Sintering of Ni-Zn ferrite nanopowders by the constant heating rate (CHR) method

• Autor(a) principal: Costa,Ana Cristina Figueiredo de Melo
• Data de Publicação: 2004
• Outros Autores: Tortella,Edener, Fagury Neto,Elias, Morelli,Márcio Raymundo, Kiminami,Ruth Herta Goldschmidt Aliaga
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Materials research (São Carlos. Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392004000400003
• topic: Ni-Zn ferrite; sintering; nanoparticle

The constant heating rate method employed in sintering studies offers several advantages over the isothermal method, particularly the fact that all the parameters that describe the sintering phenomena can be obtained from a single sample. The purpose of this work is to determine the parameters of sintering kinetics of nanosized Ni-Zn ferrite powders synthesized by combustion reaction. The nonisothermal sintering method was studied using a constant heating rate (CHR). The Ni-Zn ferrite powders, with average particle size varying from 18 nm to 29 nm, were uniaxially pressed and sintered in an horizontal dilatometer at a constant heating rate of 5.0 °C/min from 600 °C up to complete densification, which was reached at 1200 °C. The compacts were characterized by scanning electron microscopy (SEM). Experimental results revealed three different sintering stages, which were identified through the Bannister Theory. The shrinkage and the shrinkage rate analyzed showed a viscous contribution in the initial sintering stage, which was attributed to the mechanism of structural nanoparticle rearrangement.