Ceramic(s)

the designation ceramic(s) originates from the oldGreek. „Keramos “was the name for clay/tone and the formbeständigen products made of it by burning. The production of ceramic(s) belongs to the oldest agricultural engineerings of mankind. Their oldest useseems to have taken place with semi established hunter cultures in the area upper Nile. Their enormous spreading owes it however originally to the extended possibilities for the keeping (supply attitude) of food like it with the Neolithikum necessary was. Ceramic(s) plays a substantial role inFramework of the Determination of neolithischer cultures. The raw material clay/tone offered however already very early also incentives to artistic organization. Since many decades ceramic(s) in technical applications attained great importance.

This article describes the raw materials, for the production ceramicallyConstruction units to be used and - limits essentially to non-technical ceramic(s) - their dressing to actual ceramic(s). Further information about ceramic(s) is in the articles porcelain, technical ceramic(s), glass ceramic, sanitary ceramic(s) and group ceramic(s) as well as in on the left ofthis article and the following article

table of contents

term and partitioning

today is more broadly calm the term. Ceramic(s) are large from inorganic, fine-grained raw materials under Wasserzugabeat ambient temperature formed and thereafter dried articles which become during a following fuel process above 900 °C hard, more durable articles. The term includes also materials on the basis of metallic oxides. Ceramic(s) becomes today in the increasing measure for high-technical targeted applications,e.g. during sintering, used. Strict systematics of ceramic(s) - as for example with metal alloys - are hardly possible, because there are flowing transitions regarding the raw material composition, the combustion and the organization process. Ceramic products become therefore frequently after thatin each case in the foreground of the view standing aspects, z differentiated. B. after regional ceramic(s) types such as Westerwälder ceramic(s), Bunzlauer ceramic(s) or also Majolika and faience. At technical ceramic(s) the organization takes place after the used raw materials.

Common is also the partitioningin rough and fine ceramics. To the first the large group of the structural ceramics belongs (for example building and roofing tile, Kanalisationsrohre); these products are thick-walled, frequently inhomogenous, from often coincidental colouring. Fine ceramics is fine-grained against it (grain size under 0.05 mm), from more definedColouring (for example knows for household ceramic(s), table table-ware and sanitary ceramic(s)); here also the artistic products belong. Fine ceramics requires a substantially larger care than it concerning dressing of the base dimensions, the shaping and drying as well as burning with the production of coarse ceramicsis necessary. The characteristics of ceramic products certainly by kind and quantity of the crystals contained in them and the glazings functioning as connection (so-called glass phases). Ceramic(s) are formbeständig, taste and odorless, very hard and heatproof.

ceramic raw materials

Silicat raw materials

this range generally covers all raw materials, which [SiO 4] 4 - tetrahedrons in the crystal structure built.

standard of mineral mixtures

clay/tone

clay/tone is an aqueous aluminium silicate. See also clay mineral. Onedifferentiates between primary clay/tone and secondary clay/tone.

The selection and mixture of the raw materials must meet the following demands: Good mouldability of the mass, small decrease when drying and burning, high stability when burning, small or no discoloration of the final product.

Kaoline

Kaolin, also porcelain earth mentioned, is a decomposition product of feldspar. It consists to a large extent of Kaolonit, a hydratisierten mixed crystal of aluminum and silicon oxide, accompanied by quartz sand, feldspar and mica. Latter impurities are removed by dredging and sieving, thatFinal product must as plastic as possible, with drying form-stably and after burning knows to be. For the achievement of the desired characteristics Kaoline of different origin are mixed; in order to achieve a good casting behavior, one admits still plasticizing means, like water glass and/or soda .

clay/tone minerals and their mixtures

clay/tone, loams are likewise decomposition products of the feldspar and related minerals. The main parts are Illit, Montmorillonit and Kaolonit, the grain size are down enough up to 0.002 mm. Depending upon intended purpose one partitions these raw materialsin stoneware clay/tone, to stoneware clay/tone, pot-sound and - loams. Mergeltone have a high content of lime, which works strongly liquefying. Since to such pieces of broken glass lead and Zinnglasuren stick very well, they are used frequently for tiles and tiles. Bentonite are already a decomposition product of volcanic origin, it during the drying process with small additions very strongly plastifizierend the mouldability and the stability work, improve. From the high water absorption of the Bentonite during the shaping process, an enormous shrinking already results during drying. By thoseenormous drying shrinking comes it to tears in the fresh product

Nichtplasti raw materials

of feldspars is in the comparison to the lime likewise good fluxing agents, which cause a higher compression of the products however with rising firing temperature. The drying decrease is reduced, the decreasewhen burning rises however. Quartz lowers the drying and fuel decrease as lean means, however the plasticity worsens. Quartz is used as purify-granular sand or as gemahlenes course rock, it must be as pure as possible, in order to avoid unwanted discolorations. Lime becomes as dredgedChalk or as gemahlener limestone assigned. As lean means it supports the inherent stability with drying, when burning works it as fluxing agent. However lie together its sinter and its melting point close, with to high firing temperatures therefore exist the danger of deformations. Refractory clay, when gemahlener burned clay/tone or Tonschiefer is, a lean means, which the porosity increased and which reduces drying and fuel shrinking. Magnesium minerals (talcum powder, magnesite) lend a high temperature change firmness to the products; they are used preferentially for electrotechnical products.


it concerns

oxidic raw materials with in the following the specified oxidic raw materials ceramic(s), which are in many technical applications of technical ceramic(s).

alumina

alumina ceramic(s) 2 O 3, that are based on α-aluminium Corundum. They serve as sharpening and polishing agents. Of sintered corundum fireproof devices can be made.

magnesium oxide

beryllium oxide

from sintered beryllium oxide (BeO) crucibles for chemical reactions are manufactured at very high temperatures. Because of of thehigh price and Giftigkeit it is used not much.

zircon oxide

aluminum titanate

Nichtoxidi raw materials

also with in the following the specified not-oxidic raw materials concerns it ceramic(s), itself in many technicalApplications (see technical ceramic(s)) to have interspersed.

silicon carbide

silicon carbide (SiC) is used particularly as abrasive and in sliding bearings of chemical pumps, since it is very hard as well as thermally and chemically resistant. Further uses are rings in axial face seals.

The most important production (oh on procedure) comes from quartz sand and coke with 2200°C after:

SiO 2 + 3 C → SiC + 2 CO

you is comparably the reduction from quartz to raw silicon, it becomes however a surplus of carbonused. For better shaping the production from melted silicon and carbon is suitable. Here has itself charcoal, which was brought before on the correct form worked satisfactorily. Silicon can be taken up and be reacted by the pores then to SiC. It developsa special form of the silicon carbide, which so-called SiSiC, in which still some per cent of not reacted silicon are, which affects the Korrsionsbeständigkeit negatively.

In nature SiC is found only rare. It is then called Moissanit.

silicon nitride

aluminum nitride

boron nitride

is there boron nitride (BN) with standard conditions similar to graphite developed and beyond that is very temperature steady (it reacts only with 750°C with air), it is suitable as high temperature lubricants. Thosediamond-similar modification Borazon is after diamond the hardest material.

One can derive the hexagonal crystal structure, if one replaces the coal materials with graphite alternating by boron and nitrogen. Differently expressed it consists of levels of Borazin condensed at all sides - rings.Boron nitride is not electrically conductive like graphite, since the electrons are more strongly located at the nitrogen atoms.

With 60-90 kbar and 1500-2200°C is converted BN into cubic Borazon, which crystallizes in zinc blende structure similar to diamond. Borazon is similarhard like diamond, but oxidation and therefore as abrasive one uses.

boron carbide

boron carbide (B 13 C 2) is a further very hard material (in third place after diamond, and Borazon). It becomes as abrasive for armour-platesand sand jet nozzles uses. The production takes place with 2400°C from B 2 O 3 and carbon.

tungsten carbide

metallic-ceramic raw materials

other additives

organic Plastifikatoren are for example glue, waxes, gel, Dextrin, Gummiarabikum, paraffin oil. They improve the mouldability and burn with the fuel process. Feingemahlene burning out means such as sawing and cork flour, strength, coal dust make porous for the pieces of broken glass and easy and can produce interesting surface effects; they burn likewise with the fire.

dressingthe raw materials

in the industriellen ceramic(s) production the components, after they were partly before-burned, become fine according to the prescription together in attrition machines husbands. After dredging under addition of water this is removed again to a large extent in Filterpressen. The filter cake staying becomesdried and again husbands. In this form the base dimensions either one stores or one kneads immediately under addition by water and liquefying auxiliary materials in machines and if necessary. aired out. Besides the dry dressing has with that in recent time the halfwet andindustriellen production meaning won. In the Töpferwerkstatt partially this very day this process is accomplished in aufwändiger manual work. Since grinding mills are not often available, great importance is attached to dredging. The homogenization of the mass was reached in laborious kneading work,today for it usually machines are available. A goal is it, as homogeneous a one as possible to produce supple and nonporous work mass.

the shaping

the shaping takes place with coarse ceramics among other things via extrusion (for example pipes and bars) or throughCompression moulding. Fine ceramics is formed (similar to the historical development) by the following procedures:

the casting process
  • modelling
  • structure work from individual strands (e.g. with hollow containers)
  • tricks of rotationally symmetric hollow containers on the Töpferscheibe
  • pouring highly liquid mixtures into divided gypsum hollow forms, those the water absorb
  • shaping on motor drivenDisks in hollow forms by templates (so-called. The halfdry and
  • the dry shaping meaning attained
  • a pivoting
  • and

finish turns) presses and stamping machines or milling injection moulding foil pouring industrialist, because the drying times are very much shortened and a high accuracy to size of the productsone reaches.

Ungarischer Keramiker beim Arbeiten mit der Töpferscheibe
Hungarian Keramiker when working with the Töpferscheibe

drying

after the shaping is damp the blank by

  1. mechanically included water in the cavities
  2. physikochemisch bound water (adhesion, Kapillarwasser)
  3. chemically bound water (crystal water)

The drying speed depends except of the surrounding climate strongly on the prescription of the base dimensions. In order to keep the drying speed low for the avoidance of tears, the blanks can be taken off. Industrially drying takes place in air-conditioned areas. UnderNo. 2, in particular however under No. 3 water mentioned is however only driven out by the fire.

the three stages of drying

  1. leather-hard: The pieces of broken glass it cannot any longer be deformed however still as much humidity possesses thatone it to decorate can.
  2. Air-dry: The pieces of broken glass delivers at ambient temperature no more humidity and feels coolly.
  3. Fuel hoar frost: The pieces of broken glass feels no longer coolly, but proves than conditionally absorbent. (Attempt: Tongue remains onPieces of broken glass stick.)

the fuel process

the fuel process (rough or Schrühbrand) - sinters mentioned - and requires a careful control is very problematic. In so developing „pieces of broken glass “are felted with one another the crystals and cemented by glassy portions. Portion andThe characteristics of the burned property determine kind of the crystal and glass phase as well as the pores. The applied temperatures (until approximately 1350 °C; with special ceramic(s) also substantially more highly) depend on the raw mixture, thus on the product which can be produced and must inmany cases during the fuel process to be varied (temperature distribution). Besides it is frequently important that the process temporarily runs under reducing atmosphere (e.g. Avoid from yellow colouring by iron impurities with white table-ware or with sanitary ceramic(s)). Are used chamber, tunnel, Ringöfen. Forthe crafts enterprise electrical furnaces are applicable or with fossil fuels beaconed furnaces. Here is to differentiate between open systems, with those the gaseous fuels (with different flaming guidance) into direct contact with the commodity step and Muffelöfen, with those the gaseous fuelsthe fuel property indirectly heat up.

glazes

glazes are thin, glasslike coats, which fulfill two substantial demands. On the one hand they make the porous clay/tone body waterproof and give it a surface which can be cleaned easily. On the other hand they make a varied possible,decorative organization of ceramic(s). Glazes can be colored, transparency or covering, shining, halfmatte or matte. They can softly and low melting (max. 1000 °C) or hard and highly melting (over 1200 °C) its. After its chemical composition one can e.g.between Borosilikat, feldspar, salt and lead containing glazes differentiate. The glazes become frequently (e.g. Clay/tone goods) only after the Schrühbrand of the commodity applied (, syringes, brushes, stamps dip) and during a renewed fuel process (smooth fire), which must lie however below the firing temperature of the blank,glassed.

orienting organization of ceramic masses

Orientierende Übersicht
orienting overview

1 earthen property

  • alumina and/or. Kaolin and. if necessary. Quartz u./o. Feldspar, lime. Porous, translucent, crystallized pieces of broken glass.

1,1 structural ceramics

  • not fireproof. Clay bricks, shaped bricks (1.200 ··· 1.350 °C), clinker, drainpipes (1.000 ···1.150 °C), roofing tile

1,2 refractory mixtures

  • of firebricks for herd, furnaces (1,300 °C). Sillimanit, magnesite, among other things to the lining of industrial furnaces in the iron and the cement industry (1,500 °C)

1,3 other earthen property

1.3.1 stoneware

  • of pure-white to elfenbeinfarbener, porous pieces of broken glass with more transparentGlaze. Rough fire 1.150 ··· 1.250 °C; Glaze baking >960 °C, but below the temperature of edge of robbery; usually shining through or colorless.

1.3.1.1 lime or yielding A PROPERTy

  • clay/tone, kaolin, quartz, lime. Firing temperature 1.120 ··· 1.150 °C. Particularly for Unterglasurmalerei suitably.

1.3.1.2 feldspar or hard stoneware

  • clay/tone, kaolin,Quartz, feldspar. Firing temperature 1.220 ··· 1.250 °C. Nonfreezing wall slabs, sanitary article, table-ware.

1.3.1.3 mixing A PROPERTy

  • clay/tone, kaolin, quartz, lime, feldspar. Wall slabs, table-ware.

1.3.2 clay/tone goods

  • fluxing agent realms clay/tone, to 40% lime

1.3.2.1 unglazed clay/tone goods

  • yellow to red burned weatherproof ceramic(s). Terrakotta (addition ofRefractory clay or Ziegelmehl); Figures, customs and Ziergegenstände, flower pots.

1.3.2.2 glazed clay/tone goods

1.3.2.2,1 Majolika

  • a reliable differentiation between Majolika and faience is not possible, because these designations in the literature are alternately used. Originally: Colored porous pieces of broken glass with obscure colored glaze.

1.3.2.2,2 faience

  • a reliable differentiation between Majolika and faience is not possible, because these designations in the literature are alternately used. Originally: White, yellow-grey or light red-brown, porous pieces of broken glass, white covering glaze.

1.3.2.2,3 other pottery

  • of white, ochers to red-brown porous pieces of broken glasswith matte, silky fracture. Firing temperature 1.000 ··· 1.200 °C. By hand (Töpferscheibe, casting process) or by means of press formed clay/tone goods. Table-ware, Gerätschaften for house and garden, Zierkeramik.

2 sinter things

  • alumina and/or. Kaolin and. gff. Quartz u./o. Feldspar, lime. Nichtkristallisierte close masses, notor only at the edges shining through, high firmness

2,1 stoneware

  • close, not shining through. Pieces of broken glass also colored usually however brightly.

2.1.1 rough stoneware (not white-burning)

  • firing temperature 1,100 to 1.400°C. Frequently loam or approach glaze. Clinker, tiles, troughs, Kanalisationsrohre, containers for the chem. Industry.

2.1.2 purifying A THINGs (knowing or lightburning, similarly the porcelain)

  • clay/tone, quartz, feldspar. Firing temperature 1,250 to 1.300°C (common rough and glaze baking). Porcelain-similarly. Table-ware, sanitary article, chemical devices, mosaics, Ziergefässe. Transition form to the porcelain: Porcelain property, half porcelain, Vitreous China.

2,2 porcelain

  • hard porcelain: More closely transparent pieces of broken glass. Kaolin,Quartz sand, feldspar. Rough fire 900°C, glaze baking 1.400°C. A similar composition

has customs and Ziergeschirr soft porcelain however a lower temperature for the glaze baking. Preferred for Zierplastiken.

3 ceramic special estates

3,1 high temperature special estates (also mixing ceramic(s) called)

  • high-fireproof oxide ceramics with small added different metals. Tenacitythe metals is here united with the corrosion resistance and refractoriness of ceramic(s). Use as turbine blades or as cutting tools.

3.2 electrotechnical special estates

As Coarse ceramics the classes 1.1 become; 1.2; 2.1.1 designates. All different rank among the fine ceramics: Selected raw materials, careful dressing of the mixtures, aufwändigere shaping, z. T. by hand, z. T.

see also

Literature

  • small encyclopedia technology, bibliographic Institut, Leipzig, 1972
  • Lueger encyclopedia of the technology, here “materials and testing of materials - bases” (four volumes), Rowohlt paperback publishing house, Reinbek, 2003, ISBN 3499190087
  • P. Rada: The technology of ceramic(s), Dausien 1989, ISBN 3-7684-1868-5
  • Sven Frot: Dtv Atlas ceramic(s) and porcelain, Munich 2003, ISBN 3-423-03258-8

Web on the left of

  • Milan ceramic(s) in Münster (pottery homepage with detailed examples and pictures to different techniques in ceramic(s), porcelain and Raku, inclusive Video over the Raku Brenntechnik)
  • pottery Jürgelwith Dresden (much information for the probably oldest still producing pottery of Germany as well as an extensive background knowledge about ceramic(s) emergence expect you here.)
 

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