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Prodhan, A; Sanyal, Dipayan

doi:10.1023/a:1018569028471

Cited by 9 publications

(8 citation statements)

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“…Over the past decades a lot of studies relating with the effect of electric field on the structure and properties of Al-alloys have been carried out [38][39][40][41][42]. Electric field either continuous current or pulse electric discharge deeply affects crystallographic character of alloy and its properties.…”

Section: Role Of Electric Field In the Crystallization Of Al-si Alloysmentioning

confidence: 99%

Direct Electrolytic Al-Si Alloys (DEASA) – An Undercooled Alloy Self-Modified Structure and Mechanical Properties

Wang¹,

Lu²

2012

Electrolysis

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Electrolysis 108 reduction in laboratory. Frilley also obtained Mn-Si, Cr-Si, Fe-Si, Cu-Si and Si-Ni in electrolytic cells. Moreover, he found that the silicon appearance in Al-Si alloy with less than 10% Si was very fine and different from the existed alloy, but no attention had been paid on the change of structural characteristics of silicon due to limited usage of aluminum in industry at that time. Fridley's discovery revealed that electrolytic process is a powerful potential measure to improve the quality of alloy. In the middle of last century a number of works had been reported to electrolyze Al-Si alloy in Hall cells, to which pure silica, quartzite containing more than 99% SiO2 [3], sand stone with about 90% SiO2 [4] glass scrap having 72% SiO2 [5]. bauxite with 11%SiO2 [6], sand and clay [7] were added. Recently the refractories from spent potlining were successfully introduced to alumina reduction cells to produce Al-Si alloys [8]. As well known, the purity of molten aluminum is of major concern in electrolytic reduction process. The impurity is considered as a negative factor, deteriorating operation conditions. Hence, the direct electrolytic reduction of silica in Hall cell is a difficult process. There are two severe problems related with silica added into molten cryolite, in which silica must be easily dissolved. One of them is how to compensate for alumina generated by the reaction of aluminum with the added silica for achieving a desired chemical composition of alloy. Other is that direct addition of silica or other silicates often results in the formation of the heavy ridges of silicate along the bottom of the cell, as a result the cell becomes inoperable, so limiting the size and placement of the ridge is a major concern in production. In 1970s C. J. McMinn and A.T. Tabereaux [9, 10] provided a procedure to strictly control the feed of alumina and silica into the cell, stabilizing the electrolytic process and successfully producing Al-Si alloys with up to 16%Si in Hall cell. However, they viewed this process to be economical when the price of silicon greatly increases. Production of Al-Si alloys in electrolytic reduction cell had not found industrial application. Since 1970s many works have been carried out on direct electrolytic production of Al-Si alloys(DEASA) in China [11]. Most Chinese bauxites contain high content of silica, titania and small amount of rare earth oxides. It is very difficult to extract the pure alumina from bauxite by the Bayer process [12]. In electrolytic process the charge is composed of bauxite, from which the iron oxide is removed, and alumina, using which to regulate the proportion of bauxite added into salt bath in terms of the desired chemical composition of Al-Si alloy. Note that bauxite tested is easily to be dissolved into molten electrolyte compared to the commercial bauxites. It would be an important factor to successfully produce Al-Si alloys in alumina reduction cells. At the end of last century several thousand tons of DEASA ingots containing Si content fro...

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Section: Role Of Electric Field In the Crystallization Of Al-si Alloysmentioning

confidence: 99%

Direct Electrolytic Al-Si Alloys (DEASA) – An Undercooled Alloy Self-Modified Structure and Mechanical Properties

Wang¹,

Lu²

2012

Electrolysis

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“…To overcome these problems, the alloy was treated with electric current [18][19][20][21][22] during sand casting. However, ECT cannot be conducted in metal (chill) moulds because the electric current would be short circuited through the mould.…”

Section: Cu-ni Alloymentioning

confidence: 99%

“…(i) the ECT reduces the dissolved gas [19][20][21][22] (ii) this treatment increases the coefficient of heat transfer, 19 so the dendrites are refined (Fig. 2b) (iii) the fluid flow is increased by increasing current; therefore, dendrites are fragmented (Fig.…”

Section: Cu-ni Alloymentioning

confidence: 99%

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Semisolid processing of short and long freezing range Cu alloys by electric current

Prodhan

2011

Materials Science and Technology

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The present study reports the effect of ac (50 Hz) electric current treatment (ECT) on short freezing range (Cu–Ni) and long freezing range (Cu–Sn) alloys. This treatment was conducted during the semisolid state of the alloys, i.e. during casting in sand moulds. In isomorphous Cu–Ni alloy, with gradual increase in the electric current, first, the dendrites are refined; then, the refined dendrites are fragmented; and finally, the fragmented dendrites are refined. The ECT also reduces homogenisation treatment time. It is observed that a small amount of electric energy spent during sand casting saves considerable amount of energy for homogenisation treatment. The sand castings of Cu–Sn (peritectic) alloys are very much prone to interdendritic shrinkage. Thus, the density of castings is reduced. However, the ECT during casting increases the density of castings by reducing interdendritic shrinkage, modifies phase diagram of Cu–Sn alloy, increases volume fraction of the primary α phase (Cu) and reduces volume fraction of the peritectic phase. The ECT also refines the peritectic phase that transforms to δ phase on cooling to room temperature.

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“…C. M. Yen, W. J. Evans, R. M. Nowicki, and G. S. Sole [4] also studied the grain refinement and modification mechanism in Al-Si alloys with the help of a cooling curve and its 1st derivative. A. Prodhan and D. Sanyal [8] studied the solidification of aluminum with and without magnetic and electric fields by using a cooling curve and its derivative.…”

Section: Literature Reviewmentioning

confidence: 99%

Computer-aided cooling curve analysis of A356 aluminum alloy

2004

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Computer aided cooling curve analysis (CA-CCA) is very useful in the foundry industry for easy and fast evaluation of a variety of properties. Typical applications include the prediction of the temperatures and amounts of different phases appearing during solidification and monitoring of the quality of melt in terms of Si-modification, grain refinement, inoculation, and graphite spheoridization. The use of cooling curve analysis can be extended to many other areas of solidification also, assuming the calculated values are reasonably accurate. The calculation of zero curve, which is vital in cooling curve analysis, offers many problems however. In this study, an attempt was made to investigate the problems of zero curve calculation and a new method is suggested to minimize calculation errors. An in-house developed computer program was used for a complete analysis of aluminum alloy A356 to determine the latent heat and solid fraction values.

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Cited by 9 publications

References 1 publication

Direct Electrolytic Al-Si Alloys (DEASA) – An Undercooled Alloy Self-Modified Structure and Mechanical Properties

Direct Electrolytic Al-Si Alloys (DEASA) – An Undercooled Alloy Self-Modified Structure and Mechanical Properties

Semisolid processing of short and long freezing range Cu alloys by electric current

Computer-aided cooling curve analysis of A356 aluminum alloy

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