Refractory Cements and Raw Materials Specifications

Help with Refractory Cements and Raw Materials specifications:

Material Type

	Refractory Aggregate / Fill
	Your choices are...
	Alumina / Aluminum Oxide		Alumina or aluminum oxide (Al2O3) is a compound that consists of aluminum and oxygen. Typically, it used in the alpha alumina structural form. In its pure form, alumina is a white ceramic material with high hardness. Fully-dense alumina can be translucent. Alumina is used widely because of its versatility and relatively low cost. Depending on its purity and density, alumina is used to make refractory tubes, industrial crucibles, analytical labware, dielectric substrates, wear components, refractory cements, and abrasives. Alumina’s main drawback is having relatively poor thermal shock resistance, which is due to its higher coefficients of thermal expansion and lower thermal conductivity compared to other pure ceramic materials, such as silicon carbide (SiC).
	Calcium Aluminate		Calcium aluminate (CaAlO3) refractories are usually derived from calcium aluminate, calcium, or alumina-bearing minerals.  Calcium aluminate is used in refractory cements and shapes, as well as synthetic slag additions for metallurgical operations.
	Silicon Carbide		Silicon carbide (SiC) is a compound of silicon metalloid and oxygen. Typically, SiC is used in the alpha silicon carbide structural form. Silicon carbide is a black, high-hardness ceramic that is usually harder than alumina. Depending on the addition of impurities, SiC may be green or black in color.  Fully-dense SiC can be transparent (moissanite).  SiC is used widely because of its versatility and relatively low cost. Depending on its purity and density, SiC is used in refractory tubes, industrial crucibles, wafer semi-insulating substrates, wear components, refractory cements, and abrasives. SiC forms a protective SiO2 skin that prevents further oxidation at very high temperatures in non-reducing atmospheres. Because of its low coefficient of thermal expansion and high thermal conductivity, SiC has a relatively high thermal shock resistance compared to other ceramic materials.
	Carbon / Graphite		Graphite has a carbon without a crystalline structure that is referred to as amorphous, vitreous, or glassy carbon.
	Magnesia / Magnesite		Magnesia ceramics or refractories are based on compounds that consist of magnesium and oxygen. Magnesite or magnesia refractories or minerals are also known as magnesium oxide, magnesium carbonate, dead burned magnesite, calcined magnesite, periclase, or magnesia clinker. Depending on the origin and processing, magnesia is divided into caustic, dead-burnt, fused, precipitated, sintered, or calcined and synthetic magnesia forms.   The high melting point (2800° C) and heat resistance (1700°C in the reducing and 2300° C in oxidizing atmosphere) of magnesium oxide make it suitable for the production of refractories. Magnesite is the naturally-occurring mineral or ore used to produce magnesium oxide based refractories. Magnesite often contains iron, manganese, or other activator elements. Magnesium oxide refractories with a carbon bond are frequently used in the steel industry. Magnesite refractories have good resistance to molten iron and steel.
	Silica / Silicate Materials		Ceramics are based on silica and silicate materials. Silica and silicates are compounds of silicon and oxygen. For dielectric applications, silicates are modified with magnesium and/or aluminum to provide sufficient dielectric properties. Cordierite and steatite are silicates that are commonly used in dielectric applications. High-purity, amorphous, fused silica is a high-performance ceramic with very low expansion, remarkable thermal shock resistance, low thermal conductivity, excellent electrical insulation up to 1000° C, and excellent resistance to corrosion from molten metal and glass.
	Zirconia		Zirconia or zirconium oxide (ZrO2) is a refractory compound of zirconium and oxygen. Zirconia may have additions of calcia, magnesia, or yttria for stabilization into a cubic structure. Zirconia stabilized in a cubic crystal structure avoids cracking and mechanical weakening during heating and cooling. Certain zirconia materials have the ability to transformation toughen (tetragonal to monoclinic phase change) under applied stress. They are often used in wear applications that require improved fracture toughness and stiffness over alumina.  Zirconia ceramics possess excellent chemical inertness and corrosion resistance at temperatures well above the melting point of alumina. Zirconia is more costly than alumina, so it is only used where alumina will fail. Zirconia has low thermal conductivity and is an electrical conductor above 800° C. Zirconia is used to fabricate oxygen sensors or fuel cell membranes because it possesses the unique ability to allow oxygen ions to move freely through the crystal structure above 600° C. Zirconia products should not be used in contact with alumina above 1600°C.  Depending on the purity and density, zirconia is used in refractory tubes or cylinders, industrial crucibles, analytical labware, sensors, wear components, refractory cements, thermocouple protection tubes, furnace muffles, liners, and high-temperature heating element supports.
	Other		Other unlisted, specialized, or proprietary ceramic types.
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	Bond / Binder:
	Your choices are...
	Calcium Aluminate Bond		Polycrystalline ceramics are aggregate-based refractories that use a calcium aluminate bond between individual grains or aggregates.
	Carbon Bond		Carbon bonds are used in high temperature carbon-carbon composites. Carbon bonds are often created by converting an organic or resin binder to carbon using heat and a controlled atmosphere. Organic or polymer resin binders hold carbon, carbide, or other ceramics together until firing.
	Portland Cement / CaSiO3 Bond		Portland cements, as well as some refractories, are based on calcium silicate. Calcium silicate (CaSiO3) refractories are usually derived from calcium silicate, calcium, or silicate bearing minerals such hornblende, epidote, and diopside, often with calcite or dolomite or wollastonite. Wollastonite is a naturally occurring form of calcium silicate that is commonly used as filler.   Portland cement, the fundamental ingredient in concrete, is calcium silicate cement made from a combination of calcium, silicon, aluminum, and iron oxide minerals. Clinker is a fused mineral mixture of limestone, shells or chalk and shale, clay, sand, or iron ore, which is crushed into a fine powder to manufacture Portland cements. Certain grades of cements may contain additions of fine aggregates of fumed silica, fly ash, or milled slag as well as chemical additives to improve strength, entrain air, reduce heat generation and cracking, or improve corrosion resistance to sulphates or other chemicals.
	Phosphate		Magnesium phosphate cement is a rapid setting, early strength gain cement. It is usually used for special applications, such as repair of pavements and concrete structures or for resistance to certain aggressive chemicals. It does not contain Portland cement.
	Silicate / Clay Bond		Polycrystalline ceramics or aggregate-based refractories use a silicate or clay bond between individual grains or aggregates.
	Slag Cement		Slag cement uses ground granulated blast-furnace slag (GGBFS) to replace a portion of the Portland cement in a concrete mixture; this creates a more consistent mix. Slag cements fall under the category of blended hydraulic cements with two types: Type S-slag cement and Type I (SM)-slag modified Portland cement. The blast-furnace slag content of Type S is between 25 percent and 70 percent by mass. Type S contains at least 70 percent slag by mass.
	Sulfate Bond		Sulfate-bond products are polycrystalline ceramics or aggregate-based refractories, cements or adhesives that use a sulfate or oxysulfate bond between individual grains or aggregates.
	Sulfur Bond		Sulfur cement melts at temperatures between 113° C and 121° C. Sulfur concrete is maintained at temperatures around 130° C during mixing and placing. The material gains strength quickly as it cools, and is resistant to acids and aggressive chemicals. Sulfur cement does not contain Portland or hydraulic cement.
	Other		Other unlisted, specialized, or proprietary bond types.
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Product Type / Form

	Your choices are...
	Cement / Binder		Cement refers to a mixture of binder and aggregate to form concretes or mortars such as Portland cement (calcium silicate), potassium silicate, or polymer cement. Sometimes, the term "cement" is used to describe mortars and other cement products.
	Coating / Thinset		Cement-based coating products are thin-set materials applied in thinner layers than liner products, mortar or concretes. The terms thinset cement, thinset mortar, dryset mortar ,and drybond mortar are synonymous.
	Concrete		Concrete consists of specialty cement or Portland cement and water mixed with coarse aggregate (e.g., gravel or crushed stone), fine aggregate or sand.
	Grout / Filler		Grout and caulk are types of sealants used to fill in gaps between tiles, bricks, or other components.
	Investment / Mold Refractory		Investment may consist of a refractory powder with plaster or phosphate binder that is cast around a lost wax pattern.  Investment may also consist of a ceramic slurry and powder that is coated onto a hanging lost wax, plastic or foam pattern.  Permanent molds are made from refractory, ceramic, or ceramic-coated metal molds. Plastic refractory cement can be rammed around a reusable pattern to form a permanent ceramic mold or refractory shape. Refractory aggregates are also used to build up a shell in the investment casting process.
	Liner / Lining System		Cement-based liners or lining systems are much heavier, or are applied in thicker layers than cement coatings or thinsets. Liners can be prefabricated or applied on site by pouring or pumping into forms or through gunning techniques.
	Mortar		Mortars consist of a mixture of a binder or clinker and a fine aggregate. They are used to bond together brick or other components in structural applications.
	Powder / Aggregate		Stock products are available in a particulate form such as a powder, grog, grain, or fused and crushed aggregate.
	Other		Other specialized, proprietary or unlisted concrete, mortar or cement-based product types.
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Setting / Cure Technology

	Setting / Cure Technology:
	Your choices are...
	Hydraulic Setting		Hydraulically-set bonds use the hydration reaction of a salt to form a bond. Portland cement and plaster of Paris are hydraulically-setting materials.
	Air Setting		Air setting or film drying materials form a bond or "harden" through evaporation of water or an organic solvent.  Inorganic binders or cements are sometimes air setting. Refractory or high-temperature air set types may develop strong bonds after firing.
	Chemical Setting		Binders or adhesives are set through a chemical reaction process. Silicates (sodium, potassium, ethyl, etc.) are commonly used as binders in foundry, refractory, and grinding wheel applications.
	Heat Setting / Thermoset		Heat setting or thermoset bond use an elevated temperature and/or pressures to set the binder. Thermoset resin binders are cross-linked polymeric resins that are cured using heat or heat and pressure. Cured thermoset resins do not melt and flow when heated, but they may soften. Phenolic, melamine and urea formaldehyde resins are thermosetting adhesives that offer strong bonds and good resistance to high temperatures.
	Hot Melt		Hot melt bonds can be repeatedly softened by heat and hardened or set by cooling, which allows parts to be removed or repositioned during assembly. Sulfur bond is an example of hot melt cement.
	Two / Multiple Component		Two or multi-component bond or binder systems consist of two or more resins or a resin and a hardener or catalyst, that when combined, react and cure into a polymerized compound or bond.
	Other		Other specialized, proprietary or unlisted technology types.
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Processing Specifications

	Set / Cure Time		The time required for fully curing or setting a bond system. In thermosetting, hydraulic, or other chemically setting system, the time will vary depending on the actual curing temperature.  Longer cure times will be required for lower curing temperatures.  In addition, the time required for fully drying an air setting product.
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	Set / Cure Temperature		The time required for curing a thermosetting system.  The temperature will vary depending on the actual curing time allowable. Higher curing temperatures will be required for lower cure times.
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	Shrinkage		The maximum percent of linear shrinkage occurring after drying, setting and/or curing.
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Thermal & Mechanical

	Max Use Temperature		This is the maximum temperature that the refractory or ceramic material can be exposed to momentarily, without the degradation of structural or other required end-use properties. The maximum use temperature is usually equal to the melt temperature of the metal, glass, or other material contained by the refractory body in the furnace, boiler or process unit. The Curie point is the temperature above which a material loses its unique magnetic, dielectric or piezoelectric property. Ferrites or other magnetic materials lose their unique magnetic properties above the Curie temperature. The relative permeability drops to a value below 0.1 above the Curie temperature. Magnetic susceptibility is inversely proportional to temperature.
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	MOR / Flexural Strength		Modulus of rupture (MOR), cross-break strength or flexural strength (3-point or 4-point) is the maximum flexural stress a bar can withstand before failure or fracture occurs. The bar is supported by two points beneath the bar and the load is applied by one or two points above the bar. Cross break strength is used to evaluate the strength of ceramics or other materials that do not provide sufficient plastic deformation to test tensile strength reliably.
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	Compressive / Crushing Strength		The crushing or compressive strength is the maximum compressive load per unit cross section that a ceramic body can withstand before mechanical failure or breakage occurs.
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Applications

	Applications:
	Your choices are...
	Ceramics / Glass Manufacturing		Materials provide resistance to molten glass, or are compatible with ceramics and glasses during firing, calcining or fusing in a kiln or furnace.
	Chemical / Materials Processing		Materials provide high temperature and/or corrosion resistance, making them suitable for chemical-processing applications.  Examples include ceramics or refractories with resistance to molten glass, ceramics, metals, plastics or other materials during milling, firing, calcination, fusion or other processes.
	Construction & Building / Architectural		Materials are designed or suitable for use in architectural, building, and construction applications. Examples include bricks, fire bricks, or tiles.
	Flooring		Materials are suitable for flooring or floor-tiling applications.
	Foundry / Metal Processing		Materials are designed for foundry and metal-processing applications. Examples include ceramic and refractory crucibles, tubes, stoppers, liners, spouts, permanent molds, thermocouple protection tubes, combustion gas heater tubes, submersible heater tubes, die casting stalks/sleeves, and other furnace components are used in foundries for melting and casting aluminum, steel, copper alloys or other metals.
	Refractory / High Temperatures		Refractory and high-temperature materials are hard, heat-resistant products such as alumina cement, fire clay, bricks, precast shapes, cement or monolithics, and ceramic kiln furniture. Ceramic refractories have high melting points and are suitable for applications requiring wear-resistance, high temperature strength, electrical or thermal insulation, or other specialized characteristics.
	Structural		Structural applications require ceramic components with a suitable strength, elastic modulus, toughness, and other mechanical properties. Ceramics can have much higher compressive strengths and elastic moduli compared to metals.
	Thermal Insulation / Fire Proofing		Thermally-insulating ceramics and refractories provide a thermal barrier between components and a hot or cold source. These ceramics and refractory shapes are also useful in providing flame protection and fire-proofing between a burner and the surrounding environment, or between combustion and oxygen sources.
	Walls		Materials are suitable for use on walls.
	Other		Other unlisted, specialized or proprietary applications.
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Features

	Features:
	Your choices are...
	Castable		Products can be poured into a form or cavity to fabricate a refractory liner or component. Some castables may not be pumpable.
	Fiberboard / Fiber Reinforced		Fiberboards, fiber-based, or fiber-reinforced products include ceramic boards, cylinders or shapes that contain ceramic or mineral wool fibers to improve structural integrity or insulating characteristics.
	Gunning / Shotcrete (e.g., Gunnite)		Gunning mixes are cements or powdered products that are loaded with a gun into a form or onto a wall to fashion a cement wall or layer. Dry or wet gunning mixes are available.
	Porous / Foam		Porous ceramics have a large degree of open or closed internal pores that provide a thermal barrier. Certain ceramics have intrinsically low thermal conductivity, even in dense forms.  Reticulated foam refractories are useful in filtering molten metals and providing an extremely low density structure for insulation or other applications.
	Ramming		Both dry rams (vibratables) and wet mix rams are available. Wet rams are cement based products with enough plasticity to allow the wet mix to be rammed or formed into place in a furnace or in a form. Ramming material has a clay-to-putty like consistency.  Rams generally have lower water content and less plasticity than moldables.  Dry rams are supplied as a dry powder that is applied and fired in place. Silicate, phosphate or other binders are activated upon firing. The dry refractory powders or aggregates are tamped or rammed into the floor or vibrated into place between the furnace wall and a removable furnace "former." On smaller furnaces, a former less method is used where a unit is filled with dry refractory powder, fired and then the excess unfired refractory is removed for reuse. Some dry refractories are also called dry rams or dry ramming cements.
	Troweling / Patching		Troweling cements have good plastering or palming characteristics to allow the refractory to be applied by hand or rammed into place. Moldable cements usually have more water and a higher degree of plasticity than rams. Moldables or plastic cements are used to patch or form precast shapes. Patching, repair or finishing cements consist of mixtures designed for repairing crack or filling holes in refractory linings.  Some patching or repair cements may be pumpable for caulking of cracks. Other patching cements have good troweling, plastering or palming characteristics to allow cracks to be applied by hand. Finishing cements are used to make a harder finishing refractory layer on the surface of an existing refractory.
	Waterproof / Underwater Setting		Waterproof mortars, concretes or cements are not affected by exposure to water or submersion under water.
	Specialty / Other		Other unlisted, specialized, or proprietary material features.
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