• YAKHAK HOEJI
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• v.39 no.1
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• pp.68-77
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• 1995

Aluminum magnesium silicate was synthesized by reacting the mixed solutions of sodium aluminate and magnesium chloride with sodium silicate solution in this study. The optimal synthesis conditions based on the yield of the product has been attained according to Box-Wilson experimental design. It was found that the optimal synthetic conditions of aluminum magnesium silicate were as follows: Reaction temperature=$69~81^{\circ}C$; concentration of two reactants, sodium aluminate and magnesium chloride= 13.95~14.44 w/w%; molar concentration ratio of the two reactants, [NaAlO$_{2}$]/MgCl$_{2}$]=3.63~4.00; reaction time= 12~15 min; drying temp. of the product=$70~76^{\circ}C$. Aluminum magnesium silicate synthesized under the optimal synthesis condition was dispersed in 0.75, 1.0 and 1.5w/w% aqueous solution or suspension of six dispersing agents, and the Theological properties of the dispersed systems prepared have been investigated at $15^{\circ}C$ and $25^{\circ}C$ using Brookfield LVT Type Viscometer. The acid-consuming capacity of the most excellent product was 272~278 ml of 0.1N-HCl per gram of the antacid. The flow types of 5.0 w/w% aluminum magnesium silicate suspension were dependent upon the kind and concentration of dispersing agents added. The apparent viscosity of the suspension was generally increased with concentration of dispersing agents and was not significantly changed or decreased as the temperature was raised. A dispersing agent, hydroxypropyl cellulose suspension, exhibited an unique flow behavior of antithixotropy. The flow behavior of the suspension dispersed in a given dispersing agent not always coincided with that of the dispersing agent solution or suspension itself.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.84-91
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• 2020

The efficiency of the synthetic magnesium silicate used in basic polyols and edible oil purification is evaluated by its purification ability and filtration rate and is affected by the particle size and surface area of magnesium silicate. In this study, it was investigated the change on the particle size of magnesium silicate was influenced by the reaction temperature, injection rate, injection order (Si, Mg) and Mg/Si reaction mole ratio. The synthesized magnesium silicate was compared and analyzed for the synthesis, grinding, and refining processes. In the synthesis process, the reaction temperature and feed rate did not affect the average particle size change of magnesium silicate, while the reaction molar ratio of Mg / Si and the order of injection acted as main factors for the change of average particle size. The average particle size of magnesium silicate increased by 8.7 ㎛ from 54.4 ㎛ to 63.1 ㎛ at Mg injection when Mg molar ratio increased from 0.125 to 0.500, and increased by about 4.8 ㎛ from 47.3 ㎛ to 52.1 ㎛ at Si injection. The average particle size according to the order of injection was 59.1 ㎛ for Mg injection and 48.4 ㎛ for Si injection and the difference was shown 10.7 ㎛, therefore the filtration rate was about 2 times faster under the condition of Mg injection. That is, as the particle size increases, the filtration time is shortened and washing filtration rate can be increased to improve the productivity of magnesium silicate. The cake form of separated magnesium silicate after filtration becomes a solid through drying process and is used as powdery adsorbent through the grinding process. As the physical strength of the dried magnesium silicate increased, the average particle size of the powder increased and it was confirmed that this strength was affected by the reaction molar ratio. As the reaction molar ratio of Mg / Si increased, the physical strength of magnesium silicate decreased and the average particle size after grinding decreased by about 40% compared to the average particle size after synthesis. This reduction of strength resulted in an improvement of the refining ability due to the decrease of the average particle size and the increase of the amount of fine particle after the pulverization, but it resulted in the decrease of the purification filtration rate. While the molar ratio of Mg/Si was increased from 0.125 to 0.5 at Mg injection, the refining ability increased about 1.3 times, but the purification filtration rate decreased about 1.5 times. Therefore, in order to improve the productivity of magnesium silicate, the reaction molar ratio of Mg / Si should be increased, but in order to increase the purification filtration rate of the polyol, the reaction molar ratio should be decreased. In the synthesis parameters of magnesium silicate, the order of injection and the reaction molar ratio of Mg / Si are important factors affecting the changes in average particle size after synthesis and the changes of particle size after grinding due to the changes of compressive strength, therefore the synthetic parameter is an important thing that determines productivity and refining capacity.

• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.109-115
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• 2009

Magnesium is one of the lightest metals, and magnesium alloys have excellent physical and mechanical properties such as high stiffness/weight ratios, good castability, good vibration and shock absorption. However their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To improve these defects, many techniques are developed. Micro arc oxidation(MAO) is a one of the surface treatments under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy. In this study, the characteristics of anodic film were examined after coating the AZ31B magnesium alloy through the MAO process. MAO was carried out in potassium hydroxide, potassium fluoride, and various concentration of sodium silicate in electrolyte. The morphology and chemical composition of the coating layer were characterized by SEM, XRD, EPMA and EDS. The hardness of anodic films was measured by micro-vickers hardness tester. As a result, the morphology and composition of anodic film were changed by concentration of sodium silicate. Thickness and Si composition of anodic film was increased with increasing concentration of sodium silicate in electrolyte. The hardness of anodic film was highly increased when the concentration of sodium silicate was above 40 g/l in electrolyte.

• YAKHAK HOEJI
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• v.44 no.6
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• pp.545-551
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• 2000

Magnesium trisilicate was prepared by reacting Magnesium sulfate solution with Sodium silicate solution in this study. The optimum synthesis conditions base on the yield of the product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of Magnesium trisilicate were as follows; Reacting temperature : $57{\sim}90^{\circ}C$, Concentration of reactant solution : $19.1{\sim}20.0%$, Molar concentration ratio of two reactants : [Sod.silicate]/[Mg.sulfate] : $1.47{\sim}1.80$, Temperature of washing water : $45{\sim}48^{\circ}C$, Drying temperature : $65{\sim}82^{\circ}C$. The antacidic capacity of the five Magnesium trisilicate samples which shows the maximum antacidic efficacy was tested by pharmacopeia acid consuming capacity test. The five Magnesium trisilicate samples were identified by chemical analysis.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.79-85
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• 2006

Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

• YAKHAK HOEJI
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• v.15 no.1
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• pp.1-7
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• 1971

When a large quantity of insoluble drugs was added into a solution containing a small amount of soluble drugs, the latter was adsorbed to the former. Their adsorption was expected to alter the drug activity. Berberine hydrochloride (BH) was selected as a soluble drug and tested with frequently combined insoluble drugs and antacids for their adsorption phenomena in prufied water, gastric and intetinal fluid test solutions, respectively. The adsorption isotherms of kaolin and natural anuminum silicate with BH in the three media fitted the Langmuir (LM) equation, and that of talc in purified water and gastric fluid fitted it, but in intestinal fluid it fitted the Freudlich quation. The adsorption isotherm of aluminum hydroxide fitted the LM equation only in intestinal fluid. The degree of adsorption of BH in purified water and gastric fluid is in the following order: magnesium trisilicate, kaolin, natural aluminum silicate and talc; in intestinal fluid: magnesium trisilicate, kaolin, talc, natural aluminum silicate and aluminum hydroxide. Magnesium stearate did not adsorb BH.

• Journal of the Korean Ceramic Society
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• v.46 no.3
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• pp.242-248
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• 2009

Forsterite is a crystalline magnesium silicate with chemical formula $Mg_2SiO_4$, which has extremely low electrical conductivity that makes it an ideal substrate material for electronics. In this study, forsterite precursors were synthesized with magnesium silicate gels from the mixture of magnesium nitrate solution and various sodium silicate solution by the geopolymer technique. Precursors and heattreated powders were characterized by thermogravimetrical differential thermal analyzer(TG-DTA), X-ray diffractometer(XRD), scanning electron microscopy(SEM), Si magic angle spinning nuclear magnetic resonance(MAS-NMR), transmission electron microscopy(TEM). As the result of analysis about the crystallization behavior by DTA, the synthesized precursors were crystallized in the temperature range of $700^{\circ}C$ to $900^{\circ}C$. The XRD results showed that the gel composition began to crystallize at various temperature. Also, it was found that the sodium orthosilicate based precursors(named as 'FO') began to crystallize at above $550^{\circ}C$. The FO peaks were much stronger than sodium silicate solution based precursors(named as 'FW'), sodium metasilicate based precursors(named as 'FM') at $800^{\circ}C$. TEM investigation revealed that the 100nm particle sized sample was obtained from FO by heating up to $800^{\circ}C$.

• Journal of Korea Foundry Society
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• v.29 no.5
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• pp.233-237
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• 2009

The effect of electrolyte on mechanical and corrosion properties of AZ91 magnesium alloy by plasma electrolytic oxidation (PEO) method was investigated. The coating layers formed in the silicate and the aluminate electrolytes showed porous structures. The small pores were randomly distributed on the coatings formed in aluminate electrolyte while the coatings formed in silicate electrolyte showed much bigger pores. In the aluminate electrolyte, the coatings were composed of Mg, MgO and $MgAl_2O_4$, whereas Mg, MgO, $MgAl_2O_4$ and $Mg_2SiO_4$ were identified in the coatings formed in silicate electrolyte. The hardness of coatings in the silicate electrolyte was higher than that of coating grown in the aluminate electrolyte. The AZ91 alloy coated in the silicate electrolyte had higher tensile strength and elongation than that coated in the aluminate electrolyte. In addition, the coatings formed in the silicate electrolyte showed much better corrosion resistance compared to the coatings formed in the aluminate electrolyte.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6324-6329
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• 2013

The aim of this study was to prepare and evaluate tablets containing liquid choline alphoscerate, which is capable of being formulated as a solid dosage form by the adsorption of magnesium aluminum silicate. The tablets were prepared with various absorbent to choine alphoscerate ratios. The physical properties and the dissolution rate were investigated. Considering the tabletting and dissolution rate, the formula scontaining 50-75% absorbent were adequate in the tested formulations. The 62.5% absorbent formula showed superior results with the tests of hardness, friability, disintegration time, and the ratio of dissolution area under the curve. Overall, magnesium aluminum silicate can be an alternative additive to a liquid drug.

• Journal of the Korean institute of surface engineering
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• v.48 no.5
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• pp.185-193
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• 2015

Anodization of die-casted AZ91D magnesium alloy was carried out using silicate based electrolyte solution instead of fluoride based solution to improve biocompatibility of oxidized layers. The anodic layer obtained from silicate based solution has smaller size of pore and smoother surface, resulting in lower corrosion rate in simulate body solution (SBF). Effect of enhanced structural and chemical properties in oxidized layer on biocompatibility was carefully considered.