• Journal of the Korean Magnetics Society
• /
• v.5 no.4
• /
• pp.269-274
• /
• 1995

The basic composition of Mn-Zn ferrite was $Mn_{0.631}Zn_{0.316}Fe_{2.053}O_{4}$(specimen A), $Mn_{0.584}Zn_{0.312}Fe_{2.104}O_{4}$(specimen B) and $Mn_{0.538}Zn_{0.308}Fe_{2.154}O_{4}$(specimen C) with additional 0.1 mol % $CaCo_{3}$ and 0.04 mol % $V_{2}O_{5}$. For high per¬meability and acceleration of grain growth, $CaCo_{3}$ and $V_{2}O_{5}$. was added. The mixture of the law materials was calcinated at $950^{\circ}C$ for 3 hours and then milled. The compacts of toroidal type were sintered at different temperature($1250^{\circ}C$, $1300^{\circ}C$, $1350^{\circ}C$) for 2 hours in $N_2$ atmosphere. The effects of the various raw material composition and sintered temperature on the physical properties of Mn-Zn ferrite have been investigated. They turned out to be spinel structure by X-ray diffraction and the size of grain from SEM was from $18\;\mu\textrm{m}\;to\;23\;\mu\textrm{m}$. As the sintering temperature was increased from $1250^{\circ}C$ to $1350^{\circ}C$, the initial permeability and magnetic induction has increased and the both of Q factor and coercive force has decreased. The coercive force and curie temperature were almost the same at each specimen Their values were about 0.45 Oe and $200^{\circ}C$. The frequency of specimen will used in the range from 200 kHz to 2 MHz. The basic composition of $Mn_{0.584}Zn_{0.312}Fe_{2.104}O_{4}$(specimen B) sintered at $1300^{\circ}C$ shows the best results at magnetic induction (Br & Bm).

• Journal of the Korean Ceramic Society
• /
• v.39 no.9
• /
• pp.857-862
• /
• 2002

Porous ceramic supports with immobilized microorganisms for the water purifier were synthesized by firing green compacts of mixed powder comprising of fly ash, bentonite and an additive of yeast powder at 800∼1,000$^{\circ}C$ for 1h and the pore and mechanical properties of specimens were investigated. The compressive strength was increased in FB (Fly Ash + Bentonite) specimens while pore properties was decreased with increasing the bentonite content and sintering temperature. The compressive strength, bulk density, apparent density, porosity, mean pore size, pore volume and specific surface area of FB specimens at 800∼1,000$^{\circ}C$ were 89.6∼128.9 kgf/$cm^2$, 1.25∼1.43, 1.61∼1.78, 27.2∼62.2%, 7.9∼25.6 ${\mu}m$, 8.9∼$22.2{\times}10^{-5}\;cm^3/g$ and 35.2∼134.3 $m^2/g$, respectively. The pore properties of FBY (FB+yeast powder) specimens were superior to that of FB specimens, however compressive strength was decreased with increasing yeast powder content. The overall properties of 9F1B1Y (9F1B+10% of yeast powder) specimens at 900$^{\circ}C$ for 1 h were 98.7 kgf/$cm^2$, 1.20, 1.67, 68.1%, 48.9 ${\mu}m$, $29.5{\times}10^{-5}\;cm^3/g$ and 152.2 $m^2/g$, respectively. In this study, it was revealed that 9F1B1Y specimen demonstrated better S. saprophyticus adherence properties n their surface pores. Consequently, the microorganisms immobilized on porous ceramic supports showed better water purifying performance with many pores and adequate strength.

• Journal of the Korean Magnetics Society
• /
• v.16 no.5
• /
• pp.255-260
• /
• 2006

The basic composition of Ni-Zn ferrite was $(Ni_{0.35}Cu_{0.2}Zn_{0.45})_{1.02}(Fe_2O_3)_{0.98}$ (group A) and $(Ni_{0.4}Cu_{0.2}Zn_{0.4})_{1.02}(Fe_2O_3)_{0.98}$(group B) with additional 0.1 mol% $CaCO_3$ and 0.03 mol% $V_2O_5$. For high permeability and acceleration of grain growth, $CaCO_3$ and $V_2O_5$ was added. The mixture of the law materials was calcinated at $600^{\circ}C$ for 2 hours and then milled. The compacts of toroidal type were sintered at different temperature ($1,050^{\circ}C,\;1,070^{\circ}C,\;1,100^{\circ}C$) for 2 hours in air followed by an air cooling. Then, effects of various composition and sintering temperatures on the microstructure and physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, quality factor, and curie temperature of the Ni-Zn ferrite were investigated. The density of the Ni-Zn ferrite was $4.90{\sim}5.10g/cm^3$, resistivity revealed $10^8{\sim}10^{12}{\Omega}-cm$. The average grain size increased with the increase of sintering temperatures. The magnetic properties obtained from the aforementioned Ni-Zn ferrite specimens were 4,000 gauss for the maximum induction, 0.25 oersted for the coercive force, 2,997 for the initial permeability, 208 for the quality factor, and $202^{\circ}C$ for the curie temperature. The physical properties indicated that the specimens could be utilized as the core of microwave communication and high permeability deflection yoke of high permeability.