Steatite ceramics

Vickers hardness determination with correction for degree of brittleness and converted to hardness classes, compared with quartz grain dynamic abrasion hardness, for example, of microcrystalline steatitic ceramics... 

Essing H-G, Buhlmeyer G, Valentin H, et al. 1976. [Exclusion of disturbances to health from long years of exposure to barium carbonate in the production of steatite ceramics], Arbeitsmedizin Sozialmedizin Praventivmedizin 11 299-302. (German)... 

Most steatite ceramics are either dry mixed and pressed, or wet-mixed, spray-dried and pressed, but they can also be wet-mixed and extruded. Typical firing temperatures lie close to 1300 °C. Many small parts are made for the electronics components industry where low dielectric losses are required, for example for tie-bars and other parts for ganged capacitors, small trimmer capacitors, high-power capacitors (see Section 5.6.3), coil formers, lead-throughs and substrates for... 

Despite this potential instability, steatite ceramics have been widely used and adequate precautions in manufacture have prevented all but a very few cases of deterioration during component lifetimes of many years in a wide variety of environments. 

The inversion of protoenstatite to clinoenstatite involves a change in volume of 2.8% which would bring about a loss in mechanical strength in steatite ceramics. Protoenstatite in steatite ware is stabilized by the vitreous phase. A similar effect is exhibited by 1—2 mole % of MnSi03 in solid solution. 

The properties of steatite ceramics are listed in Table 25, together with those of the other materials. 

Porcelain ceramics steatite ceramics ceramics ceramics (80%TiO2) alumina (98% AI2O3) (5% CaO, 2%Hf02)... 

The diagram indicates that the mixes for the manufacture of steatite ceramics lie away from the theoretical composition of enstatite, which is a binary phase in the system MgO —Si02- The maximum enstatite content should be attainable through... 

According to Figure 4.22, what phases are present in steatite ceramics and cordierite ceramics [Note answer is not provided at the end of this book.]... 

Enstatite. Magnesium metasilicate MgSi03 m.p. 1550°C. Enstatite (orthorhombic) is stable up to about 1050°C when it inverts to proto-enstatite (orthorhombic) which is the stable high temperature form. Clino-enstatite (monoclinic) is formed as a metastable phase when proto-enstatite is cooled rapidly the transition temperature is 865°C. Thermal expansion (300-700°C) enstatite 12 x 10- proto-enstatite 10 x 10- clino-enstatite 13.5 x 10-, Proto-and/or clino-enstatite are major constituents of steatite ceramics clino-enstatite is found in magnesite refractories that have been attacked by siliceous slags. 

FIGURE 2.8 Dielectric constant and tan S for a steatite ceramic over a range of temperatures and frequencies. ... 

Talc, unlike Che micas, consists of electrically neutral layers without the interleaving cations. It is valued for its softness, smoothrtess and dry lubricating properties, and for its whitertess, chermcal inertness and foliated structure. Its most important abdications are in ceramics, insecticides, paints and paper manufacture. The more familiar use in cosmetics and toilet preparations accounts for only 3% of world production which is about 5 Mt per annum. Half of this comes from Japan and the USA. and other major producers are Korea, the former Soviet Union, France and China. Talc and its more massive mineral form soapstone or steatite arc widely distributed throughout the world and many countries produce it for domestic consumption either by open-cast or underground mining. 

Figure 9-3. Bell and spigot ceramic tower. Used by permission of General Ceramics and Steatite Corp.

Until recent times, Rockwell hardness testers, equipped with a diamond cone with included angle of 120°, were used for hardness determination of sintered microcrystalline ceramics of alundum type (alumina ceramics) or of steatitic type. Tests conducted by Palushkin (1961) showed (Table 5.4)... 

The hardness parameters specified in Table 8.1 apply to glazed bodies whose hardness is usually 0.16-0.25 degrees on the Mohs scale lower than that of unglazed material. The 7-8 hardness interval for porcelain materials given by many authors is incorrect. It is specific to materials ranked under special ceramics of steatitic or mullite-corundum type (Tables 4.4.4, 5.6, 5.7). 

Ceramic dielectrics and insulators cover a wide range of properties, from steatite with a relative permittivity of 6 to complex ferroelectric compositions with relative permittivities exceeding 20000. For the purposes of this discussion insulators will be classed with low permittivity dielectrics, although their dielectric loss may be too high for use in capacitors. Reference should be made to Table 5.10 and Fig. 5.40. 

Ceramic Cordierite Steatite Silicon Carbide 1400 F 50 High temperature. Flexible. Energy efficient Prone to contaminants... 

Ceramic Air Cooled Steatite 1200 F 50 Cost, High temperature Cooling. Efficiency... 

Steatite is a magnesium silicate ceramic body used as insulation in high- frequency equipment. The data given are abstracted from the paper by Norton (reference 2). 

The technology now exists to extrude catalyst supports directly in the OCFS form from any extrudable matrix. Thus in addition to standard support ceramics—cordierite, steatite. 

The use of trace element analysis to determine the provenance of archaeological materials has expanded rapidly in the last decade. It is now a well-established technique for the identification of obsidian source deposits (J), and is nearly as established for turquoise (2), steatite (3), and some ceramic materials (4). Native copper has received much less attention. Friedman et al. (5), Fields et al. (6), and Bowman et al. (7) used trace element analyses to determine the type of geological ore from which copper was extracted. However, only our efforts (8) and the work of Goad and Noakes (9) have focused on collecting and analyzing native copper from all potential deposits of a given region to provide a data base for statistical comparison with artifact trace element compositions. 

The main representatives of this group are steatite, cordierite and forsterite ceramics. The prevailing crystalline phases in these materials are the minerals enstatite, cordierite and forsterite, which are also responsible for the main properties. All the materials find use in electrical and electronic applications where their insulating ability, as well as further specific properties are exploited. These are ... 

In nature, it occurs in crystalline or massive varieties. The former are more distinctly laminar and cleavable. During ceramic processing, they exhibit a certain plasticity, but at the same time show a tendency to preferential orientation of flakes which results in non-uniform firing shrinkage and subsequent formation of harmful stresses. The massive varieties (called steatite or block talc) do not have this disadvantage. 

Bricks, standard and specially shaped building blocks Naphthalene (moth) balls, / ara-chlorobenzene, chlorine cleaning tablets, swimming pool chemicals Disposable cutting tools, intricate components, steatite balls, capacitors, carbon contacts and diaphragms, metal ceramics, oxide ceramics... 

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