Colemanite 광물로부터 붕소화합물의 제조 : 붕산 제조에 있어서 마이크로파 적용 (II)

임형미,지미정,장재훈,백종후,이미재,최병현,Lim, Hyung-Mi,Jae, Mi-Jung,Jang, Jae-Hun,Paik, Jong-Hoo,Lee, Mi-Jai,Choi, Byung-Hyun 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.11

본 연구는 colemanite원광을 출발원료로 하여 붕산을 추출하는 공정에서 마이크로파 적용에 대한 연구로, 황산을 첨가하고 가열하여 colemanite의 칼슘 성분을 황산칼슘으로 분리하여 내고, 액상에 존재하는 붕소 성분은 붕산으로 재결정화 하여 제조하였다 Colemanite에 황산을 첨가해 가열하는 공정에 마이크로파를 적용하면, 일반 가열원을 사용하였을 때와 비교하여 적은 양의 황산을 사용하여 추출이 가능하고, 가열시간을 단축하는 것이 가능하였다. 생성된 붕산의 순도는 일반 가열원을 사용하였을 때와 동등한 수준이고 열 특성 또한 동일하였으나, 입자의 크기는 작아졌다. We have studied microwave extraction process of boric acid from one of calcium borate ores, colemanite. Calcium and boron have separated by addition of sulfuric acid, and calcium has been separated out as calcium sulfate. It was possible to extract boron with the smaller amount of sulfuric acid and with short heating time in microwave heating compared to conventional heating process. The products of boric acid was the same purity and thermal characteristic, but smaller in particle size.

멜라민이 코팅된 수산화마그네슘 입자의 제조와 그 복합입자의 난연특성

임형미,윤준호,정상옥,이동진,이승호,Lim, Hyung-Mi,Yoon, Joon-Ho,Jeong, Sang-Ok,Lee, Dong-Jin,Lee, Seung-Ho 한국재료학회 2010 한국재료학회지 Vol.20 No.12

Magnesium hydroxide-melamine core-shell particles were prepared through the coating of melamine monomer on the surface of magnesium hydroxide in the presence of phosphoric acid. The melamine monomer was dissolved in hot water but recrystallized on the surface of magnesium hydroxide by quenching to room temperature in the presence of phosphoric acid. The core-shell particle was applied to low-density polyethylene/ ethylene vinyl acetate (LDPE/EVA) resin by melt-compounding at $180^{\circ}C$ as flame retardant. The effect of magnesium hydroxide and melamine content has been studied on the flame retardancy of the core-shell particles in LDPE/EVA resin according to the preparation process and purity of magnesium hydroxide. Magnesium hydroxide prepared with sodium hydroxide rather than with ammonia solution revealed higher flame retardancy in core-shell particles with LDPE/EVA resin. At 50 wt% loading of flame retardant, core-shell particles revealed higher flame retardancy compared to that of the exclusive magnesium hydroxide in LDPE/EVA composite, and it was possible to satisfy the V0 grade in the UL-94 vertical test. The synergistic flame retardant effect of magnesium hydroxide and melamine core-shell particles was explained as being due to the endothermic decomposition of magnesium hydroxide and melamine, which was followed by the evolution of water from the magnesium hydroxide and porous char formation due to reactive nitrogen compounds, and carbon dioxide generated from melamine.

수산화마그네슘 분산상의 제조와 PET 부직포 섬유의 난연 코팅제 적용

임형미,현미경,정상옥,이동진,이승호,Lim, Hyung-Mi,Hyun, Mi-Kyung,Jeong, Sang-Ok,Lee, Dong-Jin,Lee, Seung-Ho 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6

Magnesium hydroxide as a non-halogen flame retardant has increasing attention due to its non-toxicity, high decomposition temperature and smoke suppressant ability during combustion. For the application of magnesium hydroxide retardant to the textile by soaking and coating method, the prerequisite for the coating is a small particle size, stable dispersion, and adhesion to the textile. The dispersion of $Mg(OH)_2$ particles and stability of the coating was checked by monitoring the change of transmittance and backscattering by varying the types of dispersion agents, binder, solvent, and $Mg(OH)_2$ source, and their compositions in the coating. The $Mg(OH)_2$ dispersion coating was applied to PET(poly(ethylene terephthalate)) non-woven textile. The physical properties are characterized by surface morphology, amount of coating, particle dispersion, and adhesion test. The flame retardant $Mg(OH)_2$ coated textile has been compared by limited oxygen index(LOI) and thermal gravimetry and differential scanning calorimetry(TG-DSC). It was found that phosphorous additive may give synergistic effect on $Mg(OH)_2$ flame retardant coating to make the flame retardant PET non-woven textile.

스테인리스강 금속 표면에 내열 저방사 산화물 코팅제 적용과 방사 특성 평가

임형미,권태일,김대성,이상엽,강동필,이승호,Lim, Hyung-Mi,Kwon, Tae-Il,Kim, Dae-Sung,Lee, Sang-Yup,Kang, Dong-Pil,Lee, Seung-Ho 한국재료학회 2009 한국재료학회지 Vol.19 No.12

Inorganic oxide colloids dispersed in alcohol were applied to a stainless steel substrate to produce oxide coatings for the purpose of minimizing emissive thermal transfer. The microstructure, roughness, infrared emissive energy, and surface heat loss of the coated substrate were observed with a variation of the nano oxide sol and coating method. It was found that the indium tin oxide, antimony tin oxide, magnesium oxide, silica, titania sol coatings may reduce surface heat loss of the stainless steel at 300${\circ}C$. It was possible to suppress thermal oxidation of the substrate with the oxide sol coatings during an accelerated thermal durability test at 600${\circ}C$. The silica sol coating was most effective to suppress thermal oxidation at 600${\circ}C$, so that it is useful to prevent the increase of radiative surface heat loss as a heating element. Therefore, the inorganic oxide sol coatings may be applied to improve energy efficiency of the substrate as the heating element.

실리카 코팅된 TiO₂-천연 제올라이트 복합입자 제조와 특성평가

임형미,정지숙,이동진,이승호,Lim, Hyung-Mi,Jung, Ji-Sook,Lee, Dong-Jin,Lee, Seung-Ho 한국재료학회 2006 한국재료학회지 Vol.16 No.11

Deodorization of natural zeolites have been improved not only for polar but also for non-polar pollutants by sucessive ion exchanges of H and Ag ions starting from Korean natural zeolite with high adsorption capacity. The modified zeolites with $TiO_2$ coating on the surface revealed high deodorization and photocatalytic decomposition effects. Further modification was made with $10{\sim}20nm$ silica nano particles coating on the surface, the resulting composite particles of $SiO_2/TiO_2/modified$ natural zeolite revealed not only comparable deodorization but also better durability and resisatnce to color change compared to the $TiO_2$/modified natural zeolite without much compensation of photocatalytic decomposition effect, when the composite particles were exposed to the polypropylene non-woven fiber coated with organic binder. It is expected for the composite particle prepared here to be used as indoor building materials for indoor air quality control.

공업용 물유리를 출발물질로 한 흡수용 제올라이트 제조 공정 연구

임형미 ( Hyung Mi Lim ),정상진 ( Sang Jin Jung ),안병길 ( Byeng Gil Ahn ),최병현 ( Byung Hyun Choi ),이명영 ( Myung Young Lee ) 한국공업화학회 2003 공업화학 Vol.14 No.1

본 연구는 공업용 물유리와 액상 알루민산나트룸을 출발물질로 하여, A형 제올라이트를 합성할 때 합성 변수에 따른 결정형과 그 특성에 대한 것으로, 출발물질의 몰비, 반응온도, 숙성 조건, 결정화 조건 및 가열 속도에 따른 생성물의 결정형, 결정화도, 입자 형성, 입도, 양이온 교환능, 흡습량의 변화를 관찰하였다. 일반적으로는 숙성한 조건에서 생성된 입자가 더 작고 균일한 크기의 입자를 얻었다. 숙성과정을 거치지 않은 경우, 가열속도가 빠르면 경쟁상으로 알려진 소달라이트상이 일부 관찰되기도 한였다. 합성된 제올라이트는 주사전자현미경, X선 분말 회절 및 FT-IR 분광기를 이용해 분석하였다. 실온 고습 조건에서 흡습량을 확인한 결과 A형 제올라이트의 경우 초기 흡습 속도는시간당 0.3~0.4wt%이나 소달라이트는 시간당 0.07wt% 정도로 작고 15일 방치 후 최대 흡습량은 A형 제올라이트의 경우 26wt% 소달라이트는 14wt% 정도이다. In the synthesis of zeolite with industrial water glass and sodium aluminate, the synthesis condition and water adsorption characteristics of zeolite were studied. It was found that type of zeolite, crystallinity, morphology, cation exchange capacity, water adsorption capacity depended on molar ratio of starting material, reaction temperature, aging condition, crystallization condition, and heating rate. In general, aging led to production of zeolite particles with smaller and more uniform in size. Without aging, simultaneous formation of sodalite phase was apparent when the heating rate was fast. The products were analyzed by scanning electron microscopy, X-ray powder diffractometry, and FT-IR spectrometry. The initial water adsorption rate was 0.3~0.4wt%/h and 0.07wt%/h and the maximum water adsorption capacity was 26wt% and 14wt% for NaA and sodalite, respectively, in the humid chamber at room temperature.

침전법과 수열처리로 제조된 수산화마그네슘 비교와 이의 저밀도 폴리에틸렌-에틸렌 비닐 아세테이트 수지 난연제 적용

현미경 ( Mi Kyung Hyun ),임형미 ( Hyung Mi Lim ),윤준호 ( Joon Ho Yoon ),이동진 ( Dong Jin Lee ),이승호 ( Seung Ho Lee ),황진명 ( Chin Myung Whang ),정상옥 ( Sang Ok Jeong ) 한국공업화학회 2009 공업화학 Vol.20 No.2

나노 실리카의 분무건조를 이용한 중공구 입자 제조와 실리카중공구의 열전달 특성

윤찬기,임형미,차수진,김대성,이승호,Youn, Chan Ki,Lim, Hyung Mi,Cha, Sujin,Kim, Dae Sung,Lee, Seung-Ho 한국재료학회 2012 한국재료학회지 Vol.22 No.10

Hollow silica spheres were prepared by spray drying of precursor solution of colloidal silica. The precursor solution is composed of 10-20 nm colloidal silica dispersed in a water or ethanol-water mixture solvent with additives of tris hydroxymethyl aminomethane. The effect of pH and concentrations of the precursor and additives on the formation of hollow sphere particles was studied. The spray drying process parameters of the precursor feeding rate, inlet temperature, and gas flow rate are controlled to produce the hollow spherical silica. The mixed solvent of ethanol and water was preferred because it improved the hollowness of the spheres better than plain water did. It was possible to obtain hollow silica from high concentration of 14.3 wt% silica precursor with pH 3. The thermal conductivity and total solar reflectivity of the hollow silica sample was measured and compared with those values of other commercial insulating fillers of glass beads and $TiO_2$ for applications of insulating paint, in which the glass beads are representative of the low thermal conductive fillers and the $TiO_2$ is representative of infrared reflective fillers. The thermal conductivity of hollow silica was comparable to that of the glass beads and the total solar reflectivity was higher than that of $TiO_2$.

전기영동적층법을 통한 판상 알루미나 입자와 전기영동 수지의 배향 유무기 복합체 제조 및 물성평가

박희정,임형미,최성철,김영희,Park, Hee Jeong,Lim, Hyung Mi,Choi, Sung-Churl,Kim, Younghee 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.6

Plate-shaped inorganic particles are coated onto a stainless steel substrate by the electrophoretic deposition of a precursor slurry which includes the inorganic particles of $Al_2O_3$ and polymer resin in mixed solvents to mimic the abalone shell structure, which is a composite of plate-shaped inorganic particles and organic interlayer binding materials with a layered orientation. The process parameters of the electrophoretic deposition include the voltage, coating time, and conductivity of the substrate. In addition, the suspension parameters are the particle size, concentration, viscosity, conductivity, and stability. We prepared an organic-inorganic composite coating with a high inorganic solid content by arraying the plate-shaped $Al_2O_3$ particles and electrophoretic resin via an electrophoretic deposition method. We analyzed the effect of the slurry composition and the electrophoretic deposition process parameters on the physical, mechanical and thermal properties of the coating layer, i.e., the thickness, density, particle orientation, Young's modulus and thermogravimetric analysis results.

Colemanite 광물로부터 붕소화합물의 제조에 관한 연구 : 붕산제조 및 반응기구 (I)

최병현,임형미,지미정,장재훈,백종후,이미재,Choi, Byung-Hyun,Lim, Hyung-Mi,Jee, Mi-Jung,Jang, Jae-Hun,Paik, Song-Hoo,Lee, Mi-Jai 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.10

Colemanite($Ca_2B_6O_{11}{\cdot}5H_2O$)원광을 황산과 반응시켜 붕산을 추출하는 방법과 그 반응 기구에 대하여 연구하였다. colemanite에 황산을 첨가하고 가열하여 colemanite의 칼슘 성분을 황산칼슘으로 분리하고 붕산을 추출할 때, 첨가하는 황산 첨가량 은 colemanite에 존재하는 Ca 성분을 분리할 때 필요한 화학 양론적인 양보다 많아야 되며, 또한 초기 pH가 5 미만이어야 대부분의 colemanite가 분해되었다. 붕산으로 추출 시 영향을 주는 인자로는 분해온도, 분해시간, 황산 첨가량, 황산암모늄 첨가량, pH. 농축 정도 및 건조온도와 시간이었다. 황산 첨가 시 colemanite에 포함되어 있는 불순물 중 CaO와 MgO는 황산과 반응하여 침전을 형성하고, $SiO_2$는 불용 성분으로 황산칼슘과 함께 분리되고, $Al_2O_3,\;Fe_2O_3,\;TiO_2,\;Na_2O$ 등은 황산과 반응하여 액상 상태로 존재하였다. 이 액상에 암모니아를 첨가하여 존재하는 나머지 불순물을 수산화물 형태로 분리, 석출하였으며, pH 조정과 산성화, 농축, 재결정화 과정을 통하여 붕산을 제조하였다. We present extraction process and reaction mechanism of boric acid from one of calcium borate ores, colemanite by reaction with sulfuric acid. Colemanite has been fully decomposed under pH 5 with sufficiency amount of sulfuric acid, more than the amount stoichiometrically required. Calcium sulfate was separated out, leaving boron in the liquid phase after sulfuric acid addition. The extraction process of boric acid was affected by dissolution temperature and time, amount of sulfuric acid and ammonium sulfate, pH and a degree of concentration before recrystallization. The $SiO_2$ of the impurities which colemanite contains was insoluble so that it was separated out with calcium sulfate from liquid phase. The species of $CaO,\;Al_2O_3,\;Fe_2O_3,\;MgO$ were remained in a liquid phase after reaction with sulfuric acid. These impurities were separated out by addition of ammonia to the liquid phase, funhermore, boric acid was produced by process of pH adjustments and acidification, concentration, and recrystallization.