Effect of processing parameters of planetary mill on Ba0.7Sr0.3TiO3 electroceramic product
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Date
2007
Authors
Hj. Azlan, Umar Al-Amani
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Abstract
The study was conducted to evaluate the effectiveness of planetary ball
milling in producing Ba0.7Sr0.3TiO3 ferroelectric ceramic with a high dielectric
constant. Initially, weight loss analysis was used to determine a suitable speed and
time of milling. The analysis found that a speed of 400 rpm with a period of 4, 24
and 48 minutes was suitable and was subsequently used in further stages of this
work. Calcination study of 3 hours at 950 oC showed presence of BaCO3 remnants
with Ba0.7Sr0.3TiO3 phase being dominant. It was also observed that hard
aggregate was formed after calcination. Hence, sintering at a temperature of 1250
oC showed the pellets in a powdery form due to insufficient sintering, and required
higher sintering temperatures. A consistent and high relative density (94 – 96%)
was obtained after sintering at 1300 oC. Subsequently, the dielectric constant was
found to be around 3000 – 6500, and the values increased with increasing of
sintering temperature. The study also found that milling at high speed (600 rpm)
had produced mixed powder of nano-sized. The nano-size powders had affected
the grain size upon sintering, which was found to be less than 3.0 μm, and hence,
producing low dielectric constant (3000 – 4800) as compared to the second stage.
The effect of pre-mixing of the powders had showed that the highest dielectric
constant could be achieved at sintering temperature of 1300 oC as compared to
effect of non-premixing, i.e. at 1350 and 1400 oC.
Description
Master
Keywords
Materials and Mineral Resources Engineering , Planetary mill , Electroceramic product