Aluminium silicate clay

A great variety of aluminium-silicate bearing rocks, plastic when wet, hard when dry. Used in pottery, stoneware, tile, bricks, cements, fillers and abrasives. Kaolin is one type of clay. Some clay deposits may include appreciable amounts of quartz. Commercial grades of clays may contain up to 20% quartz. 

Control shrinkage after moulding. Any filler will decrease shrinkage most commonly used are silica, clay, calcium carbonate, alumina, talc, powdered metals and lithium aluminium silicate. 

This term is applied to a wide variety of materials known chemically as hydrated aluminium silicates, used as inorganic fillers. China clay (kaolin) shows a slight reinforcing effect treated clays show considerably greater reinforcement. 

Clays are manufactured from naturally occurring hydrated aluminium silicates. The particles of clays are hexagonal shaped platelets. The particle diameter quoted for these materials is not a true diameter, but only an estimate derived from sedimentation analysis. 

The type of clays used by the rubber industry are known to the clay industry as kaolin produced from deposits of a hydrous aluminium silicate, known as kaolinite. 

During the Balkan war in 1910 the use of hydrated aluminium silicate in combination with other drugs reduced the number of casualties among soldiers as a result of cholera from 60 % to 3 %. Research has shown that primitive tribes in the Andes, Central Africa and Australia used several types of clay to cure poisonings. Apparently these people were sometimes in the possession of small lumbs of clay. A little amount of this was suspended in water and subsequently food was soaked in this clay liquid before consumption. They explained their behaviour by saying that it prevents a sick stomach . 

Kaolin or China Clay - a white powder hydrated aluminium silicate with good absorbent properties suitable for greasy complexions prone to acne. 

Commonly used fillers for epoxy systems are calcium carbonate, micas, silica, clays, powered metals, talc, wood flour, aluminium silicate etc. The properties imparted by fillers to an epoxy system are given in Table 2.4 (Dow Chemical Company, undated d). 

This is essentially hydrated aluminium silicates derived from natural deposits. There are soft clays, hard clays, calcined clays and treated clays. This is a common filler in the manufacture of acid resistant ebonites, natural soft rubbers and in Neoprene compounding for phosphoric acid duties. 

Aluminium, on the other hand, accumulates in the clay mineral fraction because it forms insoluble aluminosilicates and hydroxyoxides. The AI remains behind in the soil as other ions leach away. Iron also accumulates in soils but this is not apparent from Table 7.3 because the silicate clay minerals, with the exception of hydrous mica, are low in Fe. Iron precipitates in soils only as hydroxyoxides. Hydrous mica is altered parent material and is not reconstituted from the soil solution as are kaolinite, montmorillonite, and allophane. The <105° C water in Table 7.3 is, roughly speaking, adsorbed water the >105° C water is hydroxyl ions and water within crystal structures. 

The clay minerals are all hydrated aluminium silicates and possess a flaky habit, that is. they are phyllosilicates. The three major families of clay minerals are the kandites (kaolinite), illites (illite) and smectites (montmorillonite). 

The main inorganic thickeners used are silicas (pyrogenic, precipitated, aerogels), sodium aluminium silicates, and also certain clays (laponite or hectonite). 

Kaolin is a hydrated aluminium silicate of variable composition, derived from clay minerals. The main constituent is kaolinite, with the formula Al2O3.2SiO2.2H2O, usually accompanied by a variable amount of feldspar, quartz, mica or similar minerals. The structure consists of hexagonal sheets, with an aspect ratio of 10. Purification is required before use. 

RTP, based in Winona, MN, USA, was probably the first independent compounder to go into commercial production with nanocompounds. Most nanocomposites currently use nanoclay, although carbon nanotubes are becoming much more widespread. In the US, Southern Clay Products of Texas is a leading producer of nanoclays with products like Cloisite w hich are high aspect ratio additives based on montmorillonite, consisting of layered magnesium aluminium silicate platelets that have been surface treated to improve their compatibility with the polymer. 

Acidic refractories (e.g. silica, fire, clay etc.) These are used in areas where slag and atmosphere are acidic. They are stable to acids but attacked by alkalis. Aluminium-silicate refractories These refractories vary widely in their physical, chemical and mineralogical characteristics depending on the nature and proportion of silica and alumina present on them. 

Aluminium silicate AI2SI2O7 solid, infusible, unreactive, clay silicate... 

Mellor (Trans. Brit. Ceram. Soc., 8, 28, 1909) for that non-crystalline variety of the hydrated aluminium silicate-Al2O3.2SiO2.2H2O - which occurs in china clay and in most clays yet examined. Kaolinite is crystalline ciayite . When X-ray analysis was subsequently able to demonstrate the crystallinity of all the clay minerals except ALLOPHANE (q.v.), the term was discarded. 

Clay minerals are aluminium silicates of either the two-layered kaolinite type or threelayered montmorillonite type. Only three clay minerals are commonly used in the polymer industries, kaolinite, montmorillonite and chlorite, and these will be discussed below. Chlorite, because it usually occurs with talc and has essentially the same properties, is discussed with that mineral. Talc (magnesium silicate) is widespread but is commonly found with other magnesium minerals such as magnesite. 

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