Sintering and Phase Transition of the ZnTiO3 Nano Powder Dilatometric Data Deconvolution

Abstract

Sintering and phase transition are often superimposed at dimensional change diagram recorded during heating. Phase transition kinetic is thus hard to deconvolute due to the superposition of the sintering and phase transition dimensional change phenomena. Metastabile perovskite phase ZnTiO3 has transition to stabile spinel Zn2TiO4 which occurs at 945oC with high kinetic rate. Nano powder with 40 nm particle diameter was pressed uniaxially at 200 MPa pressure without binder to form compact that will be consequently sintered. Dimensional change during heating was monitored using dilatometric thermo-mechanical analyzer TMA model SETSYS Evolution. Lever`s rule was used to calculate amount of the emerging phase during phase transition. The compacted specimens were treated on the non-isothermal schedule up to 1050oC.Sintering phenomenon of the ZnTiO3 nanopowder compact was also recorded up to 900oC with isothermal holding of 25 minutes where phase transition was avoided due to lower temperature and isothermal holding. Second run heating of the obtained sintered specimens were recorded with the heating schedule of non-isothermal heating up to 1050oC. Kinetic of the phase transition was obtained from dilatograms recorded during sintering and from bulk on the second run heating. Furthermore, phase transition kinetics was obtained by subsequent data subtraction of the sintering curves without phase transition from the dilatation sintering curves containing phase transition. In such a manner complex kinetics of phenomena such as sintering, linear expansion and phase transition recorded as dimensional change during heating brings the recognition of their mutual interconnected relations. Also application of these mathematical operations on dilatometric data leads to the established procedure for the sintering and phase transition data treatment.