• 제목/요약/키워드: properties of the powder

검색결과 5,408건 처리시간 0.03초

Effects of Hydrogen Reduction in Microstructure, Mechanical and Thermoelectric Properties of Gas Atomized n-type Bi2Te2.7 Se0.3 Material

  • Rimal, Pradip;Yoon, Sang-Min;Kim, Eun-Bin;Lee, Chul-Hee;Hong, Soon-Jik
    • 한국분말재료학회지
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    • 제23권2호
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    • pp.126-131
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    • 2016
  • The recent rise in applications of thermoelectric materials has attracted interest in studies toward the fabrication of thermoelectric materials using mass production techniques. In this study, we successfully fabricate n-type $Bi_2Te_{2.7}Se_{0.3}$ material by a combination of mass production powder metallurgy techniques, gas atomization, and spark plasma sintering. In addition, to examine the effects of hydrogen reduction in the microstructure, the thermoelectric and mechanical properties are measured and analyzed. Here, almost 60% of the oxygen content of the powder are eliminated after hydrogen reduction for 4 h at $360^{\circ}C$. Micrographs of the powder show that the reduced powder had a comparatively clean surface and larger grain sizes than unreduced powder. The density of the consolidated bulk using as-atomized powder and reduced atomized powder exceeds 99%. The thermoelectric power factor of the sample prepared by reduction of powder is 20% better than that of the sample prepared using unreduced powder.

울금가루 첨가에 따른 양갱의 이화학적 및 관능적 특성 (Physicochemical and Sensory Characteristics of Yanggaeng added with Turmeric Powder)

  • 이선희
    • 한국식품영양학회지
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    • 제26권3호
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    • pp.447-452
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    • 2013
  • This study investigated the quality characteristics of Yanggaeng with different amounts (in ratios of 0, 1, 2, 4% to the total materials) of tumeric powders. The proximate composition and total polyphenol content, antioxidant activities, Hunter's color values, pH, Brix and sensory properties of tumeric hanging were examined. Results of analysis of the proximate composition analysis showed that ash content was increased significantly by adding turmeric powder and the more content of turmeric powder. The higher content of tumeric powder, the higher total polyphenol and total flavonoids contents. Brix and brightness were lowered and yellowness was increased. The sensory properties were highly rated for the control without turmeric powder in four organoleptic (sensory) properties (taste, texture, odor, acceptance) except color. The group with-1% addition of turmeric powder was highly rated in the second place.

Microstructure and Properties of High Nitrogen Sintered Stainless Steel

  • Pieczonka, Tadeusz;Stoytchev, Marin
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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    • pp.568-569
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    • 2006
  • The use of the nickel free, high nitrogen stainless steel powder and nitriding during sintering of iron based materials have been shown as an alternative way to the conventional PM stainless steels containing nickel. Nitrogen as an alloying element for iron improves in an effective way the properties of sintered alloyed steels. The powder metallurgy route is a suitable way to introduce nitrogen into these alloys and, in particular, to produce high nitrogen (close to the solubility limit) stainless steels. The paper presents and discusses the nitriding behavior of nickel-free stainless steels produced by powder metallurgy method. Alloyed melt was atomized by nitrogen and in this way nitrogen was introduced into the powder. Further nitriding occurred during sintering in a nitrogen atmosphere. For comparison, compacts having the same composition as an alloyed powder were produced from elemental powders mixture. Sintering-nitriding behaviour of investigated materials has been controlled by dilatometry, chemical and X-Ray phase analysis and metallography. Mechanical properties of sintered compacts were also measured.

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용사피막의 마찰.마모 특성 평가에 관한 연구 (A Study on the Evaluation of the Friction and Wear Properties of the Sprayed Coating Layer)

  • 김영식;김윤해;김종호;최영국;강태영
    • Journal of Welding and Joining
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    • 제14권3호
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    • pp.66-74
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    • 1996
  • In this study, friction and wear properties of flame sprayed specimens and hard Cr plating specimens were tested, and their properties were compared each other in dry and lubrication condition. Ni-Cr powder and steel powder were used as the spray powder and sprayed on the steel(S45C) substrate by flame sprayed method. Each wear surface was observed with SEM after friction and wear test. The friction coefficient of the as-forged steel specimens was the highest among surface treatment specimens, and the other specimens appeared in order as follows ; hard Cr-plating specimens, Ni-Cr powder sprayed specimens, steel powder sprayed specimens. Comparing the wear volumes in dry condition, as forged steel specimens appeared the greatest wear volume, and the other specimens appeared wear volume in order as follows ; Ni-Cr powder sprayed specimens, steel powder sprayed specimens, hard Cr plating specimens. In friction and wear test, the hard Cr plating specimens were worn by the abrasive phenomenon, involving the cracks. The wear volume of steel powder sprayed specimens was lower than that of Ni-Cr powder sprayed specimens. Comparing the tensile strength of both sprayed coating layers, the steel powder sprayed coating layer was better than Ni-Cr powder sprayed coating layer.

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자동차용 피스톤의 성형기술과 기계적 성질의 개선에 관한 연구 (A Study on the Forming Technologies for a Motor Piston and Improvement of Mechanical Properties)

  • 김길준;박종옥;김영호
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2000년도 추계학술대회 논문집
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    • pp.842-845
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    • 2000
  • The purpose of this paper is to investigate the influences on mechanical properties of motor pistons manufactured by casting, conventional forging and powder forging, using the comparison of characteristics like microstructure, hardness, tensile strength, and elongation. To form conventional forging piston, the experiment of visioplasticity was performed. As the model material, plasticine was used. To form powder forging piston, the shape of piston was simplified as simple cup shape. Material properties like workability, density variation before and after forging, and strain loci of material during forging were investigated. Powder forging and conventional forging technologies were effective to gain dense microstructure. In powder forging, distribution of such dense microstructuer was uniform. For hardness, pistons from powder forging and conventional forging technologies were much better than that from casting. For tensile strength and elongation, powder forging and conventional forging technologies were also advantageous.

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그래핀 산화물 분말 첨가에 의한 비스무스 텔루라이드 기지 복합재료의 열전에너지변환 특성 고찰 (Investigation on the Thermoelectric Properties of Bismuth Telluride Matrix Composites by Addition of Graphene Oxide Powders)

  • 김경태;민태식;김동원
    • 한국분말재료학회지
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    • 제23권4호
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    • pp.263-269
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    • 2016
  • Graphene oxide (GO) powder processed by Hummer's method is mixed with p-type $Bi_2Te_3$ based thermoelectric materials by a high-energy ball milling process. The synthesized GO-dispersed p-type $Bi_2Te_3$ composite powder has a composition of $Bi_{0.5}Sb_{1.5}Te_3$ (BSbT), and the powder is consolidated into composites with different contents of GO powder by using the spark plasma sintering (SPS) process. It is found that the addition of GO powder significantly decreases the thermal conductivity of the pure BSbT material through active phonon scattering at the newly formed interfaces. In addition, the electrical properties of the GO/BSbT composites are degraded by the addition of GO powder except in the case of the 0.1 wt% GO/BSbT composite. It is found that defects on the surface of GO powder hinder the electrical transport properties. As a result, the maximum thermoelectric performance (ZT value of 0.91) is achieved from the 0.1% GO/BSbT composite at 398 K. These results indicate that introducing GO powder into thermoelectric materials is a promising method to achieve enhanced thermoelectric performance due to the reduction in thermal conductivity.

재생미분말의 가열온도에 따른 기초물성 및 시멘트혼화재 적용성에 관한 연구 (A Study on the Fundamental Properties and Application as Cementious Admixture by Heating Temperature of Recycled Powder)

  • 장종호;김용로;최세진;최희용;김문한;김무한
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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    • pp.635-640
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    • 2001
  • Recently, it has been processed to study about recycled aggregate but a study about using of recycled powder is producted when manufacturing recycled aggregate has not been acted. So in this study on the fundamental properties and application as cementious admixture by heating temperature for mortar properties of recycled powder and sand is obtained like following results. It is judged that application of recycled powder of heat treatment on $600^{\circ}C$ and cement replacement ratio below 10% is available.

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가스분무 공정에 의한 고강도 과공정 Al-Si 합금 분말의 제조 및 특성 연구 I. 분말 제조 및 성형성 (Fabrication and Properties of High Strength Hypereutectic Al-Si Powder by Gas Atomization Process I. Powder Production and Compressibility)

  • 김용진;김진천
    • 한국분말재료학회지
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    • 제12권4호
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    • pp.296-302
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    • 2005
  • In order to improve mechanical properties, the hypereutectic Al-20 wt%Si based prealloy powder was prepared by gas atomization process. Microstructure and compressibility of the atomized Al-Si powder were investigated. The average powder size was decreased with increasing the atomization gas pressure. Size of primary Si particles of the as-atomized powder was about $5-8\;\mu{m}$. The as-atomized Al-Si powder such as AMB 2712 and AMB 7775 to increase compressibility and sinterability. Relative density of the mixed powder samples sintered at $600^{\circ}C$ was reached about 96% of a theoretical density.

한지의 강도적 성질 개선을 위한 전분류 처리(제1보) - 전분류별 처리효과 - (Starch Treatment for the Improvement of Physical Properties of Hanji(I) - Effect of Starch Types -)

  • 백옥례;윤승락
    • 펄프종이기술
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    • 제35권3호
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    • pp.59-65
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    • 2003
  • This research was conducted to investigate the physical properties of Hanji made using maize, konyaku, and wheat powders at various concentrations. Regardless of the starch types, the most effective concentration to increase the physical properties of Hanji was 2 percent. They were significantly improved even at the treatment conditions of 0.1 percent. All the Hanji treated showed the increase of the breaking length, bust index, and tear index and the decrease of the folding number. The strength properties of the Hanji treated were markedly improved at 8 to 10 percent weight increase. The highest mechanical properties were found in the Hanji treated with konyaku powder.

난연성을 갖는 폴리프로필렌 분말도료의 화재안전성 연구 (A Study on the Fire Safety of Polypropylene Powder Coatings with Flame Retardant)

  • 이순홍
    • 한국안전학회지
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    • 제28권6호
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    • pp.17-22
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    • 2013
  • The production of flame-retardant polypropylene powder coating with the addition of flame retardant (PP) controlled rheology (CR) and polypropylene, were discussed comparing the mechanical properties, such as safety and topical coating properties. Mechanical properties measurements showed almost the same as AA-1 where the flame retardant is not added. These results appear to, and because it is excellent in compatibility with polypropylene and flame retardant. Physical properties of the coating film, a test piece flame retardant organic is added, although it shows the physical properties of the coating film was stable, did not show the physical properties satisfactory is the test piece flame retardant of weapons has been added. In the safety of the topic, AA-4, AA-5 the results of thermal analysis but it is excellent, the LOI is excellent in 27.8 vol% 27.0 vol% in AA-4 and AA-2, AA-3, and 27.4 vol%, did not show many obstacles flame AA-5 result UL94.