Papers by Keyword: Cordierite

Abstract: An important phase of the MgO-SiO₂-Al₂O₃ system, α-cordierite was studied for its catalytic transesterification activity in preparing palm biodiesel. The prime drawback of such solid catalyst is its low activity. To overcome this problem, the transesterification was combined with microwave irradiation. The effect of reaction time and catalyst loading on biodiesel yield was investigated in a batch reaction mode. The synthesis of biodiesel was confirmed by ¹H NMR spectroscopy. It reveals that an enhanced yield of biodiesel was obtained, whereas the maximum yield was reached in less than 30 min regardless the catalyst loading. As a solid type catalyst, this result becomes a platform to develop the flow mode reaction unit using a cordierite based structured catalyst without modifying surface chemistry of cordierite.

Abstract: The aim of this work is to propose the utilization of aluminium buff from aluminium part manufacturer as a raw material for cordierite batch composition. The powder mixtures were compacted by uniaxial pressing. The green compacts were sintered at temperature in the range 1300-1400°C for 2 hours in air. The physical properties were characterized by Archimedes method, Brazilian test and dilatometry. Phase and microstructural analysis were done by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis showed the major phase was cordierite along with sapphirine as a secondary phase. The fired properties of materials were demonstrated that the optimal properties was achieved from the specimen sintered at 1375 °C.

Abstract: Mullite-cordierite ceramics was prepared by the three composition of talc, kaolin (kaolin from Naratiwas in Thailand) (NT) and alumina. The different amounts of alumina (5, 10, 15 and 20 wt%) were added to produce various mullite-cordierite alumina mixtures which are denoted as NA, NB, NC and ND, respectively. The mixtures were pressed into rectangular shapes by hydraulic press with the pressure of 150 kg/cm² then sintered at temperature of 1300 °C and 1350 °C for 2 hours. The morphology of the synthesized mullite-cordierite samples were characterized by x-ray diffraction spectroscopy (XRD), and physical-mechanical properties were investigated. Mullite-cordierite was successfully synthesized. The XRD result was represented phases of mullite and cordierite. The NA samples sintered at temperature of 1300 °C indicated the best physical-mechanical properties including bulk density (2.23 g/cm³), flexural strength (44.4 MPa) and thermal expansion coefficients (5.00x10^-6). The other NA samples sintered at temperature of 1350 °C exhibited the bulk density, flexural strength and thermal expansion coefficients are 2.21 g/cm³, 47.8 MPa and 4.99 x10^-6, respectively. The thermal expansion coefficient of the NT sintered samples have been plotted the length change relative to measuring temperature ranging of 30-1200 °C. The suitable condition of the synthesized mullite-cordierite ceramics is finally obtained the NA samples with 5 percent weight of alumina composition sintered at the temperature of 1350 °C.

Abstract: Cordierite glass of non stoichiometric (2.8MgO 1.5Al₂O₃ 5SiO₂) can be used to synthesis the synthetic gems because of it properties. The colorant glaze material; 2% , which from trace element cam give colorant to cordierite glass sample. The XRD analysis give result that α-cordierite formed at temperature 1250°C. The density and porosity of cordierite glass decreased as the sintering temperature increased. The hardness from Vickers Hardness are increased as the sintering temperature incerased.

Abstract: α-Cordierite glass ceramic was synthesised through crystallization of glass compacts made of milled glass frits. The effect of temperatures and colorants were studied. The crystal structure of α-cordierite was analysed using X-ray diffraction technique and Rietveld structural refinement method. Density, porosity and shrinkage analysis, Vickers hardness and SEM were also performed. The result revealed that at higher sintering temperatures, the properties of α-cordierite was getting better. Low apparent porosity level and high hardness dense α-cordierite was fabricated at temperature 1350oC. The low porosity level may lead to high thermal conductivity which suggested that cordierite was candidates for FIR therapy instrumemts.________________________________________________________________________

Abstract: Porous cordierite is an advanced ceramic which is popular for its interesting properties such as excellent thermal stability, high refractoriness and low dielectric constant. In this study, samples have been prepared by the mixture of aluminium nitrate nonahydrate, magnesium nitrate hexahydrate, tetraethylorthosilicate (TEOS), ethanol and nitric acid through sol-gel route. Corn and potato starch were used as pore forming agent. The amount of pore forming agent added was varied according to their weight percent (5wt%, 10wt%, 15wt% and 20wt%). The solution was then dried in oven at 90°C before sintered at 1350°C. Particle size analyzer was used to characterize the properties of pore forming agents. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were done on the produced samples. XRD results proved that all the samples produced were pure α-cordierite without the presence of other impurity or pore forming agent. From SEM results, samples using potato starch as the pore forming agent have pore size larger than corn starch due to the larger particle size of potato starch. Majority of the samples show interconnectivity among pores. The pore shape produced by potato starch is in prolate shape whereas for corn starch is in polyhedral shape.

Abstract: The work explores feasibility of 3D finite element modeling (FEM) to study the effective linear properties of porous brittle material microstructures represented by a uniform cubic mesh. Both artificial virtually generated and real 3D tomography specimens are considered in this work. A method for assessment of the critical value of tomography resolution is proposed. A method to build approximations of the linear effective structure properties of interest at virtually zero FE size is developed. The methods do not have to be associated with mechanical modeling only but can be applied in some other cases, e.g. effective thermal conductivity or effective permeability calculations.

Abstract: Cordierite samples were prepared using quartz sand tailings, industrial alumina and magnesite tailings as raw materials by high-temperature reaction. The influence of mineral composition and sintering temperature on the final phase composition and physical properties of cordierite were studied. The results shown that a large number of cordierite generated at 1300 °C. When the ratio of Al₂O₃/SiO₂ equals to 1.08, the flexural strength of samples increased to 27.66 MPa.

Abstract: Cordierite ceramics are known for their low CTE and high compressive strength values which affords them place in fields where demanding thermal and mechanical properties are required. Development of such ceramics is greatly dependent on materials used. If raw materials are used formation of additional phases and pore/glass formation is expected. The purpose of this research is to examine the process of cordierite development from mixed compositions formed from precursors of the natural raw materials as illite clay, dolomite and quartz sand and synthetic additives – MgO, γ-Al₂O₃ and their influence on thermal and mechanical properties. It is verified that the addition of 10 wt.% of illite clay and about 20-21 wt.% dolomite in staring compositions at the sintering temperature of 1200 °C results in the development of dense ceramic material with perfect-shaped crystalline cordierite phase and secondary anorthite phase. Sintered cordierite ceramics have been tested, among other properties, for their compressive strength, coefficient of thermal expansion and modulus of elasticity after 20 cycles of thermal shock treatment.

Abstract: A novel hexaaluminate material Ca_0.6La_0.4Fe_xMn_1-xAl₁₁O₁₉ was prepared by a micro-emulsion method, and then washcoated on the cordierite substrates to produce monolithic catalysts. The obtained hexaaluminates were characterized by X-ray diffraction and scanning electron microscope. Results show that the particles of the prepared hexaaluminates samples are well-proportioned and small, and that the lower-quantity replacement of Mn²⁺ with Fe³⁺ is of benefit to forming single hexaaluminates crystal phases. After the partial replacement of Mn²⁺ with Fe³⁺ in hexaaluminate, the catalytic activity in methane combustion improved.