• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.51-53
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• 1999

The crystallization mechanism of an amorphous $Bi_{2}$$Sr_{2}$$Ca_{2 x}$$Cd_{x}$$Cu_{3}$$O_{y}$ phase were studied from the relations between crystallization and volume changes by dilatometry. Further, the effect of addition of CdO on the crystallization mechanism and superconductivity was discussed. The shrinkage of the amorphous $Bi_{2}$$Sr_{2}$$Ca_{2 x}$$Cd_{x}$$Cu_{3}$$O_{y}$ occurred with the crystallization of $Bi_{2}$$Sr_{2}$Cu$O_{6}$ phase decrease with increasing CdO content with a minimum at x=0.4. Better superconductivity was obtained in the specimens formation less amount of the$Bi_{2}$$Sr_{2}$Cu$O_{6}$ phase during the crystallization process.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.358-364
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• 2013

Borosilicate glass(GVB-Solutions in glass, 2mm, Germany) was prepared in the composition of $80.4SiO_2-4.2Na_2O-2.4Al_2O_3-13.0B_2O_3$. The 2-step crystallization was performed around $584^{\circ}C$ of glass transition temperature ($T_g$), and $774^{\circ}C$ of crystallization temperature($T_c$). The maximum nucleation rate was $8.8{\time}10^9/mm^3{\cdot}hr$ at $600^{\circ}C$ and the maximum crystal growth rate was 3.5nm/min at $750^{\circ}C$. The maximum mechanical properties were observed at 22.8% of volume fraction, the strength, hardness and fracture toughness was 555MPa, $752kg/mm^2$, $1.082MPa{\cdot}mm^{1/2}$. The crystal size of 177nm which has volume fraction of 22.8% showed maximum strength of 562MPa, it is about 157% higher than parent borosilicate glass. From these results, the crystallized borosilicate glass can be applied weight lighting of bullet proof materials.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.297-301
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• 2014

We examined the effect of ionic liquid on the crystallization efficiency of vancomycin in an increased surface area crystallization with silica gel. The crystallization efficiency was improved by the addition of ionic liquid, [BMIm][$BF_4$]. The addition of ionic liquid (20%, v/v) on the increased surface area crystallization with silica gel dramatically reduced the crystallization time by 6 folds (4 h), compared with the results of the case where the surface area-increasing material and ionic liquid had not been added. In addition, the crystal size of vancomycin was decreased and the crystal quality of vancomycin was improved by increasing the addition of ionic liquid.

• Journal of the Korean Ceramic Society
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• v.23 no.4
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• pp.1-10
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• 1986

The crystallization behaviour and the machinability of mica glass-ceramics with the content of F1 were studied. The material was made from the $K_2O-MgO-Al_2O_3-B_2O_3-SiO_2-F$ glasses by the heattreatment at 80$0^{\circ}C$-110$0^{\circ}C$ where the content of F-1 was changed in the range from 1, 3wt% to 6.1wt%. X-ray diffraction phase analysis and optical observation were adopted to study the crystallization behaviour. The machinability was measured by a manual sawing test and MOR. The crystal phases of these glass-ceramics identified by XRD were chondrodite fluoborite and norbergite at low temperature but fluorophlogopite at high temperature. The crystallization of glasses containing 1.3wt% -2.5wt% F-1 were predominately controlled by surface crystallization while the crystallization of glasses containing 3.8 wt% -6.1wt% F-1 were controlled by volume crystallization. Among the test the best machinability and strength value were obtained from those specimens contained fluoride 4.2wt% -4.4wt% and when the heattreatment was performed at 95$0^{\circ}C$-110$0^{\circ}C$ for 2 hours.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2369-2376
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• 2011

Effect of heat treatment of carbon nanofibers (CNF) on electrical properties and crystallization behavior of polypropylene was reported. Two types of CNFs (untreated and heat treated at 2300 $^{\circ}C$) were incorporated into polypropylene (PP) using intensive mixing. A significant drop in volume resistivity was observed with composites containing untreated 5 wt % and heat treated 3 wt % CNF. In non-isothermal crystallization studies, both untreated and heat treated CNFs acted as nucleating agents. Composites with heat treated CNFs showed a higher crystallization temperature than composites with untreated CNFs did. TEM results of CNF revealed that an irregular structure of CNFs can be converted into the continuous graphitic structure after heat treatment. Furthermore, STM showed that the higher carbonization temperature leads to the higher graphite degree which presents the larger carbon network size, suggesting that a more graphitic structure of CNFs led to a higher crystallization temperature of PP.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.232-237
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• 2014

We investigated the effects of silica gels on the reduction of the crystallization time for the purification of vancomycin. The shortest crystallization time for vancomycin was obtained when silica gel with a pore diameter of $40-60{\AA}$ and with a particle diameter of 230-400 mesh was used as the material. The use of silica gel as a surface area increasing material dramatically reduced the crystallization time four fold (6 h) when compared with the results where the surface area had not been similarly increased. In addition, the crystal size of vancomycin was decreased with the addition of silica gel. This improved crystallization process has a significant effect on the convenience and feasibility of the purification step for vancomycin.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.799-804
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• 2018

The separation and purification of 2,6-dimethylnaphthalene (2,6-DMN) present in the light cycle oil (LCO) fraction was investigated by a crystallization operation. Solute crystallization (SC) was performed using LCO fraction and iso-propyl alcohol as a raw material and a SC solvent, respectively. Increasing the operation temperature and volume ratio of the solvent to the raw material (S/F) resulted in improving the purity of 2,6-DMN, whereas the yield decreased. As a result of the crystallization operation in three steps containing the SC using LCO fraction (13.9% 2,6-DMN) and isopropyl alcohol, the re-crystallization 1 (RC 1) using the crystals recovered by SC and methyl acetate, and RC 2 using the crystals recovered by RC 1 and methyl acetate, the crystal with 99.9% 2,6-DMN was recovered with 19.5% yield. Furthermore, the separation and purification process of 2,6-DMN present in the LCO fraction was reevaluated by using the experimental results obtained through each operations of SC, RC 1, and RC 2.

• Korea-Australia Rheology Journal
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• v.12 no.2
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• pp.101-105
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• 2000

The crystallization behavior of homo polypropylene (PP) and PP in the PP-poly($\varepsilon$-caprolactone) (PCL) blends during isothermal crystallization has been investigated using differential scanning calorimeter (DSC) and advanced rheometric expansion system (ARES). From the storage modulus data of the homo PP and PP-PCL blends during isothermal crystallization, the volume fraction of crystallized material ($X_t$) of the homo PP and PP in the PP-PCL blends was calculated using the various rheological models. The results of $X_t$ of the homo PP and PP in the PP-PCL blends from ARES measurement were compared with the results from DSC. The $X_t$ of the homo PP was found to be higher in the ARES measurement than in the DSC. The crystallization rate of the homo PP was found to be faster in the rheological measurements than in the thermal analysis. The $X_t$ of PP in the PP-PCL blends with various compositions was obtained from the thermal analysis and rheological measurements. The $X_t$ of PP in the PP-PCL blends obtained from the thermal analysis and rheological measurements are not consistent. This discrepancy of $X_t$ may be due to the morphological changes resulted from the different crystallization kinetics of PP in the PP-PCL blends.

• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.855-862
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• 1996

The nucleation and the crystal growth rates of Ge-Se-Te chalcogenide glass by two step heat-treatment and its effect on the mechanical optical properties and water-resistance were determined. The maximum nuclea-tion and crystal growth rate were 2.1$\times$103/mm3 .min at 28$0^{\circ}C$ and 0.4${\mu}{\textrm}{m}$/min at 33$0^{\circ}C$ respectively. When the crystal volume fraction with crystal size $1.5mutextrm{m}$ was about 4% the (hardness and fracture toughness were about 117kg/mm2 and 6.0 MPa.mm1/2)respectively. The weight loss of crystallized glass in water was lower than parent glass($25^{\circ}C$ for 32 hrs : 0.03% 8$0^{\circ}C$ for 16 hrs : 0.1%) as 0.01% at $25^{\circ}C$, 0.03% at 8$0^{\circ}C$ for 16 hrs : 0.1%) at $25^{\circ}C$ 0.03% at 8$0^{\circ}C$ respectively. The IR-transmittance decreased with increasing crystal size and crystal volume fraction. The IR-transmittance of crystallized glass with the crystal size of $1.5mutextrm{m}$ (crystal volume fraction : 4%) presented 56% which was about 4% lower than that of parent glass.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.956-962
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• 1992

The predominant sintering mechanisms of low firing temperature ceramic substrate which consists of borosilicate glass containing alumina as a filler are the rearrangement of alumina particles and the viscous flow of glass powders. In this system, sintering condition depends on the volume ratio of alumina to glass and on the particle size. When the substrate contains about 35 vol% alumina filler and the average alumina particle size is 4 $\mu\textrm{m}$, the best firing condition is obtained at the temperature range of 900∼1000$^{\circ}C$. The extensive rearrangement behavior occurs at these conditions, and the optimum sintering condition is attained by smaller size of glass particles, too. The formation of cristobalite during sintering causes the difference of thermal expansion coefficient between the substrate and Si chip. This phenomenon degradates the capacity of Si chip. Therefore, the crystallization should be prevented. In the alumina filled borosilicate glass system, the crystallization does not occur. This effect may have some relation with aluminum ions in alumina. For aluminum ions diffuse into glass matrix during sintering, functiong as network former.