Objects ceramic

Deteriora.tlon. Ceramic objects are fragile, and mechanical damages through breakage and abrasions are the most likely source of destmction. Low fired ceramics can suffer through the rehydration of the body material this process results ia a complete loss of mechanical streagth. The preseace of soluble salts ia porous ceramic bodies has the same disastrous results as ia stoae (136). 

They are utilized for home use to repair broken rubber, metal, and ceramic objects. They can even be used to bond plastics, with the use of an appropriate primer. A few of the home applications include ... 

Primary clay is also known as residual clay, indicating that they are either the in situ residue of one type of weathered rock or the transported residue of many types of rocks most primary clay deposits occur, however, in situ, at the location where the clay particles were formed. The clay is usually quite pure and colorless or white, but very small relative amounts of minerals mixed with the clay, such as quartz and/or iron oxides, may impart to it a yellow, brown, or green color. Primary clay is also characterized by the extreme fineness of its particles, which usually measure below 2 micrometers (0.002 mm) in diameter. The more than 20 different types of primary clay minerals can be distinguished by their chemical composition, which varies widely, and by their physical properties. Primary clays that have been used for making ceramic objects are listed in Table 55. 

The generic name used to refer to ceramic objects shaped from a wet mixture of clay and fillers that is then dried and subsequently fired at high temperatures is pottery. Making pottery involves a number of working stages ... 

The surface of fired pottery is generally porous and readily absorbs moisture. To conceal outside imperfections, decorate the surface, and make the pottery more or less impervious to water and other liquids, many ceramic objects are glazed, that is, coated with a thin layer of glaze (Tite 2004). The nature of glaze and the glazing process are discussed in Chapter 3. 

In the present paper, attention is focussed on a particular class of ceramic objects - incensarios or paraphernalia used in the ritual burning of incense. In attempting to determine a... 

Obviously religion is also a part of a culture and many ceramic objects were used in religious ceremonies. The idea of an afterlife was common in many religions. Clay vessels containing food for the long journey to this afterlife were placed in the dead person s grave, as were implements and utensils. 

Ceramic objects are only rarely processed chemically an example is the making of microscope slides. 

A coating is applied to improve the surface properties. After sintering the surface of a clay ceramic object is dull, chemically instable, not very porous, nor wear resistant and it does not present an aesthetic... 

In practice, tensile tests on ceramic objects are hardly ever done because it is difficult to clasp them between the jaws of the testing equipment. The object is damaged by the jaw and a crack is very likely the result and this could be the place where the sample will break. The price of the test dumbbells is also a drawback of this type... 

Fig. 9.34 Four- and three-point bending test of a ceramic object.

Ceramic raw materials are powders. Together with a mixture of additives these powders are moulded into a particular shape and subsequently dried and baked. After the baking or sintering process it is possible to apply a finishing coat if necessary and then the ceramic object is ready. The entire route from raw material to finished product was elaborately discussed in chapter 9. 

A flexible ceramic foil with 15-20 mass % organic binding agents is placed between two ceramic objects. Next all of this is sintered and at the same time compressed. The foil must share properties with the ceramic material with which it is to be sintered and it should be possible to sinter it at considerably lower temperatures than the components which are joined. The method can for instance be applied when the ceramic object must be composed of more than one piece. 

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