The present study investigates the impact of quartz, mullite, spinel, and corundum fillers on the rheological properties and extrudability of silica glass suspension-based compositions. The results indicate that materials containing mullite, spinel, and corundum exhibit dilatant flow behavior, which impedes their use as inks in 3D printing. Conversely, suspensions containing quartz filler display a nonlinear viscoplastic flow. The addition of polyvinyl alcohol to compositions with quartz filler enhances their shape retention factor during extrusion by increasing their yield stress and viscosity.

A dense-sintered protoenstatite ceramics based on fluorinated talc was obtained. Influence of BaO and Al2O3 additives on the sinterability, structure and strength of ceramics was investigated. It makes possible to reduce the sintering temperature to 1225 – 1250 °C due to formation of glassy phase. Additive of ZnO intensifies solid phase sintering at 1320 °C. It significantly improves compressive strength of ceramics up to 660 MPa that exceeds the strength of traditional steatite materials by 3 times.

Zirconium silicate ceramics is widely used in different fields of engineering. One of the most actual problem of zircon ceramics is the requiring of high temperatures for its sintering. Perspective method for activation of silicate materials with the aim of intensification of synthesis and sintering processes is the low-temperature fluoridation with the ammonium hydrofluoride. In accordance with that, processes occurring during the interaction of plasma dissociated zircon and natural zircon with ammonium hydrodifluoride were studied. It was established that plasma dissociated zircon actively interacts with ammonium hydrofluoride in the solid phase. Natural zircon because of its chemical inertness reacts with ammonium hydrofluoride only when latter melts. The main product of fluorinating is ammonium hexafluorosilicate. By-products are ammonium hexafluorozirconate and ammonium heptafluorozirconate. Their quantity increases with the content of ammonium hydrofluoride in mixtures. Kinetic equation of reaction between zircon and ammonium hydrofluoride is k×τ = 1-(1-α)1/n. Activation energy of plasma dissociated zircon and natural zircon fluorinating reactions are 13.9 and 32.7 kJ/mol, respectively. Order of reactions (n) are 2.0 and 1.5, respectively. Thermal treatment of fluorinated materials at 400 °C leads to ammonium hexafluorosilicate sublimation and thermal dissociation of ammonium fluorozirconates to zirconium fluoride and fluorozirconate intermediates. It was established that low-temperature fluoridation of zircon makes possible to regulate chemical composition of minerals. Materials obtained by ammonium hydrofluoride treatment of plasma dissociated and natural zircon can be potentialy used in the functional zircon and zirconia-zircon ceramics technology.

The paper presents the results of studying the processes of synthesizing baddeleyite-zircon ceramics based on fluorinated plasma dissociated and natural zircon. It was found that obtaining densely sintered ceramics based on fluorinated natural zircon requires the addition of CaO to stabilize free ZrO2 contained in it. The addition of Y2O3 to the plasma dissociated zircon-based ceramic materials makes it possible to reduce the sintering temperature from 1,600 to 1,500°C. Obtaining highly fluorinated plasma dissociated zircon-based ceramics is complicated due to the formation of excessive amount of ZrF4.

One of the drawbacks of fusible clays is the narrow sintering interval due to a sharp increase in the amount of iron-silicate melt at a temperature of 1000-1100 degrees C, which hardens in the form of a glass phase upon cooling. This leads to a relatively low mechanical strength of the calcined samples and causes the danger of melting the granular material surface from such clays during the firing process. To increase the strength of samples of fusible clays, the influence of diabase and granitoid rocks was considered. It was found that the strengthening effect of diabase and granitoid rock additives in an amount of 20-50% in a mixture with fusible clay is due to an increase of total content of the crystalline phase (mullite, cristobalite and residual quartz) from 18-20% in clays without additives to 22-28 % - in mixtures with diabase and to 28-34% - with granitoid additives) at a temperature of 1050-1100 degrees C. This increase is due to the activation of synthesis processes of secondary mullite and crystallization from alkali-rich feldspar melt of amorphous silica, released from the structure of clay minerals. The established influence of the igneous rocks used made it possible to develop compositions and propose process flow sheet for producing aluminosilicate proppants based on fusible clays. The use of granitoid and diabase rocks in an amount of 20-70% with fusible clays produces lightweight aluminosilicate proppants with bulk density of 1.40-1.46 g/cm(3) at temperature range of 1050-1100 degrees C, which can endure destructive pressures up to 34.5-52 MPa.

The processes of forsterite, enstatite, and talc treatment by ammonium fluoride have been studied. The phase-formation processes occurring during firing of fluorinated minerals were studied. It was established that structural silica of the minerals reacts with ammonium hydrogen difluoride with the formation of ammonium hexafluorosilicate, sublimation of which leads to removal of structural silica from the minerals with partial destruction of their structure. The firing of fluorinated minerals leads to their structural transformation with formation of magnesium nesosilicates and fluoronesosilicates.