Pure Cordierite Research Articles

Cavitation erosion of samples based on cordierite-talc ceramics

In the paper, the cavitation resistance of cordierite samples with the addition of 10%, 15% and 20% talc, sintered at 1200?C, was investigated. The ultrasonic vibration method with a stationary sample according to the ASTM G32 standard was applied. The formation and development of damage to the surface of the samples was monitored using a scanning electron microscope and the level of damage to the surface of the samples was quantified using image analysis. The change in the mass of the samples as a function of the cavitation time was monitored to determine the cavitation rate. By measuring the mass loss and morphological analysis of the pits formed on the surface of the sintered samples of the cordierite-talc ceramics, the mechanism of degradation and resistance to the effect of cavitation was monitored. The obtained results were compared with the results of earlier tests of cavitation resistance of sintered cordierite samples. The addition of talc in the mixture with cordierite significantly improved cavitation resistance of the sintered material compared to sintered pure cordierite. The tests were done to see the potential application of this material in hydrodynamic conditions, especially because of the strong corrosion resistance of these refractory materials.

The Biomedical Investigation of Bioceramic Cordierite as Orthopedic Material

This study focused on the production of bioactive pure cordierite ceramic and the evaluation of its bioactivity by immersing it in simulated bodily fluid (SBF) and coating it on CP-Ti utilizing the dip coating Procedure. Cordierite is created by chemical coprecipitation, which involves combining Cordierite gel with a water-based sol-gel composed of Alumina Al2O3, magnesium oxide MgO, and silicon oxide SiO2. They used a hydraulic press to form cordierite into a cylindrical shape with a pressure of 4 bar and a holding time of 30 minutes at this pressure. Firing presses reach temperatures of 1250 Co and have a holding time of 2 hours. A Field Emission Scanning Electron Microscope (FESEM) was used to examine the microstructure, which revealed a homogenous distribution of the compounds with negligible porosities. The phase transitions that cur during the sintering Process is studied using X-ray diffraction (XRD). The structural investigation of specimens revealed the formation of the cordierite phase at 1250 Co, as well as the development of cristobalite, spinel, protoestatite, and corundum with cordierite phase. The dip coating Procedure was utilized to cover commercial pure titanium (CP-Ti) samples with cordierite powder. CP and Tafel exploration tests show that coated CP-Ti has superior passivation than uncoated Substrate. By comparing the findings of uncoated and coated CP-Ti, this paper concludes that the cordierite system acts as a good passivation layer.

Synthesis and characterization of cordierite and cordierite-zirconia by conventional approach

A wide recognition for cordierite ceramic due to its superior mechanical and electrical properties made cordierite a candidate for study. A simple approach of synthesis of cordierite and cordierite zirconia (5-15 wt %) was tried at the stoichiometric composition with standard raw material of high purity. The binder, lubricant and flux such as polyvinyl alcohol, ethylene glycol and sodium hydroxide respectively were added with 1 wt%. The powders were mixed, wet milled, dried at 100°C for 12 h, compacted and sintered at different temperatures between 600-1400°C for 3 h. The studies on XRD, FTIR and TG/DTA were carried out and the results from the studies confirmed the presence of cordierite phase alone for pure cordierite and cordierite along with zircon for cordieritezirconia compositions.

The Fabrication and Characterization Behavior of Cordierite Ceramic Materials with different Molar Fraction

The investigation was concentrated on preparation of bioactive pure cordierite ceramic and evaluate the phase transformation which excepted to form during sintering process. Cordierite prepare by chemical co precipitation, integrated Cordierite gel with water-based sol–gel which begin essentially from Alumina Al2O3, magnesium oxide MgO and silicon oxide SiO2. Different specimens were fabricated with various weight percentage of Al2O3, Mgo and SiO2 powders. All specimens were prepared in cylindrical shape by using hydraulic press at pressure of 4 bar with holding time at this pressure for 30 minutes. Firing presses achieve at 10000C and 12500C with 2 hour holding time. The characterization of microstructure has been done by using Field Emission Scanning Electron Microscope (FESEM), which revealed homogenous distribution of the compounds with few porosities. The x-ray diffraction for phase transformation which occur during sintering process. The structure analysis of specimens shows at 1250°C cordierite phase form, also the results are shown formation of cristobalite, spinel, protoestatite and corundum with cordierite phase.

Mechanical reinforcement of 3D printed cordierite-zirconia composites

In this study, composite ceramic slurries based on submicron-micron-sized cordierite-zirconia were prepared with varied zirconia content. Standard bending strength and fracture toughness testing samples were directly designed and fabricated using stereolithography 3D printing followed by different sintering schemes to study the mechanical reinforcement effect. The physical compositions and microstructures of the samples were characterized. The additively manufactured cordierite-zirconia composites exhibit excellent mechanical properties. Maximum measured bending strength (136 MPa) and fracture toughness (1.8 MPa m1/2) were reached by adding 2 wt% and 6 wt% zirconia, namely an increase of 44% and 66% relative to pure cordierite, respectively. The strengthening and toughening mechanisms of the composites were further explained mainly by microstructural analysis. This study provides an alternative and direct design and manufacturing method for the mechanical measurement and reinforcement of ceramic composite parts based on the use of 3D printing technology.

Preliminary Study on the Bioactivity Properties of Cordierite/β-Wollastonite Biocomposite Ceramics

The bioactivity properties of pure cordierite (C), pure β-wollastonite (W), and cordierite/β-wollastonite (CW) biocomposite ceramics were studied. Cordierite was prepared via melting, while β-wollastonite was prepared via the wet milling method. A bioactivity test showed that hydroxyapatite (HA) was non-existent in the pure cordierite sample after seven days of being soaked in simulated body fluid (SBF). On the other hand, the cordierite/β-wollastonite bioceramics showed that HA formation has entirely covered the surface of these samples. The XRD patterns showed that the crystallinity of W and CW samples has decreased due to the amorphous calcium phosphate (ACP) formation after seven days of soaking. SEM tests revealed that more ACP microstructures were present in cordierite/β-wollastonite samples than those in pure β-wollastonite. The effect of cordierite and β-wollastonite in biocomposite ceramics is described in this paper.

Sintering, physicomechanical, thermal expansion and microstructure properties of cordierite ceramics based on utilizing silica fume waste

In the present work, cordierite ceramics are prepared through the solid reaction method using calcined alumina, silica fume, and talc as starting materials. Pressed samples and powders are sintered and calcined at various temperatures; 1300, 1350 and 1400 °C. The particle size, phase composition and morphology of the raw materials, and the calcined and sintered cordierite samples are analyzed. The physical properties, surface area, DSC, TG, thermal expansion and electrical and mechanical properties of the cordierite samples are also studied. In addition, the physical, thermal, mechanical, and electrical properties are investigated under the effect of heat treatment. The results indicated that 1350 °C is the optimum sintering temperature with 10.323% apparent porosity and 2.112 g/cm 3 bulk density and the crystallization of the cordierite ceramic was crack-free and has low thermal expansion. It also, showed good dielectrical constant of 5.5 and good mechanical properties such as 2.71 MPa m0.5 fracture toughness and 5.38 GPa micro hardness. • Pure cordierite can be prepared using calcined alumina, fine amorphous silica fume and talc powder mixtures. • The formation of cordierite started at 1300 °C, it was enhanced by increasing the sintering temperature up to 1400 °C. • The optimum physical properties were obtained at 1350 °C with 10.323% apparent porosity and 2.112 g/cm 3 bulk density. • Thermal expansion of cordierite sintered at 1350 °C decreased, producing CTE from −8.18 × 10 −7 at 200 °C to -3x10 −7 at 900 °C. • At 1350 °C, cordierite showed good dielectrical constant of 5.5, fracture toughness of 2.71 MPa m 0.5 & 5.38 GPa micro hardness.

Preparation cordierite and zirconia-doped cordierite composite & study bioactive properties

The current study focused on studying the bioactive behavior of pure cordierite which by sol- gel technique. Cordierite gel is combined with water-based sol–gel course, beginning from fundamental magnesium carbonate and Al (NO3) 3 inorganic arrangement broke up in silica-ethanol sold. Zirconia-doped cordierite composite also prepared by a new precipitation procedure with the composition of (5–15 wt%) of ZrO2. The cylindrical samples in 13 mm diameter for the next tests were formed by cold pressing at 150 MPa then sintering at 1350 °C. The, X-ray analysis, and SEM technique were applied to find the microstructure . The bioactivity properties of produced powder were determined after immersing for 21 days in the stimulated body fluid (SBF) solution which appearance compact layer of hydroxyapatite (HA) that exhibits a biological activity with increase the amount of ZrO2 as compared with pure cordierite. Biodegradation test was done by soaking synthesized powder in the trees-HCl buffer solution for 7 days and weight loss of samples was determined the increase in weight loss is detected as the content of ZrO2 in the samples increases with respect to pure samples. Cytotoxicity estimation has done, by RAW macrophage similar the media cell line for a period of growth of 48 h. The cell addition, trainings on the powder prepared, sample, display perfect attraction between compact surface and cells.

Bond characteristics and microwave dielectric properties of (Li0.5Ga0.5)2+ doped Mg2Al4Si5O18 ceramics

Cordierite ceramic is one kind of important electronic materials for radio frequency circuit. In this work, Mg2-x (Li0.5Ga0.5)xAl4Si5O18 (0 ≤ x ≤ 0.1) ceramics with pure cordierite phase, were successfully synthesized via the traditional solid state reaction method. The dependence of microwave dielectric properties on the crystal structure was analyzed in detail by the complex chemical bond theory (P–V-L theory) and classical dielectric polarizability theory. The dielectric constant (εr) was mainly related to the density, bond ionicity and ionic polarizability of Mg2-x (Li0.5Ga0.5)xAl4Si5O18 ceramics. The quality factor (Q × f) was in relationship to the lattice energy, atomic packing fraction and centrosymmetry of [Si4Al2O18] hexagonal ring in cordierite crystal structure. The temperature coefficient of resonant frequency (τf) value was dominated by the bond energy and distortions of [MgO6] octahedron. The maximum values of Q × f = 50,560 GHz and εr = 4.72 were obtained for undoped Mg2Al4Si5O18 and Mg1.98Li0.01Ga0.01Al4Si5O18, respectively.

Low temperature synthesis of highly pure cordierite materials by spark plasma sintering nano-oxide powders

The development of cordierite ceramics, using traditional materials and conventional methods, remains a key challenge because of the high and narrow sintering temperature range. In this work, single-phase cordierite ceramics were produced by spark plasma sintering nano-oxide powders, at low temperatures. A starting mixture of Al2O3, SiO2, and MgO nano-powders with the composition of stoichiometric cordierite was first sonicated, then, sintered in the temperature range 900–1200 °C. The raw powders, sonicated powder mixture, phase transformations, and fracture surface of sintered specimens were characterized by using an x-ray diffractometer and a field emission scanning electron microscope (FE-SEM). The hardness and fracture toughness were measured using the indentation technique. The influence of testing conditions, process parameters, characterization technique, and calculation method on hardness and fracture toughness was investigated. The FE-SEM images, x-ray maps, and EDS results revealed the homogeneity and stoichiometry of the sonicated powder and sintered samples. Highly pure α-cordierite was formed at 1150 °C. Samples that were sintered at 1150 and 1200 °C had bulk density of 2.58 g/cm3 (relative density of 100%), and maintained low average grain sizes of 28.68 and 34.95 nm, respectively. With the decrease in the temperature from 1200 to 1150 °C, the hardness of cordierite was slightly increased from 8.25 ± 0.158 to 8.46 ± 0.188 GPa, the fracture toughness was marginally improved from 2.2 ± 0.158 to 2.25 ± 0.238 MPa mm1/2, and the critical strain energy release rate was raised from 32.46 to 33.95 J/m2.

In-situ synthesis and properties of porous cordierite ceramics with adjustable pore structure

Using high purity oxide (MgO, Al2O3 and SiO2) as raw materials, porous cordierite ceramics with a single phase and adjustable pore structure have been in-situ synthesized by foam gel-casting process. The effects of sintering temperature and foaming agent concentration on the phase composition, microstructure and properties were systematically investigated. The results indicated that pure cordierite could be obtained at sintering temperatures of 1430 °C and 1450 °C, while the sample sintered at 1450 °C showed better comprehensive performance. By adjusting the foaming agent concentration in the range of 2–32 g/L, the pore size of the materials could be controlled between 45.3 μm and 151.3 μm with the total porosity of 85.4–87.8%. When the sintering temperature was 1450 °C and the foaming agent concentration was 8 g/L, the prepared samples showed excellent properties and the near net size sintering was achieved. The sintering linear shrinkage was about 0.26%, the total porosity was 86.6 ± 0.2%, the bulk density was 0.35 ± 0.01 g/cm3, the compressive strength was 2.63 ± 0.33 MPa, the thermal conductivity was 0.217 ± 0.026 W/(m·K), the thermal expansion coefficient was 1.70 × 10−6/oC, and the permeability of deionized water was 3.62 × 10−11 m2.

Sintering and dielectric behavior for doped cordierite by xCuO within MgO (1-x)–Al2O3–SiO2 ceramics

Crystalline structure, morphology, quantitative chemical constitution and dielectric properties of pure cordierite ceramic (CC) bodies and these doped with xCuO in formula MgO(1-x)Al2O3SiO2 (x = 0, 0.02, 0.04 and 0.06 wt%), prepared by a conventional solid state ceramic process, were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray fluorescence (XRF) and broadband dielectric spectrometer (BDS), respectively. Experimental results showed that doping with CuO results in lowering sintering temperature, lowering porosity, increasing bulk density and formation of copper magnesium silicate (CuMgSi2O) phase. CuMgSi2O which was formed with the highest content of CuO (0.06 wt %) increases the glassy phase, i.e. crystalline phase decreases of CC. Accordingly, the dielectric properties of CC found to be affected by CuO content. For instance, the permittivity and loss tangent slightly increased upon doping with 0.02 wt % CuO and then considerably decreased for sample doped with 0.06 wt % CuO due to formation of CuMgSi2O phase. Particularly, the loss tangent attained much lower values (0.003 at 25 °C) upon doping with 0.06 wt% CuO. Interestingly, such materials of very low loss can be used as candidates for wireless communication systems as well as in several electronic devices.

Processing and properties of dense cordierite ceramics obtained through solid-state reaction and pressure-less sintering

ABSTRACTSintering of pure cordierite 2MgO:2Al2O3:5SiO2, and cordierite with the addition of 5 mass % TeO2 was studied. Green bodies were prepared from powder mixtures mechanically activated in a high-energy planetary mill, shaped by uniaxial (20 MPa) and cold isostatic pressing (1000 MPa). The pressure-less sintering of these specimens was performed at 1350°C for 1 h. High relative density over 95% of the theoretical value was obtained through solid-state reaction and pressure-less sintering of powder activated for 40 min, and for the first time reported in the literature. Phase composition and microstructures of sintered samples were determined by XRD and SEM, coupled with EDS mapping. The real part of the complex relative permittivity of the samples was measured at 200 MHz. The loss tangent of all samples was below the resolution of the measurement setup. A strong correlation between the relative permittivity and the density agrees with previously published data.

Mechanistic Insight into Etching Chemistry and HF-Assisted Etching of MgO-Al₂O₃-SiO₂ Glass-Ceramic.

The present study focuses on the etching conditions and mechanism of MgO-Al2O3-SiO2 glass-ceramic (MAS) in hydrofluoric acid (HF). The results show that the amorphous phase has 218 times higher etching rate than pure cordierite crystal at room temperature. In addition, the activation energies of cordierite and amorphous phases in the HF solution are 52.5 and 30.6 kJ/mol, respectively. The time (tad) taken for complete dissolution of the amorphous phase depends on the HF concentration (CHF). Based on the etching experiments, a new model is established and refined to assess the tad evolution. In addition, a highly crystalline cordierite phase, with the high specific surface area (59.4 m2·g−1) and mesoporous structure, has been obtained by HF etching. This paper presents novel insights into the etching chemistry and opens up avenues for further research in the area of cordierite-based catalytic ceramics.

Influence of dopant metal ions on the formation of cordierite using combined SAXS/WAXS and EXAFS/WAXS techniques

Time-resolved combined scattering and spectroscopic techniques were used to understand in detail the formation of cordierite ceramic from two sources, (a) zeolite B and (b) cordierite glass systems. Time-resolved in situ combined EXAFS/XRD (at the Zn K-edge) investigation of the zinc oxide mixed zeolite B reveal that a series of transformations occur before the formation of cordierite ceramic. In particular the study revealed that addition of small amounts of zinc oxide promote the transformation of cordierite, through the formation of ZnAl2O4, at lower temperatures compared to the system without zinc oxide. Using in situ time-resolved SAXS/WAXS technique chromium doped in the cordierite glass system was investigated which revealed that, in addition to the formation of phase pure cordierite phase some amount of MgCr2O4 spinel phase are also produced.

Processing and characterization of pure cordierite and zirconia-doped cordierite ceramic composite by precipitation technique

Pure cordierite and cordierite–ZrO2 composite (5–20 wt%) ceramics for various stoichiometric compositions were synthesized from standard raw materials by a novel precipitation technique. The analytical techniques such as X-ray diffraction, simultaneous thermogravimetric and differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and bulk density were employed to evaluate the properties and microstructure. Results show that the ceramic composites consist of cordierite and zircon phases. The cordierite–zirconia (20 wt%) increased the fracture toughness value from 3.38 to 3.94 MPa, which is mainly due to martensitic transformation present in zirconia. The flexural strength of composite was found to increase from 126.46 to 297.62 MPa. The thermal expansion coefficients of cordierite and cordierite–zirconia (20 wt%) were 4.08 × 106 and 4.42 × 106 ∘C−1 which may be due to the addition of zirconia.

Crystallization of indialite/cordierite glass ceramics for millimeter-wave dielectrics

Indialite/cordierite (Mg2Al4Si5O18) glass ceramics have been reported to show excellent millimeter-wave dielectric properties of low dielectric constant of 4.7 and high quality factor Qf of >200,000GHz when crystallized at the temperature range of 1200–1300°C. The glass ceramics were crystallized to the intermediate indialite phase at 1200°C, which phase was then transformed to the stable cordierite phase as crystallization temperature increased. In this paper, the crystallization procedure of the glass with pure cordierite composition was clarified by macro difference thermal analysis (DTA) and X-ray powder diffraction (XRPD) patterns. The crystallization of the glass occurred in two steps above the Tg of 778°C: the 1st step is the formation of β-quartz solid solutions (s. s.) at 919°C, and the 2nd step is the transformation from β-quartz s. s. to indialite at 946°C. As increasing the crystallized temperature, indialite phase converted to cordierite. This phenomenon indicates that indialite is an intermediate phase during the crystallization process from glass to cordierite.

Synthesis, characterization and sintering behavior influencing mechanical, thermal and physical properties of pure cordierite and cordierite-ceria

The study of cordierite ceramic is the need of the hour in present technological world for various advanced engineering applications. Cordierite, which has relatively poor mechanical properties, has induced the use of various dopants to study the improvement in mechanical properties. Thirst of seeking new materials with good mechanical properties has revived the research on ceria doped cordierite. Present research conducted on pure cordierite and ceria doped cordierite ceramics has investigated the results of characterization and studied their suitability. Pure cordierite and cordierite-ceria (CeO2) composite ceramics synthesized for various stoichiometric composition (5–20 wt%) were compacted at 240 MPa and sintered between 600 °C and 1350 °C for 3 h. The characterization techniques used in this study were X-ray diffraction (XRD), thermogravimetric (TG) analysis and Fourier transform infrared (FTIR). The density was calculated using the Archimedes principle. Influence of the ceria addition on cordierite’s mechanical properties such as hardness, flexural strength and fracture toughness and on thermal properties as thermal expansion was studied. XRD results confirmed the presence of cordierite and ceria in the samples heat treated at 1350 °C. Results of FTIR and TG analyses revealed the formation of cordierite and the effect of ceria addition. The mechanical properties studied were found to be encouraging and confirmed the suitability of cordierite-ceria as an alternate material for cordierite.

Extending and Enhancing the Properties of Porous Cordierite Ceramics by Mo6+ ion Incorporation via Facile Combined Synthesis Technique

Molybdenum‐doped cordierite ceramics have been fabricated through facile combined techniques, coprecipitation followed by solid state. XRD results revealed that α‐cordierite phase is predominated with increasing Mo6+ ion content. The density measurements showed that the bulk density reduced to the minimum value of 0.61 g/cm3, which corresponds to the maximum porosity of about 76.8% at 5% Mo6+ ion. The dielectric permittivity (ε) of pure cordierite is decreased with increasing Mo6+ ion content. The minimum dielectric loss of Mo‐doped cordierite at 1 MHz was equal 0.008 with 10% Mo6+, while at 1 GHz was equal 0.03 with 5% Mo6+.

Structural, Microstructure, Mechanical and Electrical Properties of Porous Zr4+-Cordierite Ceramic Composites

Zirconium-cordierite ceramic composites have been synthesized by a co-precipitation method using MgCl2·6H2O, NaAlO2, Na2SiO3·5H2O, and ZrOCl2·8H2O as starting materials. XRD, FT-IR, and SEM techniques were employed to study the effect of zirconium on the crystal structure and microstructure of the samples. XRD results revealed that spinel MgAl2O4 and t-ZrO2 phases were predominant in the samples with low Zr4+ content (10 wt.%), whereas zircon ZrSiO4 was predominant with high Zr4+ content (≥15 wt.%). The densification behavior was improved from 30.4 to 44.6% of the theoretical density (2.6 g/cm3) at 15 wt.% of Zr4+. However, microhardness of the sintered samples was enhanced from 7.1 to 7.5 GPa with increasing the Zr4+ dose from 0 to 25 wt.%. On the other hand, the gradual increase in Zr4+ content from 0 to 25 wt.% led to suppression in the electrical resistivity (ρ) from 16.6 to 2.8 × 109 Ω/cm, respectively. In addition, the dielectric permittivity (e) of the pure cordierite was decreased with Zr4+ ion addition. The maximum dielectric permittivity (e) at low frequencies (10 MHz) was 18.7 at 10 wt.% Zr4+ content, whereas at high frequencies (1 GHz) it was 38.8 at 15 wt.% Zr4+ content.