The present article gives some results of a study of the effect of the production parameters on the properties of a quartz ceramic. For the starting materials, we used transparent and nontransparent vitreous silica culler, synthetic amorphous SiO2, culler from fired articles of nontransparent vitreous silica, and synthetic silica, for the preparation of the specimens.We obtained suspensions by single-stage or two-stage wet milling of the filler (methods I and II of the preparation); we also used suspensions containing specific sieve fraction of the filler (method Ill). In the single-stage milling the solid component and the water in the ratio (80-82) : (18-20)* were put into the mill and milled to a 0.5-1.0% concentration of fractions > 0.06 ram. In the two-stage method, the mill was loaded with 70% of solid components and water in the ratio (78-80) : (20)(21)(22), milled to a concentration of less than 0.2% >0.06 mm and then 30% of filler in the form of small pellets of the same material of particle size 0.3-1.2 mm was added to the supension obtained; the whole was then milled to an 8-10% concentration of fractions >0.06 ram. In order to obtain suspensions with this fraction interval of the filler, some of the material (45-50%) with a moisture content of 20-22% was milled to a concentration of less than 0.2% > 0.06 ram; the remaining filler (50-55%) in the form of pellets of grain size 0.3-1.2 mm were added to the obtained suspensions and the mixture was agitated for 1-2 h. Suspensions of glass and synthetic silica in a stabilized form were also used. The characteristics of the suspensions are given in Table 1.The specimens were prepared from the suspensions by casting in gypsum molds using a pouring method. The specimens were fired in a small electric furnace with silicon carbide heaters. The temperature in the furnace was raised to 350~ at a rate of 70-100~ and then to the final temperature at a rate of 100-130~ In order to make the temperature uniform in the furnace space, the final temperature was maintained for 1 h. The specimens were then cooled to 60-70~ over a period of 5-6 h.The following characteristics of the specimens were determined: the shrinkage; ultimate bend, and extensive strengths; water absorption; degree of sintering (from the brilliance of the fracture); and the thermal shock resistance (heating to 1200~ into water at 10-12~The ultimate bend strength was determined on specimens in the form of rods, 8 mm in diameter and 60 mm long, in the Ivanov apparatus. The average results from tests on five specimens were calculated (Fig. 1). After heating to 800~ the strength of the specimens was virtually unchanged. The maximum ultimate bend strength was found in most specimens after firing at 1200~With a further increase in temperature, the strength of most of the specimens decreases. The exceptions are specimens Nos. 1 and 8 whose strength continues to increase with an increase in temperature. For some of the specimens (Nos. 2-5 and 7), %end again increases after the reduction.The differences in stre...
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