This book appears in the authoritative series reporting the international research and development activities conducted by the Schott group of companies. This series provides an overview of Schott's activities for scientists, engineers, and managers from all branches of industry worldwide in which glasses and glass ceramics are of interest. Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated. This new extended edition describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics. The composition, structure, and stability of polycrystalline materials with a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions. Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization. Thus glass ceramics with thermal coefficients of expansion of less than 0.3 x 10(-6)K(-1) can be obtained. Even for the mass production of high-quality cooktop panels (Ceran ), oven windows, and other household appliances, a high reproducibility of the properties is achieved. Special glass ceramics (Zerodur for technological and scientific applications such as high-precision optics or large astronomical mirrors are also discussed. The completely revised edition also features new sections on glass-ceramic applications, with details on their performance, CDC-grinding, and laser gyroscopes containing Zerodur . Thisbook,entitledLowThermal Expansion Glass Ceramics,isoneofaseries reporting on research and development activities on products and processes conducted by the Schott AG. Thescienti?callyfoundeddevelopmentofnewproductsandtechnicalp- cesses has traditionally been of vital importance at Schott and has always been performed on a scale determined by the prospects for application of our special glasses. The scale has increased enormously since the reconstruction of the Schott Glaswerke in Mainz. The range of expert knowledge required for that could never have been supplied by Schott alone. It is also a tradition in our company to cultivate collaboration with customers, universities, and research institutes. Publications in numerous technical journals, which since 1969 we have edited to a regular timeplan as Forschungsberichte ¿ ¿research reports¿¿formedthebasisofthiscooperation.Theycontainup-to-dateinf- mation on various topics for the expert but are not suited as survey material for those whose standpoint is more remote. This is the point where we would like to place our series, to stimulate the exchange of thoughts, so that we can consider from di?erent points of view the possibilities o?ered by those incredibly versatile materials, glass and glass ceramics. We would like to show scientists and engineers, interested customers,andfriendsandemployeesofour?rmtheknowledgethathasbeen won through our research and development at Schott in cooperation with the users of our materials. 1. Overview 1(12) Wolfgang Pannhorst 1.1 The Invention of Low Expansion Glass Ceramics 1(1) 1.2 Basic Research 2(1) 1.3 Main Fields of Application 3(3) 1.4 Current Developments 6(1) 1.5 Other Glass Ceramics 7(3) References 10(3) 2. The Scientific Basis 13(38) 2.1 Structure, Composition, Stability, and Thermal Expansion of High-Quartz and Keatite-Type Alumino-Silicates 13(12) Gerd Müller 2.1.1 Crystal Structures 13(2) 2.1.2 Compositional Ranges and Stability 15(5) 2.1.3 Thermal Expansion 20(4) 2.1.4 Conclusions 24(1) 2.2 Nucleation in Parent Glasses for Lithia Alumino-Silicate Glass Ceramics 25(14) Ulrich Schiffner 25(14) 2.3 Glass Ceramics Based on Lithium-Alumino-Silicate Solid Solution Crystals 39(7) Wolfgang Pannhorst 39(7) References 46(5) 3. Glass Ceramics for Household Appliances 51(70) 3.1 Cooking Systems with Ceran®: High-Tech Appliances for the Kitchen 51(8) Eva Willhauk, Raban Harikantha 51(8) 3.2 Cooking Systems with Ceran®: How It Works 59(22) Roland Dudek, Cora Krause, Klaus Kristen, Peter Naß, Kurt Schaupert, Herwig Scheidler, Wolfgang Schmidbauer, Patrik Schober, Martin Taplan, Ted Wegert, Evelin Weiss 3.2.1 The Concept of the Ceran-Top-System® 59(1) 3.2.2 Heat Flow 59(4) 3.2.3 Transmission, Temperature?Time Loading 63(2) 3.2.4 Heating Elements 65(1) 3.2.5 Gas-Fired Systems 66(1) 3.2.6 Thermal Stress in Ceran® Cooktop Panels 67(7) 3.2.7 Compaction Stress 74(2) 3.2.8 Mechanical Strength 76(1) 3.2.9 Chemical Stability 77(1) 3.2.10 Electric Demands 77(1) 3.2.11 Summary of Physical and Chemical Properties of Ceran® 78(1) 3.2.12 Electronic Touches and Controls for Glass Ceramic Cooktops 78(2) 3.2.13 Assembly of Cooking Systems Equipped with Ceran® 80(1) 3.3 Development and Production of Glass Ceramic Cooktop Panels 81(22) Helga Götz, Ioannis Kosmas, Peter Naß, Erich W. Rodek, Hinnerk Schildt, Wolfgang Schmidbauer, Fritz Schröder, Fritz Siebers, Martin Taplan, Waldemar Weinberg, Evelin Weiss, Dietmar Wennemann 3.3.1 Development of Glass Ceramic Materials 81(3) 3.3.2 Composition of Low-Expansion Glass Ceramics 84(3) 3.3.3 Decoration 87(1) 3.3.4 Composition of Ceramic Colors 88(1) 3.3.5 Production 89(2) 3.3.6 Batch Materials 91(1) 3.3.7 Melting 92(1) 3.3.8 Hot Forming of Glass Ceramics 93(2) 3.3.9 Annealing 95(1) 3.3.10 Glass Cutting and Stacking 95(1) 3.3.11 Mechanical Processing 96(1) 3.3.12 Secondary Processes 96(3) 3.3.13 Screen Printing 99(1) 3.3.14 Ceramization Process 100(3) 3.3.15 Firing of the Ceramic Colors 103(1) 3.4 Robax® Transparent Glass Ceramic 103(4) Manfred Borens, Torsten Gabelmann, Roland Leroux, Toni Münch 103(4) 3.4.1 Robax® Technical Data 104(1) 3.4.2 Development and Production ? Use of Robax® as Stove and Fireplace Sight Panels 105(1) 3.4.3 Bending of Robax® 106(1) 3.5 Surface Strengthening of Low-Expansion Glass Ceramics 107(9) Werner Kiefer 107(14) 3.5.1 Thermal Toughening of Low-Expansion Glass Ceramics 107(2) 3.5.2 Chemical Strengthening of Low-Expansion Glass Ceramics 109(3) 3.5.3 Surface Strengthening by Surface Crystallization 112(4) References 116(5) 4. Zerodur® ? A Low Thermal Expansion Glass Ceramic for Optical Precision Applications 121(116) 4.1 Development of the Optical Glass Ceramic Zerodur® 121(24) Wolfgang Pannhorst 4.1.1 Laboratory Development 121(9) 4.1.2 Development of the Technology for Large Castings 130(6) 4.1.3 Properties 136(4) 4.1.4 Internal Quality 140(1) 4.1.5 Delivery Shapes, Dimensions, and Tolerances 141(1) 4.1.6 Development of Zerodur M® 142(3) 4.2 Conventional Production of Zerodur® 145(12) Rüdiger Hentschel, Hartmut Höness, Rudolf Müller, Norbert Reisert 4.2.1 Melting 146(2) 4.2.2 Hot Forming 148(2) 4.2.3 Annealing and Ceramizing 150(4) 4.2.4 Machining 154(1) 4.2.5 Quality Assurance 155(2) 4.3 Production of Zerodur® in Special Shapes 157(47) Hartmut Höness, Alfred Jacobsen, Konrad Knapp, Thomas Marx, Hans Morian, Rudolf Müller, Norbert Reisert, Armin Thomas 4.3.1 Thin Menisci 157(30) 4.3.2 Lightweight Mirrors 187(6) 4.3.3 Thin-Walled Cylinders 193(11) 4.4 Optical Figuring of High-Quality Optical Surfaces 204(3) Ernst-Dieter Knohl 4.4.1 Introduction 204(1) 4.4.2 Lapping of Aspherical Surfaces 205(1) 4.4.3 Polishing of Aspherical Surfaces 206(1) 4.5 Special Characteristics of Zerodur® 207(11) Reiner Haug, Wilfried Heimerl, Burkhard Speit 4.5.1 Length Stability 207(5) 4.5.2 Radiation Stability 212(4) 4.5.3 Chemical Treatment 216(2) 4.6 Applications of the Glass Ceramic Zerodur® 218(14) Alfred Jacobsen, Thomas Marx 4.6.1 Reflective Optics 218(9) 4.6.2 Laser Gyroscopes 227(2) 4.6.3 Precision Engineering 229(3) References 232(5) List of Contributors 237(4) Sources of Figures 241(2) Index 243