• 한국분말재료학회지
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• 제1권2호
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• pp.181-189
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• 1994

The compacts of pure and phosphorus-coated iron powder with 0~0.8%C were sintered at $1100^{\circ}C$ for 40 min. in cracked ammonia gas atmosphere. The tensile and impact strengths were measured and the relationship of the results with carbon content, phosphorus, quenching and tempering was investigated. The results obtained can be summarized as follows : (1) The tensile strength of sintered compacts increased slowly with carbon content. Increase in tensile strength by heat treatment was evident especially in the low carbon specimen. The specimen with phosphorus showed higher strength compared to pure iron compacts value. (2) No inflection point of elasticplastic deformation on stress-strain curve was observed in sintered steel. The elastic modulus of sintered steel had the same tendency as tensile strength. But the elongation showed the opposite tendency. (3) The impact absorption energy of sintered steel without addition of phosphorus decreased successively with carbon content and by quenching and tempering. On the contrary, addition of phosphorus resulted in an increase of the impact absorption energy. Quenching and tempering did not affect the impact energy especially in high carbon content. (4) The main fracture source was pore in specimen and the propagation of crack occured mostly along the grain boundaries. But the intragranular fracture was also observed in high carbon, quenched and tempered specimen, and especially in the specimen with phosphorus.

• 한국재료학회지
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• 제30권2호
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• pp.93-98
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• 2020

Effective control of the heat generated from electronics and semiconductor devices requires a high thermal conductivity and a low thermal expansion coefficient appropriate for devices or modules. A method of reducing the thermal expansion coefficient of Cu has been suggested wherein a ceramic filler having a low thermal expansion coefficient is applied to Cu, which has high thermal conductivity. In this study, using pressureless sintering rather than costly pressure sintering, a polymer solution synthesis method was used to make nano-sized Cu powder for application to Cu matrix with an AlN filler. Due to the low sinterability, the sintered Cu prepared from commercial Cu powder included large pores inside the sintered bodies. A sintered Cu body with Zn, as a liquid phase sintering agent, was prepared by the polymer solution synthesis method for exclusion of pores, which affect thermal conductivity and thermal expansion. The pressureless sintered Cu bodies including Zn showed higher thermal conductivity (180 W/m·K) and lower thermal expansion coefficient (15.8×10^-6/℃) than did the monolithic synthesized Cu sintered body.

• Nuclear Engineering and Technology
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• 제29권3호
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• pp.196-200
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• 1997

The variation of sintered density and fain size in ex-AUC, ex-ADU and granulated ex-ADU UO$_2$ pellets in which 0.1~1.0wt% Nb$_2$O$_{5}$ were doped were examined. Pellets were sintered in an atmosphere of H$_2$ at 1$700^{\circ}C$ for 4h. All the specimens tested shooed more than 94% T.D.(Theoretical Density). Sintered density decreased with increasing the amount of Nb$_2$O$_{5}$. Powder types had little influence on the sintered density. Pore size distribution was shifted to the larger ones as Nb$_2$O$_{5}$ was added. The increase of total pore volume and grain growth due to the addition of Nb$_2$O$_{5}$ were thought to be the cause of the sintered density decrease. The largest grain size was seen in the 1. 0wt% Nb$_2$O$_{5}$ doped ex-AUC UO$_2$ pellets. Their average size was 13.9 ${\mu}{\textrm}{m}$.m}$.

• 한국표면공학회지
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• 제49권6호
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• pp.560-566
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• 2016

In this study, porcelain bonding strength and mechanical properties of sintered Ni-Cr-Ti alloy for dental prosthodontics have been researched experimentally. Mechanical and morphological characteristics of the alloys were examined by Vickers hardness test, tensile and bonding strength test, surface roughness test, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. In the sintered Ni-13Cr-xTi alloys, morphology of sintered alloy showed porous matrix diffused with alloying elements of Cr and Ti, and showed dendritic structure after melting process. From the XRD results, the second phases of NiCr, $Ni_3Cr$, and $Ni_3Ti$ were formed in the case of sintered and melted Ni-13Cr-xTi alloys. The tensile strength and hardness of Ni-13Cr-xTi alloys increased, as Ti content increased. Surface roughness increased, as Ti content increased. The bonding strength between metal and porcelain of Ni-13Cr-5Ti alloy was higher than those of Ni-13Cr and Ni-13Cr-10Ti alloys

• 한국분말재료학회지
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• 제10권4호
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• pp.241-248
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• 2003

Biaxially textured Ni tapes were fabricated by a cold working and recrystallization heat treatment processes from powder compact rods. The processing parameters associated with the cube texture formation in Ni tapes were systematically investigated by using X-ray diffraction and pole-figure analysis. The Ni powder used in this study was 5 $\mu$m in size and 99.99% in purity. To find the optimum sintering temperature, tensile tests were performed for Ni rods sintered at various temperatures. The Ni rods sintered at 100$0^{\circ}C$ showed poor elongation and low fracture strength, while the Wi rods sintered above 100$0^{\circ}C$ revealed good mechanical properties. The higher elongation and fracture strength of the Ni rods sintered at higher temperatures than 100$0^{\circ}C$ are attributed to the full densification of the sintered rods. The sintered Ni rods were cold-rolled with 5% reduction to the final thickness of 100 $\mu$m and then annealed for development of rube texture in rolled Ni tapes. The annealed Ni tapes depicted strong cube texture with FWHM(full-width at half-maximum) of in-plane and out-of-plane in the range of 8$^{\circ}$ to 10$^{\circ}$. The NiO deposited on the Ni tapes by MOCVD process showed good epitaxy with FWHM=10$^{\circ}$, which indicates that the Ni tapes can be used as a substrate for YBCO coated conductors.

• 한국토양비료학회지
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• 제44권3호
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• pp.415-424
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• 2011

This research was conducted to verified the effectiveness of a sintered porous media coated with organic matter as nutrient source and microorganisms as decomposer effective in TPH decomposition for a closed-typed biopole system. The organic matter content in the sintered porous media which was developed with bentonite increased with increasing dilution ratio of pig slurry and the sintered porous media as well as decrease in the particle size of sintered porous media. The decomposition rate of TPH was significantly increased with increasing aeration than that under atmospheric condition. Also the sintered porous media containing organic matter and microorganisms proved that the decomposition was enhanced with addition of nutrients sources in addition to aeration periodically.

• 열처리공학회지
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• 제36권4호
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• pp.215-222
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• 2023

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals, 3Y-TZP) ceramics are emerging as dental implant materials due to their superior optical and mechanical properties as well as excellent biophysical properties, in spite of low bioactivity. In this study, we investigated to sintered properties and microstructural defects of dental zirconia implants fabricated by ceramic injection molding and post-HIP (Hot isostatic pressing) processing and analyzed the processing parameters related with the obtainment of its high sinterd density. Sintered and microstructural parameters, i.e, apparent density, grain size and phase composition of zirconia implants fabricated by injection molding were dependent on the fixtute size and implant type. Maximum sintered density of 99.2% and minimum grain size of 0.3-0.4 ㎛ were obtained from large-scaled 2-body sample. In 1-body ceramic implant, high sintered density of 99.5% was obtained, but it had a little monoclinic phase and wide grain size distribution.

• 자원리싸이클링
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• 제20권1호
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• pp.37-45
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• 2011

부선 광미의 근원적 처리방안으로 경제성과 환경친화성을 고려히여 비소성 토건재료로 순환자원화 하는 연구를 수행하였다. 순신광산 광미의 평균입도는 $220\;{\mu}m$이고 삼광광산 광미의 평균입도는 $140\;{\mu}m$이었다. 따라서 이들 광미의 입도 특성을 고려하여 순신광산 광미는 비소성 투수블록의 원료 그리고 삼광광산 광미는 비소성 에코벽돌의 원료로 사용하여 제조한 시험체의 여러 특성을 조사하였다. 순신광산 광미 25 wt%이하의 배합조건에서 제조한 비소성 투수블록 시험체의 압축강도는 한국환경산업기술원(KEITI)에서 제시하고 있는 투수콘크리트 제품 규격(EL 245)인 14.70MPa 이상을 만족하였다. 그러나 투수계수 측정결과, 투수콘크리트 제품 규격(EL 245)인 $1.0{\times}10^{-2}\;cm/sec$ 이상을 만족하지 못하였다. 한편, 삼광광산 광미 40 wt% 이하의 배합조건에서 제조한 비소성 에코벽돌 시험체는 소성점토벽돌(KS L 4201) 3종 규격을 만족하였다. 또한 중금속용출시험(KSLT) 결과, 비소성 에코벽돌 시험체의 환경안정성이 확인되었다.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5438-5442
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• 2011

자동차용 경량소결부품으로 사용하기 위하여 2712 Al 합금 및 2712에 세라믹스를 각각 10, 20, 33% 첨가한 소결체의 기계적 특성에 대하여 조사하였다. 그 결과, (1)모든 소결체에서 4~7%의 기공이 잔류하는 것을 발견하였다. (2)시효처리한 2712 소결체 및 10, 20, 33% 세라믹스 함유 소결체의 인장강도 값은, 12분 소결에서는 각각 165, 260, 256, 166 N/$mm^2$, 30분 소결에서는 각각 186, 229, 219, 202 N/$mm^2$로 나타나, 세라믹스를 10% 첨가하여 12분 소결한 경우가 가장 우수한 인장강도 값을 나타내었다. 또한, 소결체의 최대 연신율값 3.6%는 세라믹스를 10% 첨가하여 30분 소결 후 시효처리한 소결체에서 나타났다. (3)시효처리 후의 소결체 표면의 최대 겉보기 경도값 ($H_RF$) 97은 세라믹스를 10% 첨가하고 30분 소결한 경우에 나타났다. (4)가장 낮은 내마모량 값 $174{\times}10^{-3}mm^3$은 10% 세라믹스를 첨가하여 시효처리한 소결체에서 나타났다. 이러한 결과들로부터 세라믹스를 10% 첨가한 2712 소결체가 Al 엔진부품 제조에 가장 적합한 것으로 판단되었다.

• 한국재료학회지
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• 제30권6호
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• pp.321-325
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• 2020

The present study demonstrates the effect of magnetic pulse compaction and spark plasma sintering on the microstructure and mechanical property of a sintered W body. The relative density of green specimens prepared by magnetic pulse compaction increases with increase in applied pressure, but when the applied pressure is 3.4 GPa or more, some cracks in the specimen are observed. The pressureless-sintered W shows neck growth between W particles, but there are still many pores. The sintered body fabricated by spark plasma sintering exhibits a relative density of above 90 %, and the specimen sintered at 1,600 ℃ after magnetic pulse compaction shows the highest density, with a relative density of 93.6 %. Compared to the specimen for which the W powder is directly sintered, the specimen sintered after magnetic pulse compaction shows a smaller crystal grain size, which is explained by the reduced W particle size and microstructure homogenization during the magnetic pulse compaction process. Sintering at 1,600 ℃ led to the largest Vickers hardness value, but the value is slightly lower than that of the conventional W sintered body, which is attributed mainly to the increased grain size and low sintering density.