• Title/Summary/Keyword: Spark Plasma Sintering(SPS)

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방전플라즈마 소결법으로 제조한 Mo-Cu 합금 소결체의 물성 및 전기적 특성에 관한 연구

  • Lee, Han-Chan;Mun, Gyeong-Il;Lee, Bung-Ju;Sin, Baek-Gyun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.277-277
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    • 2011
  • Mo-Cu 합금은 고강도이고 우수한 열전도성 및 전기전도성를 가지는 특성이 있어 현재 방열소재, 반도체 부품, 자동차 부품 등 여러 응용분야에서 연구가 활발히 진행되고 있다. 본 연구에서는 서로 고용성이 없는 Mo-Cu 합금을 제조하기 위해서 Mo, Cu 분말을 PBM (Planetary Ball Milling) 방법을 이용하여 제조 하였으며, 제조된 분말은 SPS (Spark Plasma Sintering) 공정을 이용하여 소결체를 제조하였다. Mo-Cu의 조성 변화는 Cu의 함유량을 각각 5at%Cu, 10at%Cu, 20at%Cu로 조절하여 수행하였으며, PBM 의 공정 변수로 회전수(RPM), 볼과 분말의 비율, 분산제의 양, 볼밀 시간, 분위기 변화를 주어 최적조건을 얻기 위한 실험을 진행하였다. PBM 방법을 이용하여 제조한 분말은 PSA (Particle Size Analysis)에 의해 분말의 크기를 측정하고 EDS(Energy Disperse X-ray Spectrometer) 분석에 의해 조성을 확인하였으며, XRD (X-Ray Diffraction) 분석에 의해 Cu peak이 사라지는 조건을 PBM의 최적조건으로 잡고 실험을 진행하였다. 소결체를 고밀도화하기 위해 소결공정을 SPS 방식으로 하였으며 소결체의 경도, 내마모성, 마찰계수 일함수 등을 분석하기 위해 소결체의 크기를 직경 30 mm 및 두께 5 mm로 설계하였고, 소결 공정 변수로 소결온도를 각각 $900^{\circ}C$, $1000^{\circ}C$, $1100^{\circ}C$, 소결압력을 50MPa, 60MPa, 70MPa, 유지시간을 0분, 10분, 20분으로 차이를 주어, 소결체의 밀도차이와 물성차이를 분석하였다. 그 결과 PBM의 최적조건으로는 5at%Cu 에서는 10h, 10at%Cu, 20at%Cu 에서는 20h의 최적의 밀링 시간을 확인하였고, 다른 공정 변수의 최적조건으로는 회전수 300RPM, 10:1의 볼과 분말 비, 분산제 4wt%, Ar 분위기라는 조건을 얻을 수 있었다. 각각의 공정변수 변화에 따른 소결체 최적밀도 달성조건, 소결체 물성 및 전기적 특성 등의 상관관계에 관하여 보고한다.

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Effect of Space Holder Content on Pore Size and Distribution in HA/β-TCP Composites Consolidated by SPS (SPS로 제조된 HA/β-TCP 복합재의 기공의 크기와 분포에 미치는 지지체 량의 영향)

  • Lee, Tack;Woo, Kee-Do;Kang, Dong-Soo;Lee, Hae-Cheol;Jang, Jun-Ho
    • Korean Journal of Materials Research
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    • v.25 no.4
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    • pp.165-170
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    • 2015
  • Ceramics biomaterials are useful as implant materials in orthopedic surgery. In this study, porous HA(hydroxyapatite)/${\beta}$-TCP(tricalcium phosphate) composite biomaterials were successfully fabricated using HA/${\beta}$-TCP powders with 10-30 wt% $NH_4HCO_3$ as a space holder(SH) and $TiH_2$ as a foaming agent, and MgO powder as a binder. The HA/${\beta}$-TCP powders were consolidated by spark plasma sintering(SPS) process at $1000^{\circ}C$ under 20 MPa conditions. The effect of SH content on the pore size and distribution of the HA/${\beta}$-TCP composite was observed by scanning electron microscopy(SEM) and a microfocus X-ray computer tomography system(SMX-225CT). These microstructure observations revealed that the volume fraction of the pores increased with increasing SH content. The pore size of the HA/${\beta}$-TCP composites is about $400-500{\mu}m$. The relative density of the porous HA/${\beta}$-TCP composite increased with decreasing SH content. The porous HA/${\beta}$-TCP composite fabricated with 30%SH exhibited an elastic modulus similar to that of cortical bone; however, the compression strength of this composite is higher than that of cortical bone.

Microstructure and Electric Contact Properties of Spark Plasma Sintered Ta-Cu Composite (방전플라즈마 소결법으로 제조된 Ta-Cu의 미세조직 및 전기접점 특성)

  • Ju, Won;Kim, Young Do;Sim, Jae Jin;Choi, Sang-Hoon;Hyun, Soong Keun;Lim, Kyoung Mook;Park, Kyoung-Tae
    • Journal of Powder Materials
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    • v.24 no.5
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    • pp.377-383
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    • 2017
  • Microstructure, electric, and thermal properties of the Ta-Cu composite is evaluated for the application in electric contact materials. This material has the potential to be used in a medium for a high current range of current conditions, replacing Ag-MO, W, and WC containing materials. The optimized SPS process conditions are a temperature of $900^{\circ}C$ for a 5 min holding time under a 30 MPa mechanical pressure. Comparative research is carried out for the calculated and actual values of the thermal and electric properties. The range of actual thermal and electric properties of the Ta-Cu composite are 50~300 W/mk and 10~90 %IACS, respectively, according to the compositional change of the 90 to 10 wt% Ta-Cu system. The results related to the electric contact properties, suggest that less than 50 wt% of Ta compositions are possible in applications of electric contact materials.

Mechanical Properties and Bio-Compatibility of Ti-Nb-Zr-HA Biomaterial Fabricated by Rapid Sintering Using HEMM Powders (고에너지 밀링분말과 급속소결을 이용한 Ti-Nb-Zr-HA 생체복합재의 기계적 성질 및 생체적합성)

  • Park, Sang-Hoon;Woo, Kee-Do;Kim, Sang-Hyuk;Lee, Seung-Min;Kim, Ji-Young;Ko, Hye-Rim;Kim, Sang-Mi
    • Korean Journal of Materials Research
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    • v.21 no.7
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    • pp.384-390
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    • 2011
  • Ti-6Al-4V ELI (Extra Low Interstitial) alloy has been widely used as an alternative to bone due to its excellent biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity. Therefore, nontoxic biomaterials with a low elastic modulus should be developed. However, the fabrication of a uniform coating is challenging. Moreover, the coating layer on Ti and Ti alloy substrates can be peeled off after implantation. To overcome these problems, it is necessary to produce bulk Ti and Ti alloy with hydroxyapatite (HA) composites. In this study, Ti, Nb, and Zr powders, which are biocompatible elements, were milled in a mixing machine (24h) and by planetary mechanical ball milling (1h, 4h, and 6h), respectively. Ti-35%Nb-7%Zr and Ti-35%Nb-7%Zr-10%HA composites were fabricated by spark plasma sintering (SPS) at $1000^{\circ}C$ under 70MPa using mixed and milled powders. The effects of HA addition and milling time on the biocompatibility and physical and mechanical properties of the Ti-35%Nb-7%Zr-(10%HA) alloys have been investigated. $Ti_2O$, CaO, $CaTiO_3$, and $Ti_xP_y$ phases were formed by chemical reaction during sintering. Vickers hardness of the sintered composites increases with increased milling time and by the addition of HA. The biocompatibilty of the HA added Ti-Nb-Zr alloys was improved, but the sintering ability was decreased.

Enhanced Thermoelectric Properties in n-Type Bi2Te3 using Control of Grain Size (Grain 크기 조절을 통한 n-Type Bi2Te3 열전 소재 특성 향상)

  • Lee, Nayoung;Ye, Sungwook;Jamil Ur, Rahman;Tak, Jang-Yeul;Cho, Jung Young;Seo, Won Seon;Shin, Weon Ho;Nam, Woo Hyun;Roh, Jong Wook
    • Journal of the Microelectronics and Packaging Society
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    • v.28 no.4
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    • pp.91-96
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    • 2021
  • The enhancement of thermoelectric figure of merit was achieved by the simple processes of sieving and high energy ball milling, respectively, which are enable to reduce the grain size of n-type Bi2Te3 thermoelectric materials. By optimizing the grain size, the electrical conductivities and thermal conductivities were controlled. In this study, spark plasma sintering was employed for hindering the grain growth during the sintering process. The thermoelectric figure of merit was measured to be 0.78 in the samples with 30 min high energy ball milling process. Notably, this value was 40 % higher than that of pristine Bi2Te3 sample. This result shows the properties of thermoelectric materials can be readily controlled by optimization of grain size via simple ball milling process.

Piezoelectric and Dielectric Characteristics of (Na,K)$NbO_3$ Ceramics System According to Variations of Sintering Time (소결시간변화에 따른 (Na,K)$NbO_3$계 세라믹스의 유전 및 압전특성)

  • Kim, Do-Hyung;Yoo, Ju-Hyun;Jeong, Young-Ho;Hong, Jae-Il
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.48-48
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    • 2008
  • 현재 압전재료로써 사용되고 있는 PZT계 세라믹스는 우수한 압전 및 유전특성으로 초음파 센서, 압전변압기, 액츄에이터, 필터, 레조네이터와 같은 여러 응용분야에 널리 사용되어지고 있다. 그러나 납을 60%이상 포함하므로 환경오염에 의하여 그 사용에 대한 규제가 강화되고 있어 최근에는 납을 함유하지 않은 무연 환경친화형 압전세라믹스가 주목받고 있다. 현재 무연 조성 세라믹스에는 텅스텐-브론즈 형, 비스머스 레이어형, 페로브스카이트 형 등이 이으며, 그 중 페로보스카이트 혈을 제외하고는 보통 소성법 조제시 낮은 압전특성을 갖는다. 그러므로 압전특성을 증가시키기 위하여 Hot pressing, Hot forging, RTGG(Reactive Template Grain Growth), SPS(Spark Plasma Sintering), 그러나 이는 무연 세라믹스의 대량생산 과정에서 어려운 문제를 가지고 있고, 저가격 관점에서 볼 때 보통소성법이 보다 바람직하다. 그래서 보통소성법으로 NKN세라믹스의 소결성을 향상 시키고 비교적 높은 압전특성을 얻기 위해서 $LiSbO_3$, $LiNbO_3$, $LiTaO_3$, alkaline-earth(Mg, Ca, Sr, Ba) 등을 첨가한 논문들이 보고되고 있으며, 이러한 재료들의 kp는 대략 0.3-0.4를 나타내고 있다. 따라서, 본 연구에서는 소결온도를 낮추고자 $Ag_2O$를 소결조제로 사용하였고 유전 및 압전특성을 높이고자 소결시간 변화시켜 시편을 제작하여 NKN 세라믹스의 유전 및 압전특성을 조사하였다.

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Development of High-strength, High-temperature Nb-Si-Ti Alloys through Mechanical Alloying (기계적 합금화를 통한 고강도-고내열 Nb-Si-Ti계 합금 개발에 관한 연구)

  • Jung-Joon Kim;Sang-Min Yoon;Deok-Hyun Han;Jongmin Byun;Young-Kyun Kim
    • Journal of Powder Materials
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    • v.31 no.1
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    • pp.30-36
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    • 2024
  • The aerospace and power generation industries have an increasing demand for high-temperature, high-strength materials. However, conventional materials typically lack sufficient fracture toughness and oxidation resistance at high temperatures. This study aims to enhance the high-temperature properties of Nb-Si-Ti alloys through ball milling. To analyze the effects of milling time, the progression of alloying is evaluated on the basis of XRD patterns and the microstructure of alloy powders. Spark plasma sintering (SPS) is employed to produce compacts, with thermodynamic modeling assisting in predicting phase fractions and sintering temperature ranges. The changes in the microstructure and variation in the mechanical properties due to the adjustment of the sintering temperature provide insights into the influence of Nb solid solution, Nb5Si3, and crystallite size within the compacts. By investigating the changes in the mechanical properties through strengthening mechanisms, such as precipitation strengthening, solid solution strengthening, and crystallite refinement, this study aims to verify the applicability of Nb-Si-Ti alloys in advanced material systems.

The Effects of Al-substitution on Thermoelectric and Charge Transport Properties of BiCuOSe Compounds (Al 치환이 BiCuOSe의 열전 특성에 미치는 영향)

  • An, Tae-Ho;Lim, Young Soo;Seo, Won-Seon;Park, Cheol-Hee;Park, Chan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.12
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    • pp.847-851
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    • 2015
  • The effects of Al-substitution on thermoelectric and charge transport properties of BiCuOSe compounds were investigated. The compounds were prepared by a solid-state reaction and consolidated by SPS (spark plasma sintering). In spite of the increase in the hole concentration with increasing Al amounts in BiCuOSe compound, the electrical conductivity at room temperature was kept constant due to the reduction of mobility. However, electrical conductivities of Al-substituted BiCuOSe compounds at elevated temperature (> 600 K) were higher than those of BiCuOSe, and this result was discussed in terms of it's the band gap energy. The Seebeck coefficient was drastically reduced when Al was substituted in Bi site, which indicated that the electronic structure was influenced by the Al-substitution into Bi-site.

Comparison of Ablation Characteristics of Carbon Nanotube reinforced Hybrid Al2O3 by using Ultrashort Pulse Laser (순수 알루미나와 탄소나노튜브 강화 알루미나 복합체의 극초단 펄스레이저 가공특성 비교)

  • Lee, Jun-Young;Yoon, Ji-Wook;Kang, Myung-Chang;Cho, Sung-Hak
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.12 no.6
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    • pp.23-29
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    • 2013
  • In this paper, pure $I_{ph}$ and hybrid carbon nanotube reinforced $I_{ph}$ were sintered using the SPS(spark plasma sintering) method for high densification. A nanosecond laser (${\lambda}=1063nm$, ${\tau}P=10ns$) and a femtosecond laser (${\lambda}=1027nm$, ${\tau}P=380fs$) were installed on an optical system for the micromachining test. The ablation characteristics of the pure $I_{ph}$ and CNT/$I_{ph}$ composites, such as thermal effect and ablation depth, were investigated using FE-SEM and a confocal microscope device. Laser machining results for the two mating materials showed improved performances: CNT/$I_{ph}$ composites showed good surface morphology of hole drilling without a melting zone due to the composites' high thermal properties; also, the ablated depth of CNT/$I_{ph}$ was higher than that of pure $I_{ph}$.

Deformation behavior of Copper Amorphous Composites in Super Cooled Liquid Region (과냉각 구간에서 Cu-계 아몰퍼스 복합재의 변형거동)

  • Park E. S.;Kim J. S.;Kim H. J.;Bae J. C.;Huh M. Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.279-282
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    • 2005
  • Composites comprising various volume fractions of crystalline nickel and bulk amorphous (BA) were produced by means of electroless coating of nickel on BA powder of $Cu_{54}Ni_6Zr_{22}Ti_{18}$ and subsequent spark plasma sintering (SPS) of coated BA powder. The flow curves of composites at various temperatures in the supercooled liquid region were determined by the uniaxial compression test with various strain rates. During compression at $450^{\circ}C$ with $\dot{\varepsilon}=2\times10^{-3}$, the monolithic BA sample and crystalline-BA composites displayed the superplastic deformation with $\varepsilon>1.4$. At temperatures above $460^{\circ}C$, the stress-strain curve of the monolithic BA sample depicted a sharp peak stress and a fellowing stress drop due to cracking, while those of the crystalline-BA composites displayed work-hardening up to the imposed strain. FEM analysis indicated that a fairly homogeneous strain state prevailed throughout the composite, while a higher level of stress was obtained in a harder BA.

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