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Proceedings ArticleDOI

Application of the pyroelectric sensor for study of porosity effect on thermal diffusivity of nickel copper zink ferrite

26 Aug 2003-pp 65-68

Abstract: An investigation was carried out to study the effect of the porosity on thermal diffusivity of Nickel Copper Zinc Ferrite. The experimental technique employed to measure thermal diffusivity was the photoflash technique, and the measurements were carried out at room temperature. The heating source consists of camera flash having approximately 5ms pulse duration and a thin film of polyvinylidene difluoride (PVDF) attached to the back of the samples was used as detector. Six different porosity levels were obtained by varying the grinding time following the presintering process and preceding the sintering process at 1350°C. The porosity range obtained for the Ni0.3Cu0.1Zn0.6Fe2O4 samples was 1.8-7%. The thermal diffusivity was determined from the experimental thermal transient signal. For the fitting of the experimental results, the analytical model used was based on the approximation that the pulse duration of the camera flash can be considered as Dirac-δ function. Thermal diffusivity values for Ni0.3Cu0.1Zn0.6Fe2O4 samples were in the range (7.8-8.7) × 10-7 m2/s.
Topics: Thermal diffusivity (67%), Thermal conductivity measurement (60%), Porosity (52%), Thermal conductivity (51%), Zinc ferrite (51%)

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Application of the pyroelectric sensor for study of porosity effect on thermal diffusivity
of nickel copper zink ferrite
ABSTRACT
An investigation was carried out to study the effect of the porosity on thermal diffusivity of
Nickel Copper Zinc Ferrite. The experimental technique employed to measure thermal
diffusivity was the photoflash technique, and the measurements were carried out at room
temperature. The heating source consists of camera flash having approximately 5ms pulse
duration and a thin film of polyvinylidene difluoride (PVDF) attached to the back of the
samples was used as detector. Six different porosity levels were obtained by varying the
grinding time following the presintering process and preceding the sintering process at
1350°C. The porosity range obtained for the Ni0.3Cu0.1Zn0.6Fe2O4 samples was 1.8-7%.
The thermal diffusivity was determined from the experimental thermal transient signal. For
the fitting of the experimental results, the analytical model used was based on the
approximation that the pulse duration of the camera flash can be considered as Dirac-δ
function. Thermal diffusivity values for Ni0.3Cu0.1Zn0.6Fe2O4 samples were in the range
(7.8-8.7) × 10-7 m2/s.
Keyword: Porosity; Nickel; Copper; Zinc; Ferrite; Thermal diffusivity; Cameras;
Ni0.3Cu0.1Zn0.6Fe2O4
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Journal ArticleDOI
Abstract: Frequency‐modulation time‐delay spectrometry (FM‐TDS) has been implemented in photopyroelectric measurements of thermal diffusivity, on a series of well‐characterized samples. The strategy of FM‐TDS is sample excitation by a fast linear frequency sweep, whose autocorrelation function is mathematically equivalent to a Dirac delta function. The method permits the fast recovery of high‐quality frequency and impulse‐response information. Impulse responses recovered in the time‐delay domain showed good agreement with a Green’s function model of transient heat conduction. The present work demonstrates that the FM‐TDS measurement strategy yields photothermal information equivalent to that obtainable from a pulsed laser system, with much lower excitation power.

32 citations