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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Most people would be surprised at how ceramics are used, from creating cellular phones, radio, television, and lasers to its role in medicine for cancer treatments and restoring hearing. The Magic of Ceramics introduces the nontechnical reader to the many exciting applications of ceramics, describing how ceramic material functions, while teaching key scientific concepts like atomic structure, color, and the electromagnetic spectrum. With many illustrations from corporations on the ways in which ceramics make advanced products possible, the Second Edition also addresses the newest areas in ceramics, such as nanotechnology.
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Seitenzahl: 636
Veröffentlichungsjahr: 2012
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Cover images: Background stars: © Electric_Crayon/iStockphoto; Skier: © Doug Berry/iStockphoto;
Handheld device: © Laurent Davoust/iStockphoto; Space shuttle: © lurii Kovalenko/iStockphoto;
Roller blades: © Givaga/iStockphoto; Vase: © evangelos kanaridis/iStockphoto
Copyright © 2012 by The American Ceramic Society. All rights reserved.
Published by John Wiley & Sons, Inc., Hoboken, New Jersey.
Published simultaneously in Canada.
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Library of Congress Cataloging-in-Publication Data is available.
ISBN: 978-0-470-63805-7
Table of Contents
Title
Copyright
Preface & Acknowledgments for the First Edition
Preface & Acknowledgments for the Second Edition
Foreword to the First Edition
Introduction
Chapter 1: Our Constant Companions
From Stoneware to Superconductors
Ceramics in Your Home
Ceramics on the Job
Ceramics Elsewhere
Ceramics at Play
Overview: Moving On
Chapter 2: From Pottery to the Space Shuttle
Early Ceramics
Evolution of Traditional Ceramics
Modern Ceramics
Overview: into the Future
Chapter 3: The Beauty of Ceramics
Early Ceramic Art
The Middle Ages
The Renaissance and Beyond
A Century of Ceramic Art
Overview: Enduring Beauty
Chapter 4: Ceramics and Light
Transparency, a Rare and Special Quality
Color
Phosphorescence
Lasers
More Optical Magic
Overview: Vision Into The Future
Chapter 5: Amazing Strength
Ceramics and Stress
Silicon Nitride
High-Strength, High-Toughness Zirconium Oxide
High-Strength Ceramic Fibers
Composites with High-Strength Carbon Fibers
Ceramic Stability
Dimensional Stability and Low-Thermal-Expansion Ceramics
Other Low-Thermal-Expansion Ceramics
Overview: A New Dimension of Strength and Stability
Chapter 6: Ceramics and the Electronics Age
What we mean by Electronics
Milestones in Our Understanding and Use of Electricity
The Role of Ceramics in IC Technology
Other Electrical uses of Ceramics
Nature’s Magnets
Overview: What Will the Future Bring?
Chapter 7: Piezo Power
The History of Piezoelectric Ceramics
Underwater uses for Piezoelectric Ceramics
Industrial Uses for Piezoelectric Ceramics
Pressure and Vibration Detection with Piezoelectric Ceramics
Vibration Prevention
Other uses for Piezoelectric Ceramics
Overview: Piezoelectric Ceramics Transforming our Lives
Chapter 8: Medical Miracles
Ceramics for Replacement and Repair
Diagnostic uses for Ceramics
Ceramics in Medical Treatment and Therapy
Overview: Medical Miracles yet to come
Chapter 9: Ceramics and the Modern Automobile
Ceramics Under the Hood
Ceramics in the Passenger Compartment
Ceramics in the Rest of Your Car
Ceramics in Motor Vehicle Manufacturing
Overview: Moving Down the Road
Chapter 10: Heat Beaters
Ceramics for The Refining and Processing of Metals
Ceramics for High-Temperature Industrial Processes
Energy Conversion
Aerospace Uses of Ceramics
Overview: Harnessing Heat
Chapter 11: The Hardest Materials in the Universe
The Cutting of Materials
Wear Resistance And Corrosion Resistance
Ceramic Armor
Overview: Ceramics Stop Wear and Bullets
Chapter 12: Energy Conservation and Conversion Efficiency
Why Should We be Concerned?
The Role of Ceramics in Energy Conservation
The Role of Ceramics in Increasing Efficiency of Power Generation
Overview: Becoming More Efficient
Chapter 13: From Pollution Control to Zero Pollution
The Role of Ceramics in Vehicle Pollution Control
Other Pollution Reduction Technologies Involving Ceramics
Ceramics and Renewable Energy Sources
Overview: To A Greener, Healthier Environment
Chapter 14: What’s New and What’s Coming
Nanomaterials, Nanofabrication, Nanoanalysis
The Digital Electronics Revolution
Modern Ceramic Electrochemical Devices
Overview: What’s Next?
Conclusion
About the Author
Index
Preface & Acknowledgments for the First Edition
The Magic of Ceramics was written as part of an educational outreach project of the American Ceramic Society (ACerS). ACerS, founded in 1898, scheduled a year of centennial activities in 1998 and 1999. As part of the celebration, the Education Committee created a museum exhibit to introduce the general public and students to the amazing uses of ceramics. This was the nucleus of The Magic of Ceramics.
The idea for The Magic of Ceramics was proposed to ACerS, but under special circumstances. The book would be different from the technical books that ACerS typically publishes; it would also be entertaining, colorful, and available to the general public. ACerS accepted this proposal. Mary Cassells and Sarah Godby provided the direction and support to make this book a reality.
I sincerely thank all companies and individuals who donated ceramic parts, photographs, and their time in offering information for the exhibit and the book: M. Reynolds, S. Morse, T. Johnson, B. Jones, C. Davis, D. Keck, D. Duke, E. Sturdevant, and M. Cotton, Corning, Inc.; L. Vallon, S. Dunlap, T. Taglialavore, B. Licht, B. McEntire, D. Croucher, M. Leger, E. Levadnuk, D. Parker, C. L. Quackenbush, T. Leo, and J. Caron, Saint-Gobain/Norton; F. Moore, Norton Chemicals; D. Reed, J. Mangels, and J. Moskowitz, Ceradyne, Inc.; K. Inamori, Y. Hamano, T. Yamamoto, J. Scovie, E. Kraft, and D. Carruthers, Kyocera Corp.; J. Price and M. van Roode, Solar Turbines; and H. Coors, B. Seegmiller, K. Michas, and L. Sobel, Coors Ceramics.
R. DeWolf, Thielsch Engineering; J. Knickerbocker, IBM; A. Bogue, Active Control eXperts (ACX); D. Cavenaugh and J. Greenwald, Wilbanks; M. Kokta, K. Heikkinen, and L. Rothrock, Union Carbide Crystal Products; M. and M. Kasprzyk, INEX Inc.; S. Limaye, LoTEC; T. Sweeting, HI-TECH Ceramics; C. Greskovich and B. Riedner, General Electric Co.; M. Savitz and R. Walecki, AlliedSignal Ceramic Components; M. Easley and J. Kidwell, AlliedSignal Engines; R. Schultze, AlliedSignal Filters and Spark Plugs; F. Luhrs, Rauschert Industries; J. Ormerod, Group Arnold; and M. Kreppel, Saint-Gobain/Carborundum.
B. Powell and A. Micheli, General Motors; J. Staggs, General Magnetic Co.; P.Barker, ITT Automotive; B. Knigga, Delco Electronics; C. Strug, American Superconductor; F. Kennard, Delphi Electronic Systems; G. Melde, Siemens Power Corp.; J.Wenkus, Zirmat Corp.; A. Hecker and G. Bandyopadhyay, OSRAM SYLVANIA; G. Harmon, American Marine; T. Brenner, Den-tal-ez, Inc.; A. Vohra, DOE; W. Paciorek and L. Spotten, Durel Corp.; D. Witter, MEMC Southwest; J. Estes, Motorola; B. Cuttler, Sandia National Laboratory; P. Martin, Hewlett Packard; P. Gwordz, San Jose State University; and F. Schmidt and M. Felt, Crystal Systems.
J. Sapin, Rado Watch Co., Ltd.; V. Adams and C. A. Forbes, Siemens-Westinghouse Electric; R. Wasowski, Ferro Corp.; J. Lynch, General Ceramics; K. Elder, Westvaco Corp.; Y. Manring and W. Gates, ACerS Ross Coffin Purdy Museum of Ceramics; M. Dowley, Liconix; C. Chandler and A. Feidisch, Spectra Physics, Inc.; D. Bacso, G. Cook, R. Snow, and C. Glassy, Edo Piezoelectric Ceramic Products; D. Greenspan and P. Neilson, US Biomaterials; A. Compton and W. Wolf, Owens Corning; St. Bender, the History Factory; S. Nelson, S. Logiudice, and K. Budd, 3M; L. Aubry, Selee Corp.; and L. Berthiaume, Saphikon Inc.
L. George, National Dental Association; D. Braski, Oak Ridge National Laboratory; A. Khandkar and S. Elangovan, Ceramatec; J. Hinton and V. Irick, Lanxide Corp.; A. Griffin and C. Griffin, Lone Peak Engineering, Inc.; T. Yonushonis and R. Stafford, Cummins; E. Lassow and T. Wright, Howmet Research Corp.; J. Buckley, NASA Langley; D. Day, University of Missouri-Rolla; R. Stoddard, 3M Unitek; E. Pope, Solgene Therapeutics, LLC; L. Hench and J. Leonan, Imperial College; K. George, Dynatronics; and G. Fischman, U.S. Food and Drug Administration.
D. Kingery, University of Arizona; D. and N. Ferguson; T. Garcia; E.McEndarfer, Truman State University; W. Bates; K. Nassau; Marianne Letasi, Detroit Institute of Art; S. Rossi-Wilcox, Botanical Museum of Harvard University; J. Thomas-Clark, Corning Museum of Glass; J. Clottes, International Committee on Rock Art, Foix, France; J. Lever; and Count Robert Bégouën.
I am grateful to Angie Eagan who took my sketches and created illustrations; J. Taylor, Tile Heritage Foundation, who provided slides of decorative tiles; D. Whitehouse, Corning Museum of Glass, who offered suggestions of glass art to use as illustrations; Ruth Butler, editor, Ceramics Monthly; and W. South and D. Carroll, Utah Museum of Fine Art, for helping select items from the collection.
My special thanks to Alexis Clare, Margaret Carney, Jim Jacobs, Donaree Neville, Al and Barbara Kuipers, Michael Anne Richerson, and Jennifer Richerson for reading portions of the manuscript and providing suggestions. I am especially indebted to the copy editor Susan Blake.
The last, but not least, person I want to thank is Mark Glasper, ACerS Director of Communications. He is an unsung hero in ACerS education efforts. The traveling museum exhibit would not have happened without his dedication and help.
DAVID W. RICHERSON
Preface & Acknowledgments for the Second Edition
More than 10 years have now passed since the first edition. Technology and innovation have not stood still, and advances in ceramics and other materials have played an important role. This second edition updates some of the applications of ceramics described or introduced in the first edition, but emphasizes major developments that have occurred during the past 10–15 years. Many of these advances have been in pollution control, energy harvesting and conversion, digital electronics, medicine, and “nanotechnology.”
Several figures have been added to Chapter 2 “From Pottery to the Space Shuttle” to better illustrate the role of ceramics in the evolution of civilization. The remarkable growth in the use of light-emitting diodes (LEDs) has been added to Chapter 4 “Ceramics and Light.” The role of advanced composites in the next-generation space telescope is now included in Chapter 5 “Amazing Strength and Stability.” Discussions and illustrations of the role of ceramics in neural arrays, prosthetic feet, and spinal surgery are now part of Chapter 8 “Medical Miracles.” Chapter 10 “Heat Beaters” has been modified with a discussion of the ceramic requirements to make possible the next generation of hypersonic aircraft and the replacement for the Space Shuttle. The discussion of the reasons that diamond is so hard, which has been expanded in Chapter 11 “The Hardest Materials in the Universe.” All of these changes and updates in Chapters 1–11 are relatively moderate. The major modifications for the second edition appear in Chapters 12–14.
Chapter 12 from the first edition has been expanded into two chapters. The new Chapter 12 “Energy Conservation and Conversion Efficiency” reviews the role of ceramics in conservation of electricity through new lighting technologies, increasing fuel efficiency of vehicles, and increasing efficiency of our processes of converting energy from fuels into electricity. Chapter 13 “From Pollution Control to Zero Pollution” then reviews the evolution of technologies, such as the catalytic converter, that have greatly reduced the pollution from automobiles and trucks. This new chapter then discusses ways that ceramics and other materials are making low-pollution renewable energy such as wind and solar technically feasible and cost-effective.
Chapter 14, the final chapter, discusses “What’s New and What’s Coming.” It describes how ceramics have helped make possible the digital electronics revolution and miniaturization, how ceramics can now be assembled atom by atom to achieve remarkable nanostructures, the role of ceramics in the advanced batteries we need desperately for energy storage, and the emergence of applications for electrochemical ceramics.
Many additional individuals have been very helpful in suggesting or gathering information for the second edition: Elizabeth Dann, Peter Bocko, Willard Cutler, and Tim Johnson of Corning, Inc.; Bryan McEntire and Shanna Ryan of Amedica; Dr. Zhong Lin Wang of the Georgia Institute of Technology; Dr. Rasto Brezny of the Manufacturers of Emission Controls Association; Dr. David Glass, NASA Langley; Dr. Jay Singh, Ohio Aerospace Inst., NASA Glenn Research Center; Dr. Delbert Day, Missouri University of Science and Technology; Dr. Joel Moskowitz, Ceradyne, Inc.; Ted Foster and Phil Armstrong, Air Products and Chemicals, Inc.; Dr. Kunihito Koumoto, Nagoya University; Dr. Gary Messing, Pennsylvania State University; Jay Spina and Jonas Olsson, SKF; Dr. Toshihiro Ishikawa, UBE Industries; Frank Anderson and Harrison Hartman, CoorsTek; Tony Taglialavore of Saint Gobain Advanced Ceramics; and Dr. Richard Normann, Dr. Loren Rieth, Dr. Forian Solzbacher, Dr. Michael Scarpulla, Dr. Agnes Ostafin, and Dr. Yen-Chi Chen of the University of Utah. I also greatly appreciate the encouragement I have received from numerous members of the American Ceramic Society and the staff at Wiley, Inc., and Haseen Khan at Laserwords in production of the Second Edition.
Foreword to the First Edition
I was born and raised in the Yakima Valley of eastern Washington State. My parents had homesteaded there in 1948, creating a ranch and farm in the middle of largely unirrigated, unpopulated land punctuated with sagebrush. We had no neighbors that I could see to the north, at the base of the Rattlesnake Mountains, and few to the south, east, or west. A two-lane dirt road ran by our house, which was later covered with gravel. During the summer months, after our chores were done, I would ask for my parents’ permission to walk up and down that road for a certain distance to look for agates. But I collected more than agates; I collected all manner of interesting rocks, including chunks of quartz, mica, feldspar, and granite.
At night, there were no outdoor lights to diffuse the brightness of the stars. In fact, the Milky Way was a very large stripe across the sky. In the fall of 1957, my parents and I lay on the grass and looked for the first satellite launched into space—a Russian silver sphere called Sputnik. It was during that time that I formed my own dreams to fly into space. Little did I realize at the time that my rock collection and flying in space would have something in common: they were both dependent on chemical compositions that we call ceramics.
How these two apparently diverse worlds are joined is eloquently explained in The Magic of Ceramics by David W. Richerson. This wonderfully unique and readable book describes how humans have taken the rocks around us and, through chemistry, heat, and advanced technology, applied them in glass, fiber optics, electronic and computer components, motor parts, tennis rackets, art work—in fact, the core of today’s civilized technological society.
Materials have been referred to as the enabling technology of all other new engineering endeavors. Within this realm fall metals, organics, and ceramics. Readers may not be familiar with the breadth of “ceramics,” but they will find described in these pages the many applications of ceramics in their lives. Additionally, they will be given the opportunity to understand how and why ceramics work in the applications described. For example, the author summarizes the historical evolution of high-temperature inorganic nonmetallic chemistry in the chapter “From Pottery to the Space Shuttle.” He discusses how ceramics have formed the core of art since antiquity in “The Beauty of Ceramics,” and how variations in the atoms of a single ceramic compound can change the mechanical and optical properties of the material in “Ceramics and Light.” Ceramics are central to developments in bioengineering and medicine, energy, and pollution control and could revolutionize electronics through new nanotechnology research.
Our world revolves around ceramics on a daily basis; we may utilize a computer dependent on a ceramic integrated circuit, gaze out through glass windows, drive our automobiles powered with ceramic component engines, walk on concrete walks, eat from china dishes, admire a new glass sculpture, hit a few golf balls with a composite five iron, send data over high-speed glass fiber optics, or brush our teeth over a porcelain sink. The reader will gain a better appreciation of all of these applications in The Magic of Ceramics. The author has translated a very complex and technical subject with the inherent fundamentals of chemistry, physics, and mathematics into a readable, engaging, and interesting text.
It is also my hope that the readers will gain a better appreciation for the researchers, engineers, and technologists who dedicate their lives to better understanding the composition and properties of ceramic materials and to the development of new materials—even to the extent of manipulating individual atoms.
My rock-collecting days were ended when my mother inadvertently pulled open the top drawer of my dresser a bit too far and it fell rapidly to the floor, narrowly missing her feet. All those years of collecting had yielded a sizeable poundage of rocks. I eventually attended the University of Washington, where I was introduced to ceramic engineering by the then department chair Dr. James I. Mueller. The department also had a NASA grant to help develop the ceramic tiles that cover the exterior of the Space Shuttle. It was enough to lead me through two degrees in ceramic engineering. A decade later, I was selected to be a Space Shuttle astronaut. My career as an astronaut continues, and, as I now well know, the Space Shuttle program depends on many ceramic material applications: from the quartz windows to the computer components to the heat-resistant properties of the ceramic tiles. The reader will also learn much more than I knew during my rock-collecting youth. It is my privilege to have been a part of the ceramic engineering discipline and to provide this foreword for The Magic of Ceramics.
BONNIE J. DUNBAR, PH.D.
NASA Astronaut
Introduction
Ceramics are amazing materials! Some are delicate and fragile; others are so strong and durable that they are used to reinforce metals and plastics. Some ceramics are transparent. Others are magnetic. Many ceramics withstand temperatures many times the temperature of your oven and are untouched by erosion and corrosion that destroy metals in days. Ceramics have so many different characteristics and make so many things possible in our modern society that they seem magical.
Without ceramics, we wouldn’t have television, miniature computers, extraordinary action in computer-generated movie scenes, digital electronics and wireless communications, the Internet, the Space Shuttle, CDs, synthetic gemstones, or even cars. We wouldn’t be able to refine metals from ores or cast them into useful shapes. We wouldn’t have many of the modern tools of medicine such as ultrasonic imaging, CT scans, and dental reconstructions. How can ceramics do so many things? Seems like magic, doesn’t it?
Have you ever seen a magician perform an amazing feat and wondered how it was possible? No matter how spectacular the illusion is, there is always an explanation or trick, and often the trick is as fascinating as the illusion. The magic of ceramics is much the same—the feats and explanations are equally amazing. Reading this book will show you some of the magic that ceramics do and will explain the fascinating science that makes the magic work.
You’ll learn how ceramics interact with light to produce great artistic beauty and to make the laser possible, how some ceramics can be stronger than steel and are used for inline skates and bulletproof armor, how magnetic ceramics made the first computers possible and are the secret behind recording tape and CDs, and how a whole new field of “bioceramics” has emerged to enable miraculous medical cures and repairs. Ceramics touch and enrich our lives in so many ways! I take great pleasure in sharing some of that magic with you!
Chapter 1
Our Constant Companions
It’s hard to imagine the tremendous role that ceramics play in our everyday lives. Ceramics come in nearly infinite forms and behave in equally diverse ways. Nearly everything we do brings us in contact with either ceramics or something that was made using ceramics. In fact, ceramics are virtually our constant companions; they affect our daily lives in ways that border on magic. If you think of ceramics only as decorative materials or “the stuff that dishes and toilets are made of,” you’re overlooking an important part of your world.
From Stoneware to Superconductors
What, exactly, are these remarkable materials that have such an effect on our lives? One highly regarded professor and author (W. David Kingery, in his classic text Introduction to Ceramics) defines ceramics as “the art and science of making and using solid articles which have as their essential component, and are composed in large part of, inorganic, nonmetallic materials.” Simply stated, most solid materials that aren’t metal, plastic, or derived from plants or animals are ceramics.
As you might imagine from this definition, the term ceramics covers much ground: from traditional ceramics such as pottery, tile, and glass that date from antiquity to amazing new advanced ceramics that sport strange names such as silicon nitride, aluminum oxide, and cordierite. Even synthetic gemstones such as ruby, sapphire, and cubic zirconia are ceramics. What would we do without glass or bricks or concrete? Although these traditional ceramics have been used for centuries, they are still a vital part of our lives. They’re everywhere we look. Even advanced ceramics have entwined themselves in our daily lives in an incredible number of hidden, and often magical, ways. To initiate your entry into the world of ceramics, let’s take a ceramic tour of your own everyday world. You may find it surprisingly familiar. I hope you’ll then join me for a more in-depth look into the magic of ceramics.
Ceramics in Your Home
Wake-Up Call
Good morning! If your world’s anything like mine, ceramics just woke you from a peaceful sleep. Chances are, your clock or clock radio has an alarm buzzer made from an advanced piezoelectric ceramic. This unusual ceramic vibrates with a loud noise when electricity is applied. If your clock has a quartz mechanism, as most clocks and watches now do, a tiny slice of vibrating piezoelectric quartz ceramic is the timekeeper. However, in this case, the vibrations are so rapid and small that you can’t hear them. Most people have never heard of piezoelectric ceramics, but piezoelectrics are the secret behind a wide variety of products ranging from underwater sonar (submarine searchers) to medical ultrasonic scans to “smart” skis. The secrets of these and other surprising piezoelectric applications are presented in Chapter 7.
Does the face of your alarm clock glow? This glow also may be due to a ceramic, one with the exotic name electroluminescent. The glow is caused by electricity passing through a very thin film of this special ceramic. The clockmaker can control even the color of the glow by selecting the presence of certain atoms in the ceramic. Electroluminescent ceramics also light the instrument panel in your car, the face of many wristwatches, and your cellular phone. Electroluminescence and other ways by which ceramics interact with light or produce light are described in Chapter 4.
Perhaps you prefer to awaken to the sound of soft music from your clock radio. The radio itself is full of ceramic electrical devices (capacitors, insulators, resistors), all working together to soothe you or get you on your feet.
Before you jump out of bed, though, just lie there a minute, stretch your muscles, and survey your room to begin our tour. Note the glass mirror on the dresser and, possibly, the porcelain drawer knobs. Glass also may shield numerous pictures on your walls. The early morning sun streams in through your glass windows, and decorative glass covers your overhead lighting. The light bulbs in your nightstand lamps are glass, as are the vase on the table in the corner and the bottles of colognes, cosmetics, and lotions on your vanity. Although you can’t see inside your bedroom walls, the studs are covered with ceramic plasterboard, and the electrical outlets and lights have hidden ceramic insulators (Figure 1-1). Some of the wall paint even contains ceramic pigments. Flip on the bedroom TV, if you have one, to catch the morning news. Your television is loaded with ceramic parts including the glass screen, the ceramic phosphors that produce the color, and numerous capacitors, insulators, resistors, and integrated circuits (we’ll discuss all these in the later chapters).
FIGURE 1.1 Ceramic electrical insulation such as that used in houses and buildings. Photograph courtesy of Rauschert Industries, Inc., Madisonville, TN.
Well, it’s time to drag yourself to the shower to freshen up. What do you see in the bathroom? More ceramics. As a matter of fact, your bathroom probably has more pounds of ceramic per square foot than any other room in your house. The mirrors and lights are glass. The toilet and sink are ceramic, and the tub is lined with porcelain enamel or constructed completely from glass-fiber-reinforced plastics. The floor, the counter around the sink, and the whole shower/tub compartment may be protected by colorful ceramic tiles. Besides offering beauty, these tiles provide an easy-to-clean surface that has dramatically improved sanitation and health. Ceramic tile has become so universally accepted that enough ceramic tiles are manufactured in the world each year to pave a road the width of three football fields encircling the entire Earth.
Like the bedroom, the bathroom also contains hidden ceramics. The water faucet valve (Figure 1-2) that mixes hot water with cold and also seals against leaks is probably ceramic. The thermal and electrical insulation, and maybe even the heating element, in your hair dryer and in the space heater for cold mornings are ceramic. If you have an ultrasonic denture cleaner, the source of vibration is another piezoelectric ceramic. Even your electric toothbrush might contain ceramics doing their hidden magic. Surprisingly, ceramic powders may be hiding in some of your cosmetics, too. For example, boron nitride is commonly added to facial makeup. Boron nitride, which is white like talcum powder (also ceramic), is made up of tiny flat particles that smear onto a surface (such as your face) to produce a smooth, soft texture.
FIGURE 1.2 Ceramic water faucet seals manufactured by Saint-Gobain/Carborundum Structural Ceramics, Niagara Falls, N.Y.
Source: Photograph by D. Richerson.
After showering and shaving, you may return to the bedroom to dress. The buttons on your shirt or pants could be ceramic (Figure 1-3). If so, they can withstand the most active person and the most abusive laundry situations. The stones in your rings may be cubic zirconia or even synthetic ruby or diamond. Do you wear eyeglasses and a wristwatch? Your watch, like your clock, most likely has a glass cover, an electroluminescent dial, a quartz piezoelectric mechanism, a piezoelectric alarm, and even a lithium battery containing ceramics. If it’s a digital watch, it has a liquid crystal display (LCD, not ceramic) sandwiched between special protective glass layers. Your watch is a marvel of miniaturization and precision. You may be lucky enough to have a special watch such as those made by the Rado company (Figures 1-4 and 1-5), with a cover glass fabricated from synthetic sapphire and its bezel and wristband links shaped from a special new ceramic called transformation-toughened zirconia (another ceramic that we’ll discuss later). Such watches are nearly scratchproof and works of art.
FIGURE 1.3 Ceramic buttons manufactured by CoorsTek, Golden, CO.
Source: Photograph by D. Richerson.
FIGURE 1.4 Beautifully crafted Rado watch fabricated mostly from ceramics. Photograph courtesy of the Rado Watch Co., Ltd., Lengnau, Switzerland.
FIGURE 1.5 Steps in the fabrication of the watch glass and bezel of a Rado watch. Samples courtesy of the Rado Watch Co., Ltd., photograph by D. Richerson.
As you leave the bedroom and enter the hall, you may pass your children’s rooms and perhaps another bathroom. Unless you’re braver than I or you have to venture in to wake the kids, you may want to use your already broadening knowledge to imagine the ceramics buried among their backpacks, shoes, and days-old laundry. In the hall, you should pass a smoke detector and perhaps a carbon monoxide detector. The indicator lights on both the life-saving devices are made of light-emitting ceramic parts, and the sensor in the carbon monoxide detector is ceramic.
Food for Thought
Time for breakfast, at last! Your kitchen is positively loaded with ceramics: drinking glasses, dishes, storage containers, and cookware. Some of the dishes represent a technology unheard of only years ago. For example, you may have breakage-resistant Corelle dishes. These magical, bouncing dishes are created by heating special layers of ceramic that each respond to heat in different ways. When the newly made dishes are cooled, their inside layers shrink more than their outside layers. This shrinkage pulls the outer layers tightly together, making the ceramic dishes many times stronger than traditional dishes. Such plates rarely break when dropped or accidentally banged together because technology has turned them into superceramics of everyday life.
What other items do you see in your kitchen? Do you have a ceramic teakettle on the stove, a slow cooker, or an electric mixer with glass bowls? How about the bottles in your spice rack, cupboards, or refrigerator? Open your refrigerator door. What holds the door closed? The seal is probably a thin strip of a rubberlike polymer filled with ceramic magnetic particles. You most likely also have a few ceramic magnets on the outside of your refrigerator door holding up messages, cartoons, or bits of family philosophy. (Ours are encased in colorful, plastic fuzzy creatures that hold up a cartoon of a mother with her hands in the air and a distressed expression, accompanied by the words, “Insanity is hereditary, you get it from your children.”) But, as shown in Figure 1-6, you might be surprised at all the other places in your home ceramic magnets might be important.
FIGURE 1.6 Ceramic magnets in a typical house. Illustration courtesy of Group Arnold, Marengo, IL.
FIGURE 1.7 Ceramic scissors and large kitchen knife by Kyocera.
Source: Photograph by D. Richerson.
Your kitchen probably also has a clock, a window, and maybe even a skylight, all containing transparent glass. We have a window over our sink. Hanging in front of the window are plants in ceramic pots cradled in macrame slings with ceramic beads. An artistic, circular stained-glass image of a butterfly on a flower enhances the early morning light.
After all this work looking for ceramics, you’re probably hungry. You may cook your bacon and eggs in a ceramic skillet on a ceramic stovetop, cut your bread with a ceramic knife that never dulls, and prepare a waffle or toast in an appliance with ceramic parts. Also, you almost certainly will serve your breakfast on a ceramic plate, fill a ceramic mug with coffee—or a glass with juice or milk—and head for the dining area.
The dining room in our house (Figure 1-8) is a small area just on the other side of the kitchen counter, where a large, glass-topped table consumes most of the space. Somehow we managed to squeeze in chairs, a bookcase, a TV stand complete with TV, a series of shelves under the window completely covered with plants (many in ceramic pots), a small refrigerator that mysteriously consumes at least a six-pack of soft drinks each day, and a large buffet. The top of the buffet is covered with family photographs in glass-faced frames. Each holiday, the top of the buffet sprouts a new assortment of seasonal ceramic knickknacks: a ceramic Santa Claus collection, an Easter egg tree with ceramic and real eggs, and so on throughout the year.
FIGURE 1.8 The author’s dining room showing the table set with ceramic dishes and glasses and the buffet in the background decorated with ceramic knickknacks.
Source: Photograph by D. Richerson.
FIGURE 1.9 Hummel ceramic figurines.
Source: Photograph by D. Richerson.
The Rest of the House
The family room in most homes is another source of ceramics. Think a bit while you eat breakfast. Does your family room have a television equipped with VCR and DVD players and numerous video game accessories? All of these depend on ceramic components. You might have a stereo, too, which contains numerous ceramic components. Family rooms usually have lots of pictures, lamps, and candy dishes. You might have a chess set with ceramic pieces, a game of Chinese checkers with glass marbles, or a cribbage board with ceramic markers. Some family rooms have pianos, which often are topped with ceramic knickknacks or family pictures in ceramic frames. What is the source of lighting in your family room? Do you have a skylight or a patio door or windows? Our family room is well lit with the soft luminescence from fluorescent lights, which produce the light with a ceramic phosphor as we’ll discuss in Chapter 4.
The living room or great room probably has the least ceramics in your home. Although it has no appliances, it may hold an assortment of glass-covered art, ceramic figures, and potted plants. The end tables and coffee table may be glass topped. Our great room has a Tiffany-style light fixture over the formal dining table. If you have a fireplace in your living room, it undoubtedly has a ceramic brick hearth.
Most homes have basements, or at least crawl spaces. Our basement has an office, a laundry room/furnace room, a recreation room, a hobby room, and lots of space to store the off-season ceramic knickknacks. The computer, fax, scanner, printer, and even the mouse in my office contain numerous ceramic parts and would not work without them. If you have a home office, your desk is likely filled with small objects that may boast ceramic parts: ceramic-tipped letter openers, scissors, and even pens with ceramic nibs (Figure 1-10). Do you have an office coffeepot? How about a touch-tone telephone? A clock? A tile floor? In the laundry room, your washing machine has a ceramic seal to keep the water from flooding the room, and your gas dryer has a ceramic igniter to light the gas each time you turn on the dryer.
FIGURE 1.10 A variety of ceramic items, including the tips of ballpoint pens, scissors, knives, and a golf putter. Photograph courtesy of the Kyocera Corporation.
FIGURE 1.11 Ceramic labware for chemical studies and analysis, manufactured by CoorsTek, Golden, CO.
Source: Photograph by D. Richerson.
Off to Battle
Well, the light coming in higher through the windows should tell you it’s time to get going. What would life be like without glass to let the light in and keep the weather and bugs out? In fact, ceramics do duty outside the house as well as inside. Your house, as mine, may be covered with brick. The walls and attic are probably filled with fiberglass (another hidden ceramic) insulation to protect you from the heat and cold. Fiberglass housing insulation, introduced in 1939, has resulted in estimated energy savings of more than 30,000,000,000,000,000 (that’s 30 quadrillion) Btu, enough to provide all the residential energy needs of the United States for 2 years in 1975 and 1 year in 2010. Even the shingles on the roof contain glass fibers. You’d certainly notice if these ceramic materials weren’t there, especially if it’s rainy or cold this morning. Behind our house, a concrete patio supports a glass-fiber-reinforced spa with ceramic working parts and pump seals.
For most of us, the trip to work or school starts in the garage. Our garage has a concrete floor, brick walls, fluorescent lighting, and an automatic garage-door opener containing ceramic parts to make it open and close on command. The driveway, sidewalk, and porch also are concrete. Concrete, in fact, may be the most abundant ceramic in the modern world. Each year, more than 1 billion tons of concrete are poured.
Most of us use some type of motor vehicle to get to work or school. Cars, trucks, and buses are loaded with ceramics. As a matter of fact, the typical automobile has more than 100 critical ceramic parts. (We’ll talk about many of them in Chapter 9.) As you drive to work or school, you use signal lights enclosed in glass to safely navigate through intersections. Newer versions of these use light-emitting diodes (LEDs) as the light source, which save an enormous amount of electrical energy and maintenance labor. If you drive at night, your safety is further protected by the yellowish sodium-vapor lamps lining urban streets. These lamps owe their existence to advanced ceramics, as you will learn in Chapter 12. The buildings you pass are built mostly of brick, concrete, and glass. You may even drive part of the way on a concrete highway. The painted lines on the road contain reflective ceramic particles that make them easy to see in the dark and also more resistant to wear and tear. Some of the traffic signs contain ceramic powders to make their warnings more visible in dim light. The cellular phone you use to keep in touch with the office or your family uses ceramic filters to screen out radio waves, TV signals, and police communications that would interfere with proper reception. But that isn’t where the ceramic technology ends. Your modern cellular phone probably has a digital camera that can record still and video images and high-resolution LCD imaging.
It has virtually everything that we only imagined years ago in episodes of Star Trek! And don’t forget, you will probably have your laptop computer, your iPod, your iPad, or other equivalent digital electronic devices with you just about everywhere you go.
Ceramics on the Job
The building where you work or go to school, like those you passed on your way, probably is constructed with ceramic materials similar to those in your home. Most office buildings house computers, fax machines, copiers, printers, calculators, and touch-tone telephones, all of which contain critical ceramic parts. Schools have much the same equipment. One of your coworkers or one of your children’s teachers may wear a pacemaker to control his or her heartbeat. Pacemakers have ceramic sheaths that carry wiring to them from their power pack, ceramic capacitors that enable them to store their life-giving energy, and often ceramic cases to protect them from body chemicals. Another teacher or coworker may have a ceramic hip replacement. Most likely, you and most of the people you know and work with have experienced some sort of dental or medical work involving ceramics within the past few years.
Your work day may involve ceramics in more direct ways, too. Obviously, mine does, but many other workplaces, such as school cafeterias and science laboratories, machine shops, medical facilities, restaurants, city water plants, and even grocery stores, use ceramics in important ways every day. Some workplaces have laboratories with ceramic equipment for chemical analysis or experimentation.
Ceramics Elsewhere
If you have to stop at the supermarket on your way home from work or after you pick the children up from school, you may be surprised to learn that ceramics create everyday magic there, too. The laser scanner at the checkout counter is an example. The laser itself is made possible by ceramics. When laser scanners first came out, the transparent “window” through which an item’s bar code is read was made of glass. Glass, however, tended to get scratched by all the cans and other items sliding over its surface. (You’ve probably tapped your foot in a checkout line while the cashier tried several times, without success, to get the scanner to read the price on your item.) For more efficient operation, scanner plates now are fabricated from sheets of synthetic ruby or sapphire (Figure 1-12), which are much harder than glass and resist scratches.
FIGURE 1.12 Transparent sapphire scanner plate for a laser bar code reader in a supermarket. Photograph courtesy of Saphikon Inc., Milford, NH.
Do you pass any electrical power transmission lines on your way home from work? The odd-shaped insulators that separate the electricity-carrying metal wires from each other and from the tall metal or wood towers are ceramic. And ceramics are required in many ways during the generation of electricity, whether the plant is powered by coal, nuclear energy, hydroelectric power, gas turbines, or even wind. The importance of ceramics now, and this increasing importance in the future, to energy production and pollution reduction are described in Chapters 12 and 13.
You may pass a chemical plant, a paper mill, a semiconductor plant, or an automobile manufacturing plant on your drive home, all of which use ceramics. It’s hard to imagine an industry that does not depend heavily on ceramics. Some fascinating examples are included in Chapters 10 and 11.
Is it time to see your doctor for a yearly checkup? Ceramics do heavy-duty work in doctors’ offices, clinics, and hospitals as key components in X-ray, CAT-scan, laser, and ultrasonic imaging equipment. They are sterile containers for blood, urine, and bacterial cultures. Ceramics even are used extensively in surgery, especially to allow modern noninvasive endoscopic examinations and surgical procedures such as knee repairs and gall bladder operations. You’ll be amazed at the medical applications of ceramics reviewed in Chapter 8.
Do you go out to eat with your family at the end of a long day? Ceramics are busy at work in restaurants just as they are in your kitchen at home. Even fast-food restaurants and the food services in malls and gasoline stations depend on ceramics. For example, next time you fill your glass from a soft-drink dispenser, take a closer look. The mixing valve that meters the syrup and carbonated water and guides the flow into your glass is often ceramic.
Ceramics at Play
Of course, most of us have another important life after work and on weekends. We may go to the lake, catch a game of tennis, drop the kids off at a soccer match, or take in a baseball game with our family. Most sports rely on ceramics in one way or another. Baseball bats sometimes contain a ceramic core or ceramic fibers to strengthen them. Skis (for both water and snow), paddles for canoes and kayaks, hockey sticks, and tennis rackets are all strengthened by ceramic fibers. Nearly all recreational boats are reinforced with glass fibers to protect them from damage as they streak through the waves. Bowling balls often have ceramic cores that increase the amount of energy transferred from the ball to the pins by about 5%. Ceramic core bowling balls “hit harder.” Golf-club shafts frequently are reinforced with carbon fibers to increase strength and stiffness, and the heads of some putters are made of specially toughened zirconia (an advanced ceramic that will be explained in Chapter 5), as are new golf cleats that provide good traction without damaging the greens (Figure 1-13). Maybe your favorite entertainment is travel, or watching television, or astronomy. Guess what? You’re right—ceramics are there to help you again.
FIGURE 1.13 Golf putter and cleats made from ceramic materials by CoorsTek, Golden, CO.
Source: Photograph by D. Richerson.
Overview: Moving On
It’s time to move on, even though we’ve barely scratched the surface of the world of ceramics. Ceramics truly are everywhere. Their amazing range of properties and uses has brought us many of the remarkable technologies and products that define modern civilization. (That’s where piezoelectrics, phosphors, fluorescence, zirconia, and electroluminescence come in.) Ceramics also add to the quality of our life through their beauty. They enhance our lives by their constant usefulness.
Equally important, they play a critical role in electronics, communications, transportation, manufacturing, energy generation, pollution control, medicine, defense, and even space exploration.
They have filled our past, and they enrich our present. They will pave the path to our future. Before you learn some of the science behind the magic of ceramics and explore important uses for ceramics, let’s go back in time and see how ceramics evolved from their origin as pottery to high-technology modern applications such as in the Space Shuttle.
Chapter 2
From Pottery to the Space Shuttle
History and ceramics are intertwined. Advances in civilization have always followed advances or innovations in materials. As archaeologists and anthropologists tell us, one of the first steps in human development was taken when early cultures learned to use natural materials, such as wood and rock, as tools and weapons. The next step began when they learned to use rocks to chip other rocks, such as chert and obsidian (volcanic glass), into more efficient tools and weapons. So important was this use of natural ceramic materials that the prehistoric time in which it occurred is now referred to as the Stone Age. But the Stone Age was just the beginning of the use of materials to improve our standard of life. Eventually, people learned to make pottery, to extract and use metals (the Bronze Age and Iron Age), to produce glass, and to make bricks, tiles, and cement. Much later, materials made possible the Industrial Revolution, the harnessing of electricity, and the “horseless carriage.” Only in the past two generations, during the time of our parents and grandparents, have materials ushered in the Age of Electronics, the jet airplane, near-instantaneous worldwide communications, and the exploration of outer space.
Ceramics are important partners with metals and plastics in our modern civilization. Figure 2-1 highlights some of the key ceramics developments throughout history. The evolution of ceramics was slow for many centuries but virtually exploded in the 20th century. In this chapter, we take a journey back in time to see how ceramics have evolved from the earliest dried clay articles to our amazing—often magical—modern ceramics.
FIGURE 2.1 The historical evolution of ceramics
Early Ceramics
The Birth of Pottery
Let’s imagine what life was like in the Stone Age 60,000 years ago. There were no stores, houses, or cities and not even a written language. Families used caves or makeshift lean-tos for shelter and wandered from place to place hunting food. They had no concept of metal or plastic. The only materials they knew were the natural materials surrounding them: rocks, plants, and the hides and bones of animals. Rocks are Mother Nature’s ceramics. Primitive people shaped axes and other tools by beating these natural ceramics together. They learned to chip arrowheads and spear points. Because there was no written language, the stone artifacts and other items buried in the floors of ancient cave dwellings are the only evidence archaeologists and anthropologists have to study these early humans.
As the centuries passed, cave dwellers began to draw pictures on the cave walls using colored soil mixed with water. They discovered that some types of soil (which we now call clay) became pliable when wet and could be molded into shapes, such as the bison shown in Figure 2-2 that was found in the Tuc d’Audobert Cave in France. They observed that clay became rigid when dried and hard like stone when placed in the fire. This discovery represented the birth of pottery, the first true man-made ceramics. We now call this simple pottery earthenware. In spite of the ancient origins, earthenware is still made today in nearly every corner of the world.
FIGURE 2.2 Early example of images molded in clay. Mystical clay sculptures of bison in Tuc d’Audoubert Cave in France, around 14,000 years old. Courtesy of the photographer, Count Robert Bégouën.
We don’t know exactly when our ancestors learned to mold and fire ceramics, but archaeologists have guessed around 30,000 years ago. The oldest archaeological site found so far is in the Czech Republic and dates to about 27,000 B.C. This site had a fire pit that appeared to be designed specifically for firing pottery. Animal and fertility figurines were found in and around the pit.
The Emergence of Civilization
Pottery was an important innovation that helped mankind make the transition from a nomadic lifestyle to one of stable settlements. People learned to make earthenware containers for cooking and food storage, and they became less dependent on following their food sources endlessly from place to place. They began to form settlements to which they could return after a long day’s hunt and store their food until it ran out. No longer exclusively nomads, these people now had time to put seeds into the ground and wait for them to grow into edible plants and grains. Agriculture was born, and ceramics were there to store and protect the harvest.
Pottery containers allowed travelers to wander farther and farther from home, taking food along with them for long journeys. Extended travel by boat became possible, permitting exploration and the spread of civilization as people began to trade the food, wares, and pottery with others from ever-more-distant lands. Written records were not left to tell us about these travels and trade routes, but archaeologists have been able to piece together some of the puzzle of history by studying shards of pottery, because each culture created its own distinctive pottery. For example, each culture evolved its own style and decorations for earthenware. Some cultures made pots with one color of clay and painted designs or images on the surfaces after firing using a different color of clay mixed with water, much like the earlier cave paintings. The porous surface of this earthenware allowed the clay paint to soak in a little, so that the decorations didn’t rub off during handling. An example of early decorated earthenware is shown in Figure 2-3. Other potters scratched (incised) patterns or images onto the surfaces of their pots.
FIGURE 2.3 Early Chinese pottery crafted sometime between 5000 and 3000 B.C.
Source: Photo by D. Richerson.
Ceramic materials played another important role in the emergence of civilization: communication. Even though people had learned to live in small settlements around 10,000 B.C. and developed agriculture by around 8000 B.C., they had no written language. As towns grew in size and as trade increased, keeping some sort of record of trade transactions became necessary. This was accomplished by scratching markings onto damp clay tokens, which then became hard when dried. By about 3500 B.C., this was expanded by the Sumerians into a complete language based on pictographs scratched onto clay tablets. By about 2800 B.C., the pictographs had mostly been simplified into a script of wedge-shaped markings produced using a sharpened reed. We now refer to this as cuneiform from the Latin word cuneus, a wedge. An example of a cuneiform tablet is shown in Figure 2-4. Libraries of thousands of these dried clay cuneiform tablets have been excavated from archaeological sites in the Near East and have provided us with valuable historical information about daily life, commerce, law, and literature.
FIGURE 2.4 Cuneiform tablet from the Utah Museum of Natural History collection.
Source: Photo by D. Richerson.
Ceramics in the Age of Metals
Although early ceramic materials were a life-changing innovation, they were still very fragile and broke easily. By about 4000 B.C., people had learned how to separate metals from the natural minerals, or ores, in which they occurred inside the earth. These new materials were much tougher and stronger than ceramics, and they could be beaten into useful shapes with a hammer or other tool or melted and poured into a shaped mold. The Stone Age gave way to the Chalcolithic (copper-stone), Age, the Bronze Age (around 3200 B.C.), and later the Iron Age (around 1200 B.C.).
The “metals ages” had a dramatic impact on civilization but did not replace ceramics. In fact, ceramics became even more valuable because of the very quality that had been discovered by Stone Age people so many years earlier: resistance to extreme heat. Extracting metals from ores required high temperature, and ceramics were the only materials that could withstand such temperatures. Even after the metals had been extracted from their ores, ceramic containers (known as crucibles) were required for melting the metals. The metals then were poured into ceramic molds of various shapes and cooled to form tools and other objects, both beautiful and useful.
Pottery continued to evolve during the Bronze and Iron Ages. Key innovations were the progression of improvement in the design of the chamber (kiln) in which potters fired their ware, especially in order to reach higher temperatures. Higher-temperature firing reduced porosity and increased the strength of the ceramics, so potters could make thinner-walled pots that were less heavy, that were impervious to liquids (and less likely to absorb smells and flavors and bacteria), and that opened up more possibilities for beauty of design, as you will see in Chapter 3. Potters also invented a new type of kiln that had two chambers, one for the fuel and one for the ceramic ware. This major breakthrough paved the way to new and exciting modes of colorful and intricate decoration. Because the fire didn’t directly touch the earthenware anymore, flame-sensitive ceramic paints could be applied to the pot before it was put in the kiln and then fired on to become a permanent part of the pot.
An even more exciting innovation was the creation of glazes. A potter’s glaze is a glassy coating that not only can seal the surface of the porous earthenware against leakage of liquids but also makes possible an endless variety of decorations. Early glazes were probably discovered around 3500 B.C. by potters trying to imitate the precious blue stone lapis lazuli. Small beads were carved from soapstone (talc) and coated with a powder of ground-up azurite or malachite (natural ores of copper with blue and green color). When fired, the coating interacted with the soapstone to yield a thin layer of colored glass. The potters probably borrowed this idea and started experimenting with different combinations of crushed and ground rock mixed with water and painted onto the surface of pots. They discovered mixtures that worked and that completely coated the surface of their earthenware with a watertight glassy layer. As the centuries passed, potters learned to produce glazes in many colors and textures and even in multiple layers, by using multiple firings at different temperatures. We will discuss some of these techniques and creations in the next chapter, “The Beauty of Ceramics.
Evolution of Traditional Ceramics
Invention of the Potter’s Wheel
Metals were expensive and could only be afforded by the wealthy. Much more affordable to the average person, pottery ultimately became an important part of every household and was the first traditional ceramic. An important innovation that helped pottery become affordable was the potter’s wheel. The concept of a surface that could be rotated while a pot was being formed probably was explored before 3000 B.C., but was refined by 2000 B.C. and in common use in both Mesopotamia (east of the Mediterranean Sea and south of the Caspian Sea in the valleys of the Tigris and Euphrates Rivers) and Egypt (south of the Mediterranean Sea along the Nile River). The first potter’s “wheel” was probably a mat on which a flat stone or broken piece of pottery could be slowly rotated by hand while the potter formed a mound of moist clay into a hollow, circular shape. Improved potter’s wheels could be rotated by the potter’s foot or by an assistant, so the potter could have both hands free to mold and shape the clay. The potter’s wheel dramatically increased the number of pieces that could be produced per day and contributed to broad availability of earthenware to the average person.
Earthenware spread throughout the ancient Western world and evolved independently in the Far East. During the Roman Empire (about 100 B.C. to A.D. 300), mass-production methods were established to make enough pottery to meet the needs of the Roman army and growing cities. About this same time, during the Han Dynasty (207 B.C. to A.D. 230), ceramics use blossomed in China to become an important part of daily life as wine vases, storage jars, cooking vessels, ladles, dishes and bowls, kettles, candlesticks, and even small tables.
New types of Pottery
As mentioned earlier, potters learned that firing their ware at higher temperature resulted in a stronger, less-porous ceramic pot. Chinese potters were especially intrigued by this technique and were much more aggressive than Western potters in experimenting with different kiln designs and recipes for ceramic raw materials. They succeeded in building kilns that could fire at around 2200°F (about 1200°C), nearly five times hotter than a kitchen oven. Pots fired at such high temperature had low enough porosity to hold water with no leakage even without a glaze. We now refer to this type of ceramic as stoneware.
The Chinese slowly refined stoneware during the Shang Dynasty (1500–1066 B.C.) and Chou (Zhou) Dynasty (1155–255 B.C.). A key discovery was the use of a white clay called kaolin, which needed a high temperature to fire properly. Pots made with kaolin were nearly white in color, rather than the various shades of brown and reddish tones of earthenware and prior stoneware.
By around A.D. 600, Chinese potters had discovered another secret ingredient that they called petuntse
