Cast steelcasting nozzles

Abstract

High-speed steelcasting in a well-formed Jet requires the use of nozzles with a largediameter channel of complex configuration. Nozzles of this type with the necessary physicomechanical properties are difficult to produce owing to the inadequate power of the presses at some of the establishments of the refractories industry. A modification of the presses made it possible to produce nozzles with a channel diameter of 80 mm. The difficultles involved in the manufacture of nozzles with channels 100-120 nun in diameter of complex configuration prevents them from being produced on a large scale.In recent times other methods of manufacturing refractory products, e.g., for steelcasting, have been developed among them that of casting them from free-flowlng alr-drylng granular compositions with a technological binder, e.g., orthosilicic acid ester (ethylsillcare) [1][2][3][4].With this method the use of a plasticizer which in some cases has an adverse influence on the properties is dispensed with and the pressing operation is elimlnated; the outlays on the manufacture and servicing of the forming equipment which in pressure molding wears rapidly as a result of the high specific pressure and the abrasive action of the molding composition are lower; complex-configuration products can be formed; and thermal-shock resistance of the product is high owing to the nature of the macrostructure of the casting.The planned flow sheet for the manufacture of refractory products from free-flowing, alr-hardenlng, ethylsilicate-bonded granular compositions (Fig. I) is simple and convenient in practical use.In order to assess the suitability of this method for the production of steelcasting nozzles, to refine the technology, and to study the performance of the refractories in service, an experimental batch of cast Ts/SP-23-80 type nozzles were produced at the Krasnoarmelsk Dines Plant by a simplified flow sheet (i.e., using a very simple vibrating table and paddle mixer).* The nozzles were produced from a mix of the following composition: 25 • i% ground zircon brick of particle size 0.5-3.0 mm, 25 • i% the same material but of particles size smaller than 0.5 mm, iron-free zircon concentrate finer than 0.06 mm, and ii • 0.5% binder (hydrolized ethylsilicate consisting of 40% distilled water, 60% ethylsilicate~ and 0.8% hydrochloric acid solution on 100%).The ethylsillcate was hydrolyzed in a high-speed paddle mixer (paddle speed --2600 rpm). The process was considered complete when the temperature of the solution had fallen to 20~ after which the solution was rested for 8 h.The filler (refractory material) was prepared by the usuaI method.To increase the density and strength of the products the zlrcon-briquet powder was treated with sodium methylsillconate which accelerates the coagulation and polymerization of the products of the hydrolysis of the ethylsilicate. The amount of added coagulant was 0.2% on the weight of the filler.The free-flowing composition was also prepared in a paddle mixer in the following sequence: one-third of the flne...

A refractory ceramic with ethyl silicate binder

“…The application of this technique of manufacturing r e f r a c t o r y ceramic with ESB has been indicated in [9][10][11]. The ethyl silicate binder is obtained by hydrolyzingethyl silicate in the presence of reaction catalysts.…”