• Title/Summary/Keyword: Sintered Powder

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Relationship between Hardness and Relative Ddensity in Sintered Metal Powder Compacts (금속분발소결체의 경도와 상대밀도 관계)

  • 박종진
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.168-174
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    • 1998
  • In the present study, a method for measuring the relative density by the hardness measurement was proposed for sintered metal powder compacts. It is based on the indentation force equation, by which the relative density is related with the hardness, that was obtained by the finite element analysis of rigid-ball indentation on sintered metal powder compacts. For verifying the method, it was applied to prediction of density distributions in sintered and sintered-and-forged Fe-0.5%C-2%Cu powder compacts.

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Thermoelectric Properties of PbTe Sintered Body Fabricated by Mechanical Alloying Process (기계적합금화 공정에 의해 제조된 PbTe 소결체의 열전특성)

  • 이길근;정해용;이병우
    • Journal of Powder Materials
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    • v.8 no.2
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    • pp.110-116
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    • 2001
  • Abstract To investigate the effect of mechanical alloying process to thermoelectric properties of PbTe sintered body, Pb-Te mixed powder with Pb : Te : 1 : 1 composition was mechanically alloyed using tumbler-ball mill. Thermoelectric properties of the sintered body were evaluated by measuring of the Seebeck coefficient and specific electric resistivity from the room temperature to 50$0^{\circ}C$. Sintered body of only mechanically alloyed PbTe powder showed p-type behavior at the room temperature, and occurred type transition from p-type to n-type at about 30$0^{\circ}C$. PbTe sintered body which was fabricated using heat treated powder in $H_2$ atmosphere after mechanical alloying showed stable n-type behavior under 50$0^{\circ}C$. N-type PbTe sintered body fabricated by mechanical alloying process had 4 times higher power factor than that fabricated by the melt-crushing process. Application of a mechanical alloying process to fabricate of n-type PbTe thermoelectric material seemed to be useful to increase the power factor of PbTe sintered body.

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The Application of P/M Advanced Techniques to Sintered Gears

  • Chongxi, Bao;Zhouqiang, Shen;Zhengping, Shu
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.987-988
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    • 2006
  • The processes of P/M affect the properties of sintered gears. The different techniques of P/M lead to the different properties of sintered gears. This paper summarizes new progress in powder metallurgy for sintered gears. These progresses include warm compaction, high velocity compaction, sinter hardening, high temperature sintering, infiltration, CNC powder press and surface densification etc.

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Microstructures and Heat-treatment of Sintered Steels Using Iron Powder Coated with 0.45% Phosphorus (0.45%인(P)이 피복된 철분말 소결강의 조직 및 열처리)

  • 정재우
    • Journal of Powder Materials
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    • v.1 no.1
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    • pp.27-34
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    • 1994
  • Commercial pure iron powder and iron powder of coated 0.45% phosphorus were mixed with graphite powder in dry mixer to control carbon content from 0 wt% to 0.8 wt%. Mixed powder was pressed in the mould under the pressure of 510 MPa. Compacts were sintered at 118$0^{\circ}C$ for 40 min. in cracked ammonia gaseous atmosphere. Some of these sintered specimens were quenched in oil, and tempered in Ar gas. All of these specimens were investigated for microstructure, density and hardness in relation to coated phosphorus and carbon content. The results obtained were as follows: (1) The microstructure of the sintered speciments revealed that the amount of pearlite was increased with increasing C content but decreased by P-addition. (2) The P-addition affected the microstructure of pores in which the pore shape became round and its mean size was decreased by P-addition. (3) After tempering of sintered specimens the structure of pearlite was changed from fine structure to coarse one in P added specimen. (4) Hardness was higher in P added specimens.

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Development of Granulated Powders by SUS316L Ultra Fine Powder

  • Kadomura, Takeshi;Maeta, Yu;Otuka, Isamu
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.733-734
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    • 2006
  • Granulated powders, prepared from PF-5F($D_{50}=4(\mu}m$), PF-10F($D_{50}=6{\mu}m$) and PF-20F($D_{50}=10{\mu}m$) water atomized powder, were compacted, debound and sintered to evaluate the properties of sintered parts. As a result, the relative sintered density of about 97% at sintering temperature of 1423K was obtained. It can be considered that by using granulated finer particle size powder, mechanical properties of sintered parts were also improved.

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Spark-Plasma Sintering of Mechanically-alloyed NiAl Powder and Ball-milled (Ni+Al) Powder Mixture (기계적합금화 NiAl 분말과 볼밀혼합된 (Ni+Al) 분말의 방전플라즈마소결)

  • 장영일;김지순;안인섭;김영도;권영순
    • Journal of Powder Materials
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    • v.7 no.3
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    • pp.161-167
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    • 2000
  • Mechanically-alloyed NiAl powder and ball-milled (Ni+Al) powder mixture were sintered by spark-plasma sintering(SPS) process. Mechanical alloying was performed in a horizontal attritor for 20 h with rotation speed of 600 rpm. (Ni+Al) powder mixtures were prepared by ball milling for 1 and 10 h with 120 rpm. Both powders were sintered at $1150^{\circ}C$ for 5 min under $10^{-3}$ torr vacuum with 50 MPa die pressure in a SPS facility. Sintered densities of 97% and 99% were obtained from mechanically-alloyed NiAl powder and (Ni+Al) powder mixture, respectively. The sintered compact of (Ni+Al) powder mixture showed large grain size by a very rapid grain growth, while the grain size of mechanically-alloyed NiAl powder compact after sintering was extremely fine(80 nm). The difference in densification behavior of both powders were discussed.

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Comparative Study on the Quality of Sintered Zirconia Block Fabricated by Using Domestic Powder and Global-Brand Powder (국산 지르코니아 분말 소결체 품질의 글로벌 제품과의 비교 연구)

  • Kim, Yong-In;Lee, Seung-Mi;Byeon, Jai-Won
    • Journal of Applied Reliability
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    • v.15 no.3
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    • pp.216-221
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    • 2015
  • Sintering behavior of 3%yttria-stabilized zirconia was comparatively studied using a spray-dried powder produced by a domestic and global company. Quality of the sintered block was analysed in terms of relative density, shrinkage rate, grain growth, hardness, and fracture toughness. Relative density, shrinkage rate, and hardness value of the finally sintered block was similar between domestic and global zirconia powder, respectively. But, flexural strength of the domestic powder specimen was about 70% of the sintered block produced by using a global powder. The poor sintering quality of the domestic powder was discussed in relation with compressibility of the spray-dried granule-type powder and the amount of monoclinic phase in the as-received powder.

The factors of dimensional change of Fe-Cu-C sintered objects

  • Fujinaga, Masashi;Suzuki, Yoshitomo
    • Journal of Powder Materials
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    • v.5 no.4
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    • pp.299-302
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    • 1998
  • Dimensional accuracy is one of the most important issues in the production of sintered parts. The iron-copper-carbon system is commonly used alloys in sintered structural parts production. The dimensional control of these alloys, however, is not easy because of their complex sintering behavior. This study is an effort to clarify the influence of common factors on dimensional change of Fe-Cu-C sintered structural parts. We determined the effect of such various parameters as chemical composition, particle diameter, compact density, sintering temperature and sintering time on dimensional changes. Consequently, we obtained a useful formula to predict the final dimension in function of these parameters. The effect of typical impurities in copper powder on the dimensional change of sintered parts has also been described.

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Prediction of Relative Density by Hardness in Compressed Sintered-Metal Powder (경도를 이용한 소결압축금속분말의 상대밀도 예측)

  • 김진영;박종진
    • Transactions of Materials Processing
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    • v.6 no.6
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    • pp.508-516
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    • 1997
  • Forging process on sintered powder metals has been applied to produce automotive parts which require a high level of strength. In those parts, the measurement of relative density is very important because a low relative density density causes deterioration of strength. In the present study, an indentation force equation was proposed by which the result obtained from the hardness measurement is used to evaluate the relative density. This equation was applied to the prediction of the relative density in cylindrical specimens which were first sintered and then forged at the room temperature and at an elevated temperature. The experimental results were compared with predictions with and without consideration of the workhardening effect on the powder.

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Prediction of Density Distribution in Sintered Metal Powder Compacts by Indentation Force Equation (압흔하중식에 의한 금속소결분말체내에서의 밀도분포 예측)

  • 박종진
    • Journal of Powder Materials
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    • v.4 no.3
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    • pp.188-195
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    • 1997
  • In most of sintered metal powder compacts, the sintered density distribution is controlled to be as high and uniform as possible to ensure the required mechanical properties. In general, the density distribution in the compacts is not uniform and not easy to measure. In the present study, a method for measuring the density distribution was developed, based on the indentation force equation by which the hardness and the relative density were related. The indentation force equation, expressed as a function of strength constant, workhardening coefficient and relative density, was obtained by finite element analysis of rigid-ball indentation on sintered powder metal compacts. The present method was verified by comparing the predicted density distribution in the sintered Fe-0.5%C-2%Cu compacts with that obtained by experiments, in which the density distribution was directly measured by machining the compacts from the outer surface progressively.

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