• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.235-241
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• 1996

Self-Propagating high temperature synthesis(SHS) technique was used to synthesize the spinel phase of MgAl2O from MgO and Al powder. Processing factors such as mixing time preheating temperature and ignition catalyst were varied to determine the optimum condition to form MgAl2O4 phase. The reaction products were heat treated at the temperature range of 120$0^{\circ}C$ and 150$0^{\circ}C$. to observe phase transformation of unreacted materials. Processing factors such as 48 hrs-mixing 80$0^{\circ}C$-preheating and 20wt% KNO3-ignition catalyst were effective of the formation of MgAl2O spinel. An activation energy 49.7kcal/mol. was calculated to form a MaAl2O4 spinel from unreacted materials.

• Journal of the Korean Ceramic Society
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• v.43 no.7 s.290
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• pp.427-432
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• 2006

The preparation of SiC powder by SHS in the system of $SiO_2-Mg-C$ was investigated in this study. The effects of various processing parameters such as the initial pressure of inert gas in reactor, the content of Mg and C in mixture and the size of $SiO_2$ particles on the synthesis of SiC by SHS methode were investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5 atm, and as the pressure increased, and the concentration of unreacted Mg decreased. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure SiC was $SiO_2+2.5Mg+1.2C$. SiC powder synthesized in this condition had a mixture of ${\alpha}-SiC\;and\;{\beta}-SiC$ with an irregular shape and the particle size of $0.5{\sim}0.8{\mu}m$.

• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.16-21
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• 2006

The preparation of $TiB_2$ by SHS in $B_2O_3-Mg-TiO_2$ system was investigated in this study. In the preparation of $TiB_2$, the effect on reactivity and reaction products of the initial pressure of inert gas in reactor, the content of Mg and $TiO_2$ in mixture was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 50atm, the optimum composition for the preparation of pure $TiB_2$ was $B_2O_3+5Mg+TiO_2$. The $TiB_2$ synthesized in this condition had an irregular shape and the particle size of $1\~3{\mu}m$.

• Journal of the Korean Ceramic Society
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• v.45 no.7
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• pp.418-422
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• 2008

The preparation of FeB by SHS in $B_2O_3-Mg-Fe-Fe_3O_4$ system was investigated in this study. In the preparation of FeB, the effects of the initial pressure of inert gas in reactor, the content of Mg and $Fe_3O_4$ in mixture on the reactivity and reaction products was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure FeB was $1.5B_2O_3$+3.43Mg+ 1.7Fe+$0.1Fe_3O_4$. The FeB synthesized in this condition had an irregular shape and the particle size of $5\;{\mu}m$.

• Korean Journal of Materials Research
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• v.24 no.9
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• pp.465-468
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• 2014

The crystallization effects of boron (B) powder on the phase, full width at half maximum (FWHM) values, and critical properties were investigated for in-situ reacted $MgB_2$ bulk superconductors. The semi-crystalline B powder was heat-treated at different temperatures of 1000, 1300 and $1500^{\circ}C$ for 5 hours in an Ar atmosphere. Then, using as-received and heat-treated B powders, the $MgB_2$ samples were prepared at $600^{\circ}C$ for 40 hours in an Ar atmosphere. As the heat-treatment temperature of the B powder increased, both the particle size of the B powder and crystalline phase increased. In the case of $MgB_2$ samples using B powders heat-treated at above $1300^{\circ}C$, unreacted magnesium (Mg) and B remained due to the improved crystallinity of the B powder. As the heat-treatment temperature of B powder increased, the critical current density of $MgB_2$ decreased continuously due to the reduction of grain boundary density and superconducting volume caused by unreacted Mg and B.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.22-27
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• 2005

The preparation of B4C by SHS in $B_{2}O_{3}-Mg-C$ system was investigated in this study. In the preparation of B4C, the effect on reactivity and reaction products of the initial pressure of inert gas in reactor, the content of Mg and C in mixture was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure B4C was $2B_{2}O_{3}+6.3Mg +0.94C$. The B4C synthesized in this condition had an irregular shape and the particle size of $1\~3{\mu}m$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.573-580
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• 1998

Self-propagating high temperature synthesis (SHS) technique was used to synthesize the spinel phase of $MgAl_2O_4$ from MgO and Al powder. Thermit reaction products of MgO and Al, The reaction products were heat treated at the temperature $800^{\circ}C$ preheating. Processing factors such as DTA/TG, combustium product and maxium temperature, synthesis of MgO and Al from "$MgO+2Al+3/2O_2$\rightarrow$MgAl_2O_4$". An activation energy (${\Delta}H^{\circ}$)-264.8 kcal/mol and reaction of maxium temperature 5634 K was calculated to form a $MgAl_2O_4$ spinel from unreacted materials. Pellet were increased volume 6% after thermit reaction. reaction.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.93-97
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• 2007

High purity Si powder was prepared in the system of $SiO_2-Mg$ combustion reaction. Various conditions of combustion reaction and leaching were investigated. As the particle size of Mg decreased and the compaction pressure increased the quantity of the unreacted power was decreased. In the acid leaching of MgO, increasing particle size, reaction temperature, rotating speed and reaction time made leaching effect low. Final Si powder produced by combustion and leaching reaction, has a high purity of 99.9% with irregular shape.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1491-1493
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• 2002

The 0.5$Ba_2Ti_9O_{20}$-0.5Mg$TiO_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by XRD. According to the X-ray diffraction patterns, major phases of the 0.5$Ba_2Ti_9O_{20}$-0.5Mg$TiO_3$ ceramics were coexisted. Also the secondary phase of Mg$Ti_2O_5$, Ba$Mg_6Ti_6O_{19}$ and the unreacted $TiO_2$ phase were existed. In the case of 0.5$Ba_2Ti_9O_{20}$-0.5Mg$TiO_3$ ceramics sintered $1350^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 33.7, 54,900GHz, -12.5ppm/$^{\circ}C$, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.2
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• pp.181-189
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• 2011

Cryopreservation protocols induce partially irreversible damage to mammalian sperm plasma membranes. Previous studies have indicated that adding cholesterol to the plasma membrane, as cholesterol-loaded-cyclodextrins, improves cryosurvival of sperm. Therefore, the purpose of this study was to determine if treating sperm of Markhoz bucks with cholesterol-loaded-cyclodextrins (CLC) (0, 0.75, 1.5, 2.25 and 3 mg/ml diluted $240{\times}10^6$ sperm/ml) in Tris-citric acid-glucose diluents with and without egg yolk (containing 5% glycerol) would improve the post-thaw sperm quality. The motion characteristics were evaluated with a Computer Assisted System Analyzer (CASA); acrosome integrity and vitality were measured with the triple-stain technique. Samples were recovered before and after freezing by means of putting straws into $37^{\circ}C$ water for 30 sec and then parameters were assessed. The results showed that the treatments significantly affected motility, progressive motility, recovery rate, curvilinear velocity, beat cross frequency, live sperm with reacted acrosome, live sperm with unreacted acrosome, dead sperm with reacted acrosorne, and dead sperm with unreacted acrosome during freezing (p<0.05). However; no significant differences were found for average path velocity, straight line velocity, amplitude of lateral head displacement, straightness and linearity (p>0.05). The best results were observed for extender containing 2.25 mg/ml ($240{\times}10^6$ sperm/ml) CLC supplemented with 2.6% egg yolk. In conclusion, the findings of this study indicate improved Markhoz sperm viability and motility following treatment in the presence of egg yolk.