The dissertation is aimed at developing ceramic materials based on compositions of the ZnO – ВaO – Al2O3 – SiO2 system and the technology of their formation to improve the efficiency and reliability of military-applied technologies in the field of aviation and rocketry.
Object of research – creation of ceramic materials with a set of specified electrophysical properties and the ability to maximize the transmission of electromagnetic waves in the radio frequency range.
The subject of the research is the physical and chemical regularities of formation, properties, phase composition and structure of radiopaque ceramic materials based on compositions of the ZnO – ВaO – Al2O3 – SiO2 system and technological parameters of the formation of the nose fairing by slurry casting from non-plastic slag.
The aim of the dissertation is to develop the formulation and technological parameters for the production of radiotransparent celzian-willemite ceramics with specified radiophysical properties based on compositions of the ZnO – BaO – Al2O3 – SiO2 system.
As a result of the research, the following scientific results were obtained:
– New data on the sub-solidus structure of the BaO – ZnO – Al2O3 – SiO2 system were obtained: elementary volumes, degrees of asymmetry and interconnection of tetrahedra included in the system regions containing celzian, willemite and ganite phases; temperatures and compositions of eutectics of elementary tetrahedra were calculated and model compositions promising for designing the compositions of celzian-willemite ceramics were determined; based on the results of the predictive assessment of the phase composition of the synthesis products of model compositions and the analysis of the dynamics of melt accumulation in the temperature range of 1100 – 1350 °C, the conditions for low-temperature synthesis of the target phases were determined;
– Based on the results of thermodynamic analysis of the reactions of the target and accompanying phases with aggressive chemical reagents, the conditions for obtaining radiopaque ceramics with high resistance to aggressive environments were determined. The influence of different alumina-containing materials on the properties and phase composition of celzian-willemite ceramics was determined and the expediency of using cheaper metallurgical alumina of G-00 grade was shown; the effectiveness of the additive 1 wt. % Li2O to intensify the process of formation of celzian and willemite in a low-temperature one-step synthesis and a positive effect on the performance properties of the resulting ceramic materials was determined: dielectric properties (ε = 2.41 – 2.85, tgδ = 0.0024 – 0.0075), heat resistance 225 – 250 °С, bending strength 83 – 152 MPa;
– The technological parameters of slag casting and the composition of a complex additive were determined, which improves slag flowability by 52%, improves filtration properties by 53%, and increases the strength of castings by 1.10 times;
– The possibility of using the developed material for the manufacture of protection elements for electronic equipment operating in the frequency range of 26 - 37.5 GHz and improving their performance properties was established.
The results of the research conducted within the framework of the dissertation were presented at international scientific conferences and published in well-known professional journals in Ukraine and abroad. The results of the dissertation have been implemented in the educational process of the Department of Technology of Ceramics, Refractories, Glass and Enamels of the National Technical University “Kharkiv Polytechnic Institute” in the preparation of masters. This indicates the significant scientific and practical value of the results obtained and their active use in the relevant fields of research and education.
Keywords: radiopaque ceramic materials, celzian-willemite ceramics, eutectic, modification, adhesion, aluminum oxide, alumina, subsolidus structure, modifier, technology, β-alumina, silica, glass phase, microstructure, sintering.
