|
Emery (rock)
Emery, or corundite, is a dark granular rock used to make abrasive powder. It largely consists of corundum ( aluminium oxide), mixed with other minerals such as the iron-bearing spinels, hercynite, and magnetite, and also rutile ( titania). Industrial emery may contain a variety of other minerals and synthetic compounds such as magnesia, mullite, and silica. It is black or dark grey in colour, less dense than translucent-brown corundum with a specific gravity of between 3.5 and 3.8. Because it can be a mixture of minerals, no definite Mohs hardness can be assigned: the hardness of corundum is 9 and that of some spinel-group minerals is near 8, but the hardness of others such as magnetite is near 6. Crushed or naturally eroded emery (known as ''black sand'') is used as an abrasive—for example, on emery boards and emery cloth. It is also used as a traction enhancer in asphalt and tarmac mixtures. Turkey and Greece are the main suppliers of the world's emery. These two countr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naxos Emery-mine
Naxos (; el, Νάξος, ) is a list of islands of Greece, Greek island and the largest of the Cyclades. It was the centre of archaic Cycladic culture. The island is famous as a source of Emery (rock), emery, a rock rich in corundum, which until modern times was one of the best abrasives available. The largest town and capital of the island is Chora or Naxos (city), Naxos City, with 7,374 inhabitants (2011 census). The main villages are Filoti, Apeiranthos, Apiranthos, Vivlos, Agios Arsenios, Koronos and Glynado. Geography Climate Naxos experiences a Mediterranean climate, with relatively mild winters and warm summers. The Köppen Climate Classification subtype for this climate is "hot-summer Mediterranean climate, Csa". (Mediterranean Climate). Inland areas of the island are much wetter and cooler in winter. Mythic Naxos According to Greek mythology, the young Zeus was raised in a cave on Mt. Zas ("''Zas''" meaning "''Zeus''"). Homer mentions "Dia (island ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asphalt
Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term asphaltum was also used. Full text at Internet Archive (archive.org) The word is derived from the Ancient Greek ἄσφαλτος ''ásphaltos''. The largest natural deposit of asphalt in the world, estimated to contain 10 million tons, is the Pitch Lake located in La Brea in southwest Trinidad (Antilles island located on the northeastern coast of Venezuela), within the Siparia Regional Corporation. The primary use (70%) of asphalt is in Road surface, road construction, where it is used as the glue or binder mixed with construction aggregate, aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs. In material sciences an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abrasives
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives. Abrasives are extremely commonplace and are used very extensively in a wide variety of industrial, domestic, and technological applications. This gives rise to a large variation in the physical and chemical composition of abrasives as well as the shape of the abrasive. Some common uses for abrasives include grinding, polishing, buffing, honing, cutting, drilling, sharpening, lapping, and sanding (see abrasive machining). (For simplicity, "mineral" in this article will be used loosely to refer to both minerals and mineral-like substances w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Minerals
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity towards oxyg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Machinery's Handbook
''Machinery's Handbook'' ''for machine shop and drafting-room; a reference book on machine design and shop practice for the mechanical engineer, draftsman, toolmaker, and machinist'' (the full title of the 1st edition) is a classic reference work in mechanical engineering and practical workshop mechanics in one volume published by Industrial Press, New York, since 1914. The first edition was created by Erik Oberg (1881–1951) and Franklin D. Jones (1879–1967), who are still mentioned on the title page of the 29th edition (2012). Recent editions of the handbook contain chapters on mathematics, mechanics, materials, measuring, toolmaking, manufacturing, threading, gears, and machine elements, combined with excerpts from ANSI standards. The work is available in online and ebook form as well as print. During the decades from World War I to World War II, these phrases could refer to either of two competing reference books: McGraw-Hill McGraw Hill is an American educatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emery Paper
Emery paper is a type of abrasive paper or sandpaper, that can be used to abrade (remove material from) surfaces or mechanically finish a surface. Operations include deburring, polishing Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material accordin ..., paint removal, corrosion removal, sizing, etc. This is accomplished by rubbing the abrasive-coated paper, with some pressure, against the object being processed. Abrasion may be performed by hand, electrically powered, or air powered equipment. Description Emery is a naturally occurring rock of impure crystalline aluminium oxide (Al2O3 mixed with oxides of silicon (e.g. SiO2), iron (Fe), and other elements and varying small percentages of clay and other silicates for example: kaolinite (Al4Si4O10(OH)8)). Smaller particles abrade smaller amou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permissible Exposure Limit
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupational Safety and Health Administration (OSHA). Most of OSHA's PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970. For chemicals, the chemical regulation is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic meter (mg/m3). Units of measure for physical agents such as noise are specific to the agent. A PEL is usually given as a time-weighted average (TWA), although some are short-term exposure limits (STEL) or ceiling limits. A TWA is the average exposure over a specified period, usually a nominal eight hours. This means that, for limited periods, a worker may be exposed to concentration excursions higher than the PEL, so long as the TWA is not exceeded and any applicab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occupational Safety And Health Administration
The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agency under the Occupational Safety and Health Act OSH Act, which President Richard M. Nixon signed into law on December 29, 1970. OSHA's mission is to "assure safe and healthy working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education, and assistance". The agency is also charged with enforcing a variety of whistleblower statutes and regulations. OSHA's workplace safety inspections have been shown to reduce injury rates and injury costs without adverse effects on employment, sales, credit ratings, or firm survival. History The Bureau of Labor Standards of the Department of Labor has worked on some work safety issues since its creation in 1922. Economic boom and associated l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sintering
Clinker nodules produced by sintering Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points such as tungsten and molybdenum. The study of sintering in metallurgical powder-related processes is known as powder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, which is driven by the temperature difference between the water and the ice. Examples of pressure-driven sintering are the compact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural History (Pliny)
The ''Natural History'' ( la, Naturalis historia) is a work by Pliny the Elder. The largest single work to have survived from the Roman Empire to the modern day, the ''Natural History'' compiles information gleaned from other ancient authors. Despite the work's title, its subject area is not limited to what is today understood by natural history; Pliny himself defines his scope as "the natural world, or life". It is encyclopedic in scope, but its structure is not like that of a modern encyclopedia. It is the only work by Pliny to have survived, and the last that he published. He published the first 10 books in AD 77, but had not made a final revision of the remainder at the time of his death during the AD 79 eruption of Vesuvius. The rest was published posthumously by Pliny's nephew, Pliny the Younger. The work is divided into 37 books, organised into 10 volumes. These cover topics including astronomy, mathematics, geography, ethnography, anthropology, human physiolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
