Фізико-хімічні фактори структуроутворення та інтенсифікації лиття виробів з будівельного фарфору

The development of deformation processes in the even of coagulative structure formation of clay and kaolin suspensions under identical concentrations of the disperse phase is linked to the particularities of the mineralogical composition, genesis, morphology, and crystallochemical structure of particles of the rock-forming minerals.

The thesis work has determined the priority significance of surface properties of clay particles for regulating the structure formation processes and for the technological properties of porcelain mixture during slip casting. It has been shown that the lyophilic/lyophobic balance of the surface, its energy state, development level, and dispersive properties are of key importance for the processes used in formation of the coagulative structure of kaolin dispersions. It has been determined that the technological properties of kaolin dispersions are caused by the abovementioned factors, which, if duly taken into account, would enable the directed alteration of the injection properties of kaolin-containing water systems within broadened limits. The good injection properties of the alkaline kaolin suspensions along with their lowered efficient specific surface can be explained in relation to a relatively smaller share of bound water and an accordingly greater share of immobilized water, which is more intensively filtered thru the wall boundary layer where the increased permeability is caused by the poor dispersive behavior and thus by a littler number of contacts and a greater porosity. It has been determined that the replacement of clay components with those similar in chemical composition, but having poorer dispersive behavior and greater hydrophobic properties would increase the flow rate and filtration properties of the clay suspensions while retaining lower humidity, which is especially important when stoneware casting technology is used.

The document suggests using the methods of directed modification of surface by means of hydrophobization and thermal activation. The author has proved the possibility to regulate the structural, mechanical, and rheological properties of a coagulative structure as well as to increase the flow rate and the intensification of casting in porous molds when using the preliminary hydrophobization of kaolin.

The author has evidenced the efficiency of comprehensive usage of enriched and non-enriched clay feedstock with various degrees of hydrophilic and dispersive properties found at the Ukrainian deposit fields as a factor to influence the coagulative and crystallization structure formation of porcelain mixture. It has been pointed out that imperfect structure, increased reactivity of the rock-forming minerals, and the development of the quartz-fieldspathic glass phase are the factors to intensify the formation of mullite when ceramic products are being fired. The increased content of K2O in the products being developed is a factor increasing the viscosity of the liquid phase and, accordingly, increasing the deformational stability of such products during the firing process.

New compositions of porcelain stoneware and ceramic glazes have been developed to ensure the intensification of the sanitary stoneware production processes in the course of plaster mold casting at mechanized equipment and in the course of polymeric mold casting under external pressure at high-output equipment, and such approach has been introduced for the first time in Ukraine.

Key words: sanitary stoneware; kaolin; clay; surface properties; disperse system; cast products; filtration; structure formation; properties.

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