Quartz ceramic nozzles for casting steel on continuous casting plant

Churakova, R. S.; Федорова, Е. П.; Polonskii, Yu. A.; Ermolaeva, E. I.; Pozhivanov, A. M.; Karpov, N. D.

doi:10.1007/bf01284113

Refractories

1972

DOI: 10.1007/bf01284113

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Quartz ceramic nozzles for casting steel on continuous casting plant

R. S. Churakova

Е. П. Федорова

Yu. A. Polonskii

et al.

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1979

1996

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“…

The method of free melting in single-phase PS-75 furnaces is suitable for melting blocks weighing several tons.

The design of the PS-75 furnace is shown in Fig.

…”

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confidence: 99%

Obtaining fused quartz in a semicontinuous electric furnace

et al. 1979

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Owing to its low coefficient of thermal expansion, high resistance to molten steels, slags, and certain types of glass, fused quartz is widely used for making immersion nozzles for continuous steel-castingmachines, precision casting molds, coatings, glass blocks for tank furnaces, and also for the production of ramming compounds [1][2][3][4].Transparent fused quartz, and also opaque, is distinguished by a high content of fine air inclusions, and it is produced mainly by electric melting in periodic furnaces.One of the production units for obtaining opaque fused quartz (quartz glass) is an electric resistance furnace of the semicontinuons type, the design of which was developed by the Institute of Fused Quartz [5]. This paper descries the results of determining the working characteristics of the PS-75 furnaces introduced at the Pedolsk Factory and a study of fused quartz obtained in them.The method of free melting in single-phase PS-75 furnaces is suitable for melting blocks weighing several tons.The design of the PS-75 furnace is shown in Fig. 1. The quartz sand (startiug material) enters the melter through the telescopic Charging devices. After the melting-in process is complete the melting chamber together with the telescopic hearth is raised, and the block of fused quartz remains, as it is being melted, on the hearth in a filling of quartz sand.After completion of the melting, the melting chamber is separated from the hearth, which is installed on the roll-cut platform. The block after cooling is extracted, and the sand remaining in the hearth is poured in for further use.The rate at which the melter is raised is determined by the viscous flow of the melt and the specific surface capacity of the heaters. The rise rate of the chamber without the coolers is 9, and with the coolers 8 cm/h. The coolers are designed to stabilize the shape of the blocks and reduce the duration of action on the fused quartz of temperatures at which it may crystallize (1200-1500~The fused block is covered with a ~s ~8 Fig. 1. Circuit for PS-75 electric furnace: 1) Electrodes; 2) graphite heaters; 3) barties; 4) frame of melting chamber; 5) block of fused quartz; 6) cooler.Soyuzogneupor. All-Union Institute of Refractories. Podolsk Refractories Factory. State Scientific-Research Institute of Fused Quartz.

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“…

The method of free melting in single-phase PS-75 furnaces is suitable for melting blocks weighing several tons.

The design of the PS-75 furnace is shown in Fig.

…”

mentioning

confidence: 99%

Obtaining fused quartz in a semicontinuous electric furnace

et al. 1979

Self Cite

View full text Add to dashboard Cite

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Dielectrics made of Al2O3 and SiO2 for high temperatures

Karklit

1996

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Dielectrics produced from corundum with commercial alumina and from quartz ceramics by hot pressing and by the conventional method with the use ofF-9 silicone resin are described. The effect of technological factors on the properties of the specimens is studied.In choosing dielectrics for parts of radio devices operating at a high temperature under conditions of one-sided heating, when surface fusion is possible, it is important to take into account the change in the dielectric properties of the materials in heating, namely, the permittivity s and the loss parameter tan 8. In a search for materials that would provide an admissible loss of power in devices operating at superhigh frequencies we conducted experiments with corundum refractories and quartz ceramics. Both kinds of material are known to be dielectrics with high quality parameters [I, 2]. Below we present results of an investigation of various technological factors on the properties of the articles.The initial materials for alumina dielectrics were electrofused corundum and commercial alumina that contained 99 and 99.3% AI203, respectively. The composition of the corundum differed in the content of fi'actions Nos. 63, 32, and 3. The commercial alumina was fired at a temperature ranging from 1450 to 1750°C, crushed to a grain size of less than 28 -40 gm, andmixed with electrocorundum in an optimum ratio (with respect to the final strength) of about 45 to 55 vol.%. It should be noted that the strength of the specimens depended on the degree of crushing of the alumina (Fig. 1). It seems that with excessive dispersity fine alumina particles positione.d between grains of electrocorundum form more microcracks.The specimens were pressed at a pressure of 5 0 -120 MPa and fired at different temperatures. An increase in the pressure was accompanied by an increase in ¢~c to over 100 MPa, and the open porosity Pop decreased from 27 to 15 -17%. In firing the specimens we established that their strength depended substantially on the rate of their cooling. For specimens cooled at a rate of 30 -35°C/h ¢~c was 60 -70MPa, and for specimens cooled at 130-135°C/h the strength was 110-120 MPa. This is explainable by forma-I St. Petersburg Institute of Refractudes, St. Petersburg, Russia.tion of a structure with finer grains and slower crystal growth in rapid cooling; this phenomenon has been observed in other works too [3].The data presented in Fig. 2 show that the alumina for the binder and the final articles should be fLred at higher temperatures, because their strengzh is an important factor promoting stability in a rapidly moving gas flow. The thermal stability of articles fired at 1750°C is quite high (over 60% of the initial strength was preserved after three heat cycles of 2000-20°C). The finished articles had the following properties: apparent density Pap = 3.1 g/cm 3, Pop--21 -23%, t~ c = 120 MPa at 20°C, c b = 83 MPa at 20°C and 40 MPa at IO00°C, o~ = 15 and 5 MPa, respectively.The dielectric properties of the specimens were determined by two methods, namely, a vol...

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Quartz ceramic nozzles for casting steel on continuous casting plant

Cited by 2 publications

References 0 publications

Obtaining fused quartz in a semicontinuous electric furnace

Obtaining fused quartz in a semicontinuous electric furnace

Dielectrics made of Al2O3 and SiO2 for high temperatures

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