Clay refractories

Ceramics and minerals present many common problems, but ceramics warrant special treatment because elements of low atomic number predominate in them and they consequently offer x-ray emission spectrog-raphy of the light elements an excellent opportunity to prove its usefulness. Scott,8 in making this clear, emphasized the absorption and enhancement effects to be expected, and pointed out the need for careful sample preparation. By use of a General Electric XRD-5 spectrograph and associated equipment, he set up working curves for alumina, silica, potash, lime, phosphate, titania, and iron oxide in clays, refractories, and other ceramic materials. 

Finally, siliceous clay refractories upon reheating in use are free from the tendency to shrink characteristic of the high clay materials. In addition they are able... 

Refractory Clay Products.— From the standpoint of the manufacturer the clay refractories may be subdivided into the following divisions (1) Flint-clay refra-torics (2) siliceous-clay refractories (3) plastic-clay refractories (4) grog refractories. 

Properties of Flint-clay Refractories.—These may be briefly summarized as follows The refractoriness of No. 1 materials as indicated by the softening point is usually not lower than that of cone 31 (about 1,685°C. or 3,065°F.). Kanolt has found the mean melting point of 41 samples of firebrick to be 1,649°C., determined in the Arsem furnace. 

Siliceous-clay Refractories.—Owing to the fact that the siliceous clays posses a greater degree of plasticity than the flint-clay mixtures they may be made int bri( ks in the plastic state by means of the auger machine or piston press. The are fired to about the temperature of cone 8. 

Intermediate and low-grade clay refractories Annealing furnaces, runner brick, sleeves and nozzles, ladles, oil refineries, stills, incinerators, vaults, flues, furnace stacks, (lig( sters, bake ovens, dryers, carburetors, etc. 

Insley [32] analyzed the clay refractories above the glass line in the melting end of the tank and in the refining end. Each region showed different results characteristic of the temperature and conditions at that particular location. 

Application Whiteware Structural clay Refractory Glass Abrasive Advanced Wear Membrane Electronic packaging... 

Fire Clay Refractories High temperature stability... 

Fire clay Refractories 0.3 Fireclay refractories contain 25-45% alumina... 

SEM analysis revealed a large mottled area surrounding a soUd center, with laths and needles near the perimeter, as shown in Figure 9(c). EDX analysis revealed the solid center was composed primaiily of sihca and alumina(9(d)) the mottled area was composed of silica, alumina, and soda (9(e)) the elongated lath-Uke crystals which were composed primarily of alumina (9(f)) and the needles were composed primarily of alumina with lesser amounts of silica (9(g)). SEM DX analysis provided the same information as the petrographic techniques. In addition, it provided the elemental composition of the center, laths, needles, and perimeter of the stone. The stone was a clay refractory material with some conversion to corundum, muUite, and nepheline. 

Fire Crack Firing Crack. A fire crack is a crack in glass-ware caused by local thermal shock a firing crack is a crack caused in clay-ware, or in a non-clay refractory, by too-rapid firing. 

This chapter deals with the preparation of ceramic materials such as pigments by sol-gel methods. Ceramics include a wide range of materials - from pottery to electronic materials. Accordingly, it can be classified into traditional ceramics - materials developed since the early civilizations until 1940 - and advanced ceramics - materials technically developed post-1940. Clay, refractories, glasses, cements, and concretes are considered traditional ceramics, whereas ceramics used in electrical, magnetic, electronic, and optical applications as well as in structural applications at elevated temperatures are called advanced ceramics. Traditional ceramics still constitute a major part of the ceramics industry [1]. 

All clays do not exhibit the same aptitude towards manipulation and behavior during firing. Ceramists distinguish vitrifying plastic clays, refractory plastic clays, refractory clays and red clays. 

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