Characteristics and Formation Mechanism of Segregation During the Solidification of Aluminum Alloy with Ultrasonic Radiation

An industrial experiment was carried out to study the characteristics and formation mechanism of segregation in semi-continuous direct-chill (DC) casting ofΦ300mmaluminum alloybillet with ultrasonic radiation of different powers. Results show that both microsegregation and macrosegregation of solute elements Zn, Mg, Cu are improved remarkably when ultrasonic vibration is applied to A1-Zn-Mg-Cu alloy. Meanwhile, the higher power of ultrasonic vibration is, the more homogeneous distribution of solute elements becomes, and then the more effective improvement of segregation is achieved. With a 240W ultrasonic treatment (UST), the intra-grain solution degree of elements Zn, Mg and Cu increases by 35.8%, 41.8% and 40.2% respectively while the macrosegregation ratio decreases by 10.3%, 7.4%, 6.7%. Physical and chemical effects caused by ultrasonic field exert a positive impact on the solute elements diffusion, grain refinement, the depth of sump and solution degree et al, which contribute to the improvements of segregation.

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Microstructures and Macrosegregation of Al–Zn–Mg–Cu Alloy Billet Prepared by Uniform Direct Chill Casting

Materials ◽

10.3390/ma14040708 ◽

2021 ◽

Vol 14 (4) ◽

pp. 708

Author(s):

Li Zhou ◽

Yajun Luo ◽

Zhenlin Zhang ◽

Min He ◽

Yinao Xu ◽

...

Keyword(s):

Mold Wall ◽

Direct Chill ◽

Element Distribution ◽

Direct Chill Casting ◽

Electromagnetic Stirring ◽

Alloying Elements ◽

Alloying Element ◽

Casting Method ◽

Chill Casting ◽

Cu Alloy

In this study, large-sized Al–Zn–Mg–Cu alloy billets were prepared by direct chill casting imposed with annular electromagnetic stirring and intercooling; a process named uniform direct chill casting. The effects of uniform direct chill casting on grain size and the alloying element distribution of the billets were investigated and compared with those of the normal direct chill casting method. The results show that the microstructures were refined and the homogeneity of the alloying elements distribution was greatly improved by imposing the annular electromagnetic stirring and intercooling. In uniform direct chill casting, explosive nucleation can be triggered, originating from the mold wall and dendrite fragments for grain refinement. The effects of electromagnetic stirring on macrosegregation are discussed with consideration of the centrifugal force that drives the movement of melt from the central part towards the upper-periphery part, which could suppress the macrosegregation of alloying elements. The refined grain can reduce the permeability of the melt in the mushy zone that can restrain macrosegregation.

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Investigation of the Formation Mechanism and Environmental Risk of Tire—Pavement Wearing Waste (TPWW)

Sustainability ◽

10.3390/su13158172 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8172

Author(s):

Kechen Wang ◽

Xiangyu Chu ◽

Jiao Lin ◽

Qilin Yang ◽

Zepeng Fan ◽

...

Keyword(s):

Formation Mechanism ◽

Organic Contaminants ◽

Asphalt Mixture ◽

Fine Fraction ◽

Crumb Rubber ◽

Environmental Benefit ◽

The Road ◽

Open Graded Friction Course ◽

Volatile Alkanes ◽

Physical And Chemical

Tire—pavement interaction behaviours result in large amounts of wearing waste matter, which attaches to the surface of the pavement and is directly exposed to the surrounding environment. This kind of matter imposes a great challenge to the environment of the road area. The current study is devoted to carrying out a comprehensive investigation of the formation mechanism of tire—pavement wearing waste (TPWW), as well as the resulting environmental risks. A self-developed piece of accelerated polishing equipment, the Harbin advanced polishing machine (HAPM), was employed to simulate the wearing process between vehicle tires and pavement surfaces, and the TPWW was collected to conduct morphological, physical, and chemical characterisations. The results from this study show that the production rate of TPWW decreases with the increase in polishing duration, and the coarse particles (diameters greater than 0.425 mm) account for most of the TPWW obtained. The fine fraction (diameter smaller than 0.425 mm) of the TPWW comprises variously sized and irregularly shaped rubber particles from the tire, as well as uniformly sized and angular fine aggregates. The environmental analysis results show that volatile alkanes (C9–C16) are the major organic contaminants in TPWW. The Open-Graded Friction Course (OGFC) asphalt mixture containing crumb rubber as a modifier showed the highest risk of heavy metal pollution, and special concern must be given to tire materials for the purpose of improving the environmental conditions of road areas. The use of polyurethane as a binder material in the production of pavement mixtures has an environmental benefit in terms of pollution from both organic contaminants and heavy metals.

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Study on Over-Burnt Temperature and Heat Treatment of a New Al-Mg-Si-Cu Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.284-286.1516 ◽

2011 ◽

Vol 284-286 ◽

pp. 1516-1519

Author(s):

Yi Meng ◽

Zhi Hao Zhao ◽

Jian Zhong Cui

Keyword(s):

Heat Treatment ◽

Aluminum Alloy ◽

Homogenization Temperature ◽

Microstructure Analysis ◽

Cu Alloy ◽

Homogenization Time ◽

The Way

The over-burnt temperature of a new Al-Mg-Si-Cu Aluminum alloy was studied by means of DSC and microstructure analysis, as a result of the homogenization temperature being obtained. A favorable homogenization time was got by the way of the dependence of area fractions of remnant phases on homogenization time being calculated. According to experimentation results, the over-burnt temperature of the new Al-Mg-Si-Cu Aluminum alloy was 570°C, and the way to homogenize the new alloy at 560°C for 24h was excellemt.

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OBTAINING FRUIT AND BERRY EXTRACTS WITH HIGH ANTIOXIDANT ACTIVITY WHEN USING ULTRASONIC RADIATION

Известия вузов. Пищевая технология ◽

10.26297/0579-3009.2018.4.12 ◽

2018 ◽

Author(s):

Н.Б. ЕРЕМЕЕВА ◽

Н.В. МАКАРОВА

Keyword(s):

Antioxidant Activity ◽

Raw Materials ◽

Matter Content ◽

Dry Matter Content ◽

Black Currant ◽

Ultrasonic Radiation ◽

Microbiological Parameters ◽

High Antioxidant Activity ◽

Berry Extracts ◽

Physical And Chemical

Подобраны оптимальные параметры для экстракции плодов и ягод черной смородины, малины, вишни, черноплодной рябины при ультразвуковом излучении 35 кГц с целью получения плодово-ягодных экстрактов с высокой антиоксидантной активностью. На основании экспериментальных данных выбраны технологические режимы процесса: экстрагирование сырья 75%-м этиловым спиртом при соотношении сырье : растворитель 1 : 10, температуре (40 ± 5)°C в течение 90 мин. Экстракты концентрируют под вакуумом до содержания сухих веществ 65%. Дана технологическая схема получения плодово-ягодных экстрактов. Полученные экстракты обладают высокой антиоксидантной активностью, содержат большое количество фенольных веществ, флавоноидов и антоцианов; по органолептическим, физико-химическим и микробиологическим показателям соответствуют нормативной документации. The optimal parameters for extraction of fruits and berries of fruits and berries of black currant, raspberry, cherry, chokeberry with ultrasonic radiation of 35 kHz in order to obtain fruit and berry extracts with high antioxidant activity are selected. Based on the experimental data, the technological modes of the process are selected: extraction of raw materials with 75% ethyl alcohol at a ratio of raw materials: solvent 1: 10, temperature (40 ± 5)°C for 90 min. The extracts are concentrated under vacuum to a dry matter content of 65%. Technological scheme of fruit and berry extracts is given. The obtained extracts have a high antioxidant activity, contain a large amount of phenolic substances, flavonoids and anthocyanins; organoleptic, physical and chemical and microbiological parameters correspond to the normative documentation.

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Investigation of surface topography formation mechanism based on abrasive-workpiece contact rate model in tangential ultrasonic vibration-assisted CBN grinding of ZrO2 ceramics

International Journal of Mechanical Sciences ◽

10.1016/j.ijmecsci.2019.02.031 ◽

2019 ◽

Vol 155 ◽

pp. 66-82 ◽

Cited By ~ 12

Author(s):

Zhichao Yang ◽

Lida Zhu ◽

Chenbing Ni ◽

Jinsheng Ning

Keyword(s):

Surface Topography ◽

Ultrasonic Vibration ◽

Formation Mechanism ◽

Contact Rate ◽

Rate Model

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Fabrication of the Aluminum Matrix Composite by Ultrasonic Infiltration Technique

Materials Science Forum ◽

10.4028/www.scientific.net/msf.475-479.921 ◽

2005 ◽

Vol 475-479 ◽

pp. 921-924 ◽

Cited By ~ 3

Author(s):

Gen Sasaki ◽

Junichi Adachi ◽

Yong Bum Choi ◽

Jin Pan ◽

Toshio Fujii ◽

...

Keyword(s):

Aluminum Alloy ◽

Ultrasonic Vibration ◽

Molten Aluminum ◽

Polyester Resin ◽

Glass Plate ◽

Aluminum Matrix ◽

Casting Process ◽

Aluminum Borate ◽

Glass Capillary ◽

Molten Aluminum Alloy

In order to infiltrate the molten aluminum alloy to the reinforcement preform by low pressure in casting process and acquire the high performance composites with high density, the effect of the ultrasonic vibration on the infiltration was investigated by model experiments using clear solution and glass or aluminum borate preform, which is correspond to a molten matrix and reinforcement, respectively. Ultrasonic vibration improves the wettability of liquid polyester resin on glass plate, dramatically. The final infiltration height and infiltration speed of liquid polyester resin in glass capillary were improved by the ultrasonic vibration. Furthermore, the infiltration speed of water to aluminum borate preform accelerated by ultrasonic vibration. This effect was more remarkable, when the infiltration height is lower or infiltration time is shorter. In actual, the molten aluminum alloy infiltrate to SiC preform using ultrasonic vibration easily and acquire the high dense composites without pores.

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