Porcelain bodies

The oxychlorination reaction is very exothermic and the catalyst is very active, which makes it necessary to mix the catalyst with an inert diluent to avoid overheating in a fixed-bed reactor. A low surface area, spherically- or ring-shaped alumina or chemical porcelain body can be used as a diluent with the ring-shaped catalyst. The density of the inert material should be similar to the catalyst to avoid segregation during loading, and the size should be slightly different to allow separation of the inert material from the spent catalyst. 

Table 18.12 Some typical values for the physical and mechanical properties of available stoneware and porcelain bodies...

Figure 4.9 Possible mineralogical constitution of Jingdezhen porcelain bodies. Average composition of four types of raw material are marked (Pa, Pk, Ka, Kk), and the approximate compositions of Chinese porcelains from four periods 1 = predominantly 10th to 12th Century AD 2 = 12th to 13th Century AD 3 = predominantly 14th Century AD 4 = post-17th Century AD. (From Pollard and Wood, 1986 Figure 10.7, with permission of Smithsonian Institution Scholarly Press.)...

Quartz 100.0 Average composition of Tianqi Porcelain body ... 

Fig. 8.3. Dependence of mean Mackensen-Mohs hardness on degree of sintering of porcelain body. (After A. Szymanski, 1972)...

A. Szymariski (1972) tested the hardness of porcelain bodies sintered at various temperatures, in the 1475-1713 K range, and demonstrated the existence of a correlation between the mean Mackensen-Mohs hardness and the degree of porosity of a body, determined on polished sections with an Opton analysing microscope, and also the sintering contraction due to sintering determined using the Leitz-Wetzlar heating-microscope (Fig. 8.3). The above tests were carried out on porcelain body samples collected... 

After the ceramic has been sintered, it must be cooled to room temperature and removed from the kiln. This cool-down can be very important to warping and cracking because the temperature gradient in the ceramic piece can cause stress to build up. In some cases, the sohd undergoes phase transformations during cool-down. If these phase transformations incur large changes in molar volume, then they can cause stress to build up. Such a problem occurs in the cool-down of porcelain bodies which contain the phase crystoballite. 

FIG. 222. St ress development on cooling glazed bodies (a) expansion of glaze and porcelain bodies A,B ib) stress developed on cooling ffroni Klngery, 1960). 

Figure 4. Dental porcelain furnace (a), green (b), and sintered (c) porcelain body [5]...

Fine ceramic industry silicate ceramic (clay ceramic) fine ceramic bodies, e.g. porcelain bodies 100 20 2-40 slugs for tableware ceramics, wall and floor tiles... 

The effect of natural zeolite addition on the electrical properties of porcelain bodies were investigated between 50 °C < T< 600 °C [10D2]. The addition of zeolites increases the resistivity of the samples at 50 °C and decreases the resistivity at higher temperatures. The resistivity depends on sintering temperature. The activation energy of electrical resistivity of the samples was found to be in the range of 0.79... 0.87 eV. 

Drum-head Process. A process used in Europe for the shaping of flatware it was developed on account of the shortness of the feldspathic porcelain body. A slice of the pugged body is placed on a detachable drum-head which fits on the battfng-out (q.v.) machine. The drum-head , with the shaped disk lying on it, is then removed and inverted over the jigger-head, the bat then being allowed to fall on the mould for its final jiggering. 

Tinsel. Very thin glass that has been crushed and silvered for use as a decorative material (cf. glass frost). Tirschenreuther Pegmatite. A byproduct of china-clay washing, comprising quartz and feldspar, used in porcelain bodies and in spray-dried prepared bodies. (Hutschenreuther AG, Germany). 

Figure 3.28 Phase boundary and coexisting phases in the Si02-rich section of the ternary system K20-Al203-Si02 (after Schairer and Bowen, 1947). The path A-B-C characterizes the crystallization history of a typical porcelain body (see text). Co = corundum ...

R.R. Menezes, P.M. Souto, R.H.G. A. Kiminami, Microwave hybrid fast sintering of porcelain bodies, J. Mater. Proc. Technol. 190 (2007) 223-229. 

Electrical Porcelain. A typical electrical porcelain body consists of approximately 50 percent clay [Al2Si205(0H)4] and 25 percent each of flint (Si02) and of feldspar (KAlSijOg). The high clay content gives the green body plasticity, which facilitates easy... 

In the manufacture of refractory and porcelain bodies, the desirable mullite is formed from the chemically similar minerals andalusite, kyanite and dumortierite, which decompose into mullite and silica at cone 13, cone 12 and cone 6, respectively. To break up siUimanite in the same way, cone 20 is required. Sintered and electro-fused synthetic mullites (including zirconium mullite) are used in kiln furniture and refractories for the glass and steel industries. The theoretical chemical analysis (wt%) of mullite and five typical mullite materials are as follows ... 

Classification of the official Ru wares and folk Ru wares based on the composition of porcelain body ... 

By SVM technique, it can be found that the space spanned by (Ni), (Sr) and (Ga) can be used to classify the porcelain body of official Ru wares and folk Ru wares, by the following inequality ... 

By some classical chemometric methods such as Fisher method, the samples of official Ru wares can be also clearly separated from those of folk Ru wares based on the trace element contents of porcelain body. Their projection map is shown in Fig. 11.4. But by cross validation there are some wrong prediction results. It implies that there are some overfitting effects. 

Table 11.7 Composition of porcelain body of products of two official kilns in...

Class 1 denotes the porcelain body of chips in Song Dynasty layer in Laohudong kiln site, class 2 denotes the porcelain body of chips in Yuan Dynasty layer in Laohudong kiln site and class 3 denotes the porcelain body of chips of Jiaotanxia kiln site. 

By SVM method, a criterion can be found to differentiate the porcelain body of the products of Laohudong official kiln from that of Jiaotanxia kiln at Hangzhou in Song Dynasty ... 

A typical porcelain body has the composition 50 clay-25 feldspar-25 quartz. Sketch an expected microstructure of such a body, indicating scale when (a) fired to achieve phase equilibrium (1450°C for 6 h) and (b) fired to 1300°C for 1 h. 

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