Synthesis and Characterization of High-purity Aluminum Titanate with Water Quenching Method Synthesis and Characterization of High-purity Aluminum Titanate with Water Quenching Method

Synthesis and Characterization of High-purity Aluminum Titanate with Water Quenching Method

  • 期刊名字:结构化学
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  • 论文作者:SHEN Yang,RUAN Yu-Zhong,YU Yan
  • 作者单位:College of Materials Science and Engineering
  • 更新时间:2020-07-08
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28卷3期结构化学(JIEGOU HUAXUE)Vol. 28, No. 32009.3Chinese J. Struet. Chem.365-369Synthesis and Characterization of High-purityAluminum Titanate with Water Quenching MethodSHEN Yang RUAN Yu-Zhong° YU Yan(College of Materials Science and Engineering,Fuzhou University, Fuzhou, Fujian 350108, China)ABSTRACT High-purity aluminum titanate was synthesized via a water quenching method withwaste-residue in the aluminum factory and industrial TIO2 as the main raw materials, which belongsto the comprehensive utilization of solid wastes. Compared with the conventional method, it canreduce synthesis temperature, efectively inhibit decomposition and raise the content of AT; theaddition of tiny silicon powder can improve the sintering and optimize the properties of AT. Thecrystaline phase structure and microstructure of each sample were characterized with XRD andSEM methods; the content of each crystalline phase in each sample was confirmed with RietveldQuantification method; the properties of each sample were also tested. The experimental resultsshowed that No. 4 is the optimum specimen, with the corresponding mass ratio of Al2O/TiO2 to be .1.27 and the content of AT of 97.2 wt%. The adition of optimum tiny silicon powder is confirmedto be 8wt%; its corresponding bulk density is 2.63 g/cm', bending strength is 46.34 MPa, and theretention of one thermal vibration bending strength is 71.5%.Keywords: aluminum titanate, water quenching method, aluminum waste-residue, tiny siliconpowder1 INTRODUCTIONquenching method with waste-residue in the alu-minum factory and industrial TIO2 as the main rawAluminum titanate (Al2TiOs: AT) has high melingmaterials. Sludge in aluminum factory is obtainedpoint and low coefficient of thermal expansion sofrom considerable colloid waste- residue produced bythat it has excellent thermal shock resistance, whichsurface treatment of aluminum parts, which are per-can be used under acute heat shock conditionI~6].formed by flocculation, precipitation, and dehydra-AT material can be used in the purification of auto-tion treatment. Its main composition is )-AlOOHmobile off-gas as the fler carrier, high temperaturewith superfine particles and high activity'9, which iscatalyst carrier, engine vent -pipe, and so on!7.8. Thisbeneficial to the formation of AT via solid phasematerial belongs to unstable compound, so it willreaction. It is the ideal raw material for the synthesisdecompose to be TiO2 and corundum!" 0 within theof high-purity AT materialo, ". Water quenchingtemperature range of 750~ 1300 C. Therefore, it ismethod is that the synthesized resultants at highdifficult to synthesize high-purity AT material,temperature rapidly pass the temperature range ofwhich, however, can be synthesized through a water1300~750 C via water quenching so as to avoid the中国煤化工Received 8 Aprl 2008; aceped 14 July 20080 Supporned by the Nauru Science Foundation of Fujan Province (No. T075000)0HCNMHGand the Sciece and Technology Developing Foundaion of Fuzhou University (No.2007-Q-02)②Coresponding aubo. Profssor,. doclor tutor with main research itest of eologial environment maicrials and speial inorganic materialsShen Yang. male, bom in 1981, doctor candidate. E mail: sheny11@ 163.comSHEN Y. er al: Synthesis and Characterization of High-purityAluminum Titanate with Water Quenching MethodNo. 3decomposition of AT within this temperature range,and to keep high temperature state at low tempera-2. 1 Composition of raw materials and specimensture. With this method, the content of AT in the syn-The raw materials are the sludge in aluminumthetic material can reach as high as 97wt%, which isfactory and TIO2, where the composition of sludgehigher than that obtained by the conventional me-(wt%) is as follows: Al203.61.16%, Si02.34%,thod. Thereby, using water quenching method toFe2O30.27%, Ca0.0.48%, Mg0.0.37%, K20.0.03%,synthesize high-purity AT has certain innovativeNa20.1.34%, L.0.L34.26%.significance. In this paper, the influence of Al2O3/The theoretical composition of Al2TiOs(wt%) is asTiO2 ratio in the specimen on the crytalline phasebelow: the content of Al2O3 is 56.07% and that ofstructure, microstructure and content of AT is mainlyTiO2 is 43.93 %, that's to say, the mass ratio ofdiscussed, and the properties of AT material are ana-Al2Oy/TiO2 in AT is 1.27. According to the composi-lyzed so that the optimum specimen can be deter-tion, seven specimens are confirmed as listed in Table 1.mined.2 EXPERIMENTALTable 1. Composition of Each Specimen (m%)Specimen No.Al2O3TiO2 AlzO/TIO2SludgeTiOrNo.1621.6372.5427.46No.2604(1.5070.8329.17No.3s81.3869.0930.91No.4561.2767.3232.68No.5s4461.1765.5234.48No.6S263.68 .36.32No.7s501.0061.8138.19The mixtures were prepared according to Table I.the micromorphology of each sample was observedAnd then the raw materials of each sample wereby Philips XL 30ESEM scanning electron micro-mixed, ground by Wet method for 12 h, performedscope. Besides, the properties of each sample were tested.staleness for 24 h, dried, dehydrated, sifted out, andthen pressed to the model when it was damp-dry.3 EXPERIMENTAL RESULTSThe samples were baked to be dry, and placed into aAND ANALYSIShigh temperature fumace to sinter at 1400 C for 2 h,and then took out into water to quench. The calcined3.1 Efect of different Al2O3/TiO2 ratios onblock specimen was thus obtained. The compositionthe crystalline phase formation ofof crystalline phases of the sintered samples wassynthesized specimencharacterized by Philips Xpert-MPD X-ray diffrac-XRD pttens of 7 specimens are shown in Fig. 1,tion instrument. The analysis conditions were: Cuand the content of each crystalline phase is listed intarget (Ka), tube voltage 35 KV. and tube current 20Table 2 according to the qualitative analysis of XRDmA. The content of each crystalline phase wasspectra.calculated by Rietveld Quantification software. And中国煤化工Table 2. Crysalline Phases and Contents oMHCNMHG_Specimen No.AI2OyVTIO2Al2O2AlTiO3_16.61.482.02009 Vol.28结构化_学(JIEGOU HUAXUE) Chinese J. Struct. Chem.367No.21.5014.03382.7No.338No.41.272.).397.2,17)9No.61.08.491.6No. 73.8.690.6扈E“.. 7#nn AJLneswthnmunr 6#emon 1#z26/c. ,80Fig. 1. XRD patterns of diferent specimensAccording to the qualitative analysis results ofTable 2 shows that from samples No. 1~5, theXRD spectra, each sample forms three crystalinecontents of AT are gradually increased from 82wt%phases: aluminum titanate (Al2TiOs), corundumto the highest 98.8wt% with the decrease of Al2O}/(Al2O3) and rutile (TO2), where AT is the mainTO2 ratio. When the Al2Oy/TiO2 ratio is from 1.63crystalline phase. AT has two crystalline phases of ato 1.50, the content of AT increases from 82wt% toand β which transform at 1820 C. When tem- 82.7wt% with a small extent; if the Al2O/TiO2 ratioperature reaches 1820 C, AT converts from phase βis from 1.50 to 1.38, the content of AT varies frominto phase a whose melting point reaches as high as82.7wt% to 96.8wt% with a greater increase extent;1860 C1-4. When the temperature decreases towhen the Al2O3/TiO2 ratio is from 1.27 to 1.17, the1300 C. phase β starts to decompose to be Al2O3content of AT increases from 97.2wt% to 98.8wt%and TO2; when temperature is lower than 750 C,with a mild extent; if the Al2Oy/TIO2 ratio rangesphase β is inclined to be stable; therefore, the stablefrom 1.17 to 1.08, the content of AT decreases frominterval of phase ais 1820~1860 C, and that ofβ 98.8wt% to 91.6wt%. When Al2Oy/TIO2 is 1.17, itsis 1300~ 1820 C and lower than 750 C, and thuscorresponding content of AT is the highest (98.8wtthe unstable interval of phase β decomposing to be%), but it is on the decreasing edge of AT. Therefore,Al2O3 and TiO2 is 1300~ -750 C. In 1972, MorosinNo.5 is not the optimum specimen; whereas theverified that A1* and T4+ in the Al2TIOs structurecontent of No. 4 is 97.2wt%, which is the secondexist as the form of octahedra [AlO6] and [TIO6],great中国煤化工fucuation and .and Al+ and π+ distribute in an entirely random ;can t|Y片CNMHGNo.4shouldbemanner". Octahedral [AIOo] is greatly distortedthe optimum specimen, and 1.27 is the optimumbecause AIS+ has smaller radius than Ti+.ratio of Al2O3/TiO2.SHEN Y. et al: Synthesis and Characterization of High-purity368Aluminum Titanate with Water Quenching MethodNo.3.3.2 Effect of different Al2O3/TiOz ratioas 97.2 wt%. Most crystals in the figure are basicallyon microstructure of synthesized specimenAl2TiOs, and its grains present iregular shape, growFig. 2(a)~(c) are respectively the SEM images oflarger, and have acute edge angle, clear grainNo. I, 4 and 7 calcined samples.boundary, less glass phase and high density. Fig. 2(c)Fig. 2(a) demonstrates that Al2TIOs particles in No. 1is the SEM image of No. 7 sample, whose Al2O3/sample present irregular granular shape and lamellarTIO2 ratio is 1.00. Its grains also present iregularshape with different sizes, which are bound by glassshape with more acute edge angle and some pores.phase; Al2Oy/TiO2 ratio of No. I sample is 1.63, itsThe difference of grains' size is greater, some ofcontent of Al2O3 is surplus, and thus there are Al2O3which becomes larger; Glass phases basically disap-and TIO2 without reaction which presents hexagonalpears, and density decreases gradually. The analysislamellar and column shape respectively. Fig. 2(b) isof microstructure finally determines No. 4 as thethe SEM image of No. 4 sample, whose Al2Oy/TiO2best specimen, and its coresponding Al2O3/TiO2ratio is 1.27, and the content of AT reaches as highratio is 1.27.Flg. 2. ()-(c) SEM images of specimens No. 1, 4 and 7 after calcination3.3 Properties of aluminum titanate materialamorphous structure SiO2 with superfine particle,Aluminum titanate material is difficult to be cal-high surface area and great activity. Therefore, it cancined and has low intensity so it can not be usedimprove the calcinations and intensity of AT ma-alone. Thus additive should be added to improve theterial. Based on the synthesized specimen of No. 4,calcination of AT material. In this study, tiny silicon0wt%, 4wt%, 8wt% and 12wt% tiny silicon powderspowder is used as the additive, which is the con-are added for conducting the experiment at 1400 Csiderable smoke dust produced during the produc-for 2 h. The properties of calcined sample are testedtion process of fro-silicon. Its main composition isand listed in Table 3.Table 3. Properties of the Calcined Specimens with Fine Silicon Powder AdditiveTiny sliliconBulkApparentBending strengthRetention ratepowderdensityporosityaborptionstrengthafter thermalof bending(w%)_(g/cm)(%)(%(MPa)shock (MPa)strengh(%)2.2439.514.597.390.72.5329.811.841.4429.1870.42.6323.4.946.3433.151.52.6023.71_中国煤化工.6.7Table 3 shows that the bending strength and bulkg/cm3.THCNMH GnI and retentiondensity of samples without the addition of tinyrate of one thermnal vibration bending stength aresilicon powder are respectively 14.59 MPa and 2.24 respectively 39.5%, 17.6% and 50.7%. When 4wt%2009 Vol. 28结构_化学(JIEGOU HUAXUE) Chinese_ J. Struct. Chem.369tiny silicon powder is added, the property of material4. 1 XRD analysis shows that each sample formsis optimized obviously so that the bending strengththree crystalline phases: aluminum titanate (Al2TiO),increases to 41.44 MPa, which is about 3 times thatcorundum (Al2O3) and rutile (TiO2), with the frstof sample without adding tiny silicon powder; theone to be the main crystalline phase. From samplesbulk density increases to 2.53 g/cm', the porosityNo.1~5, the contents of AT gradually increase withand water absorption respectively decrease to 29.8%the decrease of Al2Oy/TiO2 ratio; From samples No.and 11.8%, and the retention rate of one themmal5~7, the contents of AT decrease with the decre-vibration bending strength increases from 50.7% toment of Al2O3/TiO2 ratio; No. 4 is determined to be70.4% at an increase rate of 38.86%, which indicatesthe optimum specimen, and its corresponding Al2O/that the thermal stability increases obviously andTO2 ratio is 1.27 while the content of AT is 97.2that AT material has fairly great thermal shock re-wt%.sistance. With the addition of tiny silicon powder4.2 SEM analysis results show Al2TiOs, Al2O3rising from 4wt% to 8wt%, bulk density, bendingand TiO2 grains present iregular bulk shape, hexa-strength and the retention rate of one thermal vi-gonal lamellar and column shape separately. Withbration bending strength are increased, while poro-the decrement of Al2OyTiO2 ratio, the glass phase insity and water absorption decrease. Upon raising thethe sample decreases gradually, and the AT grainsaddition of tiny silicon powder to 12wt%, the changegradually convert from granularity to iregular shaperule of property is reverse. The analysis results de-with acute edge angle.termine 8wt% to be the best addition of tiny silicon4.3 The addition of tiny silicon powder is bene-powder; its corresponding bulk density is 2.63 g/cm',ficial to optimise the properties of AT material. Thebending strength is 46.34 MPa, the retention rate ofbest addition of tiny silicon powder is determined toone thermal vibration bending strength is 71.5%, andbe 8wt%; the corresponding bulk density is 2.63the porosity and water absorption are respectivelyg/cm', bending strength is 46.34 MPa, the retention23.4% and 8.9%.rate of one thermal vibration bending strength is71.5%, and the porosity and water absorption are4 CONCLUSIONrespectively 23.4% and 8.9%.REFERENCES(1) Xu, G; Han, G R. Maerials Reriew 2003, 17, 44 47.Parker, F.J. J Am. Ceram Soc. 1990, 73.929-932.(3) Liu.T. s: Perer, D. S.J. Maters Sci 1998, 33, 995-958.(4) Djambazov, s.; LePkova, D.1. Maler Sci. 1994, 29, 2521.(5) Masyuki, 1; Tsugio, s.; Tadashi, E. Masahiko, s. J. Am. Ceram. Soc. 1987. 70, 69-73.(6) Morishima, H. J. Am. Ceram. Soc. 1986, 69, 226-230.(7) Chen, H; Li, W. s. Advanced Ceramics 1993,21,3- 10.(8) Fang, Q; Zhang, L M: Shen, Q Li, M. z Bulein of the Chinese Ceramic Sociery 2003,0 22, 49-53.(9) Yu, Y; Ruan, Y. z; Huang. Q M. Chinese J. Srnct. Chem. 2003. 22, 607 613.(10) Freudenberg, B.: Moellin, A. J. Am Ceram. Soc. 1987, 70, 33- -38.(1) Freudenberg, B; Mocellin, A. J. Am Ceram. Soc. 1988. 71, 22-28.(12) Crimes, R. W: Plling, 1.1 Maler Sei. 1994, 29, 2245.中国煤化工MYHCNMHG

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