• Title/Summary/Keyword: Recycled powder

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Controlling Particle Size of Recycled Copper Oxide Powder for Copper Thermite Welding Characteristics (동 테르밋 용접 특성 향상을 위한 폐 산화동 분말 입도 제어 연구)

  • Hansung Lee;Minsu Kim;Byungmin Ahn
    • Journal of Powder Materials
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    • v.30 no.4
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    • pp.332-338
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    • 2023
  • Thermite welding is an exceptional process that does not require additional energy supplies, resulting in welded joints that exhibit mechanical properties and conductivity equivalent to those of the parent materials. The global adoption of thermite welding is growing across various industries. However, in Korea, limited research is being conducted on the core technology of thermite welding. Currently, domestic production of thermite powder in Korea involves recycling copper oxide (CuO). Unfortunately, controlling the particle size of waste CuO poses challenges, leading to the unwanted formation of pores and cracks during thermite welding. In this study, we investigate the influence of powder particle size on thermite welding in the production of Cu-thermite powder using waste CuO. We conduct the ball milling process for 0.5-24 h using recycled CuO. The evolution of the powder shape and size is analyzed using particle size analysis and scanning electron microscopy (SEM). Furthermore, we examine the thermal reaction characteristics through differential scanning calorimetry. Additionally, the microstructures of the welded samples are observed using optical microscopy and SEM to evaluate the impact of powder particle size on weldability. Lastly, hardness measurements are performed to assess the strengths of the welded materials.

Shrinkage and Creep of Recycled Aggregate Concrete Using Pozzolanic Materials (포졸란 재료를 사용한 재생골재 콘크리트의 건조수축 및 크리프)

  • 문대중;임남웅;김양배
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.637-642
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    • 2002
  • In this study, the experiments of recycled aggregate concrete with fly ash and special blended slag powder or diatom calcined at 650$\circ$ were performed on compressive strength, shrinkage and creep. The compressive strength of concrete with recycled aggregate and pozzolanic materials were higher than that of concrete with crushed stone and OPC. On the other hand, the shrinkage and creep of concrete with recycled aggregate and pozzolanic materials was smaller than that of concrete with crushed stone and OPC. Futhermore, the shrinkage and creep of recycled aggregate concrete with fly ash and special blended slag powder was a little decreased that of recycled aggregate concrete with fly ash and diatom. Relationship between compressive strength and creep coefficient was shown to the linear relation like as $\sigma$$_{c}$= -30CF+404.4.

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A Property of Porous Concrete applied by Recycled Cement and using Recycled Aggregates Made of EPS Waste (재생시멘트와 폐 EPS 재생골재를 사용한 포러스 콘크리트 물성)

  • Kim Sung-Su;Park Cha-Won;Ahn Jae-Cheol;Kang Byeung-Hee
    • Proceedings of the Korean Institute of Building Construction Conference
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    • v.y2004m10
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    • pp.59-63
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    • 2004
  • In recent days. it is necessary to find environment-friendly way of diposing industrial waste and reclying system. So this study will analyze the property of Porous concrete improved by concrete waste powder and recycled lightweight aggregate and then suggest the ways of reclying. The method deals with experimenting unit weight of capacity. thermal conductivity, compression and ultrasonic pluse velocity. Considering the relation between ultrasonic pluse velocity and unit weight & thermal conductivity through the graph. the result of relation between ultrasonic pluse velocity and unit weight & thermal conductivity on the graph expessed their high interaction shown as direct proportion on the graph. Recycled Porous concrete merits lightweight and adiabatic. Therefore. we will expect that the current using ALC and Recycled Porous concrete has be similar thermal conductivity.

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Evaluation of Physical Properties of Recycled Cement Powder for Recycling Radioactive Waste Concrete (방사화된 폐콘크리트의 고화재 활용을 위한 재생시멘트 분말의 물성 평가)

  • Choi, Yu-Jin;Kim, Ji-Hyun;Chung, Chul-Woo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.305-306
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    • 2023
  • Recently, as the radioactive waste disposal facility becomes scarce, the importance of efficient disposal of waste from nuclear power plants is increasing. This study was conducted to utilize radioactive waste concrete powder as solidifying agent for radioactive waste treatment. Paste with an age of more than one year was used with a disk mill to have a particle size of 150㎛ or less, and treated at temperatures of 500℃, 600℃ and 700℃ for 2 hours. In order to simulate the radioactive cement powder, aqueous solutions of Di-water, CsCl 1M, SrCl2 1M and CoCl2 1M were used as blending water at W/C 0.7 and to improve fluidity, polycarboxylate type superplasticizer was used at 0.4 wt.% based on the weight of recycled cement paste powder. Characterisation was carried out using vicat method, strength and density.

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A Study on the Preparation of Oil Absorbent Using Waste Polyurethane (폐폴리우레탄을 이용한 오일 흡수제의 제조)

  • Kim, Hyung-Soon
    • Journal of the Korean Society of Industry Convergence
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    • v.10 no.2
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    • pp.73-80
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    • 2007
  • The preparation of oil absorbent using waste polyurethane was studied. And the effects of shape, size, and contents of waste polyurethane foam was investigated. The waste foam was treated in shape of powder, cube and bar type generated from rigid sandwich panel process. The tests for flexural strength, combustibility, and water absorptivity were carried out to investigate the mechanical and physical properties of the recycled foams. And the cell microstructure was evaluated through Scanning Electron Micrograph. The recycled foam containing powder-shaped underfilled and showed poor properties that was generated through reactivity of the resins and increasing of slurry viscosity. For the recycled foam with the cube and bar-shaped, the underfilling was caused by interference between the waste PUFs and increasing surface areas of PUF. Low cell density, non-uniformity of cell shape and size, and low adhesion of the boundary surface (new/recycled) was showed as a result of the poor properties. Considering underfilling and the properties of PUF (new/recycled), maximum recycle contents were less than 20 wt% for the powder and above 40 wt% for the cube and bar.

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EFFECT OF IMPURITIES ON THE MICROSTRUCTURE OF DUPIC FUEL PELLETS USING THE SIMFUEL TECHNIQUE

  • Park, Geun-Il;Lee, Jae-Won;Lee, Jung-Won;Lee, Young-Woo;Song, Kee-Chan
    • Nuclear Engineering and Technology
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    • v.40 no.3
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    • pp.191-198
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    • 2008
  • The influence of fission products' contents on the DUPIC fuel powder and pellet properties was experimentally evaluated using SIMFUEL as a surrogate for actual spent PWR fuel due to the high radioactivity of spent fuel. Pure $UO_2$ and SIMFUEL pellets with fission products equivalent to a burn-up of 35,000 MWd/tU and 60,000 MWd/tU were used as impurities in this study. The specific surface area of the powder milled after the OREOX treatment increased and resulted in sintered pellets with a theoretical density (TD) higher than 95%, regardless of the impurity contents. However, the grain size of the sintered pellets decreased with the increasing impurity contents. As a result of the dissolved oxides in $UO_2$ from the impurity groups, the specific surface area of the OREOX powder increased with an increase of the impurities. The grain size of the sintered pellets was significantly decreased by the metallic and oxide precipitates.

Molding Properties and Causes of Deterioration of Recycled MIM Feedstock

  • Cheng, Li-Hui;Hwang, Kuen-Shyang
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.215-216
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    • 2006
  • To lower the cost of MIM products, the gate and runner materials and green parts with defects are usually recycled. It is necessary to understand what causes the recycled products to deteriorate. The results show that the viscosity of the 1R (recycled once) feedstock was slightly lower than that of the fresh material. However, as the number of recyclings increased, the viscosity increased, while the density decreased, and more defects were noticed duri ng solvent debinding. These deteriorations were mainly caused by the increase of the melting point of the backbone binder and the oxidation of the filler or paraffin wax.

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A Study on the Alkali Application of Recycled Aggregates as a Solution to Reduced Intial Intensity of Blast Furnace Slags (고로슬래그의 초기강도 저하 해결방안으로써 순환 잔골재의 알칼리 활용가치에 대한 연구)

  • Kwak, Yong-Jin;Zhao, Yang;Jung, sang-woon;Heo, Young-sun;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.05a
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    • pp.85-86
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    • 2013
  • Weakness of fine powder of blast furnace slags includes the decrease of initial intensity and delay of setting time. To solve this problem, there has been research on the alkali activation to induce hardening using alkaline chemical. However, the use of chemicals is dangerous and not cost effective, which can be solved by using recycled aggregates, one of construction wastes. The role of alkali activator can be substituted by alkali of non-hydrated cement included in recycled aggregates. In this study, the alkaline value of recycled aggregates will be evaluated through the comparison of molarity of sodium hydroxide (NaOH).

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Performance of one-part alkali activated recycled ceramic tile/fine soil binders

  • Mawlod, Arass Omer
    • Advances in concrete construction
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    • v.10 no.4
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    • pp.311-317
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    • 2020
  • Performance of Sustainable materials continues through using of recycled waste construction materials to minimize the utilization of the natural resources. The cement industry is a major source of CO2 in the atmosphere which is the main cause of global warming. Replacement of OPC with other sustainable cementitious materials has been the most interesting area of researches. This investigation focuses on the properties of alkali-activated mortar with the different replacement ratios of ceramic tile powder (CTP) by fine soil powder (FSP) (0 to 100)% and different molarities of sodium hydroxide concentrations. The experimental program was conducted by examining the compressive strength, water absorption, and water sorptivity. The results showed that the compressive strength of the specimens at age of (28, 56, and 90 days) increases with an increase in the amount of fine soil powder content and decreases at the age of 120 days. Also, minimum water absorption at the age of 90 days was found in the mixes containing 100% fine soil powder. However, fine soil powder replacement had a negative effect on the sorptivity and water absorption values at the age of 120 days. On the other hand, the 12M sodium hydroxide concentration was considered the optimum concentration compared to other concentrations.

4H-SiC bulk single crystal growth using recycled powder (재생 분말을 활용한 4H-SiC 벌크 단결정 성장)

  • Yeo, Im Gyu;Lee, Jae Yoon;Chun, Myong Chuel
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.32 no.5
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    • pp.169-174
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    • 2022
  • This study is to verify the feasibility of SiC single crystal growth using recycled SiC powder. The fundamental physical properties such as particle size, shape, composition and impurities of the recycled powder were analyzed, and the sublimation behavior occurring inside the reactor were predicted using the basic data. As a result of comprehensive judgment, the physical properties of the recycled powder were suitable for single crystal growth, and single crystal growth experiments were conducted using this. 100 mm 4H-SiC single crystal ingot with a height of 25 mm was grown without polytype inclusion. In the case of micro-pipe density was 0.02 ea/cm2 and resistivity characteristics was 0.015~0.020 ohm·cm2, commercial level quality was obtained, but additional analysis related to dislocation density and stacking faults is required for device application.