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Rheology of Vitreous Coatings This dissertation has been microfilmed exactly as received 68-15,372 RHODES, James Franklin, 1938- RHEOLOGY OF VITREOUS COATINGS. The Ohio State University, Ph.D., 1968 Engineering, chemical University Microfilms, Inc., Ann Arbor, Michigan RHEOLOGY OP VITREOUS COATINGS DISSERTATION Presented In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By ■ i James Franklin Rhodes, B. Ch.E., M.S. ****** The Ohio State University 1968 Approved by Department of Ceram^ Engineering ACKNOWLEDGMENTS The author wishes to express his thanks to all the individuals who have assisted him in the course of this investigation. Special gratitude is due to Dr. B.W. King, Jr, and Dr. R. Russell, Jr, for their encouragement, guidance and patience. The suggestions and advice of Mr. Lawrence E. Muttart and Dr. W.B. Shook are gratefully appreciated. The assistance of Walter Grudzinski of the General Motors Research Center in preparing the illustrations is gratefully acknowledged. Special thanks are due to the author*s wife, Paula, for her encouragement and assistance in the preparation of this disseration. The author is indebted to the National Science Foundation whose financial support allowed him to pursue this investigation. The author expresses a final note of thanks to the three women -- his mother, wife and daughter — whose sacrifices made this work possible. ii VITA January 20, 1938 Born - Cleveland, Ohio 1963 B.Ch.E., University of Detroit Detroit, Michigan 1963-1967 Research Fellow - Department of Ceramic Engineering, The Ohio State University, Columbus, Ohio National Science Foundation Fellowship 19 66 M,S., The Ohio State University Columbus, Ohio PUBLICATIONS Masterfs Thesis - "Leveling of Porcelain Enamels", March, 1 9 66, The Ohio State University Library TABLE OF CONTENTS Page ACKNOWLEDGMENTS ii VITA iii LIST OF TABLES vi LIST OF ILLUSTRATIONS viii INTRODUCTION 1 LITERATURE REVIEW 5 DISCUSSION OF LITERATURE 11 METHOD OF ANALYSIS 15 EXPERIMENTAL PROCEDURE 21 Preliminary Investigation 21 Final Experimental Procedure 27 Development of A wave Forming Method 27 Preparation of Measuring Apparatus 28 Procedure for Glass EF 9 52 Investigation of Glass-Powdered Metal Mixtures 35 Preparation of Glass EF 9 Powdered Nickel Wave Specimen 35 Measurement of Surface Tension of Glasses 607 and EF 9 56 EXPERIMENTAL DATA 41 ANALYSIS OF DATA 69 RESULTS AND DISCUSSION 103 Comparison of Leveling Models 122 Sources of Possible Error 124 CONCLUSIONS 125 iv Page SUMMARY 126 APPENDIX A - MATHEMATICAL MODEL 127 Description of Model and Assumptions 128 Theory 129 APPENDIX B - RAW MATERIALS AND EQUIPMENT DATA 164 APPENDIX C - CHEMICAL AND PHYSICAL DATA 168 BIBLIOGRAPHY 178 v LIST OP TABLES No# Title Page 1 Particle Sizing Data 22 2 Powdered Metal Investigation Data 34 3 Average Amplitudes and Cumulative Firing Data, Specimen Series D, Glass 607 42 4 Average Amplitude and Cumulative Firing Data, Specimen Series E, Owens Illinois Glass EF 9 59 5 Wave Amplitude and Cumulative Firing Time Specimen Series F, 90$ Glass EF 9 - 10# Inco 123 Nickel 64 6 Surface Tension Data, Glass EF 9 66 7 Surface Tension Data, Glass 607 66 8 Time Corrected Data, Specimen Series D, Glass 607 72 9 Corrected Time Data, Specimen Series E, Owens Illinois Glass EF 9 84 10 Corrected Time Data, Specimen Series F, 90# Owens Illinois Glass EF 9 - 10# Inco 123 Nickel Powder 88 11 Data for the Graph of C^ versus -kh 105 12 Viscosity Calculation Data, Glass 607 109 13 Viscosity Calculation Data, Glass EF 9 111 14 Viscosity Calculation Data, 90# Glass EF 9 - 10# Powdered Nickel 112 15 Log Viscosity Temperature Data, Glass 607 113 16 Log Viscosity Temperature Data, Glass EF ; 114 vi No. Title Page 17 Log Viscosity Temperature Data, 90$ Glass EF 9 - 10$ Inco Nickel 115 18 Effect of Water on Glass Viscosity 119 19 Comparison of the Viscosity of Glassy Coatings and Glass-Metal Dispersion Coatings 121 3 20 Data for Determining C^/(kh) Ratio 123 21 Data for the Determination of the Effect of aA on the Function 1/1 + a2k2 /A 132 22 Derivatives and Integrals for Solution of Stress Functions 140 23 Calculation Data for kC^C^ Ratio 152 24 Calculation Data for kC^/C^ Ratio 156 25 Elastic Theory Solutions: Stresses, Displacements, and Constants 158 26 Viscosity-JTemperature Data, Glass 607 (After English (9) ) 169 27 Owens Illinois Corporation, Glass EF 9, Physical Data 170 28 Chemical and Physical Data, International Nickel Company, Type 123 Carbonyl Nickel Powder 171 29 Chemical Composition, Glass 607 172 30 Chemical Composition, Glass EF 9 173 31 Chemical Composition, Glass 604, English 174 32 Chemical Composition, Glass 4, Parmalee et al. (18) 175 33 Viscosity Data, Glass 604, (After English (9) ) 176 34 Surface Tension Data, Glass 4 Parmalee et al. (18) 177 vii LIST OF ILLUSTRATIONS No. Title Page 1 Surface Tension Measuring Furnace 37 2 Surface Tension Measuring Furnace 38 3 Surface Tension vs Temperature, Glass 607 67 4 Surface Tension vs Temperature, Glass EF 9 68 5 Log l/a vs Corrected Time, Specimen El 89 6 Log l/a vs Corrected Time, Specimen E2 90 7 Log l/a vs Corrected Time, Specimen E3 91 8 Log l/a vs Corrected Time, Specimen E4 92 9 Log l/a vs Corrected Time, Specimen E5 93 10 Log l/a vs Corrected Time, Specimen E6 94 11 Log l/a vs Corrected Time, Specimen E7 95 12 Log l/a vs Corrected Time, Specimen E8 96 13 Log l/a vs Corrected Time, Specimen E9 97 14 Log l/a vs Corrected Time, Specimen E10 98 15 Log l/a vs Corrected Time, Specimen Ell 99 16 Log l/a vs Corrected Time, Specimen FI 100 17 Log l/a vs Corrected Time, Specimen F2 101 18 Log l/a vs Corrected Time, Specimen F3 102 19 C jj versus ■-kh 106 20 C5 versus -■kh 107 21 versus ~kh 108 Vili No. Title Page 22 Log Viscosity vs Temperature, Glass 607 116 23 Log Viscosity vs Temperature, Glass EF 9 117 24 Reference Diagram, Mathematical Model, Rheology of Vitreous Coatings 130 25 a/X versus 1/( 1 + a2k2 ) 1 3 3 26 kC2/C4 versus q 3.53 27 k C 2/ C 4 versus q 154 28 q vs -kC-j/C/j. 1 5 8 ix INTRODUCTION The motto of the Society of Rheology is "Everything flows". Rheology is that branch of physics which Is concerned with the flow, and deformation of materials. While it is true that to some extent everything does flow, the rheologlcal behavior of different types of real materials Is varied and exceedingly complex. The rheology of coatings, and especially vitreous coatings, Is no exception. Vitreous coatings are essentially glasses that are used as coatings for various types of substrates. Those used on metal substrates are called porcelain enamels those used on ceramic substrates are called glazes. Some porcelain enamels are used In a dry process whereby a finely ground glass is sprinkled on hot ware. The enamel adheres to the piece which Is then reheated so that the glass can flow into a smooth coating. All glazes and most porcelain enamels utilize a "wet process" whereby finely ground materials are dispersed In a water suspension. This water suspension (called a slip) is applied to the substrate, dried, and fired. In the firing process, the coating fuses, becomes vitreous, flows out and bonds to the substrate. 1 2 Up to the ^>oint where the wet coating has dried, its rheological behavior is similar to a paint. At the beginning of thei fusion process, the coating acts as a sintering-reacting solid. Upon completion of reactions and fusion into a monolithic layer, it behaves as a glass. The total rheological picture of vitreous coatings is thus a complex one. Since it is beyond the scope of any single investigation to cover all the rheological phenomena of a vitreous coating, this work will be confined to the study of the final rheological phase, the flow of the fused vitreous coating. The glass industry has developed methods for exact measurements of viscosity for highly viscous systems. These viscosity-temperature relations are used to determine control points for glass manufacturing and fabrication. The high viscosities (7.65 log poise and greater) are conven- tionally determiLned by measuring the rate of elongation of uniform glass fibers. Low viscosities (less than 5 log poise) are generally determined with rotational viscometers. Paint technologists have also applied exact rheological measurements to the evaluation, development, and quality control of organic coatings. Plow cups and rotational viscometers are generally used to determine the rheological properties of paints. Neither the methods of the glass technologist nor those of the paint technologist are readily applicable to studying the rheology of fused vitreous coatings. Vitreous 3 coatings generally involve blends of various glassy components with crystalline oxide raw materials; in addition, they quite often contain a precipitated crystalline phase. Therefore, the methods developed by the glass technologist for homogeneous fibers cannot be used. Conventional rotational viscometers are convenient for melts having viscosities less than 5 log poise. Many various methods of viscometry have been developed in the past and Rheological Abstracts (35) lists many newly developed methods each year. However, most methods require intricate apparatus. The porcelain enamel industry uses the flow button test (11) as a relative viscosity measure­ ment in the development and quality control of porcelain enamel glasses, but exact control points have not been established. The flow button test was developed by Kinzie (12) and modified by Marbaker (13). Dekker (8 ) has developed a method for calculating viscosity-temperature curves from flow button data. Dekker*s method gives good agreement with his known data, but it is rather complicated to us?.
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