Technology for Producing Ceramic Materials for Hydrocyclone Linings
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TECHNOLOGY FOR PRODUCING CERAMIC MATERIALS FOR HYDROCYCLONE LININGS R. A. Shishkin1, 2, 3 and Yu. V. Yuferov1, 2 Translated from Steklo i Keramika, No. 2, pp. 24 – 29, February, 2020. The development of effective ceramic lining materials is an important problem of industry. Materials with aluminum phosphate binder can be considered as new for use in hydrocyclones. The present work is devoted to research on the content of the binder and its modification as well as the calcination temperature on the properties of the final products. Special attention is focused on the basic properties for using ceramic materials as lining: porosity, water absorption, and density. Several composite materials with enhanced properties due to reinforcement with coarse-grained silicon carbide have been obtained. Key words: aluminum phosphate binder, lining, hydrocyclones, composite material, silicon carbide, alumina, sodium fluorosilicate, calcination, porosity.
Hydrocyclones are generally used to solve a wide range of problems in industry, ranging from the removal of sludge and residues of water from pulp to the separation of unstable emulsions and suspensions [1]. The mechanical properties determining the service life of hydrocyclones are especially important for the lining. Even though diverse linings made from ceramic materials do exist, new and more efficient and cost-effective validated solutions are always being sought. The following types of ceramic materials are most widely used [2, 3]: – materials smelted from basalt at 1300°C, which are least expensive and least reliable; – chromium carbide coating; – aluminum oxide, stable under high loads, obtained by extrusion, isostatic pressing, slip casting; – oxide or nitride bound silicon carbide; both types of silicon carbide possess low shrinkage, making them ideal for the fabrication of large and complex molds, but the drawbacks are porosity 10 – 14% and a skin effect, which appears as a result of inadequate penetration of nitrogen or oxygen into the interior of the initial material; – silicon carbide, permeated by aluminum (Alanx); the aluminum is used to fill pores, which makes it possible to obtain the highest mechanical strength among all ceramic lin1 2
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ing materials, but such a material is very expensive, making general use of Alanx impossible; – smelted aluminum zirconium silicate ZrO2–Al2O3– SiO2 (AZS), which possesses excellent durability; its main drawbacks are voids and cracks that are formed during casting. In view of their low cost the materials based on aluminum phosphate binder can be regarded as promising lining products for hydrocyclones. It is extremely important to study the possibility of obtaining products at high temperatures in order to secure the requisite technical and economic characteristics for a lining. Products based on phosphate binders can be regarded as alternatives to the conventional and widely used materials. The articles [4, 5] describe a technology for producing silicon carbide nozzles, but just as other works [6 – 8] they are concerne
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