• 제목/요약/키워드: Pressure compaction process

검색결과 63건 처리시간 0.033초

압축성형공정에 대한 알루미나 성형체 밀도분포의 FE 분석 (FE Analysis of Alumina Green Body Density for Pressure Compaction Process)

  • 임종인;육영진
    • 한국세라믹학회지
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    • 제43권12호
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    • pp.859-864
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    • 2006
  • For the pressure compaction process of the ceramic powder, the green density is very different with both the ceramic body shape and the processing conditions. The density difference cause non-uniform shrinkages and deformations, and make cracks in the sintered ceramics. In this paper, Material properties of the alumina powder mixed with binder and the friction coefficient between the powder and the tool set were determined through the simple compaction experiments: Also the powder flow characteristics were simulated and the green density was analyzed during the powder compaction process with Finite Element Method (FEM). The results show that the density distributions of the green body were improved at the optimized processing condition and both the possibility of the farming crack generation and rho deformation of the sintered Alumina body were reduced.

Property of New SEGLESS that is Segregation-free Steel Powder Mixture for Warm Compaction

  • Nishida, Satoshi;Furuta, Satoshi
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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    • pp.731-732
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    • 2006
  • Recently warm compaction techniques are focused on and commercialization of one high-density compaction process in the P/M industry. Another development is a new SEGLESS using a developed lubricant that reduces ejection force at room temperature compaction. It is possible to achieve high-density by reducing lubricant amount. In this paper we confirmed that green density was $7.35g/cm^3$ at 686MPa of compaction pressure when the new SEGLESS was applied to relatively lower temperature warm compaction process, such as $80^{\circ}C$.

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Comparison of Different Permeability Models for Production-induced Compaction in Sandstone Reservoirs

  • To, Thanh;Chang, Chandong
    • 지질공학
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    • 제29권4호
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    • pp.367-381
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    • 2019
  • We investigate pore pressure conditions and reservoir compaction associated with oil and gas production using 3 different permeability models, which are all based on one-dimensional radial flow diffusion model, but differ in considering permeability evolution during production. Model 1 assumes the most simplistic constant and invariable permeability regardless of production; Model 2 considers permeability reduction associated with reservoir compaction only due to pore pressure drawdown during production; Model 3 also considers permeability reduction but due to the effects of both pore pressure drawdown and coupled pore pressure-stress process. We first derive a unified stress-permeability relation that can be used for various sandstones. We then apply this equation to calculate pore pressure and permeability changes in the reservoir due to fluid extraction using the three permeability models. All the three models yield pore pressure profiles in the form of pressure funnel with different amounts of drawdown. Model 1, assuming constant permeability, obviously predicts the least amount of drawdown with pore pressure condition highest among the three models investigated. Model 2 estimates the largest amount of drawdown and lowest pore pressure condition. Model 3 shows slightly higher pore pressure condition than Model 2 because stress-pore pressure coupling process reduces the effective stress increase due to pore pressure depletion. We compare field data of production rate with the results of the three models. While models 1 and 2 respectively overestimates and underestimates the production rate, Model 3 estimates the field data fairly well. Our result affirms that coupling process between stress and pore pressure occurs during production, and that it is important to incorporate the coupling process in the permeability modeling, especially for tight reservoir having low permeability.

알루미나 분말 기지혼합체의 상온 반복압축 후 가압소결 -상온 반복압축 효과- (Hot Pressing after Cold Cyclic Compaction of Alumina Powder Matrix Mixtures -Effects of Cold Cyclic Compaction-)

  • 손건석;서정;박병학;김기태
    • 한국세라믹학회지
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    • 제30권2호
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    • pp.157-163
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    • 1993
  • Hot pressing after cold cyclic compaction of Al2O3 powder mixtures containing SiC whiskers or Al2O3 short fibers is studied with emphasis on the effects of cold cyclic compaction. The green density of the mixtures increases as the cycle number increases and the cyclic pressure becomes higher. The higher green density is also obtained by cold cyclic compaction with the lower pressrue than a single stroke cold compaction. To achieve a higher densification during hot pressing, cold cyclic compaction before hot pressing is more efficient compared to the conventional hot pressing process (without cold cyclic compaction). Moreover, a low cyclic pressure did not affect on toughening mechanism by whisker reinforcement.

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분말 가압 성형 공정 변수 최적화에 관한 연구 (Study on the Optimization of Powder Compaction Process Parameters)

  • 김정래;금영탁
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2005년도 추계학술대회 논문집
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    • pp.476-479
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    • 2005
  • In this study, the process parameters in powder compaction are optimized for getting high relative densities. To find optimized parameters, the analytic models of powder compaction are firstly prepared by 2-dimensional rod arrays with random green densities using a quasi-random multi-particle array. Then, using finite element method, the changes in relative densities are analyzed by varying the size of the particle, the amplitude of cyclic compaction, and the coefficient of friction, which influence the relative density in cyclic compactions. After the analytic function of relative density associated process parameters are formulated by aid of the response surface method, the optimal conditions in powder compaction process are found by the grid search method.

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An improved model of compaction grouting considering three-dimensional shearing failure and its engineering application

  • Li, Liang;Xiang, Zhou-Chen;Zou, Jin-Feng;Wang, Feng
    • Geomechanics and Engineering
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    • 제19권3호
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    • pp.217-227
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    • 2019
  • This study focuses on an improved prediction model to determine the limiting grouting pressure of compaction grouting considering the ground surface upheaval, which is caused by the three-dimensional conical shearing failure. The 2D-dimensional failure curve in Zou and Xia (2016) was improved to a three-dimensional conical shearing failure for compaction grouting through coordinate rotation. The process of compaction grouting was considered as the cavity expansion in infinite Mohr-Coulomb (M-C) soil mass. The prediction model of limiting grouting pressure of compaction grouting was proposed with limit equilibrium principle, which was validated by comparing the results in El-Kelesh et al. (2001) and numerical method. Furthermore, using the proposed prediction model, the vertical and horizontal grouting tube techniques were adopted to deal with the subgrade settlement in Shao-huai highway at Hunan Provence of China. The engineering applicability and effectiveness of the proposed model were verified by the field test. The research on the prediction model for the limiting grouting pressure of compaction grouting provides practical example to the rapid treatment technology of subgrade settlement.

초고압 성형을 통한 Mo 나노 분말의 치밀화 (Densification of Mo Nanopowders by Ultra High Pressure Compaction)

  • 안치형;최원준;박천웅;이승영;김영도
    • 한국재료학회지
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    • 제28권3호
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    • pp.166-173
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    • 2018
  • Molybdenum (Mo) is one of the representative refractory metals for its high melting point, superior thermal conductivity, low density and low thermal expansion coefficient. However, due to its high melting point, it is necessary for Mo products to be fabricated at a high sintering temperature of over $1800-2000^{\circ}C$. Because this process is expensive and inefficient, studies to improve sintering property of Mo have been researched actively. In this study, we fabricated Mo nanopowders to lower the sintering temperature of Mo and tried to consolidate the Mo nanopowders through ultra high pressure compaction. We first fabricated Mo nanopowders by a mechano-chemical process to increase the specific surface area of the Mo powders. This process includes a high-energy ball milling step and a reduction step in a hydrogen atmosphere. We compacted the Mo nanopowders with ultra high pressure by magnetic pulsed compaction (MPC) before pressureless sintering. Through this process, we were able to improve the green density of the Mo compacts by more than 20 % and fabricate a high density Mo sintered body with more than a 95 % sintered density at relatively low temperature.

분말야금 공정 중 성형압력과 소결 온도가 밀도와 치수에 미치는 영향 (The Influence of Compaction Pressure and Sintering Temperature on Density and Dimension of n Powder Metallurgy Product)

  • 조주현;권영삼;정성택;이민철;전만수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 춘계학술대회 논문집
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    • pp.347-351
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    • 2007
  • The influence of compaction pressure and sintering temperature on the hydraulic cylinder block fabricated by powder metallurgy is investigated in this study. The cylinder block is powder compacted under various compaction pressures and sintered under various sintering temperatures, and its density and dimensions are measured to reveal the relation of the process condition with the product quality. Moreover, finite element analyses of the density distributions are conducted under the same conditions with the experiments and the predicted results are compared with the measured ones.

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기계화학적 합금화된 나노 Fe-6.5Si 분말의 자기 펄스압에 의한 동적성형 (Dynamic Compaction of Mechanochemically Alloyed Fe-Si Nano Powders by Magnetic Pulsed Pressure)

  • 이근희;이창규;김흥회;윤종운;이기선
    • 한국분말재료학회지
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    • 제12권1호
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    • pp.24-29
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    • 2005
  • Nano Fe-6.5wt%Si powders have been synthesized by mechano-chemical process (MCP) for an application of soft magnetic core. Owing to hard and brittle characteristics of Fe-6.5Si nano powders having large surface area, it is very difficult to reach high density more than 70% of theoretical density (~7.4 g/$cm_3$) by cold compaction. To overcome such problem a magnetic pulsed compaction (MPC), which is one of dynamic compaction techniques, was applied. The green density was achieved about 78% (~5.8 g/$cm_3$) by MPC at room temperature.

분말가압 성형공정의 멀티스케일 시뮬레이션과 공정변수 최적화 (Multi-scale Simulation of Powder Compaction Process and Optimization of Process Parameters)

  • 심진우;심정길;금영탁
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 추계학술대회 논문집
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    • pp.344-347
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    • 2007
  • For modeling the non-periodic and randomly scattered powder particles, the quasi-random multi-particle array is introduced. The multi-scale process simulation, which enables to formulate a regression model with a response surface method, is performed by employing a homogenization method. The size of ${Al_2}{O_3}$ particle, amplitude of cyclic compaction pressure, and friction coefficient are considered as optimal process parameters. The optimal conditions of process parameters providing the highest relative density are finally found by using the grid search method.

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