• 제목/요약/키워드: wet chemical method

검색결과 319건 처리시간 0.028초

Wet compaction test를 이용한 혼합지료의 적용 (Application of WCT (Wet Compaction Test) to Mixed Fiber Furnishes)

  • 서영범;이춘한
    • 펄프종이기술
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    • 제37권4호통권112호
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    • pp.8-17
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    • 2005
  • WCT (Wet compaction test) is a new fiber evaluation method developed recently by Seo and its test results can be used as a predictor for pulp quality and its paper property Bleached chemical pulps (SwBKP, HwBKP), recycled pulp (OCC), and mechanical pulp (BCTMP) were used for the furnishes to be tested by WCT We compared the WCT results to conventional fiber evaluation tests such as WRV (Water Retention Value), free ness, and fiber length in this study, and found that WCT always gave better regression coefficients in relation to pulp quality (drainage), and paper properties (density, tensile, tear, and burst strength). WCT may be used on-line in papermachine.

Preparation and Characterization of Pitch/Cokes Composite Anode Material for High Power Lithium Secondary Battery

  • Yu, Lan;Kim, Ki-Jung;Park, Dae-Yong;Kim, Myung-Soo;Kim, Kab-Il;Lim, Yun-Soo
    • Carbon letters
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    • 제9권3호
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    • pp.210-217
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    • 2008
  • Petroleum pitch and coke with wet mixture method or with dry mixture method were investigated to develop the composite anodic carbon material of high power lithium ion battery. Cokes coated with pitch were obtained by the heat treatment of mixture of cokes and pitch with different weight ratios at $800{\sim}1200^{\circ}C$. The charge and discharge characteristic of the consequent composite anodic carbon material assembled in batteries was tested. Cokes with wet mixture method have a smooth surface and their capacity changed little with changing temperature and content as compared to the cokes with dry mixture method. Although the reversible capacities showed different values by the anode manufacturing method, the composite anode with the mixture of 20 wt% of petroleum pitch and 80 wt% of coke showed the higher power capability and initial efficiency than the pitch based anode. However, the reversible capacity of the composite anode showed the reduced value as compared with the pitch based anode.

Effect of Aging Process and Time on Physicochemical and Sensory Evaluation of Raw Beef Top Round and Shank Muscles Using an Electronic Tongue

  • Kim, Ji-Han;Kim, Dong-Han;Ji, Da-som;Lee, Hyun-Jin;Yoon, Dong-Kyu;Lee, Chi-Ho
    • 한국축산식품학회지
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    • 제37권6호
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    • pp.823-832
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    • 2017
  • The objective of this study was to determine the effect of aging method (dry or wet) and time (20 d or 40 d) on physical, chemical, and sensory properties of two different muscles (top round and shank) from steers (n=12) using an electronic tongue (ET). Moisture content was not affected by muscle types and aging method (p>0.05). Shear force of dry aged beef was significantly decreased compared to that of wet aged beef. Most fatty acids of dry aged beef were significantly lower than those of wet aged beef. Dry aged shank muscles had more abundant free amino acids than top round muscles. Dry-aging process enhanced tastes such as umami and saltiness compared to wet-aging process according to ET results. Dry-aging process could enhance the instrumental tenderness and umami taste of beef. In addition, the taste of shank muscle was more affected by dry-aging process than that of round muscle.

$SrTiO_3$의 습식 직접 합성법 (A Study of $SrTiO_3$ Synthesis by Direct Wet Process)

  • 이종근;이경희;이병하
    • 한국세라믹학회지
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    • 제21권2호
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    • pp.165-173
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    • 1984
  • It is desirable to establish reliable synthetic methods for electro-ceramic materials. To synthesize $SrTiO_3$ in this study direct solid state reactions and wet chemical processes were used. Previous study of $SrTiO_3$ synthesis included oxalated-method($SrTiO(C_2O_4)_2$.$4H_2O$) co-precipitation$(SrCO_3+TiO(OH)_2)$ and direct solid state reaction$(SrCO_3+TiO(OH)_2)$ The methods in question lead to intermediate inclusion during the reactions and less controllable in particle sizes of $SrTiO_3$. To obtain highly pure $SrTiO_3$ so-called "direct wet process method" was added in this investigation. In the study the "direct wet process" was for the first time applied to synthesize chemically pure and fine particle $SrTiO_3$. $SrCl_2$ and $TiCl_4$<\ulcornerTEX> at KOH solution at room temperature to 10$0^{\circ}C$ precipitated $SrTiO_3$ The particle size increased as temperature increased.mperature increased.

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변성 폴리아크릴 아미드의 합성 및 제지공정의 보류시스템에 응용 (Synthesis of modified polyacrylamides and their applications for the retention system of papermaking)

  • 손동진;윤지현;최은정;김봉용
    • 한국펄프종이공학회:학술대회논문집
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    • 한국펄프종이공학회 2009년도 춘계학술발표회 논문집
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    • pp.23-28
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    • 2009
  • The purpose of this study was to improve not only wet-end performances but also paper characteristics by the modification of various factors like molecular design and ionic characteristics of polyacrylamides First of all physical characteristics were observed after modify molecular design of the cationic polyacrylamides to linear, branched and cross-linked. In addition it was found analysis method to confirm branch degree of cationic polyacrylamides to combine ionic titration characteristics and spectroscopic behavior, After application of these structure modified polyacrylamides to the multiple retention systems with inorganic microparticles, it was found adjusting of branch degree of polyacrylamides was very important to optimize wet-end improvement. Second, After polymerization of amphoteric polyacrylamide to have both of cationic and anionic functional group in the polymer, we observed not only physical characteristics but also wet-end improvement to apply recycled pulp and found that the improvement of solution stability to prevent hydrolysis and increase of ash retention dramatically to compare traditional cationic polyacrylamide retention aid, Finally, After polymerization of anionic polyacrylamide, we observed not only wet-end improvement but also paper characteristics to apply preflocculation of PCC and it was found the improvements of flocculation efficiency, retention, ash retention, optical properties of the paper and bursting strength to compare traditional preflocculant of cationic polyacrylamide.

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습식 화학적 식각 방법에 의한 시간에 따른 GaAs(100) 단결정 웨이퍼에서의 마이크로 구멍의 제작 및 분석 (Fabrication and Time-Dependent Analysis of Micro-Hole in GaAs(100) Single Crystal Wafer Using Wet Chemical Etching Method)

  • 이하영;곽민섭;임경원;안형수;이삼녕
    • 한국재료학회지
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    • 제29권3호
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    • pp.155-159
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    • 2019
  • Surface plasmon resonance is the resonant oscillation of conduction electrons at the interface between negative and positive permittivity material stimulated by incident light. In particular, when light transmits through the metallic microhole structures, it shows an increased intensity of light. Thus, it is used to increase the efficiency of devices such as LEDs, solar cells, and sensors. There are various methods to make micro-hole structures. In this experiment, micro holes are formed using a wet chemical etching method, which is inexpensive and can be mass processed. The shape of the holes depends on crystal facets, temperature, the concentration of the etchant solution, and etching time. We select a GaAs(100) single crystal wafer in this experiment and satisfactory results are obtained under the ratio of etchant solution with $H_2SO_4:H_2O_2:H_2O=1:5:5$. The morphology of micro holes according to the temperature and time is observed using field emission - scanning electron microscopy (FE-SEM). The etching mechanism at the corners and sidewalls is explained through the configuration of atoms.

알칼리 촉진제 성능 측정의 새로운 전환점: 도입 방식의 단순화를 통한 탐구 (Advancing the Frontier in Alkaline Promoter Performance Evaluation: Exploring Simplified Adoption Methods)

  • 윤원중;이지연;김재훈
    • 청정기술
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    • 제30권1호
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    • pp.62-67
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    • 2024
  • 본 연구에서는 이산화탄소를 기반으로한 피셔-트롭시 반응에 사용되는 철계 촉매에 알칼리 금속인 Na를 함침 및 물리적 혼합 방식으로 도입하여 각각의 성능을 비교하였다. 제조된 촉매는 3.5 MPa, 330 ℃, H2/CO2 = 3의 가스 조성비에서 공간속도 4,000 mL h-1 gcat-1 조건으로 반응성을 평가하였다. 두 가지 촉매를 비교한 결과 Na를 함침한 경우 Na가 촉매 전체에 균일하게 분산되어 있지만 물리적 방법으로 혼합한 촉매는 상대적으로 표면에 위치하였다. 또한 Na를 함침한 촉매가 더 높은 액체 탄화수소(C5+) 수율과 낮은 CO 선택도를 보였다. 결론적으로 촉매 내의 Na 분포가 반응에 미치는 영향을 파악하였으며 도입 방식을 통해 이를 조절할 수 있음을 확인하였다.

Processing of Porous Ceramics by Direct Foaming: A Review

  • Pokhrel, Ashish;Seo, Dong Nam;Lee, Seung Taek;Kim, Ik Jin
    • 한국세라믹학회지
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    • 제50권2호
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    • pp.93-102
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    • 2013
  • Macro porous ceramics possessing controlled microstructures and chemical compositions have increasingly proven useful in the industrial sphere. Their sintered structures have found application in both established and emerging, areas such as thermal insulation in buildings, filtration of liquids and molten materials, refractory insulation, bone scaffolds and tissue engineering. Stable ceramic foams can be formed by wet chemical methods using inorganic particles(e.g., $Al_2O_3$ or $SiO_2$). The wet foams are dried and sintered with improved porosity and mechanical properties. This review examines the different techniques used to prepare porous ceramics from ceramic foams, focusing on the explanation of this versatile method of direct foaming from the past to the present. Comparisons of the processes and the processing parameters are explained with the produced microstructures.

Synthesis and Characterization of Nb, Mo-doped and Nb/Mo-codoped Monoclinic VO2 Nanoparticles and Their Thin Films by Hydrothermal/Post-Thermal Transformation and Wet-Coating Method

  • Kim, Jongmin;Jung, Young Hee;Kwak, Jun Young;Kim, Yeong Il
    • 대한화학회지
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    • 제63권2호
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    • pp.94-101
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    • 2019
  • Nb, Mo-doped and Nb/Mo-codoped $VO_2(M)$ nanocrystallites with various doping levels were synthesized for the first time by a hydrothermal and post thermal transformation method. The reversible phase transition characteristics of those doped $VO_2(M)$ was comparatively investigated. Nb-doping of $VO_2(M)$ by this method resulted in a very efficient lowering of the transition temperature ($T_c$) with a rate of $-16.7^{\circ}C/at.%$ that is comparable to W-doping, while Mo-doping did not give a serious reduction of $T_c$ with only a rate of $-5.1^{\circ}C/at.%$. Nb/Mo-codoping gave a similar result to Nb-doping without a noticeable difference. The thin films of Nb-doped and Nb/Mo-codoped $VO_2(M)$ with a thickness of ca. 120 nm were prepared by a wet-coating of the nanoparticle-dispersed solutions. Those films showed a good thermochromic modulation of near infrared radiation with 30-35% for Nb-doped $VO_2(M)$ and 37-40% for Nb/Mo-codoped ones. Nb/Mo-codoped $VO_2(M)$ film showed slightly enhanced thermochromic performance compared with Nb-doped $VO_2(M)$ film.

Characterization of Hexagonal Tungsten Bronze CsxWO3 Nanoparticles and Their Thin Films Prepared by Chemical Coprecipitation and Wet-Coating Methods

  • Kwak, Jun Young;Hwang, Tai Kyung;Jung, Young Hee;Park, Juyun;Kang, Yong-Cheol;Kim, Yeong Il
    • 대한화학회지
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    • 제62권2호
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    • pp.118-123
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    • 2018
  • The hexagonal tungsten bronze $Cs_xWO_3$ nanoparticle was synthesized by a chemical coprecipitation method of ammonium tungstate and $Cs_2CO_3$ in acidic condition. This synthetic method for cesium tungsten bronze is reported for the first time as far as we know. The synthesized $Cs_xWO_3$ as precipitated showed a weak crystallinity of hexagonal unit cell with a crystallite size of about 4 nm without annealing. When the synthesized $Cs_xWO_3$ was annealed in $N_2$ atmosphere, the crystallinity and crystallite size systematically increased maintaining the typical hexagonal tungsten bronze structure as the annealing temperature increased. The analyzed Cs content in the bronze was about 0.3 vs W, which is very close to the theoretical maximum value, 1/3 in cesium tungsten bronze. According to XPS analysis, the reduced tungsten ions existed as both the forms of $W^{5+}$ and $W^{4+}$ and the contents systematically increased as the annealing temperature increased up to $800^{\circ}C$. The $Cs_xWO_3$ thin films on PET substrate were also prepared by a wet-coating method using the ball-milled solution of the annealed $Cs_xWO_3$ nanoparticles at various temperatures. The near-infrared shielding property of these thin films increased systematically as the annealing temperature increased up to $800^{\circ}C$ as expected with the increased contents of reduced tungsten ions.