Loading [MathJax]/jax/output/CommonHTML/jax.js
  • Title/Summary/Keyword: all ceramic

Search Result 1,146, Processing Time 0.032 seconds

Electrochemical Properties of Al Doped Li(Ni1/3Co1/3Mn1/3-xAlx)O2, Cathode Materials (알루미늄이 첨가된 Li(Ni1/3Co1/3Mn1/3-xAlx)O2 양극활물질의 전기화학적 특성)

  • Kim Seon-Hye;Shim Kwang-Bo;Kim Chang-Sam
    • Journal of the Korean Electrochemical Society
    • /
    • v.9 no.2
    • /
    • pp.64-69
    • /
    • 2006
  • Cathode materials of Al-doped Li(Ni1/3Co1/3Mn1/3xAlx)O2 (x=0.0, 0.005, 0.01 0.05) for lithium ion batteries were synthesized with ultra-sonic spray pyrolysis method and single-step heat treatment. No secondary phases were found in all synthesized powders. The intensity ratio of I003toI104, however, slightly decreased and the particle size increased with the Al contents. The cells with bare, 0.5 and 1.0 at% Al-doped powders showed the initial discharge capacities of 182, 180 and 184mAhg1 in a voltage range of 3.04.5V at 1C rate, and the capacity retentions of 81, 77 and 78% at the end of 30 cycles, respectively. But in the voltage range of 3.04.6V, the Al-doping significantly enhanced the cycle stability. For example, the discharge capacity after 50 cycles was maintained to 70% in the 0.5 at% Al-doped sample compared to only 30% in no doped sample. The improvement of the cycle stability was thought to be due to Mn3+ ion decrease as the Al doping from the XPS analysis results.

Development of Continuous Beer Maturation Precess Using Immobilized Yeast (고정화 효모를 이용한 맥주의 연속 숙성공정 개발)

  • 박상재;이율락;김상호;최차용
    • KSBB Journal
    • /
    • v.15 no.5
    • /
    • pp.438-443
    • /
    • 2000
  • Continuous processes using immobilized yeast were investigated in order to shorten beer maturation time. Three silica-based ceramic media and one cellulose-based medium were used. Diacetyl (DA) was one of the most distinctive compounds causing immature flavors. Heat treatment of green beer (GB) to convert a-acetolactate to DA was essential to shorten the time for beer maturation. The longer heat treatment time was needed at the lower temperature. Oxygen concentration in GB had a large influence on the conversion of a-acetolactate to DA. The lower the oxygen concentration in GB, the lower conversion ratio to DA. Heat treated GB was fed continuously to four kinds of immobilized yeast columns. DA concentration after immobilization columns was reduced to less than 0.1ppm at 35C 180∼150 minutes retention time in all columns tested. This concentration is enough to fit the quality speification of commercialized product. Formation of a-acetolactate from residual sugars was higher in ceramic media column than cellulose media cloumn. The taste of beers from test processes were not the same as that of traditionally produced beer, but no off-flavors were detected in test samples, which shows that immobilized yeast columns have potentials as rapid processes for beer maturation.

  • PDF

Development of Novel Materials for Reduction of Greenhouse Gases and Environmental Monitoring Through Interface Engineering

  • Hirano, Shin-Ichi;Gang, Seok-Jung L.;Nowotny, Janusz-Nowotny;Smart, Roger-St.C.Smart;Scrrell, Charles-C.Sorrell;Sugihara, Sunao;Taniguchi, Tomihiroi;Yamawaki, Michio;Yoo
    • Korean Journal of Materials Research
    • /
    • v.9 no.6
    • /
    • pp.635-653
    • /
    • 1999
  • The present work considers work considers research strategies to address global warming. Specifically, this work considers the development of technologies of importance for the reduction of greenhouse gas emission and, especially, the materials that are critical to these technologies. It is argued that novel materials that are essential for the production of environmentally friendly energy may be developed through a special kind of engineering: interface engineering, rather than through classical bulk chemistry. Progress on the interface engineering requires to increase the present state of understanding on the local properties of materials interfaces and interfaces processes. This, consequently, requires coordinated international efforts in order to establish a strong background in the science of materials interfaces. This paper considers the impact of interfaces, such as surfaces and grain boundaries, on the functional properties of materials. This work provides evidence that interfaces exhibit outstanding properties that are not displayed by the bulk phase. It is shown that the local interface chemistry and structure and entirely different than those of the bulk phase. In consequence the transport of both charge and matter along and across interfaces, that is so important for energy conversion, is different than that in the bulk. Despite that the thickness of interfaces is of an order to a nanometer, their impact on materials properties is substantial and, in many cases, controlling. This leads to the conclusion that the development of novel materials with desired properties for specific industrial applications will be possible through controlled interface chemistry. Specifically, this will concern materials of importance for energy conversion and environmental monitoring. Therefore, there is a need to increase the present state of understanding of the local properties of materials interfaces and the relationship between interfaces and the functional properties of materials. In order to accomplish this task coordinated international efforts of specialized research centres are required. These efforts are specifically urgent regarding the development of materials of importance for the reduction of greenhouse gases. Success of research in this area depends critically on financial support that can be provided for projects on materials of importance for a sustainable environment, and these must be considered priorities for all of the global economies. The authors of the present work represent an international research group economies. The authors of the present work represent an international research group that has entered into a collaboration on the development of the materials that are critical for the reduction of greenhouse gas emissions.

  • PDF

Recycling of useful Materials from Fly Ash of Coal-fired Power Plant (석탄화력발전소에서 발생되는 비회로부터 유용성분의 회수)

  • Kim, Dul-Sun;Han, Gwang Su;Lee, Dong-Keun
    • Clean Technology
    • /
    • v.25 no.3
    • /
    • pp.179-188
    • /
    • 2019
  • Upon the combustion of coal particles in a coal-fired power plant, fly ash (80%) and bottom ash (20%) are unavoidably produced. Most of the ashes are, however, just dumped onto a landfill site. When the landfill site that takes the fly ash and bottom ash is saturated, further operation of the coal-fired power plant might be discontinued unless a new alternative landfill site is prepared. In this study, wet flotation separation system (floating process) was employed in order to recover unburned carbon (UC), ceramic microsphere (CM) and cleaned ash (CA), all of which serving as useful components within fly ash. The average recovered fractions of UC, CM, and CA from fly ash were 92.10, 75.75, and 69.71, respectively, while the recovered fractions of UC were higher than those of CM and CA by 16% and 22%, respectively. The combustible component (CC) within the recovered UC possessed a weight percentage as high as 52.54wt%, whereas the burning heat of UC was estimated to be 4,232kcalkg1. As more carbon-containing UC is recovered from fly ash, UC is expected to be used successfully as an industrial fuel. Owing to the effects of pH, more efficient chemical separations of CM and CA, rather than UC, were obtained. The average SiO2 contents within the separated CM and CA had a value of 53.55wt% and 78.66wt%, respectively, which is indicative of their plausible future application as industrial materials in many fields.

Heat Transfer Modeling by the Contact Condition and the Hole Distance for A-KRS Vertical Disposal (A-KRS 수직 처분공 접촉 조건 및 처분공 간의 거리에 따른 열전달 해석)

  • Kim, Dae-Young;Kim, Seung-Hyun
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.17 no.3
    • /
    • pp.313-319
    • /
    • 2019
  • The A-KRS (Advanced Korean Reference Disposal System) is the disposal concept for pyroprocessed waste, which has been developed by the Korea Atomic Energy Research Institute. In this disposal concept, the amount of high-level radioactive waste is minimized using pyrochemical process, called pyroprocessing. The produced pyroprocessed waste is then solidified in the form of monazite ceramic. The final product of ceramic wastes will be disposed of in a deep geological repository. By the way, the decay heat is generated due to the radioactive decay of fission products and raises the temperature of buffer materials in the near field of radioactive waste repository. However, the buffer temperature must be kept below 100C according to the safety regulation. Usually, the temperature can be controlled by variation of the canister interdistance. However, KAERI has modelled thermal analysis under the boundary condition, where the waste canisters are in direct contact with each other. Therefore, a reliable temperature analysis in the disposal system may fail because of unknown thermal resistence values caused by the spatial gap between waste canisters. In the present work, we have performed thermal analyses considering the gap between heating elements and canisters at the beginning of canister loading into the radioactive waste repository. All thermal analyses were performed using the COMSOL software package.

A Study on STR Analysis According to the Method of Developing Latent Fngerprints Deposited on Non-Porous Surfaces in the Marine Environment (해양환경 내 비다공성 표면에 유류된 잠재지문 현출방법에 따른 STR 분석 연구)

  • Kim, Jin-Sun;Kim, Sea-In;Yoon, Hyun-Kyoung;Choo, Min-kyu
    • The Journal of the Korea Contents Association
    • /
    • v.22 no.10
    • /
    • pp.733-741
    • /
    • 2022
  • Among the various evidence found in maritime crimes, fingerprints and DNA are very important in that they can identify a suspect. In this study, 5 types of non-porous surfaces (plastic, stainless, glass, ceramic, FRP), which are often found as evidence in the actual marine environment, were selected, and latent and blood fingerprints were passed down and immersed at the Donghae Maritime Police Station's exclusive pier for about 7 days. After that, DNA extraction, quantification, and STR profile were analyzed after fingerprint developing CA fumming method and 4 powder methods (Swedish black powder, Concentrated black powder, Supranano red powder, Dazzle orange powder). Among the fingerprint developing methods, when Supranano red powder was applied, a relatively high amount of DNA was found. As a result of STR profile analysis, an average of 16.8 to 9 loci were secured, and all 20 were confirmed in glass and ceramic materials. As a result of the study, it was possible to secure the STR profile by extracting and quantifying DNA after applying the fingerprint developing method to virtual evidence immersed for about 7 days, and further research is needed to secure the STR profile by analyzing DNA after applying various fingerprint developing methods such as VMD and SPR.

The compressive fracture strength of ceromer crown by the difference of occlusal thickness (Ceromer crown의 교합면 두께에 따른 압축 파절 강도의 비교)

  • Kim, Jee-Yeon;Park, Ha-Ok;Yang, Hong-So
    • Journal of Dental Rehabilitation and Applied Science
    • /
    • v.18 no.3
    • /
    • pp.205-215
    • /
    • 2002
  • This study investigated the compressive fracture strength of Targis ceromer crown by the difference of occlusal thickness on a maxillary first premolar. Control group was a castable IPS-Empress all-ceramic crown with occlusal thickness of 1.5 mm constructed by layered technique. Experimental groups were Targis crowns having different occlusal thicknesses of 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, respectively. The classification of Targis group is T10, T15, T20, T25 and T15N (for no-thermocycling and occlusal thickness of 1.5mm). Ten samples were tested per each group. Except occlusal thickness, all dimension of metal die is same with axial inclination of 10and marginal width 0.8mm chamfer. All crowns were cemented with Panavia F and thermocycled 1,000 times between 5 and 55 water bath with 10 sec dwelling time and 10 sec resting time. The compressive fracture strength was measured by universal testing machine. The results were as follows : 1. Fracture strength was increased as the occlusal thickness increased : compressive fracture strength of Group T10, T15, T20, T25 was 66.65±4.88kgf, 75.04±3.01kgf, 87.07±7.06kgf and 105.03±10.56kgf, respectively. 2. When comparing material, Targis crown had higher fracture strength than IPS-Empress crown : the mean compressive strength of group T15 was 75.04±3.01kgf and the value of group Control was 37.66±4.28kgf. 3. Fracture strength was decreased by thermocycling : the compressive fracture strength of T15 was 75.04±3.01kgf, which is lower than 90.69±6.88kgf of group T15N. 4. The fracture line of crowns began at the loading point and extended along long axis of tooth. IPS-Empress showed adhesive failure pattern whereas Targis had adhesive and cohesive failure. In the SEM view, stress was distributed radially from loading point and the crack line was more prominent on Targis crown.

Comparative study in fracture strength of zirconia cores fabricated with three different CAD/CAM systems (3종의 CAD/CAM 시스템에서 지르코니아 코어의 파절 강도에 관한 비교 연구)

  • Shin, Eon-Sick;Lee, Young-Soo;Park, Won-Hee
    • The Journal of Korean Academy of Prosthodontics
    • /
    • v.46 no.1
    • /
    • pp.22-30
    • /
    • 2008
  • Purpose: The purpose of this study is to compare three different CAD/CAM systems through the fracture strength of zirconia core and to evaluate the clinical availability of each system. Material and methods: The following three groups of 30 maxillary mesial incisor core for all-ceramics(each group 10) were fabricated as follows: group 1. Adens(R) CAD/CAM system, group 2. Cerasys(R) CAD/CAM system, group 3. 3M Lava(R) CAD/CAM system. All specimens were manufactured consistently thickness 0.5mm and relief 40μm. Specimens were subjected to compressive loading on the lingual area by Z250/SN5S(R). Each group's mean and standard deviation were calculated and Kruskal Waillis test, Wilcoxon Rank Sum test were utilized to find out the relationship among the groups. Results: The results were as follows: 1. The mean fracture strength of Adens(R) system was 615.89±156.1N, the Cerasys(R) system was 863.98±151.5N, and the 3M Lava(R) system was 1143.1±286.6N. 2. The fracture strength of the systems showed the significant statistical differences in order of 3M Lava(R) system, Cerasys(R) system, Adens(R) system. Conclusion: In this study, in spite of the differences among the groups, every group showed clinically useful results. It is necessary to study further clinical experiments on a long term basis.

Investigation of Microstructure and Ionic Conductivity of Li1.5Al0.5Ti1.5(PO4)3 Ceramic Solid Electrolytes by B2O3 Incorporation (Li1.5Al0.5Ti1.5(PO4)3 세라믹 고체전해질의 B2O3 첨가에 따른 미세구조 및 이온전도도에 대한 연구)

  • Min-Jae Kwon;Hyeon Il Han;Seulgi Shin;Sang-Mo Koo;Weon Ho Shin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.36 no.6
    • /
    • pp.627-632
    • /
    • 2023
  • Lithium-ion batteries are widely used in various applications, including electric vehicles and portable electronics, due to their high energy density and long cycle life. The performance of lithium-ion batteries can be improved by using solid electrolytes, in terms of higher safety, stability, and energy density. Li1.5Al0.5Ti1.5(PO4)3 (LATP) is a promising solid electrolyte for all-solid-state lithium batteries due to its high ionic conductivity and excellent stability. However, the ionic conductivity of LATP needs to be improved for commercializing all-solid-state lithium battery systems. In this study, we investigate the microstructures and ionic conductivities of LATP by incorporating B2O3 glass ceramics. The smaller grain size and narrow size distribution were obtained after the introduction of B2O3 in LATP, which is attributed to the B2O3 glass on grain boundaries of LATP. Moreover, higher ionic conductivity can be obtained after B2O3 incorporation, where the optimal composition is 0.1 wt% B2O3 incorporated LATP and the ionic conductivity reaches 8.8×10-5 S/cm, more than 3 times higher value than pristine LATP. More research could be followed for having higher ionic conductivity and density by optimizing the processing conditions. This facile approach for establishing higher ionic conductivity in LATP solid electrolytes could accelerate the commercialization of all-solid-state lithium batteries.

Microleakage of endodontically treated teeth restored with three different esthetic post and cores (심미적 포스트 코어의 종류에 따른 미세누출에 관한 연구)

  • Park, Ji-Geun;Park, Ji-Man;Park, Eun-Jin
    • The Journal of Korean Academy of Prosthodontics
    • /
    • v.47 no.1
    • /
    • pp.53-60
    • /
    • 2009
  • Statement of problem: At present, as the esthetic demands are on the increase, there are many ongoing studies for tooth-colored post and cores. Most of them are about fiber post and prefabricated zirconia post, but few about one-piece milled zirconia post and core using CAD/CAM (computer-aided design/computer-aided manufacturing) technique. Purpose: The objective of this study was to compare microleakage of endodontically treated teeth restored with three different tooth-colored post and cores. Material and methods: Extracted 27 human maxillary incisors were cut at the cementoenamel junction, and the teeth were endodontically treated. Teeth were divided into 3 groups (n=9); restored with fiber post and resin core, prefabricated zirconia post and heat-pressed ceramic core, and CAD/CAM milled zirconia post and core. After the preparation of post space, each post was cemented with dual-polymerized resin cement (Variolink II). Teeth were thermocycled for 1000 cycles between 555C and dyed in 2% methylene blue at 37C for 24 hours. Teeth were sectioned (bucco-lingual), kept the record of microleakage and then image-analyzed using a microscope and computer program. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (α=0.05). Results: All groups showed microleakage and there were no significant differences among the groups (P>.05). Prefabricated zirconia post and heat-pressed ceramic core showed more leakage in dye penetration at the post-tooth margin, but there was little microleakage at the end of the post. Fiber post and resin core group and CAD/CAM milled zirconia post and core group indicated similar microleakage score in each stage. Conclusion: Prefabricated zirconia post and heat-pressed ceramic core group demonstrated better resistance to leakage, and fiber post and resin core group and CAD/CAM milled zirconia post and core group showed the similar patterns. The ANOVA test didn't indicate significant differences in microleakage among test groups. (P>.05)