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Glaze Defects
Glaze defects are any flaws in the surface quality of a ceramic glaze, its physical structure or its interaction with the body. Glaze and body mismatch Certain glaze defects are a result of differences in the thermal expansion coefficient of the glaze and the clay body. Crazing Crazing is a spider web pattern of cracks penetrating the glaze. It is caused by tensile stresses greater than the glaze is able to withstand."Ceramics Glaze Technology". J. R. Taylor, A. C. Bull. ''Institute Of Ceramics / Pergamon Press.'' 1986. Common reasons for such stresses are: a mismatch between the thermal expansions of glaze and body; from moisture expansion of the body; and in the case of glazed tiles fixed to a wall, movement of the wall or of the bonding material used to fix the tile to the wall.Dictionary Of Ceramics. Arthur Dodd & David Murfin. 3rd edition. ''The Institute Of Minerals.'' 1994. The cracks can allow the ingress of water into the cracks. Once fired, ware tends to be more resista ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percival David Collection DSCF3075
Perceval (, also written Percival, Parzival, Parsifal), alternatively called Peredur (), is a figure in the legend of King Arthur, often appearing as one of the Knights of the Round Table. First mentioned by the French author Chrétien de Troyes in the tale ''Perceval, the Story of the Grail'', he is best known for being the original hero in the quest for the Holy Grail, Grail before being replaced in later literature by Galahad. Etymology and origin The earliest reference to Perceval is found in Chrétien de Troyes's first Arthurian romance ''Erec et Enide'', where, as "Percevaus Welsh person, li Galois" (Percevaus of Wales), he appears in a list of Arthur's knights. In another of Chrétien's romances, ''Cligés'', Perceval is a "renowned vassal" who is defeated by the knight Cligés in a tournament. He then becomes the eponymous protagonist of Chrétien's final romance, ''Perceval, the Story of the Grail''. In the Welsh romance ''Peredur son of Efrawg'', the corresponding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bisque (pottery)
Biscuit (also known as bisque) refers to any pottery that has been fired in a kiln without a ceramic glaze. This can be a final product such as biscuit porcelain or unglazed earthenware (such as terracotta) or, most commonly, an intermediate stage in a glazed final product. Confusingly, "biscuit" may also be used as a term for pottery at a stage in its manufacture where it has not yet been fired or glazed, but has been dried so that it is no longer plastic (easily deformed). The porous nature of (fired) biscuit earthenware means that it readily absorbs water, while vitreous wares such as porcelain, bone china and most stoneware are non-porous even without glazing. The temperature of biscuit firing is today usually at least 1000°C, although higher temperatures are common. The firing of the ware that results in the biscuit article causes permanent chemical and physical changes to occur. These result in a much harder and more resilient article which can still be porous, and this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Vapour
Water vapor, water vapour, or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Water vapor is transparent, like most constituents of the atmosphere. Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is less dense than most of the other constituents of air and triggers convection currents that can lead to clouds and fog. Being a component of Earth's hydrosphere and hydrologic cycle, it is particularly abundant in Earth's atmosphere, where it acts as a greenhouse gas and warming feedback, contributing more to total greenhouse effect than non-condensable gases such as carbon dioxide and methane. Use of water vapor, as steam, has been important for cooking, and as a major component in energy production and transport systems since the Industrial Revolution. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or Chemical Changes, chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, Tile, tiles and bricks. Various industries use rotary kilns for pyroprocessing (to calcinate ores, such as limestone to Lime (material), lime for Cement kiln, cement) and to transform many other materials. Etymology According to the Oxford English Dictionary, kiln was derived from the words cyline, cylene, cyln(e) in Old English, in turn derived from Latin ''culina'' ('kitchen'). In Middle English, the word is attested as kulne, kyllne, kilne, kiln, kylle, kyll, kil, kill, keele, kiele. In Greek the word ''καίειν, kaiein'', means 'to burn'. Pronunciation The word 'kiln' was originally pronounced 'kil' with the 'n' silent, as is referenced in ''Webster's Dictionary of 1828'' and in ''English Words as Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonate
A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group . The term is also used as a verb, to describe carbonation: the process of raising the concentrations of carbonate and bicarbonate ions in water to produce carbonated water and other carbonated beverageseither by the addition of carbon dioxide gas under pressure or by dissolving carbonate or bicarbonate salts into the water. In geology and mineralogy, the term "carbonate" can refer both to carbonate minerals and carbonate rock (which is made of chiefly carbonate minerals), and both are dominated by the carbonate ion, . Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock. The most common are calcite or calcium carbonate, , the chief constituent of limestone (as well as the main component of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molten
Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which increases the substance's temperature to the melting point. At the melting point, the ordering of ions or molecules in the solid breaks down to a less ordered state, and the solid melts to become a liquid. Substances in the molten state generally have reduced viscosity as the temperature increases. An exception to this principle is elemental sulfur, whose viscosity increases in the range of 130 °C to 190 °C due to polymerization. Some organic compounds melt through mesophases, states of partial order between solid and liquid. First order phase transition From a thermodynamics point of view, at the melting point the change in Gibbs free energy ''∆G'' of the substances is zero, but there are non-zero changes in the enthalpy (' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceramic Glaze
Ceramic glaze, or simply glaze, is a glassy coating on ceramics. It is used for decoration, to ensure the item is impermeable to liquids and to minimize the adherence of pollutants. Glazing renders earthenware impermeable to water, sealing the inherent porosity of earthenware. It also gives a tougher surface. Glaze is also used on stoneware and porcelain. In addition to their functionality, glazes can form a variety of surface finishes, including degrees of glossy or matte finish and color. Glazes may also enhance the underlying design or texture either unmodified or inscribed, carved or painted. Most pottery produced in recent centuries has been glazed, other than pieces in bisque porcelain, terracotta, and some other types. Tiles are often glazed on the surface face, and modern architectural terracotta is often glazed. Glazed brick is also common. Sanitaryware is invariably glazed, as are many ceramics used in industry, for example ceramic insulators for overhead power li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parts Per Million
In science and engineering, the parts-per notation is a set of pseudo-units to describe the small values of miscellaneous dimensionless quantity, dimensionless quantities, e.g. mole fraction or mass fraction (chemistry), mass fraction. Since these fraction (mathematics), fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are * parts-per-million - ppm, * parts-per-billion - ppb, * parts-per-trillion - ppt, * parts-per-quadrillion - ppq, This notation is not part of the International System of Units - SI system and its meaning is ambiguous. Applications Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Absorption Spectroscopy
Atomic absorption spectroscopy (AAS) is a spectro-analytical procedure for the quantitative measurement of chemical elements. AAS is based on the absorption of light by free metallic ions that have been atomized from a sample. An alternative technique is atomic emission spectroscopy (AES). In analytical chemistry, the technique is used for determining the concentration of a particular element (the analyte) in a sample to be analyzed. AAS can be used to determine over 70 different elements in solution, or directly in solid samples via electrothermal vaporization, and is used in pharmacology, biophysics, archaeology and toxicology research. Atomic emission spectroscopy (AAS) was first used as an analytical technique, and the underlying principles were established in the second half of the 19th century by Robert Wilhelm Bunsen and Gustav Robert Kirchhoff, both professors at the University of Heidelberg, Germany. The modern form of AAS was largely developed during the 1950s by a t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetic Acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. Historically, vinegar was produced from the third century BC and was likely the first acid to be produced in large quantities. Acetic acid is the second simplest carboxylic acid (after formic acid). It is an important Reagent, chemical reagent and industrial chemical across various fields, used primarily in the production of cellulose acetate for photographic film, polyvinyl acetate for wood Adhesive, glue, and synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry, acetic acid is controlled by the E number, food additive code E260 as an acidity regulator and as a condiment. In biochemistry, the acetyl group, derived from acetic acid, is funda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quality Control
Quality control (QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as "a part of quality management focused on fulfilling quality requirements". This approach places emphasis on three aspects (enshrined in standards such as ISO 9001): # Elements such as controls, job management, defined and well managed processes, performance and integrity criteria, and identification of records # Competence, such as knowledge, skills, experience, and qualifications # Soft elements, such as personnel, integrity, confidence, organizational culture, motivation, team spirit, and quality relationships. Inspection is a major component of quality control, where physical product is examined visually (or the end results of a service are analyzed). Product inspectors will be provided with lists and descriptions of unacceptable product defects such as cracks or surface blemishes for example. History and introductio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cadmium
Cadmium is a chemical element; it has chemical symbol, symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in group 3 element, groups 3 through group 11 element, 11. Cadmium and its Congener (chemistry), congeners in group 12 are often not considered transition metals, in that they do not have partly filled ''d'' or ''f'' electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Friedrich Stromeyer, Stromeyer and Karl Samuel Leberecht Hermann, Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium occurs as a minor component in most zinc ores and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
