Cordierite Composition Research Articles

BATCH COMPOSITION INFLUENCE ON SINTERING AND CRYSTALLIZATION PROCESSES OF CORDIERITE GLASSES OBTAINED BY THERMAL PLASMA MELTING

This article focuses on the production of glasses and glass-ceramic materials with a cordierite (2MgO∙2Al2O3∙5SiO2) composition. The processes of crystallization and sintering of cordierite glasses, which are based on natural raw materials, pure oxides and pre-synthesized cordierite, have been investigated. It has been determined that cordierite glasses produced via plasma melting exhibit high structural defects attributed to rapid heating and cooling rates. The relaxation of microstresses in the glasses takes place within the temperature range of 480 – 490 °C. Glasses based on synthesized cordierite exhibit a crystallization temperature of 930 – 1020 °C, depending on the presence and type of nucleating agents. This is approximately 20 – 50 °C lower compared to glasses based on component mixtures. The primary crystallization product of studied glasses at 900 °C is the high-quartz solid solution with formula MgO∙Al2O3∙3SiO2, which is dissociate above 1000 °C with the formation of cordierite. The addition of 5% ZrO2 to the batch increases the viscosity of softened glasses and their crystallization temperature, resulting in increased activity of glass powders in the sintering processes due to the higher impact of liquid-phase sintering on the general densification process of glass-ceramics. This allows for the production of glass-ceramics with open porosity of 2 – 4% at 1300 – 1350 °C. The addition of 5% TiO2 to the batch reduces the glass crystallization temperature. However it does not significantly effect on the cordierite glass-ceramics sintering processes. For citation: Sharafeev S.M., Shekhovtsov V.V., Zvyagina E.E. Batch composition influence on sintering and crystallization processes of cordierite glasses obtained by thermal plasma melting. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 80-87. DOI: 10.6060/ivkkt.20246707.7032.

Low-temperature cordierite ceramics with porous structure for thermal shock resistance products

This article shows the results of the study of low-temperature (1100−1150 °C) porous ceramics of cordierite composition. The technological manufacturing parameters, the features of the microstructural and phase composition of ceramics have been studied. A decrease in the sintering temperature is achieved by appending a part of components using eutectic glass of MgO–Al2O3–SiO2 pseudoternary system. The principle of reactive formation of the structure of the ceramic sample is implemented in the process of its low-temperature firing. The formation of α-cordierite occurs in the process of firing ceramics by means of intensive interaction between eutectic glass components and crystalline fillers, as well as in the result of glass crystallization. By means of the thin layers of the glassy phase, cordierite crystals form a hard base with a branched system of interconnected open pores (30.0−31.3 %). The cordierite-phase crystals, forming the structure of ceramics, have a particle size ranging from 0.2 to 0.3 μm to 1.0−2.0 μm. The specific surface area of the porous cordierite ceramics is in the range of 4.2–4.7 m2/g. The developed cordierite ceramics is characterized by its low coefficient of linear temperature expansion (1.7–2.6)·10−6 °С−1, which determines its high thermal shock resistance (1000−1150°С). The ceramics may be used as filtering elements in high-temperature filtering units, as well as catalyst carriers in the exhaust systems of combustion engines for discharging the sooty component.

Densely sintered carbide-silicon ceramics on a glass-crystal binder of cordierite composition

The high density of silicon carbide ceramics is a prerequisite for obtaining materials with high strength. A promising technology for preparation of such materials at relatively low temperatures is the use of glass crystal bonds. The paper presents the results of studies on ceramic materials based on silicon carbide using glass in the pseudoternary system MgO–Al2O3–SiO2 as a glass binder. The composition of the glass corresponds to a ternary eutectic with a temperature of 13650C, which is located at the boundary of the primary crystallization fields, where one of the phases is cordierite. It has been determined that it is necessary to mechanically activate the components of the raw material mixture to obtain densely sintered ceramics. In this case, the most rational ratio between SiC filler and glass binder, which provides the maximum mechanical compressive strength (up to 700 MPa), is 60:40. It has been established that the crystallization of the glass binder plays a decisive role in determining the formation temperature of dense silicon carbide materials. The compaction occurs due to the movement of dispersed silicon carbide particles in the softened glass melt under the influence of thermal vibrations. The subsequent process of fine-dispersed crystallization of the glass binder during cooling during firing provides strengthening of the structure of the synthesized materials. The proposed integrated approach to the intensification of the sintering process is promising for obtaining durable silicon carbide ceramics with low synthesis temperatures (up to 16000C). A sufficiently high strength of the experimental ceramics will ensure its competitiveness with respect to traditional materials, including those used as wear and impact resistant.

고령토 광물을 활용한 저 열팽창 코디어라이트 세라믹스 합성에 관한 연구

Cordierite (2MgO·2Al2O3·5SiO2) in the MgO·Al2O3·SiO2 system exhibits a low thermal expansion coefficient, high thermal shock resistance, low dielectric constant, and excellent electrical insulation properties. However, the material has a narrow sintering-temperature range. If the sintering temperature is too low, the crystal structure of cordierite does not form sufficiently; conversely, if it is slightly higher than ideal, the material decomposes into postelite, spinel, and mullite, leading to a significant increase in its thermal expansion coefficient. To overcome this problem, we adjusted the composition of cordierite by mixing it with predetermined amounts of kaolin minerals. After sintering at 1340℃, the resulting ceramic showed satisfactory physical properties, such as bulk density, absorption rate, and porosity. The optimal mixing conditions included a MgO/Al2O3 molar ratio of 1.006 and SiO2/Al2O3 molar ratio of 2.4277. Given its low thermal expansion coefficient(2.20 × 10−6/℃ at 800℃ and 2.57 × 10−6/℃ at 1000℃) and favorable physical and shrinkage properties, the cordierite prepared in this work may have potential applications in the development of kiln furniture materials for sintering next-generation secondary battery cathode materials.

Ultra-high-frequency radio-transparent ceramics of cordierite composition doped with MgO–Al2O3–B2O3–SiO2 glass: Synthesis, microstructure, thermal and physical properties

The paper presents the results of a study of radio-transparent cordierite ceramics, in which a part of the components was introduced using the eutectic glass of the MgO–Al2O3–SiO2 pseudoternary system. The formation of α-cordierite occurs during the sintering of ceramics due to the intensive interaction of components of the eutectic glass with crystalline fillers, as well as due to the crystallization of glass. At the same time, densely sintered material was obtained at relatively low temperatures (1300–1350°С). The crystalline phase of α-cordierite fully forms the structural matrix of the ceramic material. Crystals of the cordierite phase are formed in the form of regular-shaped flat prisms, mostly 1–3 μm in size. The pores between cordierite crystals are completely filled with glassy phase, which ensures their strong connection, uniform and dense microstructure of the material, as well as high strength, dielectric and thermal characteristics.

Investigation of Li2O and TiO2 effects on MAS glass-ceramic produced from waste material

Among glass-ceramics, MgO-Al2O3-SiO2 (MAS) system occupies an important place due to its good characteristics. In this study, the magnesite waste being an industrial waste was evaluated for the production of MAS glass ceramics and the properties of the glassceramics produced were examined. For this purpose, mixtures were prepared using magnesite waste, quartz, kaolin and alumina raw materials according to the chemical composition of cordierite. Furthermore, in the mixtures prepared with the additions of TiO2 and Li2O added as a nucleating agent the effects of these additions on the crystallization temperatures were investigated. Crystallization temperatures of the glass samples were determined by the differential thermal analysis (DTA) and characterized by X-ray analysis (XRD). Subsequently, the glass-ceramic transformation was performed at 1000, 1050, 1100, 1150 and 1200?C for 1, 3, 5 and 10 hours. The products obtained were analyzed using X-ray (XRD) and scanning electron microscope (SEM). In addition, the microhardness of glassceramic products and their corrosion resistance in an acidic environment were measured and compared in this study.

Investigation of Li2O and TiO2 effects on MAS glass-ceramic produced from waste material

Among glass-ceramics, MgO-Al2O3-SiO2 (MAS) system occupies an important place due to its good characteristics. In this study, the magnesite waste being an industrial waste was evaluated for the production of MAS glass ceramics and the properties of the glass-ceramics produced were examined. For this purpose, mixtures were prepared using magnesite waste, quartz, kaolin and alumina raw materials according to the chemical composition of cordierite. Furthermore, in the mixtures prepared with the additions of TiO2 and Li2O added as a nucleating agent the effects of these additions on the crystallization temperatures were investigated. Crystallization temperatures of the glass samples were determined by the differential thermal analysis (DTA) and characterized by X-ray analysis (XRD). Subsequently, the glass-ceramic transformation was performed at 1000, 1050, 1100, 1150, and 1200?C for 1, 3, 5 and 10 hours. The products obtained were analyzed using X-ray (XRD) and scanning electron microscope (SEM). In addition, the microhardness of glass-ceramic products and their corrosion resistance in an acidic environment were measured and compared in this study.

Determining patterns in the formation of cordierite phase during the synthesis of density-sintered low-temperature ceramics based on glasses of the MgO–Al2O3–SiO2 system

The search for effective modifiers of the structure of densely baked cordierite ceramics to reduce the firing temperature is a relevant task but typically requires a large amount of experimental research. The object of this study is the reaction of the formation of the cordierite phase with the participation of glass components of the eutectic compositions of the MgO– Al2O3–SiO2 system under low-temperature firing conditions. In this case, thermodynamic analysis was used as a tool to assess the probability of chemical reactions. Thermodynamic analysis can significantly reduce the volume of the experimental sample. This paper reports the results of theoretical and experimental studies into the features of the course of chemical reactions with the participation of glass components of eutectic compositions of the MgO–Al2O3–SiO2 system. It was revealed that once the stoichiometric ratio is maintained, the resulting product of the interaction between the components of eutectic glasses of the MgO–Al2O3–SiO2 system with charging components is cordierite. Changes in the mineralogical composition of cordierite compositions depending on the firing temperature have been determined. The formation of the cordierite phase is preceded by the process of transformation of meta kaolinite Al2O3·2SiO2, which is a product of kaolin dehydration, into mullite 3Al2O3·2SiO2. Subsequently, the formation of cordierite (in addition to crystallizing directly from eutectic glasses) occurs with the participation of the mullite phase. The formation of the cordierite phase occurs in several stages and is completed at a temperature of 1300 °C. The established features of the reactions of cordierite formation make it possible to determine the most optimal compositions for glasses of the MgO–Al2O3–SiO2 system to obtain low-temperature cordierite ceramics with a high degree of sintering. At the same time, it is also possible to control the phase composition of ceramics and its properties

Characterization of cordierite based h‐BN doped ceramics as an electronic substrate/circuit board material

AbstractIn this study, h‐BN was added to the cordierite composition obtained from zeolite, which was prepared by the determined stoichiometry to facilitate machinability and increase thermal conductivity. Sintering behavior, hardness, machinability, and thermal/electrical properties of the samples obtained by sintering the compounds at different times were investigated. Thanks to these features, it is aimed to use cordierite as an alternative material to integrated circuit substrates and electronic packaging materials. The produced samples were analyzed by X‐ray diffraction analysis, examined by scanning electron microscopy, and field emission scanning electron microscopy. Afterward, thermal properties such as thermal diffusivity, thermal conductivity, and electrical properties such as electrical conductivity and dielectric permittivity were measured. The hardness and machinability of samples were investigated. Cordierite, spinel, glassy phase, and h‐BN phase were detected, and it was observed that the blocky cordierite grains turned into equiaxed grains with the increase of the h‐BN. According to the results obtained from the thermal conductivity test, it was seen that the h‐BN additive increased the thermal conductivity value in general. In addition, it was determined that with the increase of h‐BN, the hardness decreased, and the machinability properties of the samples improved.

A comparative study of physicomechanical and in vitro bioactivity properties of β-wollastonite/cordierite scaffolds obtained via gel casting method

This study aimed to fabricate and characterise β-wollastonite/cordierite scaffolds synthesised via gel casting method, with different β-wollastonite and cordierite powder (wt.%) ratios of 100:0 (W), 70:30 (W7C3), 50:50 (W5C5), 30:70 (W3C7), and 0:100 (C). β-Wollastonite was synthesised by wet-milling silica and calcium oxide, and then, sintered at 950 °C for 3 h. Cordierite was synthesised using silica, magnesia, and alumina as the raw materials through the quenching method after the ingredients have been melted at 1400 °C and sintered at 980 °C for 2 h. Next, the effect of cordierite composition on the phase composite, and microstructure, as well as the physicomechanical and in vitro bioactivity properties of β-wollastonite/cordierite scaffolds were thoroughly investigated. The sintering linear shrinkage for all scaffolds was observed at 5.35%–15.25%, while bulk density was increased from 1.30 to 1.62 g/cm3. The X-ray diffraction analysis showed that all scaffolds, except the 100% cordierite (C), contained hydroxyapatite phase after being immersed in simulated body fluid (SBF). An apatite layer can be seen on the surface of the W, W3C7, W5C5, and W7C3 scaffolds. Scaffolds with porosities ranging from 70.3% to 53.3% showed compressive strengths ranging from 4.34 to 11.59 MPa. After one week of immersion in SBF, the compressive strength of the scaffolds has decreased dramatically (up to 75%). It was concluded that the W3C7 scaffolds have the best composition for fabricating porous scaffolds.

Effects of partial substitution of calcium alumino-titanate on the properties and microstructure of mullite–cordierite composites

In order to realize the recycling of calcium alumino-titanate (CAT, a solid waste), the effect of small amounts (3–9% weight ratio) of CAT on the sintering properties of the mullite–cordierite system was investigated. The thermal-shock stability, volume stability, and mechanical properties of samples with different amounts of CAT were characterized and tested. The influence of CAT on the phase composition and microstructure of the mullite–cordierite system was also deduced from thermodynamic calculations. Experimental results, which agreed with the calculations, demonstrate that CAT could promote the close combination and aggregation of matrix materials, thus strengthening the consolidation process and enhancing desirable properties.

Fabrication of Large-Area Mullite-Cordierite Composite Substrates for Semiconductor Probe Cards and Enhancement of Their Reliability.

This work aims to fabricate a large-area ceramic substrate for the application of probe cards. Mullite (M) and cordierite (C), which both have a low thermal expansion coefficient, excellent resistance to thermal shock, and high durability, were selected as starting powders. The mullite–cordierite composites were produced through different composition ratios of starting powders (M:C = 100:0, M:C = 90:10, M:C = 70:30, M:C = 50:50, M:C = 30:70, and M:C = 0:100). The effects of composition ratio and sintering temperature on the density, porosity, thermal expansion coefficient, and flexural strength of the mullite–cordierite composite pellets were investigated. The results showed that the mullite–cordierite composite pellet containing 70 wt% mullite and 30 wt% cordierite sintered at 1350 °C performed exceptionally well. Based on these findings, a large-area mullite–cordierite composite substrate with a diameter of 320 mm for use in semiconductor probe cards was successfully fabricated. Additionally, the changes in sheet resistance and flexural strength were measured to determine the effect of the environmental tests on the large-area substrate such as damp heat and thermal shock. The results indicated that the mullite–cordierite composite substrate was extremely reliable and durable.

Effect of sintering temperature on mechanical and bioactivity properties of bioactive glass and cordierite composite

In this study, a composite of bioactive glass (BG) and cordierite (BG-cord) was proposed to increase the strength and bioactivity of BG. Both BG and cordierite were separately synthesized with the method of glass melting, then, they were used to fabricate BG-cord with a variation of sintering temperature (600 to 1000 °C). The highest diametral tensile strength (DTS=30.54 MPa) was shown by the BG-cord with sintering temperature at 925 ºC. Bioactivity tests were conducted by soaking in Hank’s balanced salt solution (HBSS) for 7, 14, and 21 days. Apatite formation was examined by using a scanning electron microscope. The results showed that the sample showed good bioactivity with regards to the formation of apatite on the samples, confirmed by the detection of carbonate (C-O) and phosphate (P-O) absorption peaks by Fourier transform infrared spectroscopy and crystalline peaks in the X-ray diffraction pattern.

Physical and Mechanical Properties of Non-Stoichiometric Cordierite with Treated FGD Sludge Addition Sintered at 1250°C

The effects of addition treated FGD sludge in non-stoichiometric cordierite, by benefiting from its high mechanical strength and good thermal performance, can hold promise for more practical applications of non-stoichiometric cordierite. Treated FGD sludge waste from borosilicate glass industrial were used as a flux to reduce the sintering temperature of cordierite. Cordierite ceramics were prepared using silica (SiO2), alumina (Al2O3), talc, kaolin, magnesia (MgO) and treated FGD sludge via solid-state reaction method. The cordierite were prepared by adjusting the ratio of FGD sludge and magnesia in the cordierite composition, respectively. 4 composition of cordierite with 0%, 1.5%, 3.0% and 4.5% of FGD sludge were prepared to obtain the formation of α-cordierite that can be determine by X-ray diffraction (XRD) analysis. Porosity, density, shrinkage and flexural strength for each of cordierite composition were determined to obtain the best composition of treated FGD sludge required for sintering aids of cordierite. Only FGD 3.0% able to synthesis pure α-cordierite while FGD 1.5 % shows an improvement in both porosity and density. The increasing amount of treated FGD sludge lead to decreasing in mechanical strength of cordierite ceramic due to porous formation.

A Study of Cordierite Ceramics Synthesis From domestic kaolin

This work aims to study the effect of chlorine ion on the formation of the cordierite phase (2MgO.2Al2O3.5SiO2) from domestic kaolin at various calcined temperatures.. The cordierite phase was synthesized by a solid-state reaction technique from the mixture of kaolin, aluminum nitrate nonahydrate (Al(NO3)3.9H2O), and magnesium chloride hexahydrate (MgCl2.6H2O) which was designed to the stoichiometric composition of cordierite in the absence and presence of chlorine ion (NH4Cl). The structure and formation of cordierite phase were characterized by X-ray diffraction (XRD) and thermogravimetric - differential thermal analysis (TG-DSC). Phase composition of samples calcined at various temperatures was calculated by using Match! (Version 3.7.0) software. It is noteworthy that the presence of chlorine ion in the mixture declined the formation temperature of cordierite by 50 °C. The cordierite phase was calculated to be 61.3 wt.% and 5.5 wt.% at 1150 °C for the present and absent chlorine ion, respectively. The presence of chlorine ion affected the cordierite formation rate and suppressed the temperature of formation. Cordierite phase could be obtained up to 89.6 wt.% at 1250 °C and 30 wt.% NH4Cl. This investigation found that cordierite ceramic could be synthesized from domestic kaolin at lower temperature by using NH4Cl additive.

ON THE POSSIBILITY OF OBTAINING EFFECTIVE PHOSPHORIC FERTILIZERS AS A RESULT OF INTERACTION OF PHOSPHORITE-CONTAINING WASTE WITH ACTIVATED GLAUCONITE SANDS

The aim of the study is to synthesize technical glass ceramics containing magnesium oxide and fluoride in boroaluminosilicate systems. As a result of the work, the range of compositions was determined, in which it is possible to obtain transparent sitalls with the required physicochemical characteristics. The optimal ratio of oxides for the synthesis of the initial glass has established, and the temperature ranges of nucleation and growth of crystals in glass for the formation of a cordierite crystalline phase have been determined. The processes of crystallization of glasses of cordierite composition, containing B2O3, have studied by a one-stage mode of heat treatment of glasses at 1000-1200 oC. The sequence of crystallization of phases in glasses and their effect on the properties of glass-crystalline materials of the system (MgO•Al2O3)-B2O3-SiO2, the compositions were in the region of metastable segregation of the system along the section of 2MgOꞏ2Al2O3∙5SiO2-2(MgO∙Al2O3)5B2O3, were determined

Aspects of development and properties of densely sintered of ultra-high-frequency radio-transparent ceramics of cordierite composition

Aspects of development and properties of densely sintered of ultra-high-frequency radio-transparent ceramics of cordierite composition

A Modified Scheffe's Simplex Lattice Design Method in Development of Ceramic Carriers for Catalytic Neutralizers of Gas Emissions

A modified Scheffe's simplex lattice design method is proposed to study the properties of multicomponent materials. This modified Scheffe's method allowed determining the optimal compositions of cordierite and corundum based ceramic materials that are used as catalyst carrier for gas purification equipment. The obtained material (0.63-1.25 mm weight fraction of cordierite of 0.35 mass% fraction; < 0.63 mm weight fraction of cordierite of 0.35 mass% fraction; < 0.06 mm weight fraction of corundum of 0.2 mass% fraction; 1.25-2.5 mm weight fraction of cordierite of 0.2 mass% fraction) was used successfully for the manufacturing of catalytic neutralizers of gas emissions.

Physico-chemical properties and structural transformations in the synthesis of boroalumosilicate glass-crystal materials

The aim of this work is to study the areas of glass formation and metastable liquation of the pseudo-ternary system (MgO·Al2O3)-B2O3-SiO2, and study of the crystallization process of glasses of cordierite composition. The crystallization process of glasses of cordierite composition containing B2O3 by a single-stage heat treatment at 1000 oC and 1200 oC, the nature of crystallization, the thermal properties of glasses and glass crystalline materials of the system (MgO·Al2O3)-B2O3-SiO2 were studied. It revealed that during the isolation of a boron-containing solid solution, the residual glassy phase enriched with oxides of MgO and Al2O3, which lead to an increase in the thermal expansion coefficient of the glass phase. The research results provide possibility to synthesize glass-ceramics with certain thermophysical parameters by stopping further glass crystallization at the stage of formation of a certain amount and ratio of the required crystalline and glassy phases.

Effect of sintering atmosphere on the crystallizations, porosity, and thermal expansion coefficient of cordierite honeycomb ceramics

High-porosity cordierite ceramics were sintered in two different atmospheres, that is, in air (oxidizing) or in double-enclosed crucibles (mildly reducing). Paste slurries of cordierite compositions mixed with organic binders and pore formers were extruded into honeycomb-type substrates to produce diesel particulate filters (DPFs). The present study was conducted to explore the effects of sintering atmosphere on pore size, crystallization, amorphous phase, and thermal expansion coefficient (CTE) of sintered DPF honeycombs. Crystal phases were quantitatively analyzed using the Rietveld refinement method using powder X-ray diffraction (XRD) data. Amorphous phases were quantified using the Rietveld-internal standard method, and their presence was qualitatively confirmed by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) analysis. The most notable features observed were a dramatic decrease in the pore-size distribution and an enhanced rate of cordierite/indialite phase crystallization when sintering was performed in a double-enclosed crucible. A relatively high concentration of carbon monoxide (CO) in the double-enclosed crucible reduced the liquid-phase viscosity. This low-viscosity liquid phase spread relatively easily on the surfaces of crystal phases and enhanced the crystallization rate owing to a relatively large liquid–solid contact area in the mildly reducing atmosphere. The higher CTEs of DPFs produced in air compared with those produced in enclosed crucibles are discussed in relation to the amounts of amorphous and crystal impurity phases and crystal texture.