A model for initial-stage sintering thermodynamics of an alumina powder

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dc.contributor.authorSarikaya, Yüksel
dc.contributor.authorAda, Kezban
dc.contributor.authorÖnal, Müşerref
dc.date.accessioned2020-06-25T17:44:11Z
dc.date.available2020-06-25T17:44:11Z
dc.date.issued2008
dc.departmentKırıkkale Üniversitesi
dc.descriptionOnal, Muserref/0000-0002-1540-8389
dc.description.abstractA model was proposed to calculate several thermodynamic parameters for the initial-stage sintering of an alumina powder obtained after calcinations at 900 degrees C for 2 h of a precursor. The precursor was synthesized by an alumina sulphate-excess urea reaction in boiling aqueous solution. The cylindrical compacts of the powder with a diameter of 14 mm were prepared under 32 MPa by uniaxial pressing using oleic acid (12% by mass) as binder. The compacts were fired at various temperatures between 900 and 1400 degrees C for 2 h. The diameter (D) of the compacts before and after firing was measured by a micrometer. The D Value after firing was taken as a sintering equilibrium parameter. An arbitrary sintering equilibrium constant (K,) was calculated for each firing temperature by assuming K(a) = (D(i) -D)/(D-D(f)), where D(i) is the largest value before sintering and D(f) is the smallest value after firing at 1400 degrees C. Also, an arbitrary change in Gibbs energy (Delta G(a)degrees) was calculated for each temperature using the K(a) value. The graphs of In K(a) vs. 1/T and Delta G(a)degrees vs. T were plotted, and the real change in enthalpy (Delta H degrees) and the real change in entropy (AS') were calculated from the slopes of the obtained straight lines, respectively. Inversely, real Delta G degrees and K values were calculated using the real Delta H degrees and Delta S degrees values in the Delta G degrees = -RT In K = Delta H degrees-T Delta S degrees relation. The best fitting Delta H degrees and Delta S degrees values satisfying this relation were found to be 157,301 J mol(-1) and 107.6 J K(-1) mol(- 1), respectively. (c) 2008 Elsevier B.V. All rights reserved.en_US
dc.description.sponsorshipScientific and Technical Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TUBITAK-106T056]en_US
dc.description.sponsorshipThe authors thank the Scientific and Technical Research Council of Turkey for supporting this study under the project No: TUBITAK-106T056.en_US
dc.identifier.citationclosedAccessen_US
dc.identifier.doi10.1016/j.powtec.2008.03.005
dc.identifier.endpage12en_US
dc.identifier.issn0032-5910
dc.identifier.issue1en_US
dc.identifier.scopus2-s2.0-55749105499
dc.identifier.scopusqualityQ1
dc.identifier.startpage9en_US
dc.identifier.urihttps://doi.org/10.1016/j.powtec.2008.03.005
dc.identifier.urihttps://hdl.handle.net/20.500.12587/4033
dc.identifier.volume188en_US
dc.identifier.wosWOS:000261856800002
dc.identifier.wosqualityQ1
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.language.isoen
dc.publisherElsevier Science Saen_US
dc.relation.ispartofPowder Technology
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanıen_US
dc.rightsinfo:eu-repo/semantics/closedAccessen_US
dc.subjectAlumina powderen_US
dc.subjectLinear shrinkageen_US
dc.subjectSinteringen_US
dc.subjectThermodynamicsen_US
dc.titleA model for initial-stage sintering thermodynamics of an alumina powderen_US
dc.typeArticle

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