• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.279-280
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• 2003

실리콘웨이퍼 제조공정에서 폐기되는 HF에는 순수한 실라카만 함유되어 있지만 브라운관 업체에서 폐기되는 HF 폐액에는 유리의 조성에 따라서 다양한 성분들이 소량씩 함유되어 있다. 몰비로 Si:F=1:6이 되도록 조정한 후에 20% NaOH를 사용하여 pH를 6으로 조정하여 규불화소다를 얻고, 이어서 pH를 9로 조정하여 NaF를 었었다. 규불화소다에 NaCl, 칠레초석을 다양하게 첨가하여 금속 융제로 사용한 결과에 의하면 규불화소다의 양이 증가할수록 융제의 특성은 우수하였고, 가장 이상적인 첨가량은 50%~60%이었다. 따라서 각 공정에서 폐기되는 HF는 $Na_2SiF_{6}$와 NaF를 제조함으로서 재활용이 가능하였다.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1087-1093
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• 1999

Bioglass which is one of the surface active bionmaterials has a good biocompatibility but a poor mechanical strength, In the present work therefore two types of fluoride-containing bioglasses were coated on an alumina to improve mechanical strength. Crystallization of the coating layer and the hydroxyapatite formation on the bioactive glass coatings in tris-buffer solution were studied. When bioactive glass coated alumina was heat-treated Na2CaSi3O8 crystal was formed on the layer at lower temperature while wollastonite(CaSIO3) was obtained at higher temperature. Hydroxyapatite forming rate on the coating layer with Na2CaSi3O8 crystal was delayed with SiO2 contents in glass composition. However the hydroxyapatite was developed in 20minutes regardless SiO2 contents when the coating layer crystallized into wollastonite. More amount of P3+ ions were leached out of the coating layer with wollastonite than that with Na2CaSi3O8 crystal while Na+ and Ca2+ ions were leached out more easily from the Na2CaSi3O8 crystal containing coating layer.

• Journal of the Korean Society of Clothing and Textiles
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• v.6 no.1
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• pp.9-15
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• 1982

The influence of builders on calcium deposition on the fabric was studied by laundering the cotton fabric with sodium carbonate, sodium metasilicate, sodium tripolyphosphate and built detergents in hard water. The laundry variables were: 1) Washing cycles: 5, 10, 20, 30 and 40 cycles. 2) Water hardness: 100 ppm, 150 ppm, 200 ppm and 300 ppm. 3) Builders: $Na_2\;CO_3,\;Na_2\;SiO_3$ and STPP. 4) Detergents: Na-DBS, $Na-DBS+Na_2CO_3,\;Na-DBS+Na_2\;SiO_3,\;Na-DBS+STPP,\;Na-DBS+Na_2\;CO_3+STPP$, and $Na-DBS+Na_2\;SiO_3+STPP$. The fabric was washed for 15 minutes at 23+$1^{\circ}C$ in a washing machine(Gold Star WP 3007) under the similar condition with those of home laundering, and rinsed 3 times in the same water hardness for 5 minutes. The calcium deposits on the fabric was determined by EDTA-BACK titration methods. The results of this study were as follows: 1) The amount of calcium deposits on the fabric was increased with increasing wash cycles. This deposit was due to the build up of insoluble calcium carbonate. 2) As the water hardness increased, the amount of calcium deposits on the fabric was increased. 3) Alkaline builders, such as, $Na_2CO_3$ and $Na_2SiO_3$, promoted calcium deposition on the fabric, however STPP prevented calcium deposition on the fabric. 4) Fabric laundered with $Na-DBS+Na_2CO_3$ showed the highest calcium deposits on the fabric, and decreased with the order of $Na_2CO_3$, $Na-DBS+Na_2SiO_3$, and Na-DBS. And fabrics washed with phosphate-built detergents showed a small amount of calcium deposition.

• Resources Recycling
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• v.28 no.2
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• pp.54-61
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• 2019

In order to recover pure alumina from black dross, leaching of mechanically activated black dross with NaOH solution resulted in an aluminate solution containing a small amount of Si(IV). Selective adsorption of Si(IV) onto hydrotalcite was investigated from 5 M NaOH solution where the concentration of Al(III) and Si(IV) was 13000 and 150 mg/L, respectively. Only Si(IV) was selectively loaded onto hydrotalcite, while Al(III) remained in the solution. Effect of the calcination treatment of hydrotalcite and concentration of calcined hydrotalcite and NaOH on the loading of Si(IV) was investigated. Although the loading percentage of Si(IV) was low from 5 M NaOH solution, most of the Si(IV) was removed by adjusting the concentration of NaOH by 48 times dilution with water when the concentration of calcined hydrotalcite was higher than 4.5 g/L. The loading of Si(IV) onto calcined hydrotalcite followed Freundlich adsorption isotherm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.4
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• pp.190-195
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• 2009

Na-tetrasilicic fluorine mica powders were synthesized by skull melting method. The staring materials having chemical composition of $Mg_3(OH)_2Si_4O_{10}:Na_2SiF_6:SiO_2=8.3:24.8:66.9$ mol% were charged into a cold crucible of 13 cm in diameter and 14cm in height and heated by R.F. generator at working frequency of 2.84 MHz. The materials were maintained for 1hr as a molten state and cooled down in the container. In this study, the specific electric resistance of mica was estimated and the columnar and plate shaped mica were synthesized.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.25-34
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• 1996

A SOx sensor using NASICON electrolyte was developed for monitoring of air pollution. The following galvanic cell with $Na_{2}SiO_{3}(Pt)$ reference electrode was assembled : Pt | $Na_{2}SiO_{3}$ | NASICON | $Na_{2}SO_{4}$ | Pt, $SO_{2}$, air $Na_{2}SO_{4}$ was used as an indicator electrode to protect NASICON electrolytes from chemical reaction with $SO_{2}$. The EMFs were measured after injecting $SO_{2}$ in the initial concentrations range of $5{\sim}95ppm$ at $400{\sim}550^{\circ}C$. The measured and calculated potentials were in good agreement above $500^{\circ}C$. However, the cells were unstable below $500^{\circ}C$, most likely due to incomplete attainment of chemical equilibrium. Response time was within 10 min. Based on the stability and response time of this cell, the NASICON solid electrolyte with $Na_{2}SiO_{3}(Pt)$ as the reference electrode and $Na_{2}SO_{4}$ (Pt)as the indicator electrode showed the possibility of a reliable, inexpensive commercial solid-state SOx sensor.

• Journal of Radiation Protection and Research
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• v.15 no.2
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• pp.57-65
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• 1990

Newly developed LiF(Mg, Cu, Na, Si) thermoluminescence phosphors sealed in a plastic capsules (32mm dia., 0.9mm wall thickness) were used for in-phantom dosimetry of $^{60}Co$ $\gamma$-irradiation. The absorbed doses in water were determined by applying the general cavity theory to the absorbed dose in TLD cavity, which was computed from exposure. The absorbed doses at various sites in the water-phantom were measured by LiF(Mg, Cu, Na, Si) TLD and compared with doses obtained by the ionization method. Both results were consistent within the experimental fluctuation$({\pm}3%)$ Central axis percentage depth doses and phantom-air ratios measured by LiF(Mg. Cu, Na, Si) TLD showed good agreement with the published values[Br. J. Radiology, Suppl. 17(1983)].

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.111-118
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• 1996

In order to improve the chemical durability of glass in the $Na_2O$-CaO-$SiO_2$ system, it was investigated in the effect of $B_2O_3$ and ZnO addition and changing amount of each composition, $Na_2O$, $Al_2O_3$, $Li_2O$. In this minimize the change of softening point of glass was as follow.(wt%)$B_2O_3$:3.36%, ZnO:2.88%, $Na_2O$:9.93%, $Al_2O_3$, $Li_2O$:0.19%, $SiO_2$:70.56%, CaO:11.22%, $K_2O$:0.14%

• Advances in Energy Research
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• v.5 no.1
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• pp.13-29
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• 2017

The roles of Na, Mn, W and silica, and the synergistic effects between each metal in the $MnNa_2WO_4/SiO_2$ catalyst have been investigated for oxidative coupling of methane (OCM). The crystallisation of amorphous silica during calcination at $900^{\circ}C$ was promoted primarily by Na, but Mn and W also facilitated this process. The interaction between Na and Mn tended to increase the extent of conversion of $Mn_3O_4$ to $Mn_2O_3$. The formation of $Na_2WO_4$ was dependent on the order in which Na and W were introduced to the catalyst. The impregnation of W before Na resulted in the formation of $Na_2WO_4$, but this did not occur when the impregnation order was reversed. $MnWO_4$ formed in all cases where Mn and W were introduced into the silica support, regardless of the impregnation order; however, the formation of $MnWO_4$ was inhibited in the presence of Na. Of the prepared samples in which a single metal oxide was introduced to silica, only $Mn/SiO_2$ showed OCM activity with significant oxygen conversion, thus demonstrating the important role that Mn plays in promoting oxygen transfer in the reaction. The impregnation order of W and Na is critical for catalyst performance. The active site, which involves a combination of Na-Si-W-O, can be formed in situ when distorted $WO_4^{2-}$ interacts with silica during the crystallisation process facilitated by Na. This can only occur if the impregnation of W occurs before Na addition, or if the two components are introduced simultaneously.

• Resources Recycling
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• v.7 no.5
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• pp.52-57
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• 1998

Effect of Si in the electrochemical corrosion characteristics of Mg-Li-Al light alloy has been investigated by means of potentiodynamic polarization study. The elecrochemical behaviors were evaluated in 003% NaCl solution and the solution buffered with KH$_{2}PO_{5}{\cdot}$NaOH at room temperature. It was found that the addition of very small quantity of Si (0.48 wt%) in Mg-Li-Al light alloy increased corrosion rates and amount of corrosion products and decreated the pitting resistance of the alloy. From the results it was concluded that Si which is added to increase the strength of Mg-Li-Al alloy is harmful to corrosion properties of the alloy.