The United Kingdom of England

Campbell, James

doi:10.4324/9780203434826_chapter_3

Cited by 21 publications

(7 citation statements)

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“…The net volume flow rate of liquid entering , on the other hand, is the volume flow rate of liquid entering minus that leaving . When the net volume expansion rate of exceeds the net volume flow rate of liquid entering , a void (i.e., crack) can occur in  [5] if crack initiation sites are available, such as folded oxide films, micropores or the external surface of the weld or casting [3,6,7]. Kou [5] showed that near f S = 1 the lateral growth rate of grains toward each other to bond together to resist cracking is proportional to │d(f S ) 1/2 /dT│, where T is temperature and f S fraction of solid.…”

Section: Introductionmentioning

confidence: 99%

Evidence of back diffusion reducing cracking during solidification

2017

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Al-Mg alloys, despite their wide freezing temperature range T f , can have good resistance to cracking during solidification. To help understand why, the mushy zone of 5086 Al (~ Al-4.0Mg) was quenched during arc welding and the cooling curve measured to locate the beginning of the original mushy zone (liquidus temperature T L) and the end (eutectic temperature T E). Since little eutectic was visible just slightly behind the beginning of the quenched mushy zone, little liquid was here in the original mushy zone, i.e., solidification already ended well above T E. Since no dendrites were visible, either, and since the highest Mg content measured was well below the maximum solubility in solid Al, C SM (17.5 wt% Mg), microsegregation was very mild here in the original mushy zone. These results suggest significant Mg back diffusion occurred during solidification (because of very high C SM), causing: 1. fraction solid f S to increase much faster with decreasing temperature T, 2. T f to narrow down, and 3. dendritic grains to bond together extensively (f S ≈ 1) to resist intergranular cracking earlier (well above T E). Since │d(f S)/dT│ increased, │dT/d(f S) 1/2 │ decreased to decrease the crack susceptibility index, i.e., the maximum │dT/d(f S) 1/2 │. All these changes reduce the crack susceptibility. For comparison, 2014 Al (~ Al-4.4Cu) was also quenched during arc welding. At the end of the quenched 2014 Al mushy zone, continuous eutectic, dendrites and microsegregation were all very clear. Thus, solidification ended at T E and thin liquid films still separated grains at the end of the original mushy zone to allow intergranular cracking. Calculated T-(f S) 1/2 curves showed the index is reduced significantly by back diffusion in Al-4.0Mg (~ 5086 Al) but not in Al-4.4Cu (~ 2014 Al).

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Section: Introductionmentioning

confidence: 99%

Evidence of back diffusion reducing cracking during solidification

2017

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“…Cetakan pasir mampu menahan temperatur tinggi dan menghasilkan produk cor berdinding tipis dengan menggunakan pengikat/binder anorganik seperti silika (SiO2), sodium hydroxide (NaOH) dan sodium okside (Na2O). Karakteristik penting dari pasir sebagai bahan refraktori alami adalah mampu menahan suhu tinggi saat bertemu dengan cairan logam dan terjadi penggabungan dengan cairan [4].…”

Section: Pendahuluanunclassified

Daur Ulang Pasir Silika Bekas Inti Cor Melalui Teknik Ball Mill Untuk Mengembalikan Daya Ikatnya

Slamet¹,

Bastian²

2018

Simet

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ABSTRAKTeknik pengecoran merupakan metode pembentukan material logam yang sudah lama dikenal oleh manusia. Metode ini mempunyai banyak keuntungan yaitu dapat menghasilkan benda sesuai dengan aslinya, tidak dibatasi leh ukuran dan sesuai untuk produk massal. Media yang sering digunakan adalah pasir dan sebagian pola dilengkapi dengan inti cor. Pasir silika digunakan pengrajin cor untuk membuat inti cor. Pasir silika ini hanya bisa digunakan untuk sekali pakai untuk satu cetakan. Pasir silika tidak dapat digunakan lagi karena tidak mempunyai daya ikat antar partikelnya. Metode yang dilakukan adalah menghancurkan kembali bongkahan pasir inti bekas cor ke dalam mesin ball mill dengan variasi kecepatan putar, waktu giling, diameter dan jumlah bola baja yang digunakan per 1000 gr. Pasir silika selanjutnya dilakukan pengayakan dengan menggunakan mesh 100 dan 150. Hasil penggilingan dengan teknik ball mill menunjukkan bahwa kecepatan putar mesin ball mill yang meningkat tidak secara signifikan meningkatkan prosentase hasil. Penambahan waktu giling mampu meningkatkan prosentase hasil untuk semua ukuran mesh. Penambahan waktu giling dari 30 menjadi 60 menit pada kecepatan putar yang sama dan penambahan diameter bola dari 20 menjadi 25 mm mampu meningkatkan 14,10% lebih tinggi pada mesh 100. Perlakuan yang sama dengan mesh 150 terjadi peningkatan sebesar 3,88%. Pasir silika daur ulang digunakan untuk membuat kembali inti cor. Semakin kecil ukuran mesh pasir silika menunjukkan ikatan partikel yang lebih kuat dengan bentuk pola inti yang lebih sempurna.Kata kunci: ball mill, pasir silika, inti cor, pengecoran logam, mesh. ABSTRACTCasting technique is a method of forming metal material that has long been known by humans. This method has many advantages that can produce objects in accordance with the original, not limited to size and suitable for bulk products. Media that is often used is sand and some patterns are equipped with cast core. Silica sand is used to make cast core. This silica sand can only be used for single use for one mold. cast core silica sand is not usable again because it has no binding power. The method used is to destroy the cast core again into ball mill machine with variation of rotation speed, milling time, diameter and number of steel balls used per 1000 gr. The silica sand is further carried out by using mesh 100 and 150. The results with ball mill technique show that the speed of rotary ball mill machine increased not significantly increase the percentage of results. The addition of milling time can increase the yield percentage for all mesh sizes. The addition of milling time from 30 to 60 minutes at the same rotational speed and the addition of spherical diameter from 20 to 25 mm can increase 14.10% higher at mesh 100. The same treatment with mesh 150 has increased by 3.88%. Recycled silica sand is used to rebuild the cast core. The smaller the size of the silica sand mesh shows stronger particle bonds with a more perfect core shape.

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“…ЄСПЛ неодноразово зазначав, що поняття «суд» у контексті права на справед-ливий судовий розгляд не обов'язково має розумітися як суд класичного типу, інтегрований у стандартну систему судів держави [11]. Воно має розглядатися в сутнісному сенсі цього слова відповідно до його судових функцій [12].…”

Section: цивільне право і цивільний процесunclassified

The Recognition and Enforcement of Foreign Judgements in Civil Cases in the Context of Practice of European Court of Human Rights

Tsuvina

2017

Problems of Legality

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The United Kingdom of England

Cited by 21 publications

References 0 publications

Evidence of back diffusion reducing cracking during solidification

Evidence of back diffusion reducing cracking during solidification

Daur Ulang Pasir Silika Bekas Inti Cor Melalui Teknik Ball Mill Untuk Mengembalikan Daya Ikatnya

The Recognition and Enforcement of Foreign Judgements in Civil Cases in the Context of Practice of European Court of Human Rights

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