Abstract
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.
Highlights
The sintering of ferrites via solid state, as well as of other ceramic materials, is a thermal process that causes reduction of the surface area through the formation of grain boundaries, neck growth between particles and usually densification
By means of the nonisothermal, constant heating rate (CHR) method, this study aimed to evaluate the effect of Zn2+ concentrations on the sintering kinetics of Ni1-xZnxFe2O4 nanometric powder with x = 0.3; 0.5; 0.7% mol of Zn2+ obtained by combustion reaction
The early, intermediate and final stages of Ni-Zn ferrite sintering were evaluated to investigate the effect of the concentration of Zn2+ on the sintering of nanometric powders of Ni-Zn ferrites synthesized by combustion reaction
Summary
The sintering of ferrites via solid state, as well as of other ceramic materials, is a thermal process that causes reduction of the surface area through the formation of grain boundaries, neck growth between particles and usually densification. The sintering stages represent the geometrical evolution that occurs during the transformation of a compact powder into a dense and resistant solid[1,2] During these stages, the overall interface free energy of a set of particles decreases because the reduction of solidvapor interface energy is greater than the increase of solid-solid interface energy (grain boundary) of the system[3]. Solid state sintering may be performed by two alternative processes: densification, with a change of the solid-vapor interface (particle-pore) into solid-solid interface with less energy, or grain growth, with the transformation of numerous small grains (the compact’s particles) into a smaller number of large grains. The microstructural changes that occur during solid sate sintering result from the combined effect of densification and grain growth[4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
