Papers by Keyword: Aluminum Titanate

Abstract: Magnesium-stabilized aluminum titanate powder was prepared via non-hydrolytic sol-gel method using titanium tetrachloride and anhydrous aluminium chloride as precursors, anhydrous ethanol as the oxygen donor, magnesium powder, magnesium fluoride, magnesium ethoxide and anhydrous magnesium acetate as stabilizers. The effect of magnesium stabilizers on low temperature synthesis of aluminum titanate was investigated, and their role and mechanism in stabilizing aluminum titanate were also studied by XRD, FT-IR and thermal expansion dilatometer. The results show that introducing magnesium powder or magnesium fluoride can’t stabilize aluminum titanate, they also lead to the failure of aluminum titanate low-temperature synthesis at 750 °C due to its promotion of non-hydrolytic homogeneous condensation. Anhydrous magnesium acetate and magnesium ethoxide can react with aluminum alkoxide and titanium alkoxide in the precursor mixture to form heterogeneous condensation bonds, which promotes magnesium ion to dope into aluminum titanate lattice at 750 °C, and hence to improve its thermal stability.

Abstract: The thermal stability of aluminum titanate (AT) ceramics is the main problem that restricted its extensive applications in many fields. In this paper, AT ceramics doped with single or composite additives of MgO, SiO2, mullite were fabricated by solid phase synthesis method. The thermal stability was tested by heated for 50h at 1100°C, and the phases of the samples were tested by X-ray diffraction (XRD) , and the microstructure were tested by SEM. The mechanism of the thermal stability of AT with additive was discussed based on DSC/TGA and electron back scatter diffraction pattern (EBSP). The results show that the adding of composite additives can improve the thermal stability of AT ceramics.

Abstract: Aluminum titanate (Al₂TiO₅) film was prepared via sol-gel method at low temperature, using ethyl acetoacetate and anhydrous citric acid as compound chelating agent, tetrabutyl titanate (Ti (OC₄H₉)₄) and aluminum chloride (AlCl₃^.6H₂O) as precursors, ethanol as solvent. The phase transformation of Al₂TiO₅ xerogel during heat treatment, the effect of different chelating agents on the synthesis of Al₂TiO₅, and the phase composition and morphology of film were investigated by means of differential thermal and thermo gravimetric analysis (DTA-TG), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FE-SEM). The results demonstrate that Al₂TiO₅ can be synthesized at 750 °C by using compound chelating agent, rather than single chelating agent. Compound chelating agent contributes to the formation of Al-O-Ti heterogeneous bond, which is the key to preparing Al₂TiO₅ at low temperature. High quality Al₂TiO₅ film could be coated on the SiC substract at 750°C.

Abstract: This paper described the properties of porous aluminum titanate (AT) ceramics. The AT samples with composition of 41 wt% Al₂O₃, 50 wt% TiO₂, 4.5 wt% MgO and 4.5 wt% Fe₂O₃ while 0~60 wt% graphite was used as pore former. The pore structures of the samples sintered at 1250~1350 ^oC were analyzed by scanning electron microscopy and Hg porosimetry, while the crystal phases of the aluminum titanate were analyzed by X-ray diffraction. After sintered at, the samples have open porosities of 25~51%, depending on the graphite amount and the sintering temperature. The porosity increases and the flexural strength decreases with the increasing amount of graphite.

Abstract: The major problem associated with application of aluminum titanate is decomposition to Al₂O₃ and TiO₂ oxides during heat treatment (in the range of 900-1280 °C ). In the present study, a stable compound of magnesium aluminum titanate ceramics (Mg_0.6Al_0.8Ti_1.6O₅) has been successfully synthesized with a straightforward non hydrolytic sol-gel process using inorganic metal compound. The raw materials were MgCl₂.2H₂O, AlCl₃, TiCl₄, and citric acid that were dissolved in ethanol. Prepared gel was dried at 120 °C and calcined at various temperatures using microwave heating. The results of X-ray Diffraction (XRD) and Simultaneous Thermal Analysis (STA) demonstrate that the direct crystallization of mono-phase magnesium aluminum titanate from fluffy precursor at a temperature below aluminum titanate decomposition temperature range is feasible. The formation of crystalline Mg_0.6Al_0.8Ti_1.6O₅ phase starts at about 400 °C. Also, Field Emission Scanning Electron Microscopy (FESEM) study and BrunauerEmmettTeller (BET) analysis represent the nanometric size of the mesoporous particles. The average particle size and specific surface area of powders were lower than 20 nm and more than 98 m²g^-1, respectively, at low temperatures.

Abstract: In this work, rods of Al₂O₃–TiO₂ eutectics containing 65 and 60 wt% Al₂O₃ were grown using the laser floating zone method. Raman spectroscopy was used to determine the phase composition. Creep strength of Al₂O₃–Al₁₆Ti₅O₃₄ (65AT) eutectic at 1500°C has 320 MPa, which is about higher than β–Al₂TiO₅/Al₂O₃ (60AT) crystal. Temperature dependence flexure strength, hardness, elasticity and fracture toughness of the Al₂O₃–Al₁₆Ti₅O₃₄ and β–Al₂TiO₅/Al₂O₃ crystals were analyzed. The relationship between the microstructure and the mechanical properties were analyzed the 60 and 65AT eutectic crystals.

Abstract: Mullite-aluminum titanate-cordierite multiphase ceramics were prepared by high alumina clinker, Aluminum Titanate and Cordierite. The sintering property and thermal shock resistance of composite materials were tested. The experimental results show that the sinter property and themal shock resistance of Mullite-aluminum titanate-cordierite multiphase ceramics are relatively preferably, which the materials composition are 30 wt.% high alumina clinker, 60 wt.% cordierite and 10 wt.% aluminum titanate. The component samples show porosity of 33.17%, volume density 1.9 % and normal temperature flexural strength 20.66 MPa. Thermal residual flexural strength of the samples is still as high as 10.29 Mpa by 5 times thermal residual tests, and there are only little flexural strength lower after three times earthquake test.

Abstract: Aluminium titanate (AT) ultrafine powder was prepared via hydrolytic sol-gel (HSG) method using aluminium nitrate (Al (NO₃)₃·9H₂O) and titanium tetrachloride (TiCl₄) as precursors as well as ethanol as solvent. Water required for hydrolysis reaction was supplied by the crystal water of aluminium nitrate itself. The effect of gelation processes, i.e. reflux and solvothermal treatment, on synthesis of AT powder was investigated by means of DTA-TG, XRD, SEM, and TEM, etc. The result shows that the gelation process has significant effect on the synthesis of AT powder. By reflux process, AT powder was synthesized at 1350 °C with average particle size above 1μm and serious agglomeration. Through solvothermal treatment process, however, AT powder with average particle size less than 150 nm was prepared at 1050 °C at a relatively high synthesis rate, which is due to the refinement reactants by the solvothermal treatment.

Abstract: The stabilized aluminum titanate (Al2TiO5) film was coated on the silicon carbide (SiC) substrate via nonhydrolytic sol-gel method (NHSG), using anhydrous aluminum chloride and titanium tetrachloride as precursors, ethanol as oxygen donor, different iron sources as stabilizers, and dimethyl mixed dibasic acid (DBE) with the characteristic of environmental protection and high boiling point as solvent. The phase transformation of modified Al2TiO5 xerogel during heat treatment, the effect of different iron stabilizers on the stabilization of Al2TiO5 film, and the influence of the coating process parameters on film-forming quality were investigated by means of DTA/TG, XRD and SEM. The results indicate that ethanol iron as the stabilizer, Al2TiO5 crystal phase can be formed at 750°C. While the temperature is raised further to 1000°C, Al2TiO5 is stable without decomposition, and has better synthesis effect. Selecting iron chloride, iron sulfate and iron ethanol as stabilizers respectively, only iron ethanol is effective to thermal stability of Al2TiO5 film. The best optimal vertical sliding velocity is 3.75 mm/s.

Abstract: Aluminum titanate has been synthesized by using industrial waste from ferroalloy plant, and titanium white as the main raw materials. The influence of MgO addition and calcining temperature on crystalline structure, micro-morphology and properties of synthesized Aluminum titanate are discussed. The synthesized product was characterized by XRD and SEM, and the crystallinity, cell parameters of crystalline phase are calculated by X' Pert plus software. The experimental result show the crystalline phase Through the research of effect of different concentration of MgO and different of calcining temperature on the crystalline structure of aluminum titanate prepared from industrial waste from ferroalloy plant, the optical concentration of MgO is 1%, and the optical calcining temperature is 1500°C.The grains of main crystalline phase aluminum titanate grow completely with typical orthorhombic feature, the average grain size of No.2 specimen in the micro structures is 10~20um.