Salnyk V. Physical and Chemical Factors of Structure Formation and Intensification in Cast Porcelain Ware Used for Construction Purposes

This thesis work is dedicated to the development of the physical and chemical grounds for the technology to produce sanitary stoneware thru different methods of structure formation into porous molds, including pressurized processes. The comprehensive research of the initial feedstock and of the disperse systems based on such feedstock have resulted in the formulation and scientific substantiation of the objective laws explaining how the energy state of the particles' surface during the disperse phase influence their lyophilic behavior, coagulative structure formation, and filtration intensification under normal conditions and under external pressure. The document describes the particularities of the chemical and mineralogical composition and properties of kaolins and clays found at the Ukrainian deposit fields and those of the feedstock coming from abroad. The thesis work also gives the details of how the coagulative structure of clayish water systems is formed and the analysis of kinetic properties in filtration during the formation of cast products by plaster mold casting under the normal conditions and by polymeric mold casting under external pressure.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.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.