Refractory Brick Industry Visiting..by Subhajit Mondal скачать в хорошем качестве

Refractory Brick Industry Visiting..by Subhajit Mondal

A refractory material or refractory is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractories are polycrystalline, polyphase, inorganic, non-metallic, porous, and heterogeneous. They are typically composed of oxides or carbides, nitrides etc. of the following materials: silicon, aluminium, magnesium, calcium, boron, chromium and zirconium. Instagram:-   / subhajit6375   Facebook:-   / subhajit.mondal.984349   ASTM C71 defines refractories as "...non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 1,000 °F (811 K; 538 °C) Refractory materials are used in furnaces, kilns, incinerators, and reactors. Refractories are also used to make crucibles and moulds for casting glass and metals and for surfacing flame deflector systems for rocket launch structures.[4] Today, the iron- and steel-industry and metal casting sectors use approximately 70% of all refractories produced.[5] Contents 1 Refractory materials 2 Uses 3 Classification of refractory materials 3.1 Based on chemical composition 3.1.1 Acidic refractories 3.1.2 Basic refractories 3.1.3 Neutral refractories 3.2 Based on method of manufacture 3.2.1 Shaped 3.2.2 Unshaped (monolithic refractories) 3.3 Based on fusion temperature 3.4 Based on refractoriness 3.5 Based on thermal conductivity 4 Refractory anchorage 5 See also 6 References Refractory materials Refractory materials must be chemically and physically stable at high temperatures. Depending on the operating environment, they must be resistant to thermal shock, be chemically inert, and/or have specific ranges of thermal conductivity and of the coefficient of thermal expansion. The oxides of aluminium (alumina), silicon (silica) and magnesium (magnesia) are the most important materials used in the manufacturing of refractories. Another oxide usually found in refractories is the oxide of calcium (lime).[6] Fire clays are also widely used in the manufacture of refractories. Refractories must be chosen according to the conditions they face. Some applications require special refractory materials.[7] Zirconia is used when the material must withstand extremely high temperatures.[8] Silicon carbide and carbon (graphite) are two other refractory materials used in some very severe temperature conditions, but they cannot be used in contact with oxygen, as they would oxidize and burn. Binary compounds such as tungsten carbide or boron nitride can be very refractory. Hafnium carbide is the most refractory binary compound known, with a melting point of 3890 °C.[9][10] The ternary compound tantalum hafnium carbide has one of the highest melting points of all known compounds (4215 °C).[11][12] Molybdenum disilicide has a high melting point of 2030 °C and often used as a heating element. Uses Refractory materials are useful for the following functions:[13][2] Serving as a thermal barrier between a hot medium and the wall of a containing vessel Withstanding physical stresses and preventing erosion of vessel walls due to the hot medium Protecting against corrosion Providing thermal insulation Refractories have multiple useful applications. In the metallurgy industry, refractories are used for lining furnaces, kilns, reactors, and other vessels which hold and transport hot mediums such as metal and slag. Refractories have other high temperature applications such as fired heaters, hydrogen reformers, ammonia primary and secondary reformers, cracking furnaces, utility boilers, catalytic cracking units, air heaters, and sulfur furnaces.[13] Classification of refractory materials Chemical composition Method of manufacture Fusion temperature Refractoriness Thermal conductivity Based on chemical composition Acidic refractories Acidic refractories are generally impervious to acidic materials but easily attacked by basic materials, and are thus used with acidic slag in acidic environments. They include substances such as silica, alumina, and fire clay brick refractories. Silica refractories are refractories containing more than 93% silicon oxide (SiO2). They are acidic, have high resistance to thermal shock, flux and slag resistance, and high spalling resistance. Silica bricks are often used in the iron and steel industry as furnace materials. ‪@experiment_facts7‬ #Refractory Brick || Disclaimer || Some content is used under fair use for Educational Purposes. Copyright Disclaimer under Section 107 of the Copyright Act 1976, allowance is made 4 "fair use" for purposes such as criticism, comment, news, reporting, teaching, scholarship and research. Fair use is a use permitted buy copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favour of fair use.