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The effects have been examined of adding nanocrystalline zirconium dioxide powder stabilized by yttrium oxide on the production and properties of a composite material based on zircon. It is found that the zirconium dioxide particles at the boundaries of the zircon grains slow the consolidation of the zircon matrix in sintering and zircon grain growth.Keywords: nanocrystalline zirconium dioxide, ceramic composite material.The high prices are a factor retarding the general introduction of ceramic materials in various branches of industry. The cost of a ceramic can be substantially reduced by the direct employment of mineral raw materials.Zircon is zirconium orthosilicate ZrSiO 4 and is used as a natural mineral raw material in the refractories industry, casting, and generally in the production of building materials and drainage fitments. About 10% of zircon is processed to give zirconium dioxide [1]. A ceramic based on zircon has a comparatively low coefficient of linear expansion and moderate thermal conductivity. The thermal shock resistance of zircon exceeds that of corundum, zirconium dioxide, and mullite, and also it has high chemical resistance in acid media [2].Ceramic materials have a wide range of properties and on many parameters are better than metals and polymers, but they have a major shortcoming: low level of failure viscosity, which is due to the ionic-covalent type of atomic bonds. A method of increasing the resistance to crack growth in ceramic materials is to produce composite structures. There are two most effective lines: producing a transformation-hardened ceramic with dispersed inclusions of metastable ceramic phase or a ceramic strengthened by fibers. Particles of metastable tetragonal zirconium dioxide are used to strengthen various ceramic matrices. The most effective results have been obtained on adding them to a corundum matrix [3,4]. Added nanodimensional powders favor the consolidation of the ceramic and reduce the sintering temperature [5].The present concerns the effect of added ZrO 2 nanopowder stabilized by Y 2 O 3 on the making of a composite based on ZrSiO 4 . EXPERIMENTALWe used a zircon concentrate termed Zircon standard grade (Possen Erzconter), for which the certificate states the following wt.% composition: ZrO 2 + HfO 2 66.0, SiO 2 (total amount) 32.7, SiO 2 (free) 0.26, Fe 2 O 3 0.2, TiO 2 0.25, Al 2 O 3 0.18, CaO 0.1, MgO 0.03, Cr 2 O 3 0.002, P 2 O 5 0.14; the zirconium dioxide stabilized by 5 wt.% yttrium oxide was added in the form of a powder made by the reaction between a solution containing the chlorides of these metals and an aqueous solution of ammonia (Start Scientific Production Business Corporation, Perm, Russia) [6].The powders were ground and mixed in a SAND planetary mill at a speed of 160 rpm in the dry or in 0.5% aqueous solution of polyvinyl alcohol (PVA); the ratio of the masses of powder, grinding bodies, and liquid were 1:2:1. The dried and ground powders were used in making specimens by cold uniaxial pressing (CP) and cold isostatic pressing (CIP). The...

Titanium dioxide nanopowder samples consolidated by method of cold uniaxial compaction at 200 MPa and conventionally sintered in air at 1300?? with isothermal tempering during 60 minutes or spark-plasma sintering at 1300?? and 30 MP? were studied using the method of light combination scattering spectroscopy (Raman spectroscopy) and scanning electron microscopy. The samples were found to differ significantly in terms of color, density, phase composition and microstructure.

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