• Title/Summary/Keyword: 불산 처리

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Study on enhanced electron emission current of carbon nanotube by thermal and HF treatments (열 및 불산 처리를 통한 탄소나노튜브의 전자 방출 특성의 향상 연구)

  • Kim, K.S.;Ryu, J.H.;Lee, C.S.;Lim, H.E.;Ahn, J.S.;Jang, J.;Park, K.C.
    • Journal of the Korean Vacuum Society
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    • v.17 no.2
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    • pp.90-95
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    • 2008
  • We studied the effect of thermal annealing and hydrofluoric (HF) acid treatment on the field emission properties of carbon nanotube field emitter arrays (CNT-FEAs) grown with the resist-assisted patterning (RAP) process. After thermal and HF treatment, it was observed that the electron emission properties were remarkably improved. The enhanced electron emission was also found to depend strongly on the sequence of the treatments; the electronemission current density is 656 $mA/cm^2$ with the process of thermal treatment prior to HF treatment while the current density is reduced by 426 $mA/cm^2$ with the reversal processes. This is due to the increased crystalline structure by thermal annealing and then strong fluorine bond was formed by HF treatment.

Acid Property and Catalytic Activity on Mordenites Treated by Hydrochloric Acid and Hydrofluoric Acid (염산 및 불산처리 모더나이트의 산특성과 촉매활성)

  • Han, Young-Taek;Ha, Baik-Hyon
    • Applied Chemistry for Engineering
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    • v.2 no.1
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    • pp.77-85
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    • 1991
  • A series of samples having different $SiO_2/Al_2O_3$ ratio were prepared by treating hydrogen mordenites with boiling hydrochloric acid and with hydrofluoric acid. The acidities of these samples were measured by TPD of $NH_3$ and by pyridine adsorption using IR, and the catalytic activities and selectivities of isomerization were measured for the reaction of ortho-xylene. For the samples treated by boiling hydrochloric acid, the acidities decreased with the increasing $SiO_2/Al_2O_3$ ratio caused by the extraction of framework aluminum. The sample having the $SiO_2/Al_2O_3$ ratio or 22 showed better activity than the others. For the samples treated by hydrofluoric acid, the content of chemically binding fluorine increased with the increasing contact time of hydrofluoric acid solution. The catalytic activities decreased with the hydrofluoric acid treatment due to the decreased acid sites resulted from the extraction of aluminum and silicon as well as the hydroxyl group replacement by the fluoride ion. The slightly increasing catalytic activities, however, came from the newly created acid sites, due to the removal of surface silicon, having enhanced by the inductive effect of binding fluorin with further acid treatment.

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알루미늄 무질산 디스멋용액 연구

  • Go, Geum-Seok
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2016.11a
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    • pp.127-127
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    • 2016
  • 일반적인 알루미늄 표면처리 방식중 De Smut 는 질산 50~60% 용액에 상온에서 수초에서 수분 침적으로 Smut가 거의 제거가 되므로 도금공정에서 문제가 되지않았다. 단지 NOx 의 발생으로 작업공간 에서의 환경이 열악해 질 수 있다는 것이 문제 였다, 그러나 환경문제에 있어서 정부의 질소 규제 가 시작 되면서 알루미늄을 재료로 표면처리 하는 업체 에서는 질산 사용이 곤란해 해졌다. 그러나 질산이 금속과 의 친화력은 스테인레스, 알루미늄, 등 많은 금속에서 소지금속의 용해를 방지 하면서 산화스케일( De Smut)을 제거하는 데 유용한 산이어서 아직도 이용되고 있는 실정이다. 본 연구에서 는 우선 스테인레스 강의 산세시 불산과 질산의 혼산을 사용 하는 것을 불산, 불화암모늄, 황산, 과산화 수소 혹은 불산, 염산, 과산화 수소 등으로 전환 사용 하는 것 에 착안 하여 황산, 과산화수소 시스템에서 혹은 불산, 황산, 과산화 수소, 등으로 Smut 제거가 가능 한지 알아보고 그 효과를 살펴보았다.

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Treatment of Mixed Fluoride Wastewater Using Cement Paste (시멘트 페이스트를 이용한 혼합 불산폐수 처리)

  • Byun, Hye-Jung;Choi, Won-Ho;Park, Joo-Yang
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.8
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    • pp.909-914
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    • 2007
  • Fluorine compounds are the essential chemicals for wet processes of semiconductor and LCD production line. Problems of conventional treatments for fluoride wastewater are their high operation costs and low fluoride removal capacity. In this study, cement paste containing various Ca-bearing hydrates such as portlandite, calcium silicate hydrate(CSH), and ettringite was investigated for fluoride removal. The objectives of this study are to assess the feasibility of using cement paste cured mixture of cement and water as an alternative agent for treatment of fluoride wastewater and to investigate fluoride removal capacity of the cement paste. The performance of cement paste was comparable to that of lime in the kinetic test. In column experiment where the effluent fluoride concentrations were below 0.5 mg/L. Then the leached calcium reached the maximum level of 800 mg/L. The nitrate reduced to the level of less than 10 mg/L. Nitrate in the wastewater was exchanged with interlayer sulfate of these cement hydrate LDHs. Phosphate concentration could be reduced to 10 mg/L by forming calcium phosphate. These results indicate that the cement paste generally has advantageous characteristics as an economical and viable substitute for lime to remove fluoride.

기판 세정공정 변화에 따른 실리콘 웨이퍼/비정질 실리콘 박막 나노계면 및 이종접합 태양전지 소자 특성 연구

  • O, Jun-Ho;Lee, Jeong-Cheol;Kim, Dong-Seok;Kim, Ga-Hyeon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.423.1-423.1
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    • 2014
  • 본 발표에서는 실리콘 이종접합 태양전지에서 중요한 실리콘 웨이퍼 표면/계면 제어에 대하여 발표한다. 다시 말하여, 실리콘 웨이퍼 기판 세정공정 변화에 따른 실리콘 웨이퍼 표면의 소수전하수명(minority carrier lifetime, MCLT) 및 태양전지 소자특성 변화에 대하여 연구하였다. 구체적으로, 실리콘 웨이퍼 클리닝 최초단계로써 KOH damage etching 공정을 도입할 때, 이후 클리닝 공정을 통일하여 적용한 웨이퍼 표면의 MCLT 및 상기 웨이퍼를 이용하여 플라즈마 화학기상증착법(PECVD)을 통하여 제작한 태양전지 소자 효율은 KOH etching 시간이 10분일 때 최대치에 도달한 후 감소하였다. 또한, RCA1, RCA2, Piranha로 이루어진 웨이퍼 클리닝 단계의 사이에, 또는 맨 마지막에 묽힌 불산용액(DHF, 5 %) 처리를 하여 표면 산화막 제거 및 수소종단처리를 하여 기판의 passivation 특성을 향상시키고자 할 때, 불산용액 처리 순서에 따른 웨이퍼 표면의 MCLT 및 태양전지 소자 효율을 비교하였다. 그 결과, 묽은불산용액을 클리닝 단계 사이에 적용하였을 때의 MCLT 및 태양전지 소자의 특성이 더 우수하였다.

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Effect of Fluorination of Carbon Nanotubes on Physico-chemical and EMI Shielding Properties of Polymer Composites (고분자 복합재의 물리화학적 및 전자파차폐 특성에 미치는 탄소나노튜브의 불소화 영향)

  • Lee, Si-Eun;Kim, Doyoung;Lee, Man Young;Lee, Min-Kyung;Jeong, Euigyung;Lee, Young-Seak
    • Polymer(Korea)
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    • v.39 no.1
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    • pp.114-121
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    • 2015
  • Mutli-walled carbon nanotubes (MWCNTs) were surface-modified by a hydrofluoric acid solution to remove impurities and improve interfacial bonding and dispersion of nanotubes in an epoxy matrix. The crystallinity on the surface of treated MWCNTs was investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical properties were characterized by tensile test, and the enhancement of mechanical properties of the modified MWCNTs/epoxy composites was indicated by a 33% increase in tensile strength. The electromagnetic interference shielding effectiveness (EMI-SE) of modified MWCNTs/epoxy composites was improved with an increase in concentration of hydrofluoric solution, and EMI-SE showed the maximum increase with 25% HF. However, mechanical and EMI-SE properties didn't show further increase with over 50% HF concentration because the properties of MWCNTs were influenced by degradation of crystallinity and intrinsic properties of MWCNTs. The mechanical and electrical property enhancements of the polymer composites are attributed to the modification of MWCNTs which improve crystallinity of MWCNTs and dispersion in the epoxy resin.

Effect of Inorganic Constituents Existing in Empty Fruit Bunch (EFB) on Features of Pyrolysis Products (팜 부산물에 존재하는 무기성분이 급속열분해 생성물의 특성에 미치는 영향)

  • Moon, Jaegwan;Lee, Jae Hoon;Hwang, Hyewon;Choi, In-Gyu;Choi, Joon Weon
    • Journal of the Korean Wood Science and Technology
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    • v.44 no.5
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    • pp.629-638
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    • 2016
  • In this study, the effect of inorganic constituents on the physicochemical properties of pyrolytic products produced from empty fruit bunch (EFB) by fast pyrolysis were investigated. Inorganic constituents were removed from the EFB by means of washing treatment with hydrofluoric acid (HF) and distilled water (D.I water). Ash content decreased from 6.2 wt% (EFB) to 2.4 wt% (HF-EFB) and 3.5 wt% (D.I-EFB), respectively. As a result of the inorganic component, a quantity of potassium in EFB has showed the highest removal efficiency in both HF and D.I water (HF: 80.3%, D.I water: 72.8%). Fast pyrolysis was performed with demineralized EFB in the fluidized bed reactor under the temperature of $500^{\circ}C$ at the residence time of 1.3 sec. The yield of bio-oil was determined to 57.3 wt% for HF-EFB and 52.1 wt% for D.I-EFB, respectively. Biochar yield decreased whereas yield of non-condensable gas increased with decreasing inorganic content of EFB. Water content decreased from 26.9% (EFB) to 9.9% (HF-EFB) and viscosity increased from 16.1 cSt (EFB) to 334 cSt (HF-EFB).

Removal of Impurities from Metallurigical Grade Silicon by Acid Washing (금속급(金屬級) 실리콘에서 산세척(酸洗滌)에 의한 불순물(不純物)의 제거(除去))

  • Lee, Man-Seung;Kim, Dong-Ho
    • Resources Recycling
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    • v.20 no.1
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    • pp.61-68
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    • 2011
  • Impurity removal from metallurgical grade silicon by acid washing at $50^{\circ}C$ was investigated by employing sulfuric, nitric acid and the mixture of hydrochloric and hydrofluoric acid. Acid washing treatment had no effect on the removal of boron and the concentration of this clement after treatment was rather increased. In our experimental range, the removal percentage of phosphorus was 60%. In the acid washing with sulfuric and nitric acid, the removal percentage of major impurities was below 50%, which indicates that refining effect was not great with these acids. Acid washing with the mixture of hydrochloric and hydrofluoric acid led to removal percentage of higher than 90%. Data on the purity of silicon after acid washing at various conditions are reported.

A Study on the Tetrafluoroborate Decomposition Reaction and Removal of Fluoride Using Aluminum (알루미늄을 이용한 불화붕산염의 분해 반응 및 불소 처리에 관한 연구)

  • Joo, Hyun-Jong;Kim, Moon-Ki
    • Journal of Korean Society of Environmental Engineers
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    • v.35 no.4
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    • pp.257-262
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    • 2013
  • The fluorine-containing waste water tends to show a higher removal efficiency through the coagulative precipitation process with calcium. However the tetrafluoroborate produced from the etching process is difficult to remaval due to it's low reactivity with calcium. The objective of this study is improving the efficiency of fluoride ion removal in tetrafluoroborate through decomposing. Research on tetrafluoroborate decomposition depending on reaction pH, temperature, and aluminum dosage were conducted, using a laboratory-scale reactor. The result shows that the reaction of tetrafluoroborate with aluminum is faster with lower pH, higher water temperature, and higher Al/T-F (Aluminum/Total Fluoride) mole ratio. It is found that there was no big change in concentration after over 120 minutes of reaction. This study is to be able to improve the efficiency of tetrafluoroborate and fluoride wastewater treatment by using aluminum.

A COMPARATIVE STUDY OF THE SHEAR BOND STRENGTH AND ADHESIVE FAILURE PATTERN OF METAL BRACKETS BONDED ON NATURAL TEETH AND PORCELAIN TEETH (자연 치관과 포세린 치관상에서 교정용 브라켓 부착시 전단 결합 강도와 파절 양상에 관한 비교 연구)

  • Lee, Hyun-Sun;Kim, Jong-Soo;Yoo, Seung-Hoon
    • Journal of the korean academy of Pediatric Dentistry
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    • v.35 no.2
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    • pp.195-204
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    • 2008
  • Orthodontic brackets often need to be bonded to porcelain such as porcelain fused to metal crowns and porcelain jacket crowns. The purpose of this study was to evaluate the clinical usability of direct bonding system on porcelain teeth by measuring shear bond strength according to various conditions and observing adhesive failure patterns. The specimens, 20 maxillary premolars and 80 porcelain teeth that were produced by duplication of the labial surface of a maxillary first premolar were used and randomly divided into four groups of twenty teeth each. The 5 different preparation procedures tested: (1) application of 37% phosphoric acid on natural teeth, (2) sandblasting on porcelain surfaces, (3) sandblasting and application of 9.6% hydrofluoric acid on porcelain surfaces, (4) sandblasting and application of silane on porcelain surface, (5) sandblasting and application of 9.6% hydrofluoric acid and silane on porcelain surfaces. The metal brackets were bonded with Transbond $XT^{(R)}$ bonding material. The shear bond strength was tested by the micro universal testing machine(Kyung-Sung, Korea) and the amount of residual adhesive on the tooth surface after debonding was examined by stereoscope and assessed with an adhesive remnant index. The results of this study suggest that the direct bonding system on porcelain teeth with sandblasting, HF and porcelain primer is clinically useful.

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