What is fine ceramics?
Fine ceramics defined as “Nonmetal and inorganic material with new functions and properties, produced under precise control such as chemical composition, crystal structure, micro structure/grain boundary, shape and manufacturing process.”
Traditional ceramics including refractories are mainly produced using natural raw material. On the contrary, fine ceramics is produced using pure refined artificial raw material under precisely controlled process. In general, fine ceramics has the properties of hard and high strength, but it is rather brittle compared with metal or refractories.
Metal, organic materials, and ceramics are referred to as “The Big Three” materials. The English word for ceramics is derived from the Greek word “keramos”, which means “burned clay.”
The term ceramics originally referred almost exclusively to china. Today, we often refer to non-metallic, inorganic substances such as refractories, glass, and cements as ceramics. For this reason, ceramics are now regarded as “non-metallic, inorganic substances that are manufactured through a process of molding or shaping and exposure to high temperatures.”
Among ceramics, porcelains are used in electronics and other high-tech industries, so they must meet highly precise specifications and demanding performance requirements. Today, they are called Fine Ceramics (also known as “advanced ceramics”)* to distinguish them from conventional ceramics made from natural materials, such as clay and silica rock. Fine Ceramics are carefully engineered materials in which the chemical composition has been precisely adjusted using refined or synthesized raw powder, with a well-controlled method of forming and sintering.
Also, according to ISO** 20507 (“Fine ceramics – Vocabulary”) and JIS*** R 1600, Fine Ceramics are “produced with precisely controlled chemical compositions, microstructures, configurations and production processes to fulfill intended functions, and are composed mainly of non-metallic, inorganic substances.”
History of Fine Ceramics
Fine Ceramics (also known as “advanced ceramics”) are used to make components that require high levels of performance and reliability, such as advanced semiconductor packages and automotive engine parts. In fact, Fine Ceramics support the latest technologies in diverse applications throughout modern society. Do you know the history of Fine Ceramics? They share common origins with the conventional ceramics that we use every day, like tableware, vases, pottery and other household items.
The history of ceramics begins with earthenware. Thousands of years ago, humans learned how to make earthenware vessels by kneading, forming and firing clay. Prior to this discovery, the only other man-made items were stone tools made by chipping rocks. In this sense, earthenware could be called “the root of all industrial products.” After the Stone Age, countless advancements were made over the millennia before Fine Ceramics appeared as we know them today.
History of Pottery in Japan
The history of pottery in Japan dates back over 10,000 years ago to the Jomon period (14,000 – 400 B.C.). The Jomon people, a society of hunters, were among the first in the world to create pottery vessels. Their earthenware is characterized by a distinctive rope-like pattern. Japan’s subsequent Yayoi period (500 B.C. – 300 A.D.) brought the advent of rice cultivation, along with “Yayoi ware” pottery in various shapes. The Yayoi fired clay vessels surrounded by piled wood at temperatures ranging from 600 to 800℃ (1,112 – 1,472℉). This method is called Noyaki, or “open-firing.”
About 1,500 years ago, a new firing method using a tunneled, sloping kiln (Anagama) was introduced from Korea. In this method, clay shaped on a potter’s wheel was fired at temperatures of over 1,000℃ (1,832℉) for extended periods. Vessels made using this method are called “Sue ware.”
With the introduction of the potter’s wheel and Anagama, ceramic technology in Japan was drastically improved. Because of these advancements, hard, well-shaped ceramics became producible in large volumes. In later years, Anagama was further developed into Noborigama, a climbing kiln, which was able to fire many items at the same time.
In the Nara period (710 – 794), people started to use glaze made from vitreous powders. The glazing and firing of biscuit ceramics resulted in bright and soft-colored vessels that also prevented water leakage.
Porcelain was introduced from Korea during the Azuchi Momoyama period (1568 – 1603). Porcelain is a dense ceramic made by firing combinations of clay and feldspar.
Ceramics in the Era of Electrical Technology
Moving forward several centuries, Japanese pottery culture began to experience a period of rapid development. In the 19th century, with the invention of the electric light by Thomas Alva Edison and the telephone by Alexander Graham Bell, a new era which could be referred to as the “era of electricity” began. Ceramics, previously used only as vessels, started to play entirely new roles suited to this new era.
In general, ceramics do not conduct electricity. Compared to other insulators, such as paper and wood, ceramics are less affected by environmental factors such as temperature and humidity, giving ceramic components higher reliability. Through the history of ceramics going back more than 10,000 years, we have learned modeling technology to produce ceramic products in a myriad of shapes. Ceramics have thus come into widespread use as insulators or as insulating materials in areas ranging from power lines to household products, and have become important materials that allow people to use electricity easily.
The Era of Electro-Ceramics
The 20th century brought the advent of electronics, with the start of radio and television broadcasts and the invention of the transistor. This era was facilitated by ceramics from the beginning, when large vacuum tubes of the early 20th century relied on ceramic materials. Within wireless equipment, only ceramics possessed the properties necessary to provide high signal output even over high frequency ranges. Ceramics could not be replaced with other materials.
Ceramics have benefited from significant advances in material composition as well. In addition to natural raw materials, artificially synthesized raw materials are now commonplace. Metallization and other technologies to permit stronger ceramic-to-metal bonding were developed. During this period, ceramics rapidly grew closer to today’s Fine Ceramics.
Semiconductors, the core component of the electronics era, have also been supported by ceramics. Transistors and integrated circuits (ICs) were developed in U.S. laboratories shortly after the Second World War. However, because they were extremely sensitive to external moisture and strong light, these early transistors and ICs were not immediately available for practical use. Fortunately, ceramic packages were able to shut out external moisture and light while maintaining the electrical performance of transistors and ICs. It is no exaggeration to say that the semiconductor revolution was launched in these packages.
In addition, ceramics have helped to reduce the size of capacitors and inductors in electronics. Since the middle of the 20th century, ceramics have undergone a continual evolution, and now possess excellent dielectric and magnetic properties. As a result, electronic components were miniaturized and made highly functional. Ceramics thus made a significant contribution to the downsizing of electronic equipment. If capacitors had not been made of ceramics, the portable electronic devices we depend on every day, such as pocket-sized smartphones and laptop computers, would never have appeared. In fact, a modern smartphone uses more than 600 ceramic capacitors.
Fine Ceramics as the New Material “Standard-Bearer”
Fine Ceramics can be made to possess a wide variety of unique characteristics through variations in raw materials, synthesizing methods and production processes. Consequently, they have become the standard for new materials in countless fields of advanced technology. Because of their light weight, rigidity, physical stability and chemical resistance, large ceramic components several meters in size are now used in equipment for manufacturing semiconductors and liquid crystal displays. In addition, their high reliability and successful integration with metals allows them to be used in a growing range of automotive components.
With their dielectric and piezoelectric properties, Fine Ceramics serve as base materials for many essential electronic components, including compact, highly efficient capacitors, filters, and resonators. They perform key roles in various other industries as well. For example, their chemical inertness is very useful in the heavy chemical industry, while their abrasion resistance is valued in textile manufacturing. Beyond industrial applications, Fine Ceramics are increasingly used in the everyday goods we depend on, such as knives, pens, jewelry, decorative items and even medical and dental implants — all of which make use of the unique material characteristics of Fine Ceramics.
Fine Ceramics Raw Material
Alumina is the most widely used Fine Ceramic today globally and epitomizes Fine Ceramics. It offers superior mechanical strength, electrical insulation, high frequency retention, thermal conductivity, heat resistance and corrosion resistance. Sapphire is a single-crystal form of alumina.
Zirconium dioxide (ZrO₂)
Zirconia is the strongest and toughest material among Fine Ceramics. It is used to create special blades for high-performance scissors and knives, once considered impossible application.
Single-crystal zirconia is also used in decorative applications and jewelry due to its high refractive index, which produces a diamond-like brilliance.
Among Fine Ceramics, this lightweight, corrossion resistant material offers the highest level of toughness and thermal shock resistance at high temperatures, making it ideal for use in engine components.
This artificial compound is synthesized from silica sand and carbon. It provides the best combination of heat resistance, light weight and corrosion resistance, and maintains its strength at high temperatures (1,500℃ / 2,732℉).
Low thermal expansion gives cordierite superior thermal shock resistance. Due to its porous properties, it is used for honeycomb carriers as well as refractories for electric heaters and industrial chemical equipment materials.
This magnetic ceramic exhibits high permeability, electrical resistance and abrasion resistance. It is widely used in magnetic heads and magnetic cores for high frequency electronics.
Barium titanate is used for capacitors due to its high dielectric constant and superiority in storing electricity. Additives can drastically change its dielectric properties.
Lead Zirconate Titanate
A piezoelectric material vibrates when electrical signals are applied, and also converts vibration into electrical signals. Lead zirconate titanate offers strong piezoelectric properties for electronic component applications, such as resonators, buzzers and filters.
Characterized by low microwave loss, superior high temperature insulating properties and a smooth surface, fosterite is suitable for use in electron tubes and circuit boards.
In addition, its high coefficient of thermal expansion is close to that of metals and glass, allowing forsterite to be joined or bonded to these materials reliably.
With a low coefficient of thermal expansion and superior thermal shock resistance, this material is used for heat-resistant components, wire-wound resistive bobbins and electron tube components.
Mullite offers heat resistance, thermal shock resistance and excellent resistance to the structural fatigue mechanism known as “creep.” It also displays a coefficient of thermal expansion similar to silicon semiconductor chips, making it useful in semiconductor package applications.
This material offers electrical and mechanical properties superior to conventional porcelains, and excellent machinability.
With excellent thermal conductivity, aluminum nitride is used in applications that require heat dissipation, such as semiconductor packages.