• Title, Summary, Keyword: fluidity

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Effects of Si Content and Melt Treatment on the Fluidity of Al-Si Alloy during Squeeze Casting (알루미늄 - 규소 합금의 용탕단조시 유동도에 미치는 규소 함량 및 용탕 처리의 영향)

  • Lee, Hag-Ju;Kwon, Hae-Wook
    • Journal of Korea Foundry Society
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    • v.26 no.6
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    • pp.241-248
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    • 2006
  • The effects of silicon content and melt treatment on the fluidity of Al-Si alloys during squeeze casting were investigated. The fluidity of Al-3.0 wt%Si alloy was found to be lower than that of Al-1.0 wt%Si and the fluidity of the alloy with more than 3.0 wt%Si increased with the silicon content upto 13.0 wt% and rather decreased with15.0 wt%. The fluidity was also increased by the separated treatment of grain refinement or eutectic modification, and even more by the simultaneous treatment of both. The fluidity of hypereutectic alloy was increased by the refinement of primary silicon particle.

The Effect of Grain Refinement on Fluidity of Al-4.8%CU-0.6%Mn Alloy (입자미세화가 Al-4.8%Cu-0.6%Mn 합금의 유동도에 미치는 영향)

  • Kwon, Young-Dong;Lee, Zin-Hyoung;Kim, Kyoung-Hyun
    • Journal of Korea Foundry Society
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    • v.22 no.3
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    • pp.109-113
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    • 2002
  • A good fluidity of high strength Al-alloys is required to cast thin wall castings needed to reduce the weight of cast parts. The fluidity, measured as the length to which the metal flows in a standard channel, is affected by many factors, such as the pouring temperature, solidification type of the alloy, the channel thickness, melt head, mold materials and temperature, coating etc. Therefore the experimentally measured fluidity scatters very much and makes it difficult to estimate the fluidity of a melt with a few measurements. The effect of Ti content and grain refinement on the fluidity of high strength aluminum alloy was investigated with a test casting with 8 thin flow channels to reduce the scattering of the fluidity results. The fluidity of Al-4.8%Cu-0.6%Mn Al-6.2%Zn-1.6%Mg-1.0%Cu and well-known commercial aluminum alloy, A356 was tested. Initial content of Ti was varied from 0 to 0.2wt% and Al-5Ti-B master alloy was added for grain refinement. The flow length varied linearly with superheat. By adding Ti and Al-5Ti-B, the fluidity increased. The grain size decreased by adding grain refiner at the same time. The fluidity depended on the degree of grain refinement. The fluidity of the alloy solidifying in mushy type is improved by grain refinement, because grain refinement increases the solid fraction at the time of flow stoppage.

Effects of Limestone Powder on the Fluidity of Ordinary Portland Cement Paste (보통 포틀랜드 시멘트 페이스트의 유동특성에 미치는 석회석 미분말의 영향)

  • Lee, Seung-Heun;Park, Jeong-Soo;Lee, Jeong-In;Cho, Jae-Woo
    • Journal of the Korean Ceramic Society
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    • v.50 no.2
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    • pp.149-156
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    • 2013
  • This study examines the effects of limestone's factors on the fluidity of cement paste when of up to 15%. As the substitution ratio of limestone powder increases, the fluidity of the paste is also improved; however, it has no correlation to the $CaCO_3$ content of the limestone, fineness of the limestone, and fluidity of the pastes. Regardless of clay content of the limestone, it showed a similar mini-slump, so there was no correlation between the clay content and the fluidity of the paste. Also, the total organic carbon content of the limestone and the fluidity of the paste showed no correlation. Regardless of the limestone's grade or fineness, n value of powder gained by using the Rosin-Rammler distribution function showed that the fluidity of the paste increased as the n value reduced. It was also shown that particle size distribution of ordinary Portland cement with limestone powder had a major effect on the fluidity of the paste.

The Influence of Alloying Elements on the Fluidity of Al-Zn-Mg Alloys (Al-Zn-Mg계 알루미늄 합금의 유동성에 미치는 합금원소의 영향)

  • Cho, Jea-Sup;Kim, Jee-Hun;Sim, Woo-Jeong;Im, Hang-Joon
    • Journal of Korea Foundry Society
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    • v.32 no.3
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    • pp.127-132
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    • 2012
  • Al-Zn-Mg alloys, being high strength aluminum alloys, have attracted attention as a material of automobile parts that require higher mechanical properties and lightness. Automobile parts with complex shapes are manufactured by low-priced casting method, but Al-Zn-Mg alloys are difficult to cast because of its poor hot cracking, feeding, and fluidity. Thus fluidity experiments on Al-Zn-Mg alloys were conducted for the castability evaluation. The effects of Mg and Zn, representative elements of Al-Zn-Mg alloys, on fluidity were observed. Spiral mold was used for fluidity experiments and the lengths of solidified specimens were measured after melting and gravity casting. Correlation between microstructures and fluidity length based on the alloy composition was considered. According to the experimental results, as the amount of Mg and Zn increased, fluidity decreased. Also, it was confirmed that fluidity change by the variation of Mg composition was greater than that of Zn.

Effects of Mineral Admixture on the Paste Fluidity and Mortar Strength Development of High Chloride Cement (염소 고함유시멘트의 페이스트 유동성과 모르타르 강도발현성에 미치는 무기질 혼화재의 영향)

  • Jeong, Chan-Il;Park, Soo-Kyung;Lee, Eui-Hak;Lee, Kyung-Hee
    • Journal of the Korean Ceramic Society
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    • v.44 no.1
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    • pp.43-51
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    • 2007
  • Fluidity, setting time, hydration heat, bond water ratio, compressive strength, SEM and BET of OPC were measured by adding 1.0 wt% KCl and replacing 20 wt% mineral admixture in order to examine effects of blast furnace slag (BFS), limestone powder (LSP), and fly ash (FA) on fluidity and strength development of the cement contained much chloride. In general, the cement contained much chloride was high in heat of hydration, short in its setting time, low in its fluidity and low in its strength at 28 days due to the rapid hydration in its initial stage. As a result of the experiment, it has been demonstrated that fluidity became improved but the compressive strength at 28 days was decreased as replaced LSP to the cement contained much chloride. the fluidity and compressive strength at 28 days was improved as replaced BFS, the initial compressive strength development was improved due to the activation of initial reaction by KCl. Fluidity, initial compressive strength and late compressive strength at 28 days of cement contained much chloride replaced 5 wt% LSP and 15 wt% BFS concurrently was better than OPC, but the hydration heat was lower.

Effects of Coating Materials on Fluidity and Temperature Loss of Molten Metals from Runner Systems in Full Moulds.

  • Cho, Nam-Don;Kim, Yong-Hyun;Choi, Jung-Kwon
    • Journal of Korea Foundry Society
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    • v.10 no.1
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    • pp.31-42
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    • 1990
  • The full mould casting process in one of the newly developed techniques which has many advantages. Unbonded sand mould has been prepared for the major mould and $CO^2$ gas mould has been used occasionally for comparison. Patterns were built up with expanded polystyrene and coated with three different materials. Silica, graphite and zircon were used for the coating layer. The effects on fluidity and temperature loss of molten metals were investigated. The molten metals were Al-5% Si alloy, Cu-30% Zn alloy and gray iron of approximately 4.0% of carbon equivalent. Experimental variables were runner section area, superheat, sprue height, coating materials, coating thickness and apparent density of EPS pattern. The effects of coating materials on fluidity and temperature loss of the molten metals during transient pouring are summarized as follows : As runner section area, superheat and sprue height increased, fluidity increased. Temperature loss decreased as runner section area and sprue height increased. However, reversed effects were observed in the case of superheat increment. The coating materials decreased the fluidity of each alloy in the order of silica, graphite and zircon. Zircon brought to the highest temperature loss among the coating materials used. The fluidity increased in the order gray iron, Cu-30% Zn and Al-5% Si alloy while temperature loss in the reverse order. Especially in case of reduced pressure process, the fluidity was increased apparently. Al-5% Si alloy showed the lowest temperature loss among the alloys. The increment of the apparent density of EPS pattern resulted in the fluidity decrease and temperature loss increase. The relation between fluidity and temperature loss of each alloy can be expressed by the following equation within the coating thickness limit of 0.5-1.5㎜. F^*={\frac{a}{T^*-b}}-c$ where, $F^*$ : fluidity in the Full mould, $T^*$ : temperature loss in the mould. a : parameter for full mould. b, c : constants.

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The Execution and Estimation of Construction Cost of High Fluidity Concrete Applying Flowing Concrete Method (유동화공법에 의해 제조한 고유동 콘크리트의 시공 및 원가분석)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.4 no.2
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    • pp.129-136
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    • 2004
  • High fluidity concrete(HFC) requires high dosage of superplasticizer to acquire sufficient fluidity, and high contents of fine powder and viscosity enhancing admixtures to resist segregation. The use of high amount of admixtures to make HFC at batcher plant in ready mixed concrete company is one of the reasons to raise the manufacturing cost of HFC. For this reason, new type of manufacturing method of HFC are described using both flowing concrete method and segregation reducing superplasticizer(SRS) in order to gain economical profit and offer the convenience for quality control.. As dosage of melamine based superplasticizer increases, it shows that fluidity and bleeding increase, while air contents and ratio of segregation resistance decrease. It also shows that addition of viscosity agent into superplasticizer reduce bleeding and improve segregation resistance of concrete. Dosage of AE agent into superplasticizer containing viscosity agent recovers loss of air contents during flowing procedure. Combination of proper contents of superplasticizer, viscosity agent and AE agent make possible to develope segregation reducing type superplasticizer. Compressive strength of high fluidity concrete applying flowing method with it is higher than that of base concrete. No differences of compressive strength between compacting methods are found. For the estimation of construction cost of high fluidity concreting using segregation reducing type superplasicizer, under same strength levels, although material cost of high fluidity concrete is somewhat higher than that of plain concrete due to segregation reducing type superplasticizer cost, labor cost and equipment cost of high fluidity concrete is cheaper than that of plain concrete. However, based on the strength differences, high fluidity concrete shows lower material cost, labor cost and equipment cost than that of plain concrete due to decreasing in size of member and re-bar caused by high strength development of concrete.

A Study on the Quality Properties of Exposed High Fluidity Concrete using Fly Ash and Limestone Powder (플라이애시 및 석회석 미분말을 사용한 고유동 노출 콘크리트의 품질특성에 관한 연구)

  • Choi, Yun-Wang;Oh, Sung-Rok;Kim, Ji-Hoon;Kim, Kyung-Hwan
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.1 no.1
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    • pp.67-75
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    • 2013
  • Recently, the interest is increasing about the exposed concrete, accordingly, exposed concrete is expanding the use. However, concrete structures is difficult to apply the general concrete for exposed concrete, due to complex section and compact reinforcement, increasingly. Therefore, in this paper, for application of high fluidity concrete as exposed concrete, exposed high fluidity concrete using fly ash and lime stone powder was manufactured and observed quality property(fluidity properties, mechanical properties and Surface Properties) of exposed high fluidity concrete. The experiments are based on the OPC and LSP10, was evaluated Impact on the quality of concrete according to mixing ratio of FA(0, 10, 15 and 20). As a result, fluidity properties, mechanical properties and Surface Properties of exposed high fluidity concrete were satisfied to requirement conditions, fluidity and surface finishability was improved depending on mix of fly ash and limestone powder. Through this, we utilize of basic research data for development of high fluidity concrete for exposed concrete.

Fluidity Retention of Cement-Based Composites Using High range water reducing AE agent (고성능AE감수재를 사용한 시멘트복합체의 유동성 유지성능)

  • 김기형;김인수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.93-98
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    • 1998
  • Fluidity retention of concrete used high range water reducing AE agent(HWAE) is varied according to type, dosage amount and dosing method of HWAE. The type and substitution ratio of mineral admixture also have influence on the fluidity retention of concrete using HWAE. For the purpose of improving the fluidity retention in concrete used HWAE, 3 types of HWAE and ground granulated blast furnace slag(SG) are applied in cement-based composites such as cement paste, mortar and concrete respectively. According to using the HWAE of naphthalene sulfonates and SG, the fluidity retention of mortar and concerete is improving the fluidity retention and strength of concrete regardless of type of HWAE.

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Adsorption and Fluidity Properties of Recycled Cement Powder (재생미분말의 흡착특성과 유동특성)

  • Lee, Jong-Kyu;Chu, Yong-Sik;Jung, Suk-Jo
    • Journal of the Korean Ceramic Society
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    • v.43 no.12
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    • pp.846-851
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    • 2006
  • This paper discuss the adsorption and fluidity properties of recycled cement powder with different hydration hysteresis and particle size. Reactivity of hydrated fine powder was negligible low. Therefore, the adsorption and fluidity properties with super-plasticizer for hydrated recycled cement powder was very important for using additive material. Adsorption amount of super-plasticizer was increased by the finer hydrated recycled cement powder addition. And the fluidity of hydrated recycled cement powder was very poor than un-hydrated cement powder. To Improve the fluidity of hydrated recycled cement powder, PC super-plasticizer is the more effective than NS super-plasticizer.