• Title/Summary/Keyword: Shell powder

Search Result 311, Processing Time 0.024 seconds

Thickness Control of Core Shell type Nano CoFe2O4@SiO2 Structure (두께 조절이 가능한 코어셸 형태의 SiO2 coated CoFe2O4 구조)

  • Yu, Ri;Kim, Yoo-Jin;Pee, Jae-Hwan;Kim, Kyung-Ja
    • Journal of Powder Materials
    • /
    • v.17 no.3
    • /
    • pp.230-234
    • /
    • 2010
  • Homogenous silica-coated $CoFe_2O_4$ samples with controlled silica thickness were synthesized by the reverse microemulsion method. First, 7 nm size cobalt ferrite nanoparticles were prepared by thermal decomposition methods. Hydrophobic cobalt ferrites were coated with controlled $SiO_2$ using polyoxyethylene(5)nonylphenylether (Igepal) as a surfactant, $NH_4OH$ and tetraethyl orthosilicate (TEOS). The well controlled thickness of the silica shell was found to depend on the reaction time and the amount of surfactant used during production. Thick shell was prepared by increasing reaction time and small amount of surfactant.

Development and Characterization of Oyster Shell Powder Filled Polypropylene Composite

  • Shah, Atta ur Rehman;Prabhakar, M.N.;Lee, Dong-Woo;Kim, Byung-Sun;Song, Jung Il
    • Composites Research
    • /
    • v.27 no.5
    • /
    • pp.201-206
    • /
    • 2014
  • Utilizing waste materials in making useful products is a globally increasing trend. This can reduce the cost and environmental issues. In this study, oyster shell powder (OSP) is reinforced as a filler in polypropylene (PP) matrix to make a new composite. The purpose is to improve fire retardant properties of PP as a result of OSP reinforcement. Mechanical, fire retardant and water absorption properties of the new composite have been studied in this research. Concentration of OSP reinforcement in PP has been varied by wt% and its effect on the above mentioned properties has been observed. SEM (scanning electron microscopy) images of tensile and bending fractured surfaces have been taken to observe the failure mechanism during mechanical tests. An increase in the fire retardancy has been observed as a result of the OSP reinforcement while tensile strength decreased. Stiffness also increased with the addition of OSP in PP.

Quality characteristics of dumpling shell with sea tangle powder (다시마 분말을 첨가한 만두피의 품질 특성)

  • Park, In-Duck
    • Food Science and Preservation
    • /
    • v.22 no.2
    • /
    • pp.190-196
    • /
    • 2015
  • This study investigated the effects of sea tangle powder (SP) on the physicochemical and sensory characteristics of dumpling shells. Various dumpling shell samples were prepared with wheat flour containing different amounts of SP. The characteristics of the dumpling shell samples were investigated based on their viscosity, cooking properties, color values, and texture properties. Their sensory characteristics were evaluated by using seven scores. According to the amylograph data, the composite SP-wheat flour samples showed an increased gelatinization temperature with an increasing SP content, whereas the initial viscosity at $95^{\circ}C$ was decreased after 15 minutes. The increase of SP amount decreased the values of L and b whereas the a value increased. With regard to the textural characteristics, the dumpling shells with an increased amount of SP showed increased hardness, cohesiveness, and adhesiveness, whereas the SP addition reduced the springiness of the dumpling shell. The dumpling shell with the addition of 3% SP showed the highest overall acceptability in the sensory evaluation.

Studies of Egg-Shell Calcium (II) -A Study on Absorption Rate of Egg-Shell Calcium in Rat- (난각칼슘에 관한 연구 (II) - 난각칼슘의 흡수율에 관한 연구 -)

  • 이숙경;김연태
    • Journal of Food Hygiene and Safety
    • /
    • v.18 no.2
    • /
    • pp.73-78
    • /
    • 2003
  • This study was to investigate interaction between ionization rate and absorption rate of calcium(Ca) in each feeding Ca sources in rats. The results were as follows. 1. The ionized Ca ions 134 into rats were absorbed in about two hours while Ca from other sources like powdered egg-shell Ca or precipitable Ca carbonate caused more than five hours to be absorbed. This means that the ionization of Ca is essential for the fast absorption in rat. 2. Absorption rate were increased in the rank order to brown rice vinegar-Ca acetate > brewed vinegar-Ca acetate > precipitated Ca carbonate > egg-shell Ca powder by feeding sources in rat and absorption rate of brown rice vinegar Ca was appeared 4 times highly than egg-shell Ca powder. 3. Absorption rate of brewed vinegar Ca acetate were appeared excellent, 1.4 times highly in case of the brewed vinegar at no ventilation condition than ventilation condition. 4. Ca concentration in blood serum was significantly enhanced the increased ionization rate of Ca in the above experiment rat models regardless of dietary Ca levels.

Preparation of FeAl nanopowders by Plasma Arc Discharge Process (플라즈마 아크방전(PAD)법으로 제조된 FeAl 나노분말 특성)

  • Park Woo-Young;Youn Cheol-Su;Yu Ji-Hun;Oh Young-Woo;Choi Chul-Jin
    • Journal of Powder Materials
    • /
    • v.11 no.6 s.47
    • /
    • pp.522-527
    • /
    • 2004
  • Nano sized FeAl intermetallic particles were successfully synthesized by plasma arc discharge pro-cess. The synthesized powders shouted core-shell structures with the particle size of 10-20 nm. The core was metallic FeAl and shell was composed of amorphous $AI_{2}O_{3}\;and\;a\;little\;amount\;of\;metallic\;Fe_{3}O_{4}.$ Because of the difference of Fe and Al vapor pressure during synthesis, the Al contents in the nanoparticles depended on the Al contents of master alloy.

Bandgap Tuning and Quenching Effects of In(Zn)P@ZnSe@ZnS Quantum Dots

  • Sang Yeon Lee;Su Hyun Park;Gyungsu Byun;Chang-Yeoul Kim
    • Journal of Powder Materials
    • /
    • v.31 no.3
    • /
    • pp.226-235
    • /
    • 2024
  • InP quantum dots (QDs) have attracted researchers' interest due to their applicability in quantum dot light-emitting displays (QLED) or biomarkers for detecting cancers or viruses. The surface or interface control of InP QD core/ shell has substantially increased quantum efficiency, with a quantum yield of 100% reached by introducing HF to inhibit oxide generation. In this study, we focused on the control of bandgap energy of quantum dots by changing the Zn/(In+Zn) ratio in the In(Zn)P core. Zinc incorporation can change the photoluminescent light colors of green, yellow, orange, and red. Diluting a solution of as-synthesized QDs by more than 100 times did not show any quenching effects by the Förster resonance energy transfer phenomenon between neighboring QDs.

Stretch-Flangeability of Harmonic Structure Material Manufactured by Powder Metallurgy Method (분말야금법으로 제조한 하모닉 구조재료의 신장플랜지 가공성)

  • Yoon, Jae Ik;Lee, Hak Hyeon;Park, Hyung Keun;Ameyama, Kei;Kim, Hyoung Seop
    • Journal of Powder Materials
    • /
    • v.24 no.2
    • /
    • pp.128-132
    • /
    • 2017
  • Harmonic structure materials are materials with a core-shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretch-flangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.

Synthesis of Au@TiO2 Core-shell Nanoparticle-decorated rGO Nanocomposite and its NO2 Sensing Properties

  • Kumar Naik, Gautam;Yu, Yeon Tae
    • Journal of Sensor Science and Technology
    • /
    • v.28 no.4
    • /
    • pp.225-230
    • /
    • 2019
  • $Au@TiO_2$ core-shell decorated rGO nanocomposite (NC) was prepared using a simple solvothermal method followed by heat treatment for gas sensor application. The crystal structure and morphology of the composites were characterized by X-ray powder diffraction and transmission electron microscopy, respectively. The $NO_2$ sensing response of the $Au@TiO_2/rGO$ NC was tested at operating temperatures from $250^{\circ}C$ to $500^{\circ}C$, and was compared with those of the bare rGO and $Au@TiO_2$ core-shell NPs. The $Au@TiO_2/rGO$ NC-based sensor showed a far higher response than the rGO or $Au@TiO_2$ core-shell based sensors, with the maximum response detected when the operating temperature was $400^{\circ}C$. This improved response was due to the high rGO gas absorption capability for $NO_2$ gas and the catalytic effect of $Au@TiO_2$ core-shell NPs in oxidizing $NO_2$ to $NO_3$.

Recent progress on Performance Improvements of Thermoelectric Materials using Atomic Layer Deposition (원자층 증착법을 이용한 열전 소재 연구 동향)

  • Lee, Seunghyeok;Park, Tae Joo;Kim, Seong Keun
    • Journal of Powder Materials
    • /
    • v.29 no.1
    • /
    • pp.56-62
    • /
    • 2022
  • Atomic layer deposition (ALD) is a promising technology for the uniform deposition of thin films. ALD is based on a self-limiting mechanism, which can effectively deposit thin films on the surfaces of powders of various sizes. Numerous studies are underway to improve the performance of thermoelectric materials by forming core-shell structures in which various materials are deposited on the powder surface using ALD. Thermoelectric materials are especially relevant as clean energy storage materials due to their ability to interconvert between thermal and electrical energy by the Seebeck and Peltier effects. Herein, we introduce a surface and interface modification strategy based on ALD to control the performance of thermoelectric materials. We also discuss the properties of the interface between various deposition materials and thermoelectric materials.

Study on Physical Properties of Mortar Using Eggshell Powder for Filler (계란 껍데기 분말을 채움재로 활용한 모르타르의 물리적 특성에 관한 연구)

  • Seo, Eun-Seok;Kim, Bong-Joo;Hong, Sang-Hun;Kim, Han-Nah;Jung, Ui-In
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2020.06a
    • /
    • pp.75-76
    • /
    • 2020
  • Use fire resistant construction methods, of which fire resistant boards are used to protect buildings and structures from fire. However, in the case of fire resistant boards, the unit price of the main raw material is high and the cost efficiency is low. There have been studies to apply oyster shells to fire resistant boards to solve these problems. On the other hand, egg shells are also considered to be applicable to fire-resistant boards with components like oyster shells, but there is no case of using egg shells as building materials. Therefore, in this study, we confirmed the physical properties of egg shell powers used as mortar filler and compared them with the fire resistant board flexural strength standard. As a result, it was judged that the powder of egg shells could be used as a building material, because the standards for the flexural strength of fire resistant boards were satisfied except for a part.

  • PDF