquidus data and primary fields ............... 77 Tentative Phase diagram ........................ 80 SUMMARY ............................................ 84 BIBLIOGRAPHY ....................................... 86 AUTOBIOGRAPHY . 90 iii LIST OF TABLES Table Fage 1. Compilation of important optical and x-ray d a t a .......................................... 25 2. Thermal data for firings in the system Na2 0—AI2O3—B2O3 . ........................ 26 3. Selected thermal data for AI2O3-B2OZ mix­ tures ....................................... 27 4-. X-ray results of selected firings on the stability of 2AI2OV.B2O3 in sealed platinum capsules ........................... 29 5. Summary of firing data of selected tour­ malines ....................................... 30 6. Experimental data on attempted sillimanite s y n t h e s i s .................................... 31 7. Compositional and thermal data for solid • state reactions in the system AI0O3-B2O2- S i 0 2 .............................. • • • 33 8 . Experimental data for the determination of liquidus temperatures in the system alumina-boron oxide-silica ............... 36 iv LIST OF ILLUSTRATIONS Figure Page 1 . Diagrammatic presentation of the experiment­ al work carried out in the system alumina- boron oxide ................................... 42 2. X-ray diffractometer patterns: (A) the com­ pound 9AI2O3.2B2O3; (B) the compound 2AI2O3. B203 . 48 3. X-ray diffractometer patterns of magnesium tourmalines................................... 55 4. X-ray diffractometer patterns of alkali tourmalines................................... 5 5 5. Tentative phase diagram for the system alumina-boron oxide ........................ 5 9 6. X-ray diffractometer patterns: (A) mullite; (B) sillimanite; (C) sillimanite synthesis. 69 7» X-ray diffractometer patterns: (A) mullite; (B) decomposed alkali tourmaline; (C) sil­ limanite synthesis; (D) 9AI2O3.2B2O3. 72 8 . Preliminary phase diagram for the system alumina-boron oxide-silica .................. 82 v INTRODUCTION This investigation is concerned with the high tem­ perature equilibrium phase relations between the oxides of aluminum, boron and silicon at atmospheric pressure. The elements silicon and aluminum list second and third respectively in abundance of all elements in crust- al rocks, and form, in coordination with oxygen, the ba­ sic building blocks of many minerals. Their oxides are well known for their natural occurrence as quartz and corundum. Not so abundant is the lesser known element boron, which in nature occurs chiefly in such minerals as axinite, tourmaline, dumortierite, kernite and borax. Technologically the properties of the highly re­ fractory AI20^ and SiOg are well known. They become ex­ tremely important when combined into the compounds 3Al2 0^.2Si02 (mullite) and the various polymorphs of A^Oj.SiC^. They are of great value in the ceramic in­ dustry and are used in porcelahs and ceramic ware be­ cause they are highly refractory, have relatively low thermal expansion and good resistance to heat shock (Poster I960). Lastly, boron oxide has long been used as a flux and mineralizer in both ceramic technology 1 2 and experimental mineralogy, and boroaluminate has been suggested as a refractory. Because of its great importance in silicate tech­ nology, the system A^O^-SiO^, has, ever since its first presentation by Bowen and Greig (1924), attracted large numbers of investigators and has consequently been changed and rechanged. However, the lack of available information on the phase relations between these oxides and both binary and ternary, stands in sharp con­ trast with the wealth of data accumulated over the years for the system AlgO^-SiOg* An investigation of the system A^O^-B^O^-SiOg > therefore, is of importance - mineralogically and tech­ nologically - from both the theoretical and the prac­ tical point of view. PRESENTATION OP THE PROBLEM The thermal relations of with many other ox­ ides, both refractory and non-refractory, are well known. Reliable phase diagrams depicting the equilib­ rium relations of boron oxide with these oxides are readily available (Levin et al, 1956). There are, how­ ever a few exceptions. The binary system for example, does not appear to have been thoroughly investigated heretofore, while the only work in the ternary system has been confined to liquidus determinations in the high silica portion of the diagram by Dietzel and Scholze (1954)* High vis­ cosity of the melts, especially in the high SiC^ reg­ ions, and high volatility of boron oxide, especially at the elevated temperatures necessitated by the re­ fractory nature of two of the oxides, is believed to account for the absence of systematic studies of phase equilibria in these systems to date. It is in view of these considerations that the main purpose of this investigation, to develop a suit­ able phase diagram for the systems AlgOj-BgO^ and 5 within limits of the experimental equipment at hand, seems warranted. Furthermore, a most vexing problem in petrology, that of the precise relationship between the polymorphs of AlgO^.SiC^, is bound to receive additional attention in any thermochemical investigation among the oxides in question. Subsequently experiments were carried out to synthesize the mineral sillimanite at atmospheric pres­ sure. They have, however, led to results which cast doubt on the synthesis reported in the literature. Fur­ thermore, a correlation was made between the product of this synthesis and that of the decomposition product of alkali tourmalines, which is believed to be a boron-con­ taining mullite. LITERATURE SURVEY The Binary Systems Of all three binary systems involved, only one, the system Al20 ^-Si0 2 , bas been systematically investigated and presented as a phase diagram. Knowledge of the other two binary systems is limited to direct knowledge from studies made of the thermal behavior of compositions of the oxides or compounds, or deduction from other, chief­ ly ternary systems. As already pointed out, the system AlgO^-BgOj will be described in the present study, while investigations in the system SiO^-B^O^ are currently be­ ing finished and prepared for publication by my colleague Thomas J. Rockett in the mineralogical laboratories of the Ohio State University. The first reliable diagram for the system Alo0 -Si0o d $ £ was prepared as early as 1924 in a classic study by Bowen and Greig. It showed that mullite (3A120^.2Si02), as the only stable compound at high temperatures, melted incon- gruently to corundum and liquid at 1810°C. A eutectic be­ tween Si02 and mullite occurred at a composition
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