Types of modern cement

Non-Portland hydraulic cements
Pozzolan-lime cements. Mixtures of ground pozzolan and lime are the cements used by the Romans, and can be found in Roman structures still standing (e.g. the Pantheon in Rome). They develop strength slowly, but their ultimate strength can be very high. The hydration products that produce strength are essentially the same as those produced by Portland cement. Slag-lime cements. Ground granulated blast furnace slag is not hydraulic on its own, but is "activated" by addition of alkalis, most economically using lime. They are similar to pozzolan lime cements in their properties. Only granulated slag (i.e. water-quenched, glassy slag) is effective as a cement component. Supersulfated cements. These contain about 80% ground granulated blast furnace slag, 15% gypsum or anhydrite and a little Portland clinker or lime as an activator. They produce strength by formation of ettringite, with strength growth similar to a slow Portland cement. They exhibit good resistance to aggressive agents, including sulfate. Calcium aluminate cements are hydraulic cements made primarily from limestone and bauxite. The active ingredients are monocalcium aluminate CaAl2O4 (CaO · Al2O3 or CA in Cement chemist notation, CCN) and mayenite Ca12Al14O33 (12 CaO · 7 Al2O3, or C12A7 in CCN). Strength forms by hydration to calcium aluminate hydrates. They are well-adapted for use in refractory (high-temperature resistant) concretes, e.g. for furnace linings. Calcium sulfoaluminate cements are made from clinkers that include ye'elimite (Ca4(AlO2)6SO4 or C4A3S in Cement chemist's notation) as a primary phase. They are used in expansive cements, in ultra-high early strength cements, and in "low-energy" cements. Hydration produces ettringite, and specialized physical properties (such as expansion or rapid reaction) are obtained by adjustment of the availability of calcium and sulfate ions. Their use as a low-energy alternative to Portland cement High Temperature Cement has been pioneered in China, where several million tonnes per year are produced.[40][41] Energy requirements are lower because of the lower kiln temperatures required for reaction, and the lower amount of limestone (which must be endothermically decarbonated) in the mix. In addition, the lower limestone content and lower fuel consumption leads to a CO2 emission around half that associated with Portland clinker. However, SO2 emissions are usually significantly higher. "Natural" cements correspond to certain cements of the pre-Portland era, produced by burning argillaceous limestones at moderate temperatures. The level of clay components in the limestone (around 30–35%) is such that large amounts of belite (the low-early strength, high-late strength mineral in Portland cement) are formed without the formation of excessive amounts of free lime. As with any natural material, High Temperature Insulation such cements have highly variable properties. Geopolymer cements are made from mixtures of water-soluble alkali metal silicates and aluminosilicate mineral powders such as fly ash and metakaolin.

What Is Mastic Adhesive?

Mastic adhesive is made from the sticky resin of the mastic tree, which grows in the Mediterranean. Because of its sticky nature, it is used as a bonding agent in many commercial applications. Some types include construction adhesive, industrial adhesive, and ceramic tileadhesive. Depending on the application, the adhesive is available in thin liquid, thick glue, or paste form.

When used in construction, mastic adhesive is typically in liquid form and applied with a caulking gun. The adhesive is squeezed out by hand in a thin line along wall or ceiling joints. The strength of the adhesive helps hold load-bearing walls in place. In ceilings, the quick-setting adhesive eliminates the need to support heavy drywall for extended periods of time. Construction adhesive is also used as a temporary hold for fixtures so they can be nailed or screwed in place by one person.

Industrial uses for this adhesive include repairing duct work in the heating and air industry. This is due to its heat resistant properties and the ability to seal and form and a strong bond. The adhesive also bonds with most any material, so repairs to concrete, brick, or mortar are also possible. The adhesive for industrial uses comes in a finely ground powder that is mixed to form a paste. It is smeared onto the repair area and allowed to dry.

New method of growing high-quality graphene promising for next-gen technology

New method of growing high-quality graphene promising for next-gen technology (Nanowerk News) Making waves as the material that will revolutionize electronics, graphene – composed of a single layer of Carbon atoms – has nonetheless been challenging to produce in a way that will be practical for innovative electronics applications. Researchers at UC Santa Barbara have discovered a method to synthesize high quality graphene in a controlled manner that may pave the way for next-generation electronics application.

Kaustav Banerjee, a professor with the Electrical and Computer Engineering department and Director of the Nanoelectronics Research Lab at UCSB that has been studying carbon nanomaterials for more than seven years, led the research team to perfect methods of growing sheets of graphene, as detailed in a study to be published in the November 2011 issue of the journal Carbon.

UCSB researchers have successfully controlled the growth of a high-quality bilayer graphene on a copper substrate using a method called chemical vapor deposition (CVD), which breaks down molecules of methane gas to build graphene sheets with carbon atoms. (Image: Peter Allen) "Our process has certain unique advantages that give rise to high quality graphene," says Banerjee. "For the electronics industry to effectively use graphene, it must first be grown selectively and in larger sheets. We have developed a synthesis technique that yields high- quality and high-uniformity graphene that can be translated into a scalable process for industry applications."

Using adhesive tape to lift flakes of graphene from graphite, University of Manchester researchers Geim and Novoselov were awarded the 2010 Nobel Prize in Physics for their pioneering isolation and characterization of the material. To launch graphene into futuristic applications, however, researchers have been seeking a controlled and efficient way to grow a higher quality of this single-atom-thick material in larger areas.

The discovery by UCSB researchers turns graphene production into an industry-friendly process by improving the quality and uniformity of graphene using efficient and reproducible methods. They were able to control the number of graphene layers produced – from mono-layer to bi-layer graphene – an important distinction for future applications in electronics and other technology.

"Intel has a keen interest in graphene due to many possibilities it holds for the next generation of energy- efficient computing, but there are many roadblocks along the way," added Intel Fellow, Shekhar Borkar. "The scalable synthesis technique developed by Professor Banerjee's group at UCSB is an important step forward."

As a material, graphene is the thinnest and strongest in the world – more than 100 times stronger than diamond – and is capable of acting as an ultimate conductor at room temperature. If it can be produced effectively, graphene's properties make it ideal for advancements in green electronics, super strong materials, and medical technology. Graphene could be used to make flexible screens and electronic devices, computers with 1,000 GHz processors that run on virtually no energy, and ultra-efficient solar power cells. Key to the UCSB team's discovery is their understanding of graphene growth kinetics under the influence of the substrate. Their approach uses a method called low pressure chemical vapor deposition (LPCVD) and involves disintegrating the hydrocarbon gas methane at a specific high temperature to build uniform layers of carbon (as graphene) on a pretreated copper substrate. Banerjee's research group established a set of techniques that optimized the uniformity and quality of graphene, while controlling the number of graphene layers they grew on their substrate.

According to Dr. Wei Liu, a post-doctoral researcher and co-author of the study, "Graphene growth is strongly affected by imperfection sites on the copper substrate. By proper treatment of the copper surface and precise selection of the growth parameters, the quality and uniformity of graphene are significantly improved and the number of graphene layers can be controlled."

Professor Banerjee and credited authors Wei Liu, Hong Li, Chuan Xu and Yasin Khatami are not the first research team to make graphene using the CVD method, but they are the first to successfully refine critical methods to grow a high quality of graphene. In the past, a key challenge for the CVD method has been that it yields a lower quality of graphene in terms of carrier mobility – or how well it conducts electrons. "Our graphene exhibits the highest reported field-effect mobility to date for CVD graphene, having an average value of 4000 cm2/V.s with the highest peak value at 5500 cm2/V.s. This is an extremely high value compared with the mobility of silicon." added Hong Li, a Ph.D. candidate in Banerjee's research group.

"Kaustav Banerjee's group is leading graphene nanoelectronics research efforts at UCSB, from material synthesis to device design and circuit exploration. His work has provided our campus with unique and very powerful capabilities," added David Awschalom, Professor of Physics, Electrical and Computer Engineering, and Director of the California NanoSystems Institute (CNSI) at UCSB where Banerjee's laboratory is located. "This new facility has also boosted our opportunities for collaborations across various science and engineering disciplines."

"There is no doubt graphene is a superior material. Intrinsically it is amazing," says Banerjee. "It is up to us, the scientists and engineers, to show how we can use graphene and harness its capabilities. There are challenges in how to grow it, how to transfer or not to transfer and pattern it, and how to tailor its properties for specific applications. But these challenges are fertile grounds for exciting research in the future."

High temperature insulation wool

High-temperature superconductors (abbreviated high-Tc or HTS) are materials that behave as superconductors at unusually high temperatures. The first high-Tc superconductor was discovered in 1986 by IBM researchers Karl Müller and Johannes Bednorz, who were awarded the 1987 Nobel Prize in Physics "for their important break-through in the discovery of superconductivity in ceramic materials".

Whereas "ordinary" or metallic superconductors usually have transition temperatures (temperatures below which they superconduct) of about 30 K (−243.2 °C), HTS superconductors have been observed with transition temperatures as high as 138 K (−135 °C). Until recently, only certain compounds of copper and oxygen (so-called "cuprates") were believed to have HTS properties, and the term high-temperature superconductor was used interchangeably with cuprate superconductor for compounds such as bismuth strontium calcium copper oxide (BSCCO) and yttrium barium copper oxide (YBCO). However, several Iron based compounds (the Iron pnictides) are now known to be superconducting at high temperatures.

History Of Adhesive

History Of Adhesive

The oldest known adhesive, dated to approximately 200,000 BC, is from spear stone flakes glued to wood with birch-bark-tar, which was found in central Italy.[4] The use of compound glues to haft stone spears into wood dates back to approximately 70,000 BC. Evidence for this has been found in Sibudu Cave, South Africa and the compound glues used were made from plant gum and red ochre. The Tyrolean Iceman had weapons fixed together with the aid of birch-bark-tar glue.

6000-year-old ceramics show evidence of adhesives based upon animal glues made by rendering animal products such as horse teeth. During the times of Babylonia, tar-like glue was used for gluing statues. The Egyptians made much use of animal glues to adhere furniture, ivory, and papyrus. The Mongols also used adhesives to make their short bows, and the Native Americans of the eastern United States used a mixture of spruce gum and fat as adhesives to fashion waterproof seams in their birchbark canoes.

In medieval Europe, egg whites were used as glue to decorate parchments with gold leaf. The first actual glue factory was founded in Holland in the early 18th century. In the 1750s, the English introduced fish glue. As the modern world evolved, several other patented[clarification needed] materials, such as bones, starch, fish skins and isinglass, and casein, were introduced as alternative materials for glue manufacture. Modern glues have improved flexibility, toughness, curing rate, and chemical resistance.

In the late 19th century in Switzerland, casein was first used as a wood glue. Today, it is used to glue grocery bags.

Adhesive

An adhesive, also known as glue, is a material, typically liquid or semi-liquid, that adheres or bonds items together. Adhesives come from either natural or synthetic sources. The types of materials that can be bonded are vast but adhesives are especially useful for bonding thin materials. Adhesives cure (harden) by either evaporating a solvent or by chemical reactions that occur between two or more constituents.
Adhesives are useful for joining thin or dissimilar materials, minimizing weight, and providing a vibration-damping joint. A disadvantage of most adhesives is that most do not form an instantaneous joint, unlike many other joining processes, because the adhesive needs time to cure.
The earliest known date for a simple glue is 200,000 BC and for a compound glue 70,000 BC.

Mesh

Mesh
       Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to web or net in that it has many attached or woven strands Types of mesh A plastic mesh is extruded, oriented, expanded or tubular. Plastic mesh can be made from polypropylene, polyethylene, nylon, PVC or PTFE. A metal mesh can be woven, knitted, welded, expanded, photo-chemically etched or electroformed (screen filter) from steel or other metals.In clothing, a mesh is often defined as a loosely woven or knitted fabric that has a large number of closely spaced holes, frequently used for modern sports jerseys and other clothing. A mesh skin graft is a skin patch that has been cut systematically to create a mesh. Meshing of skin grafts provides coverage of a greater surface area at the recipient site, and also allows for the egress of serous or sanguinous fluid. However, it results in a rather pebbled appearance upon healing that may ultimately look less aesthetically pleasing. Uses of meshes Meshes are often used to screen out unwanted things, such as insects. Wire screens on windows and mosquito netting can be considered as types of meshes. Wire screens can be used to shield against radio frequency radiation, e.g. in microwave ovens and Faraday cages. Metal and nylon wire mesh filters are used in filtration Wire mesh is used in guarding for secure areas and as protection in the form of vandal screens. Wire mesh can be fabricated to produce park benches, waste baskets and other baskets for material handling. A huge quantity of mesh is being used for screen printing work. Surgical mesh is used to provide a reinforcing structure in surgical procedures like inguinal hernioplasty, and umbilical hernia repair. Meshes are also used as drum heads in practice and electronic drum sets.

High temperature insulation

High temperature insulation Calcium silicate
    Calcium silicate (often referred to by its shortened trade name Cal-Sil or Calsil) is the chemical compound Ca2SiO4, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO2. It is one of group of compounds obtained by reacting calcium oxide and silica in various ratios[3] e.g. 3CaO•SiO2, Ca3SiO5; 2CaO•SiO2, Ca2SiO4; 3CaO•2SiO2, Ca3Si2O7 and CaO•SiO2, CaSiO3. Calcium orthosilicate is a white powder with a low bulk density and high physical water absorption. It is used as an anti-caking agent and an antacid. A white free-flowing powder derived from limestone and diatomaceous earth, calcium silicate has no known adverse effects to health[citation needed]. It is used in roads, insulation, bricks, roof tiles, table salt[4] and occurs in cements, where it is known as belite (or in cement chemist notation C2S).


High temperature insulation
   Calcium silicate is commonly used as a safe alternative to asbestos for high temperature insulation materials. Industrial grade piping and equipment insulation is often fabricated from calcium silicate. Its fabrication is a routine part of the curriculum for insulation apprentices. Calcium silicate competes in these realms against rockwool as well as proprietary insulation solids, such as perlite mixture and vermiculite bonded with sodium silicate. Although it is popularly considered an asbestos substitute, early uses of calcium silicate for insulation still made use of asbestos fibers.

Natural adhesives

Natural adhesives
      Natural adhesives are made from organic sources such as vegetable matter, starch (dextrin), natural resins or from animals e.g. casein or animal glue. They are often referred to as bioadhesives. One example is a simple paste made by cooking flour in water. Animal glues are traditionally used in bookbinding, wood joining, and many other areas but now are largely replaced by synthetic glues. Casein is mainly used to adhere glass bottle labels. Starch based adhesives are used in corrugated board production and paper sack production, paper tube winding, and wall paper adhesives. Masonite, a wood hardboard, was bonded using natural lignin, (although most modern MDF particle boards use synthetic thermosetting resins). Another form of natural adhesive is blood albumen (made from protein component of blood), which is used in the plywood industry. Animal glue remains the preferred glue of the luthier. Casein based glues are made by precipitating casein from milk protein using the acetic acid from vinegar. This forms curds, which are neutralized with a base, such as sodium bicarbonate (baking soda), to cause them to unclump and become a thicker plastic-like substance

Synthetic adhesives

Synthetic adhesives
     Synthetic adhesives are based on elastomers, thermoplastics, emulsions, and thermosets. Examples of thermosetting adhesives are: epoxy, polyurethane, cyanoacrylate and acrylic polymers. See also post-it notes. The first commercially produced synthetic adhesive was Karlsons klister in the 1920s.

Aluminium

Aluminium ( /ˌæljuːˈmɪniəm/ al-ew-min-ee-əm) or aluminum (American English;  /əˈluːmɪnəm/ ə-loo-mi-nəm) is a chemical element in the boron group with symbol Al and atomic number 13. It is silvery white, and it is not soluble in water under normal circumstances.
Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It makes up about 8% by weight of the Earth's solid surface. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals.[6] The chief ore of aluminium is bauxite.
Aluminium is remarkable for the metal's low density and for its ability to resist corrosion due to the phenomenon of passivation. Structural components made from aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The most useful compounds of aluminium, at least on a weight basis, are the oxides and sulfates.
Despite its prevalence in the environment, aluminium salts are not known to be used by any form of life. In keeping with its pervasiveness, aluminium is well tolerated by plants and animals.[7] Owing to their prevalence, potential beneficial (or otherwise) biological roles of aluminium

Cement kiln

          Cement kilns are used for the pyroprocessing stage of manufacture of Portland and other types of hydraulic cement, in which calcium carbonatereacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of cement are made per year, and cement kilns are the heart of this production process: their capacity usually define the capacity of the cement plant. As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, improvement of kiln efficiency has been the central concern of cement manufacturing technology

Thank for Info : http://en.wikipedia.org

Silicon nitride

          Silicon nitride is a chemical compound of silicon and nitrogen. If powdered silicon is heated between 1300 °C and 1400 °C in an atmosphere of nitrogen, trisilicon tetranitride, Si₃N₄ is formed. The silicon sample weight increases progressively due to the chemical combination of silicon and nitrogen. Without an iron catalyst, the reaction is complete after several hours (~7), when no further weight increase due to nitrogen absorption (per gram of silicon) is detected. In addition to Si₃N₄, several other silicon nitride phases (with chemical formulas corresponding to varying degrees of nitridation/Si oxidation state) have been reported in the literature, for example, the gaseous disilicon mononitride (Si₂N); silicon mononitride (SiN), and silicon sesquinitride (Si₂N₃), each of which are stoichiometric phases. As with other refractories, the products obtained in these high-temperature syntheses depends on the reaction conditions (e.g. time, temperature, and starting materials including the reactants and container materials), as well as the mode of purification. However, the existence of the sesquinitride has since come into question.

The Si₃N₄ phase is the most chemically inert (being decomposed by dilute HF and hot H₂SO₄). It is also the most thermodynamically stable of the silicon nitrides. Hence, Si₃N₄ is the most commercially important of the silicon nitrides and is generally understood as what is being referred to where the term "silicon nitride" is used.

          Silicon nitride (i.e. Si₃N₄) is a hard ceramic having high strength over a broad temperature range, moderate thermal conductivity, low coefficient of thermal expansion, moderately high elastic modulus, and unusually high fracture toughness for a ceramic. This combination of properties leads to excellent thermal shock resistance, ability to withstand high structural loads to high temperature, and superior wear resistance. Silicon nitride is mostly used in high-endurance and high-temperature applications, such as gas turbines, car engine parts, bearings and metal working and cutting tools. Silicon nitride bearings are used in the main engines of the NASA's Space shuttles. Thin silicon nitride films are a popular insulating layer in silicon-based electronics and silicon nitride cantilevers are the sensing parts of atomic force microscopes.

Thank for Info : http://en.wikipedia.org

Pressure-sensitive adhesive

          Pressure sensitive adhesive (PSA, self adhesive, self stick adhesive) is adhesive which forms bond when pressure is applied to marry the adhesive with the adherend. No solvent, water, or heat is needed to activate the adhesive. It is used in pressure sensitive tapes, labels, note pads, automobile trim, and a wide variety of other products.

          As the name "pressure sensitive" indicates, the degree of bond is influenced by the amount of pressure which is used to apply the adhesive to the surface.

          Surface factors such as smoothness, surface energy, removal of contaminants, etc. are also important to proper bonding.

          PSAs are usually designed to form a bond and hold properly at room temperatures. PSAs typically reduce or lose their tack at low temperatures and reduce their shear holding ability at high temperatures; special adhesives are made to function at high or low temperatures. It is important to choose an adhesive formulation which is designed for its intended use conditions.

Thank for Info : http://en.wikipedia.org

Refractory

          A fire brick, firebrick, or refractory brick is a block of refractory ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency. Usually dense firebricks are used in applications with extreme mechanical, chemical, or thermal stresses, such as the inside of a wood-fired kiln or a furnace, which is subject to abrasion from wood, fluxing from ash or slag, and high temperatures. In other, less harsh situations, such as in an electric or natural gas fired kiln, more porous bricks, commonly known as "kiln bricks" are a better choice. They are weaker, but they are much lighter, easier to form, and insulate far better than dense bricks. In any case, firebricks should not spall under rapid temperature change, and their strength should hold up well during rapid temperature changes.


Thank for Info : http://en.wikipedia.org

Refractory metals

          Refractory metals are a class of metals that are extraordinarily resistant to heat and wear. The expression is mostly used in the context of materials science, metallurgy and engineering. The definition of which elements belong to this group differs. The most common definition includes five elements: two of the fifth period (niobium andmolybdenum) and three of the sixth period (tantalum, tungsten, and rhenium). They all share some properties, including a melting point above 2000 °C and high hardness at room temperature. They are chemically inert and have a relatively high density. Their high melting points make powder metallurgy the method of choice for fabricatingcomponents from these metals. Some of their applications include tools to work metals at high temperatures, wire filaments, casting molds, and chemical reaction vessels in corrosive environments. Partly due to the high melting point, refractory metals are stable against creep deformation to very high temperatures.


Thank for Info : http://en.wikipedia.org

Oil shale

Oil shale

          Oil shale, also known as kerogen shale, is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons called shale oil (not to be confused with tight oil—crude oil occurring naturally in shales) can be produced. Shale oil is a substitute for conventional crude oil; however, extracting shale oil from oil shale is more costly than the production of conventional crude oil both financially and in terms of its environmental impact. Deposits of oil shale occur around the world, including major deposits in the United States of America. Estimates of global deposits range from 2.8 to 3.3 trillion barrels (450×10⁹ to 520×10⁹ m³) of recoverable oil.

          Heating oil shale to a sufficiently high temperature causes the chemical process of pyrolysis to yield a vapor. Upon cooling the vapor, the liquid shale oil—an unconventional oil—is separated from combustible oil-shale gas (the term shale gas can also refer to gas occurring naturally in shales). Oil shale can also be burnt directly in furnaces as a low-grade fuel for power generation and district heating or used as a raw material in chemical and construction-materials processing.

          Oil shale gains attention as a potential abundant source of oil whenever the price of crude oil rises. At the same time, oil-shale mining and processing raise a number of environmental concerns, such as land use, waste disposal, water use, waste-water management, greenhouse-gas emissions and air pollution. Estonia and China have well-established oil shale industries, and Brazil, Germany, Russia also utilize oil shale.

          Oil shales differ from oil-bearing shales, shale deposits which contain petroleum (tight oil) that is sometimes produced from drilled wells. Examples of oil-bearing shales are the Bakken Formation, Pierre Shale, Niobrara Formation, and Eagle Ford Formation.

Thank for Info : http://en.wikipedia.org

Refractory anchorage

          All refractory require anchorage systems such as wire formed anchors, formed metal (for example, hexmetal) or ceramic tiles to support the refractory linings. The anchorage used for refractory on roofs and vertical walls are more critical as they must remain able to support the weight of refractory even at the elevated temperatures and operating conditions.

          The commonly used anchorages have circular or rectangular cross-section. Circular cross-section are used for low thickness refractory and they support less weight per unit area; whereas the rectangular cross-section is used for high thickness refractory and can support higher weight of refractory per unit area. The number of anchors to be used depend on the operating conditions and the refractory materials. The choice of anchors material, shape, numbers and size has significant impact on the useful life of the refractory

Thank for Info : http://en.wikipedia.org

High Temperature Insulation Wool

In the 1950s, the term “Refractory Ceramic Fibre” was coined for the aluminium silicate fibres developed at this time. On account of their chemical purity and resistance to high temperatures (classification temperature >1000 °C) as well as on the basis of their use in other applications, this definition was made to differentiate aluminium silicate wools from the conventional “mineral wools”. Because of the ambiguity of the term “ceramic” and the development of new materials for the high temperature range, the nomenclature was changed to High Temperature Insulation Wool (HTIW) at the end of the 1990s.

Basically, there are two types of inorganic HTIW. In addition to the more commonly used amorphous HTIW (Alumino Silicate Wool ASW/RCF and Alkaline Earth Silicate Wool (AES)), Polycrystalline Wool (PCW) is also available. Owing to the costly production and limited availability compared to mineral wool, HTIW products are almost only used in industrial applications and processes up to 1800 °C.

REFRACTORY CASTABLES

REFRACTORY CASTABLES

Refractory castables can be used to create the monolithic linings within all types of furnaces and kilns. They can be further classified into the following sub-categories: conventional, low iron, low cement, and insulating for installation either by gunning or manually. There is a wide variety of raw materials that refractory castables are derived from, including chamotte, andalusite, bauxite, mullite, corundum, tabular alumina, silicon carbide, and both perlite and vermiculite can be used for insulation purposes.

CONVENTIONAL DENSE CASTABLES

Conventional dense castables are created with high alumina cement, and can withstand temperatures from 1300^oC to 1800^oC. These refractory castables are great for common furnace applications, burner blocks, speciality muffle furnaces and oiler work. Resistance is a key quality that varies with the choice of materials, resulting in abrasion, thermal shock and slag attack. Casting and gunning techniques are the method of installing the materials. For the ease of castable placement, gunning materials and water are combined together at the gunning equipment’s nozzle. This is a great method of placement for bulk materials, in cases when circumstances make formwork overly time consuming or simply impractical. In general, the method of installation will depend on cost and accessibility.

INSULATING CASTABLES

Another product that we supply is the Refractory castables that are low density. These insulating castables pose very low thermal conductivity and are utilized for either high temperature face work or when used for a backup lining, which is found behind dense castables or brick work. Here, the insulating castables are able to decrease the lining’s overall density or the cold face temperature. Their strength, which ranges from low to medium, is based on the fact that their density is low and is the main reason that they are not resistant to abrasion. They are most suitable where they do not have to stand up to much wear and tear.

LOW CEMENT CASTABLES

This type of refractory castable is prepared with a lower amount of cement than the standard dense castable is normally created with. Low cement castable refractories fluctuate in alumina content, which provides exceptional physical properties, including low porosity, great abrasion properties and high vigour. These products will commonly necessitate installation that is controlled, however, the big advantage of low cement castables is that they are easily pumped into position, and some may not require vibration, because they are free flowing.

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