Technology & Engineering
Glass Ceramics
Glass ceramics are a type of material that combines the properties of glass and ceramics. They are produced by controlled crystallization of glass, resulting in a material with high strength, thermal resistance, and transparency. Glass ceramics find applications in various fields, including cookware, dental materials, and electronics, due to their unique combination of properties.
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eBook - PDFMetals and Materials
Science, Processes, Applications
- R. E. Smallman, R J Bishop(Authors)
- 2013(Publication Date)
- Butterworth-Heinemann(Publisher)
Chapter 10 Ceramics and glasses 10.1 Classification of ceramics The term ceramic, in its modern context, covers an extremely broad range of inorganic materials; they contain non-metallic and metallic elements and are produced by a wide variety of manufacturing techniques. Traditionally, ceramics are moulded from silicate minerals, such as clays, dried and fired at temperatures of 1200-1800°C to give a hard finish. Thus we can readily see that the original Greek word keramos, meaning 'burned stuff or 'kiln-fired material', has long been directly appropriate. Modern ceramics, however, are often made by processes that do not involve a kiln-firing step (e.g. hot-pressing, reaction-sintering, glass-devitrification, etc.). Although ceramics are sometimes said to be non-metallic in character, this simple distinction from metals and alloys has become increasingly inadequate and arbitrary as new ceramics with unusual properties are developed and come into use. Ceramics may be generally classified, according to type or function, in various ways. In industrial terms, they may be listed as pottery, heavy clay products (bricks, earthenware pipes, etc.), refractories (firebricks, silica, alumina, basic, neutral), cement and concrete, glasses and vitreous enamels, and engineering (technical, fine) ceramics. Members of the final group are capable of very high strength and hardness, exceptional chemical stability and can be manufactured to very close dimensional tolerances. These will be our prime concern. Their introduction as engineering components in recent years has been based upon considerable scientific effort and has revolutionized engineering design practice. In general, the development of engineering ceramics has been stimulated by the drive towards higher, more energy-efficient, process temperatures and foreseeable shortages of strategic minerals.
eBook - PDF- Shigeyuki Somiya(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
These definitions reveal basic inconsistencies in what can be called ceramics. In the British definition, for instance, glass is not included among ceramics, but the broader U.S. and Japanese versions do admit glass to the ceramics family. Technological change is also forcing changes in the limits placed on the term ceramics. In the past, the use of ceramics referred to technology, science, or art relating to nonmetallic, inorganic solid materials or to the production of goods from them or to their use. This definition covers all ceramic products, which may take many forms: poly crystalline material, single crystals, and amorphous materials in bulk, lumps, grains, thick or thin films, and fibers. Crystalline ceramics include long-familiar ceramic products: pottery and porcelain vessels, refractories, glass, and cement. It more broadly includes electronic ceramics, including magnetic substances, insulators, integrated circuit substrates, dielectric substances, and heating elements; engineering 1. Ceramics: Definitions 7 ceramics, including ceramic engines and cutting tools; and bioceramics, including ceramic teeth and bones. These ceramic products in general are inorganic, nonmetallic solid materials formed at high temperatures from crystalline or amorphous materials, pores, and liquids. The ceramics industry traces its roots back to those early earthenwares at the beginning of human history. Over the ages, humankind has developed a range of products formed of bodies based on natural materials such as clay and silicates—dishes and other tableware for daily use of pottery and porcelain, refractory substances, cement, and bottle glass. These are known as classical, traditional, or conventional ceramics. In contrast, ceramics formed of bodies with non-naturally occurring materials such as alumina, zirconia, or titania, or of synthetic materials, are called new ceramics or modern ceramics.
- R. E. Smallman, R J Bishop(Authors)
- 1999(Publication Date)
- Butterworth-Heinemann(Publisher)
Chapter 10Ceramics and glasses
10.1 Classification of ceramics
The term ceramic, in its modern context, covers an extremely broad range of inorganic materials; they contain non-metallic and metallic elements and are produced by a wide variety of manufacturing techniques. Traditionally, ceramics are moulded from silicate minerals, such as clays, dried and fired at temperatures of 1200–1800°C to give a hard finish. Thus we can readily see that the original Greek word keramos , meaning ‘burned stuff’ or ‘kiln-fired material’, has long been directly appropriate. Modern ceramics, however, are often made by processes that do not involve a kiln-firing step (e.g. hot-pressing, reaction-sintering, glass-devitrification, etc.). Although ceramics are sometimes said to be non-metallic in character, this simple distinction from metals and alloys has become increasingly inadequate and arbitrary as new ceramics with unusual properties are developed and come into use.Ceramics may be generally classified, according to type or function, in various ways. In industrial terms, they may be listed as pottery, heavy clay products (bricks, earthenware pipes, etc.), refractories (firebricks, silica, alumina, basic, neutral), cement and concrete, glasses and vitreous enamels, and engineering (technical, fine) ceramics. Members of the final group are capable of very high strength and hardness, exceptional chemical stability and can be manufactured to very close dimensional tolerances. These will be our prime concern. Their introduction as engineering components in recent years has been based upon considerable scientific effort and has revolutionized engineering design practice. In general, the development of engineering ceramics has been stimulated by the drive towards higher, more energy-efficient, process temperatures and foreseeable shortages of strategic minerals. In contrast to traditional ceramics, which use naturally-occurring and, inevitably, rather variable minerals, the new generation of engineering ceramics depends upon the availability of purified and synthesized materials and upon close microstructural control during processing. Ceramics are subject to variability in their properties and statistical concepts often need to be incorporated into design procedures for stressed components. Design must recognize the inherent brittleness, or low resistance to crack propagation, and modify, if necessary, the mode of failure. Ceramics, because of their unique properties, show great promise as engineering materials but, in practice, their production on a commercial scale in specified forms with repeatable properties is often beset with many problems.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 3 Ceramic Engineering Ceramic engineering is the science and technology of creating objects from inorganic, non-metallic materials. This is done either by the action of heat, or at lower temperatures using precipitation reactions from high purity chemical solutions. The term includes the purification of raw materials, the study and production of the chemical compounds concerned, their formation into components and the study of their structure, composition and properties. Ceramic materials may have a crystalline or partly crystalline structure, with long-range order on atomic scale. Glass Ceramics may have an amorphous or glassy structure, with limited or short-range atomic order. They are either formed from a molten mass that solidifies on cooling, formed and matured by the action of heat, or chemically synthe-sized at low temperatures using, for example, hydrothermal or sol-gel synthesis. The special character of ceramic materials gives rise to many applications in materials engineering, electrical engineering, chemical engineering and mechanical engineering. As ceramics are heat resistant, they can be used for many tasks that materials like metal and polymers are unsuitable for. Ceramic materials are used in a wide range of industries, including mining, aerospace, medicine, refinery, food and chemical industries, packaging science, electronics, industrial and transmission electricity, and guided lightwave transmission. ____________________ WORLD TECHNOLOGIES ____________________ Bearing components made from 100% silicon nitride Si 3 N 4 Ceramic bread knife ____________________ WORLD TECHNOLOGIES ____________________ History The word ceramic is derived from the Greek word κεραμικός ( keramikos ) meaning pottery.
eBook - PDFIndustrial Minerals and Their Uses
A Handbook and Formulary
- Peter A. Ciullo(Author)
- 1996(Publication Date)
- William Andrew(Publisher)
ELEVEN CERAMICS & GLASS John F. Mooney, Ph.D. Mu liakeramik Cikarang, Bekasi, Indonesia The broad term “ceramics” is comonly taken to mean any of a large family of materials, usually inorganic, requiring high temperatures in their processing or manufacture. In practice, these materials are generally divided into categories as follows: 1. Glass 2. Whitewares, including artware and structural ceramics. 3. Refractories A brief description of these categories will follow to allow the non- ceramist a better understanding of the use of “Ceramic” materials. MAJOR CLASSIFICATIONS OF CERAMICS Glass Glass has been variously described as a supercooled liquid, a randomly structured material, or a non-crystalline solid. In general the term ”glass” refers to an amorphous solid with non-directional properties, characterized by its transparency, hardness and rigidity at ordinary temperatures, and capacity for plastic working at elevated temperatures Major commercial uses of glass include: Plate or “float” glass, as used for windows and windshields. Glass tubing, or formed shapes, used for electric lighting envelopes. Glass containers such as tumblers and bottles. Electronic materials for cathode ray tubes, insulators, microchips. Ophthalmic glasses for lenses, eyewear. Decorative artware. Glass-ceramics for everything from nose cones to cookware. Various specialty glasses, particularly for fiber optics. 460 Industrial Minerals and Their Uses Whi teware Whiteware is the earliest known form of ceramic, predating recorded history as evidenced by the “ceramic” artifacts uncovered from various anthropological digs in the form of earthenware vessels and figures representing early man. This family is characterized by a crystalline matrix held together by a glassy phase and usually covered by a glazed coating. The major classifications of whiteware are: 1. Ceramic tiles, glazed and unglazed, for floors, walls and external use. 2. Sanitaryware in the form of toilets and lavatories.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Library Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 2 Ceramic Engineering Simulation of the outside of the Space Shuttle as it heats up to over 1,500 °C (2,730 °F) during re-entry into the Earth's atmosphere Ceramic engineering is the science and technology of creating objects from inorganic, non-metallic materials. This is done either by the action of heat, or at lower temperatures using precipitation reactions from high purity chemical solutions. The term includes the purification of raw materials, the study and production of the chemical compounds concerned, their formation into components and the study of their structure, composition and properties. Ceramic materials may have a crystalline or partly crystalline structure, with long-range order on atomic scale. Glass Ceramics may have an amorphous or glassy structure, with limited or short-range atomic order. They are either formed from a molten mass that solidifies on cooling, formed and matured by the action of heat, or chemically synthe-sized at low temperatures using, for example, hydrothermal or sol-gel synthesis. The special character of ceramic materials gives rise to many applications in materials engineering, electrical engineering, chemical engineering and mechanical engineering. ________________________ WORLD TECHNOLOGIES ________________________ As ceramics are heat resistant, they can be used for many tasks that materials like metal and polymers are unsuitable for. Ceramic materials are used in a wide range of industries, including mining, aerospace, medicine, refinery, food and chemical industries, packaging science, electronics, industrial and transmission electricity, and guided lightwave transmission. Bearing components made from 100% silicon nitride Si 3 N 4 ________________________ WORLD TECHNOLOGIES ________________________ Ceramic bread knife History The word ceramic is derived from the Greek word κεραμικός ( keramikos ) meaning pottery.
eBook - PDFMaterials Science and Engineering, P-eBK
An Introduction
- William D. Callister, Jr., David G. Rethwisch, Aaron Blicblau, Kiara Bruggeman, Michael Cortie, John Long, Judy Hart, Ross Marceau, Ryan Mitchell, Reza Parvizi, David Rubin De Celis Leal, Steven Babaniaris, Subrat Das, Thomas Dorin, Ajay Mahato, Julius Orwa(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
CHAPTER 13 Applications and processing of ceramics 409 SUMMARY GLASSES • The familiar glass materials are noncrystalline silicates that con- tain other oxides. In addition to silica (SiO 2 ), the two other primary ingredients of a typical soda–lime glass are soda (Na 2 O) and lime (CaO). GLASS‐CERAMICS • Glass‐ceramics are initially fabricated as glasses and then, by heat treatment, crystallised to form fine‐grained polycrystalline materials. • Two properties of glass‐ceramics that make them superior to glass are improved mechanical strengths and lower coefficients of thermal expansion (which improves thermal shock resistance). CLAY PRODUCTS • Clay is the principal component of whitewares (e.g. pottery and tableware) and structural clay products (e.g. building bricks and tiles). Ingredients (in addition to clay) may be added, such as feldspar and quartz; these influence changes that occur during firing. REFRACTORIES • Materials that are employed at elevated temperatures and often in reactive environments are termed refractory ceramics. • Requirements for this class of materials include high melting tem- perature, the ability to remain unreactive and inert when exposed to severe environments (often at elevated temperatures), and the ability to provide thermal insulation. • Common refractory ceramic materials include the following: fire- clay, high‐alumina, extra‐high alumina, silica, periclase (high MgO content), zircon (zirconium silicate), and silicon carbide. ABRASIVES • The abrasive ceramics are used to cut, grind, and polish other softer materials. • This group of materials must be hard and tough and be able to withstand high temperatures that arise from frictional forces. • Two classifications of ceramic abrasive ceramics are naturally occurring and manufactured. Those that occur naturally include diamond, corundum (Al 2 O 3 ), emery, garnet, and sand.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environment. Ceramics generally can withstand very high temperatures such as temperatures that range from 1,000 °C to 1,600 °C (1,800 °F to 3,000 °F). Exceptions include inorganic materials that do not include oxygen such as silicon carbide or silicon nitride. A glass is often not understood as a ceramic because of its amorphous ( non -crystalline) character. However, glass making involves several steps of the ceramic process and its mechanical properties are similar to ceramic materials. Traditional ceramic raw materials include clay minerals such as kaolinite, whereas more recent materials include aluminium oxide, more commonly known as alumina. The modern ceramic materials, which are classified as advanced ceramics, include silicon carbide and tungsten carbide. Both are valued for their abrasion resistance, and hence find use in applications such as the wear plates of crushing equipment in mining operations. Advanced ceramics are also used in the medicine, electrical and electronics industries. Crystalline ceramics Crystalline ceramic materials are not amenable to a great range of processing. Methods for dealing with them tend to fall into one of two categories - either make the ceramic in the desired shape, by reaction in situ, or by forming powders into the desired shape, and then sintering to form a solid body. Ceramic forming techniques include shaping by hand (sometimes including a rotation process called throwing), slip casting, tape casting (used for making very thin ceramic capacitors, etc.), injection moulding, dry pressing, and other variations. A few methods use a hybrid between the two approaches. Non-crystalline ceramics Non-crystalline ceramics, being glasses, tend to be formed from melts. The glass is shaped when either fully molten, by casting, or when in a state of toffee-like viscosity, by methods such as blowing to a mold.
eBook - ePubGlass
Mechanics and Technology
- Eric Le Bourhis(Author)
- 2014(Publication Date)
- Wiley-VCH(Publisher)
2Glass, A Ceramic Material1)2.1 Four Classes of Materials
A commonly used classification of materials separates them into four categories (Askeland, 1989; Ashby and Jones, 1991; Mozdierz et al., 1993):- metals
- ceramics
- polymers and
- composites.
The last mentioned are obtained from mixing materials from the three main categories. This is illustrated in Figure 2.1 , where the three main categories of materials are shown at the centre while the composites made of two of these are shown at the periphery. This classification is based on the type of bonding and the related properties as discussed in more detail below.Materials classes.Figure 2.1This classification can be examined in view of the Mendeleev table (Figure 2.2 ; see also Appendix B). Most elements in the left-hand side of the table display a metallic behaviour while the other elements are considered as non-metals.Metals and non-metals in the Mendeleev table.Figure 2.2Metals may be pure or alloyed with other metals and also non-metals (steel being an Fe–C alloy). They are conductors of electricity and heat. Ceramics are inorganic materials and result from the combination of either (i) metals and non-metals (ionic ceramics, e.g. NaCl, MgO, Al2 O3 , TiN, ZrO2 ) or (ii) only non-metals (covalent ceramics, e.g. SiO2 , Si3 N4 ). Combination with oxygen, nitrogen and carbon yields oxides (SiO2 , MgO, Al2 O3 ), nitrides (TiN, Si3 N4 ) and carbides (WC) respectively. Ceramics show a refractory behaviour; they are electrically and thermally resistant. Polymers are formed by organic chains (–CH2 –) and show thermal and electrical resistances. Composites are formed by two or more materials pertaining to two different classes of materials. For instance, a polymer matrix can be reinforced by ceramic fibres to form a new material with properties combining those of its constituents. The proposed classification is mostly based on the type of bonding between the constituents of the related materials. It suggests that the structure at the nanoscale determines the properties of the material. This is true for many properties (elasticity, thermal expansion; see Chapter 7 and Appendices A and C) while defects happen to play a major role in others (diffusion, fracture, plasticity; see Chapters 6 –9 and Appendices E, J and M). We generally distinguish four types of bonding as listed in Table 2.1 (see also Figure 2.3 ). Ionic and covalent bonds show the highest binding energy. Such bonds are formed in covalent and ionic ceramics (Figure 2.3 ). The lowest binding energy is obtained for van der Waals (VDW) bonds. These bonds are formed between polymer chains in thermoplastics. VDW and covalent bonds are found between chains in thermosets that are effectively stronger than thermoplastics. In Figure 2.3
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
Chemical or thermal treatmtents can increase the strength of glasses, and the controlled crystallization of certain glass compositions can produce optical quality glass-ceramics. AREVA, Ltd., currently produces a lithium disilicate based glass-ceramic known as TransArm TM , for use in transparent armor systems. It has all the workability of an amorphous glass, but upon recrystallization it demonstrates properties similar to a crystalline ceramic. Vycor TM is 96% fused silica glass, which is crystal clear, lightweight and high strength. One advantage of these type of materials is that they can be produced in large sheets and other curved shapes. Nanomaterials It has been shown fairly recently that laser elements (amplifiers, switches, ion hosts, etc.) made from fine-grained ceramic nanomaterials—produced by the low temperature sintering of high purity nanoparticles and powders—can be produced at a relatively low cost. These components are free of internal stress or intrinsic birefringence, and allow relatively large doping levels or optimized custom-designed doping profiles. This highlights the use of ceramic nanomaterials as being particularly important for high-energy laser elements and applications. Primary scattering centers in polycrystalline nanomaterials—made from the sintering of high purity nanoparticles and powders—include microstructural defects such as residual porosity and grain boundaries. Thus, opacity partly results from the incoherent scattering of light at internal surfaces and interfaces. In addition to porosity, most of the interfaces or internal surfaces in ceramic nanomaterials are in the form of grain boundaries which separate nanoscale regions of crystalline order. Moreover, when the size of the scattering center (or grain boundary) is reduced well below the size of the wavelength of the light being scattered, the light scattering no longer occurs to any significant extent.
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