Quartz Transition Research Articles

Effect of impregnation temperature and concentration of alumina sol on the properties of 3D printed silica ceramics

Due to the glass transition of molten quartz and the layer-by-layer 3D printing method, the strength of the finished ceramics is low. Therefore, it is necessary to find a suitable method to improve the mechanical properties of 3D printed silica ceramics used as casting molds for turbine blades. Vacuum impregnation is a very attractive method to introduce new phases into ceramic pores through liquid impregnation, thereby improving the mechanical properties of ceramic parts. In this study, 3D printed silica ceramics were impregnated with alumina sol, and the effect of impregnation temperature and concentration of alumina sol on the properties of the samples were investigated. The cristobalite content and mechanical properties of silica ceramics impregnated by alumina sol with different concentration and temperature were compared. The impregnation of alumina sol can promote the formation of cristobalite phase in the ceramics, and the appropriate amount of cristobalite can improve the mechanical properties of the ceramics. When the concentration of alumina is 15 wt% and the impregnation temperature is 60℃, the overall performance of alumina sol impregnated samples is the best, with a flexural strength of 22.70 ± 0.46 MPa, a bulk density of 1.70 ± 0.02 g /cm3, and a porosity of 25.89 ± 1.32 %.

Fluid overprints and mineralization of the Zhuguangshan granite-related U district in China: Recorded by cathodoluminescence textures and chemistry of quartz

Most high-grade U ores are mined from quartz veins hosted in granites. The veins formed at shallow depths during episodic hydrothermal activity, however, the evolution of multiple stage fluids is not well constrained. In this study, we collected 56 quartz samples from the world-class, granite-related, Zhuguangshan U district (>17,000 t U from seven deposits) in southern China. Their textures and compositions were analyzed using scanning electron microscope cathodoluminescence (SEM-CL, n = 98) and laser ablation-induction coupled plasma-mass spectrometry (LA–ICP–MS, n = 643). Four types of quartz were identified, including magmatic quartz, early hydrothermal euhedral quartz, ore stage hydrothermal quartz (U-rich), and late hydrothermal quartz. New quartz textures and chemical compositions show that the transition of early hydrothermal quartz from the magmatic to hydrothermal stages is discontinuous, unlike the continuous trend observed in most magmatic-hydrothermal systems. Ore stage quartz is CL dark (with a peak at 650 nm), occurs as rims on early barren quartz, and has high contents of Mn, Al, and Sb. Altered textures of magmatic quartz developed through fluid-rock reactions at low temperatures, while rimmed textures of hydrothermal quartz formed during subsequent late-stage U-bearing fluid events, which played a crucial role in U mineralization. Quartz in the Zhuguangshan U district has distinct features compared to other magmatic-hydrothermal systems that can guide exploration for high-grade ore in this, and perhaps other, granite-related U systems.

The Role of α−β Quartz Transition in Fluid Storage in Crust From the Evidence of Electrical Conductivity

AbstractAqueous fluids are extensively present in the middle to lower crust, as revealed by seismic and magnetotelluric soundings. The α−β quartz phase transition significantly affects many physical properties and leads to substantial microcracks that can provide pathways for the migration of crustal fluids. A systematic investigation of macroscopic physical properties and microstructure of quartz is crucial to elucidate their correlation. In the present study, the effects of water content, trace elements, orientations, and phase transition on the electrical conductivity of quartz were thoroughly evaluated at 400−900°C and 1 GPa. Individual annealing experiments were simultaneously conducted on quartz single crystals at different peak temperatures and 1 GPa to investigate the evolution and spatial distribution of microcracks using X‐ray microtomography (CT) and backscattered electron imaging. We found that trace element content and orientations, rather than H2O, are the dominant factors controlling the conductivity of quartz. The distinct changes in conductivity of single crystals at around α−β phase transition temperature are attributed to the transformation of microcracks from isolated to interconnected networks, as confirmed by two‐dimensional (2‐D) and three‐dimensional (3‐D) microstructure images. Based on the variation in electrical conductivity and microstructure across the transition, it thus is proposed that the intragranular microcracks caused by quartz phase transition can serve as fluid or melt pathways within highly conductive zones present in the middle to lower crust, while α‐quartz acts as an impermeable cap.

The influence of phase transitions in quartz on the properties of thin films of metal oxides formed on its surface

The influence of phase transitions in quartz on the properties of thin films of metal oxides formed on its surface

P‐Wave Velocities Across the α → β Quartz Transition at Lower Continental Crust Pressure and Temperature Conditions

AbstractThe quartz α → β transition is a displacive phase transition associated with a significant change in elastic properties. However, the elastic properties of quartz at high‐pressure and temperature remain poorly constrained experimentally, particularly within the field of β‐quartz. Here, we conducted an experimental study on the quartz α → β transition during which P‐wave velocities were measured in‐situ at pressure (from 0.5 to 1.25 GPa) and temperature (200–900°C) conditions of the continental lower crust. Experiments were carried out on samples of microcrystalline material (grain size of 3–6 μm) and single‐crystals. In all these, the transition was observed as a minimum in P‐wave velocities, preceded by an important softening while P‐wave velocities measured in the β‐quartz field were systematically lower than that predicted by thermodynamic databases. Additional experiments during which acoustic emission (AE) were monitored showed no significant peak of AEs near or at the transition temperature. Microstructural analysis nevertheless revealed the importance of microcracking while Electron Back‐Scatter Diffraction (EBSD) imaging on polycrystalline samples revealed a prevalence of Dauphiné twinning in samples that underwent the transition. Our results suggest that the velocity change due to the transition known at low pressure might be less important at higher pressure, implying a change in the relative compressibilities of α and β quartz. If true, the velocity changes related to the α → β quartz transition at lower crustal conditions might be lower than that expected in thickened continental crust.

Extraction of local structure differences in silica based on unsupervised learning.

Silica exhibits a rich phase diagram with numerous stable structures existing at different temperature and pressure conditions, including its glassy form. In large-scale atomistic simulations, due to the small energy difference, several phases may coexist. While, in terms of long-range order, there are clear differences between these phases, their short- or medium-range structural properties are similar for many phases, thus making it difficult to detect the structural differences. In this study, a methodology based on unsupervised learning is proposed to detect the differences in local structures between eight phases of silica, using atomic models prepared by molecular dynamics (MD) simulations. A combination of two-step locality preserving projections (TS-LPP) and locally averaged atomic fingerprints (LAAF) descriptor was employed to find a low-dimensional space in which the differences among all the phases can be detected. From the distance between each structure in the found low-dimensional space, the similarity between the structures can be discussed and subtle local changes in the structures can be detected. Using the obtained low-dimensional space, the β-α transition in quartz at a low temperature was analyzed, as well as the structural evolution during the melt-quench process starting from α-quartz. The proper differentiation and ease of visualization make the present methodology promising for improving the analysis of the structure and properties of glasses, where subtle differences in structure appear due to differences in the temperature and pressure conditions at which they were synthesized.

Radiation modification of quartz and its spectral characteristics

The nature of the structural phase transition of quartz under neutron irradiation was studied by X-ray diffraction analysis. The kinetics of gamma luminescence (GL) bands in quartz crystals grown on seeds irradiated with neutrons with a dose of 5-1018..1019 and 5-1019 n/sm2 after additional neutron irradiation of 1016- 8.1020 n/sm2 in the temperature range 77-300 K. Based on experimental data, it is shown that all the structural characteristics of the seed are transferred to the grown crystal. This opens up the possibility of obtaining quartz crystals with predetermined properties. Diffraction parameters of quartz irradiated with neutrons and grown on neutron-irradiated seeds (n/sm2). Based on the results of studies of GL, the redistribution of the intensities of photoluminescence bands under illumination (λw = 300-340 nm) without heating and with heating in the temperature range 300-720 K, the dependence of the intensities of luminescence bands on the neutron fluence, it was assumed that the luminescence centers are at 550 and 660 nm are, respectively, peroxide radicals and non-bridging oxygen atoms located at the interfaces between the α- and β-phases of quartz.

Study on the mechanical properties of granite responses of cyclic heating and water cooling considering microcosmic and energy.

Investigating the coupling effects of temperature levels and heating-water cooling cycles on the physical and mechanical responses of HDR (hot dry rock) is a vital issue during the exploitation of geothermal energy. In this study, the physical properties of granite specimens were measured first after each heating and water-cooling cycle. Then, uniaxial compressive tests were conducted on those granites to obtain their mechanical properties. With the increase in heating temperature (T) and cycles of heating and water cooling (N), P-wave velocity, uniaxial compression strength (UCS), and elastic modulus (E) showed a decreasing tendency, and the decrease of those four properties corresponding to T variation is greater than N variation. Due to the α-β phase transition of quartz happening at 573°C, the density UCS and E of granite decreased rapidly when the heating temperature increased from 450°C to 600°C at N = 1. With the increase of T and N, the failure mode of granite gradually changes from tensile failure to shear failure and, finally, comminute failure. The failure mechanism of granite gradually transfers from brittleness-dominated to ductility-dominated due to accumulated thermal damage. Finally, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to determine the damage mechanism of cyclic heating-cooling. The micro test results show that the high-temperature treatment changes the mineral composition and the microcracks number of the granite and finally affects the macroscopic physical and mechanical properties. The study conclusions of this manuscript are important for exploiting geothermal resources.

New insight into the plastic deformation mechanisms during the SiO2 phase transition process.

The removal of lattice impurities is the key to the purification of high-purity quartz (HPQ), especially for the intracell lattice impurities. Generally, the intracell lattice impurities can be migrated to the quartz surface via roasting, then removed by acid leaching. In order to reveal the phase transition of quartz during the roasting process, the evolution of structure, bond length, volume, lattice parameter and lattice stress in original, Ti4+, Al3+/Li+ and 4H+ substituted SiO2 phases were employed to investigate the mechanisms of plastic deformation based on density functional theory calculations. Results showed that the evolution of bond lengths and volumes were mainly dominated by phase transition, and the interstitial volume in high temperature SiO2 phases was higher than that in low temperature, indicating that the phase transition from α-quartz to β-cristobalite was beneficial to the migration of interstitial impurities. In addition, the phase transition from α-quartz to β-cristobalite needs to overcome the energy barriers while the phase transition from α-cristobalite to β-cristobalite needs to overcome the lattice stress. This study therefore provides an excellent theoretical basis for the plastic deformation mechanism, for the first time, beneficial to understanding the removal mechanisms of lattice impurities.

The effect of thermal stabilization process on mineralogy, morphology and engineering properties of red soil in southern Iran

Red soil from southern Iran is widely utilized in structural foundations, road construction, brick making, and high-level landfills. When subjected to heat, soils undergo significant changes in their physical, mechanical, and microstructural characteristics. This study aims to investigate the impact of temperature on the engineering properties of red soil, with a focus on the microstructural perspective. To achieve this, we conducted a series of macrostructural tests (unconfined compressive strength, gradation, weight loss, and permeability) and microstructural analyses (pH, electrical conductivity, X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM)) on Iran red soil samples. The samples were subjected to temperatures ranging from 100 ℃ to 900 ℃ for 2 h. The key findings of this research highlight significant changes in the engineering properties of red soil, particularly at temperatures between 500 ℃ and 900 ℃. Microstructural observations revealed various alterations, including dehydration, dehydroxylation, changes in soil texture, formation of cavities, and increased porosity within the soil structure. Notably, at high temperatures (approximately 900 ℃), new crystalline minerals such as Gehlenite, Diopside, Anorthite, Sanidine, and Mullite were formed. The unconfined compressive strength values exhibited a remarkable increase, reaching nearly 20 times, from 0.12 MPa to 2.3 MPa, concurrently with the formation of new compounds, including the α -β quartz transition. Overall, this study sheds light on the profound effects of temperature on the engineering properties of red soil in southern Iran, offering crucial insights for its practical applications in construction and related fields.

Numerical modelling of thermal weakening of granite under dynamic loading

A numerical method to predict thermal weakening of granite rock under low- and moderate rate dynamic loading conditions is developed. Thermal weakening of granite under uniform heating, leading to degradation of the material stiffness and strength, is modelled with the continuum approach, using a damage-viscoplasticity model. The viscoplastic part is based on a special power law criterion for granite under compression and the rounded tensile cut-off surface, while the damage part is equipped with separate damage variables in tension and compression. The strain rate sensitivity of rock is accounted for by viscoplasticity. The global thermo-mechanical initial/boundary value problem is solved with an explicit (in time) staggered method with mass scaling applied to increase the critical time step. Rock heterogeneity is described as random clusters of linear tetrahedral finite elements assigned with the constituent mineral, here quartz, feldspar, and biotite, material properties. The temperature dependence of the thermal and elasticity properties of the minerals is included in the model up to 850 °C, i.e. well beyond the α-β transition of quartz. However, as the model aims to predict the thermal weakening, the temperature dependence of the rock strength is not used as an input. In the numerical examples, low-rate uniaxial tension and compression tests are first simulated on heated and intact rock samples to demonstrate the performance of the model. Finally, crushing of heat-treated and intact granite balls by diametral dynamic compression is numerically replicated with a fair accuracy.

Influence of beta-to-alpha quartz transition on residual stresses of a feldspar glass matrix composite: A relationship with catastrophic fracture due to thermal shock

A wide range of porcelain-based materials is composed of quartz crystalline particles dispersed in a homogeneous glassy phase. During the cooling stage these composites are subjected to stresses related to the transition from β to α quartz at 573 °C. This work studies, numerically and experimentally, the influence of the cooling rate, the quantity, and the size of the quartz crystalline particles on the stresses suffered by the material throughout the cooling process. This procedure allows calculating the instantaneous profile of stresses through the cross-section specimen during the whole cooling stage. For this, a dense glass matrix from sodium feldspar was prepared. The results reveal that the evolution of the stress profile is strongly affected by the cooling rate. The evolution of the tension state in the sample during the cooling can help to understand the catastrophic fracture suffered during the β to α quartz transition related to thermal shock.

Development of the Median Tectonic Line-related shear zone, southwest Japan: An analysis of strain localization processes

The development of a mylonite zone along the Median Tectonic Line (MTL), southwest Japan, which developed in the Cretaceous granitic rocks, was examined to understand strain localization during cooling. The mylonites are E-W trending, north-dipping, and represent the hanging wall of the MTL. The mylonite zone includes both protomylonite and mylonite, which were derived from two distinct protoliths: tonalite (protomylonite) and granite (mylonite) and occur at distances of c. 0–300 m and 300–700 m from the MTL, respectively. We used quartz microstructures and crystallographic preferred orientations (CPOs) and two-feldspar thermometry to infer the spatiotemporal development of deformation conditions in the MTL mylonite zone. The mylonitic granite is sub-divided into southern and northern mylonite zones, which exhibit A- and B-type quartz microstructure formed by subgrain rotation and grain boundary migration recrystallization, respectively. In both the mylonitic granite and protomylonitic tonalite, quartz c-axis CPOs primarily display a moderate-temperature Y-maximum pattern, as well as a less common low-temperature type-I crossed-girdle pattern. In the northern zone, quartz deformation initially occurred at moderate temperatures of 435 °C–490 °C, forming mylonitic granite with B-type quartz microstructure. As temperature decreased to 355 °C–435 °C, the strain localized into the southern zone to form A-type quartz microstructure. The protomylonitic tonalite formed under similar temperature conditions. At temperatures below 355 °C, ductile deformation ceased in the majority of the granite and tonalite, with only a narrow zone of ultramylonite up to 50 m wide, deforming adjacent to the MTL at conditions approximating the brittle–ductile transition in quartz (c. 300 °C). Strain localization did not occur within a single shear zone, but in several deforming strands that formed in distinct protoliths, one of which developed into the narrow ultramylonite zone reworked as the brittle MTL, likely controlled by cooling.

Thermally Induced Microcracks in Granite and Their Effect on the Macroscale Mechanical Behavior

AbstractUnderstanding the thermal effects on rock is critical for the exploration of geothermal resources and the temperature‐driven evolution of Earth. The macroscale mechanical behavior of granite under thermal loading can be complicated due to microcracking and the heterogeneity of minerals. In this study, the thermally induced microcrack propagation of granite was first observed in real time by an ultrahigh‐temperature instrument on an optical microscope. The previous investigation believed that the α–β quartz transition at approximately 573°C leads to a sharp decrease in macroscale mechanical behavior. However, the present experimental results revealed that microcracks initiate at 300°C and coalesce between 400 and 600°C, which is the main reason for the sharp decrease in macroscale mechanical properties of granite. Additionally, an accurate grain‐based model based on the mineralogical morphology of granite samples adopted mechanical parameters of minerals obtained from microscale rock mechanical techniques. It is able to well reproduce the process of microcracking and the strength evolution of granite during heating. The numerical results show that the heterogeneity of thermal expansion and mechanical properties of minerals produce local thermal stress concentrations in granite. The uneven tensile‐compressive stress between feldspar and quartz and the shear stress around biotite result in the initiation and propagation of microcracks. The present work is potentially useful for understanding and predicting the mechanical behavior of granites under thermal loading with different mineral compositions and microstructures.

Investigation of the Temperature Dependence of the Chemical-Mechanical Properties of the Wufeng-Longmaxi Shale.

Shale rocks have been widely investigated to evaluate the productivity of oil/gas. The high temperature generated by the explosive fracturing to stimulate the gas reservoir has a significant impact on the chemical-mechanical properties of shale rocks. Pioneering works have been carried out at temperatures below 500 °C, but little has been done to quantify the correlation between the chemical and mechanical properties of shale at temperatures above 500 °C. Therefore, an experimental study on the effect of temperature on the chemical-mechanical properties of shale rocks is presented in this paper. The temperatures used in our experiments are between 0 and 800 °C. Results indicate that there exist strong chemical reactions leading to a big reduction in the sample's weight and mechanical strength for a temperature over 500 °C. Thermogravimetric analysis data demonstrates that the weight of shale powders has little change below 400 °C and largely decreases after 600 °C. It shows that the chemical reaction rate corresponding to shale compositions varies with temperature. X-ray diffraction and Fourier transform infrared are integrated to quantify the occurrence of contained reactions including the decomposition of kerogen, carbonates, and quartz transition. This can provide a temperature range for all possible reactions. Changes in the compositional information of shale samples have been proven to significantly influence the mechanical properties. A 25% decrease in dynamic Young's modulus emerges as the temperature approaches 700 °C. As the brittle minerals, for instance, carbonates, decrease with temperature, a brittle-ductile transition happens in shale. This work provides very meaningful results different from that at low temperatures to help people better understand the effects of high temperatures in many fields, such as explosive fracturing and radioactive waste disposal.

Investigation of the microstructural characteristics of heated sandstone by micro-computed tomography technique

Heritage buildings always pose challenges due to experiencing high temperatures and pressure over time. Sandstone is one of the common sedimentary rock types used for these buildings. Therefore, it is very important to understand the microstructural variations of rocks associated with these constructions along with the mechanical variations. In this study, the microstructural and mechanical alteration of selected types of sandstones is investigated after it is heated from room temperature to 800 °C. Micro X-ray computed tomography (µXCT), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG) and derivative thermogravimetry (DTG) techniques were used to identify the physical, chemical, mineralogical and microstructural changes of sandstone after different heat treatments. The mechanical alteration of the heated rock specimens was also studied using the point load index (PLI). The main changes in microstructure were observed when the sandstone’s temperature was greater than 400 °C. The total porosity measured by µXCT of sandstone increased by more than 70% at 800 °C compared to its porosity at room temperature. When the temperature increases, the open porosity increases while the closed porosity decreases. Noticeable changes in rock mineralogy were identified at temperatures exceeding 400 °C, which can be attributed to the phase transition of quartz, decomposition of feldspar and dehydroxylation of kaolinite. The TG and DTG analyses and point load index were in good agreement concerning these changes in rock mineralogy. Microstructural variation is one of the main reasons for the discrepancy in threshold values between different sandstones.

Thermal damage and acoustic emission characteristics of granite based on Brazilian splitting test

Rapid and non-destructive evaluation of the thermal stability of surrounding rocks and rock strength is important in field construction. Physical properties and acoustic emission (AE) characteristics of granites can be changed at high temperatures. Thus, investigations on the relationships between rock strength and physical properties could help to evaluate the thermal stability via a physical measuring method. In this study, granite selected from a geothermal drilling project was heated at 25–600°C and different physical properties and tensile strength were measured. Moreover, the thermal damage degree was evaluated and the tensile failure pattern was quantitatively characterized. Notably, the tensile strength of granites could be indirectly acquired through P-wave velocity, hardness, colour, mass loss and volume expansion. The experimental results showed that the variations could be roughly divided into two stages. (1) At 25–400°C, the mass, volume, P-wave velocity, hardness, tensile strength, colour and AE parameters changed slightly. The failure mode and damaged section did not differ significantly within this temperature range. (2) At 400–600°C, these physical and mechanical properties and AE parameters changed significantly. The formation of micro-cracks was aggravated by the loss of structural water and phase transition of quartz, leading to complex failure modes and jagged morphology of damaged sections. The thermal damage factor and the compressive damage factor defined by the P-wave velocity at different conditions increased greatly. In summary, there was no major damage and the internal structure was still relatively intact at 25–400°C. However, the granite showed serious damage in the high-temperature environment (400–600°C), resulting in great changes in physical and mechanical properties and AE characteristics.

Fracture properties and dynamic failure of three-point bending of yellow sandstone after subjected to high-temperature conditions

The effect of high temperature on the fracture mechanical behavior of rocks is a critical topic of research in underground engineering. In this study, a single-side straight-crack three-point bending (SC3PB) yellow sandstone sample was heat treated at 25, 200, 400, 600, and 800 ℃. The fracture toughness of the sample was measured after heat treatment, and the deformation and failure process of yellow sandstone under load was monitored using acoustic emission and digital image correlation technology. The results revealed that the p-wave velocity, peak load and fracture toughness of yellow sandstone decreased considerably when temperature exceeded 400 ℃. By contrast, with the increase in temperature, the crack length and peak propagation rate increased considerably. Furthermore, with the increase in load, a high-strain band was observed in the the von-Mises strain in the loading direction. The fracture toughness was linearly correlated with the p-wave velocity, peak load and thermal damage. When temperature was higher than 400 ℃, the main fracture expanded and the plastic characteristics increased after the peak load. The rapid change in the physical and mechanical properties of 400-600℃ yellow sandstone was attributed to the α/β phase transition of quartz, the dehydroxylation of kaolinite and the escape of intermineral binding water and crystal water. Therefore, the physical and mechanical properties and fracture behavior of SC3PB yellow sandstone changed substantially at the threshold temperature of 400 ℃.

Силикаты магния при высоких динамических нагрузках

Research on the dynamic compression of geological materials is important for understanding composition and physical condition of the deep interior of the Earth and other planets. It also provides some data on the interaction processes related to the formation and evolution of planets. Magnesium silicates dominate in Earth's mantle and, thus, are expected to become the major phases in rocky exoplanets. In particular, enstatite Mg2[Si2O6] and forsterite Mg2SiO4 are essential constituents of Earth's mantles. Strong emphasis is put on the phase transition possibility for magnesium silicates under study. A remarkable fact is the dissociation of Mg2SiO4 into the following oxides: MgO and SiO2 (stishovite). The experiments have been carried out at a pressure value of 33 GPa, which corresponds to that in Earth's mantle at a depth of 1000 km. In this paper, the results of modeling the shock-wave loading of enstatite and forsterite as the mixtures of quartz SiO2 and periclase MgO are presented. The proposed model assumes that the components of the mixture under shock-wave loading are in thermodynamic equilibrium. The components of the material under study are considered in a phase transition region as a mixture of low- and high-pressure phases. The model is also valid for a polymorphic phase transition region. The calculations of magnesium silicates are performed with account for the polymorphic phase transition of quartz and periclase. The results are validated using the data obtained in dynamic experiments.

DEVELOPMENT OF RESOURCE-SAVING TECHNOLOGY OF POROUS-HOLLOW CERAMIC STONES

A resource-saving technology of porous ceramic materials using low-quality non-sintering sandy loam as a basic raw material has been developed. Based on the analysis of the plastic properties of two- and three-component ceramic masses, including sandy loam, expanded clay and fuel slag in various ratios, it was found that the required level of their plasticity provides the content of the main raw material in the following range (wt%): fuel slag – 15 – 20; sandy loam – 50 – 65; expanded clay – 20 – 30. By the method of planning the experiment, the rational composition of the three-component ceramic mass was substantiated. This which contains: 62.5 wt. % sandy loam, 20 wt. % medium-sintering plastic clay as a plasticizer and 17.5 wt. % fuel slag of TPP as a porous agent. For the developed mass, the main technological properties were investigated, which made it possible to recommend the drying mode of the raw material – 60 hours, the optimal firing temperature – 950 °С. Such conditions ensure that samples are obtained without drying cracks and signs of deformation. Оn the results of dilatometric analysis of mass the rational mode of firing high-hollow semifinished products was designed. The firing mode provides for a 44-hour firing and a decrease in the heating rates in the areas of dehydration of clay minerals, direct quartz transition and intensive sintering of the mass, as well as a decrease in the cooling rate in the area of the reverse quartz transition. The proposed firing mode provides the degree of sintering and their properties necessary for ceramic materials. Based on the developed mass under the recommended drying and firing modes, porous ceramic materials with an apparent density of 1.48 g/cm3, a compressive strength of 18.2 MPa and frost resistance of 30 cycles were obtained. The developed materials belong to the group of conditionally effective, and if 50% of the voids are organized, they can be classified as effective.