scholarly journals Melt Conditioned Direct Chill Casting (MC-DC) of Wrought Al-Alloys

2008 ◽  
Vol 141-143 ◽  
pp. 403-408 ◽  
Author(s):  
Reza Haghayeghi ◽  
Yuan Liu ◽  
Zhong Yun Fan
Keyword(s):  
Liquid Metal ◽  
Processing Parameters ◽  
Direct Chill ◽  
Al Alloys ◽  
Experimental Investigations ◽  
Chemical Compositions ◽  
Compositional Uniformity ◽  
New Development ◽  
Twin Screw ◽  
High Degree

Melt Conditioned Direct Chill (MC-DC) casting is a new development for producing high-quality billets and slabs. In the MC-DC process, liquid metal is continuously fed into a MCAST (melt conditioning by advanced shear technology) machine, where the liquid metal is subjected to high shear rate and high degree of turbulence provided by a twin screw mechanism at temperatures either above or below the alloy liquidus, and the conditioned liquid metal is then fed continuously into a Direct Chill (DC) caster to produce billets or slabs. The MC-DC process is applicable to both Al- and Mg-alloys. In this paper we present our experimental investigations of the effects of processing parameters on the microstructural and compositional uniformity of 5xxx and 7xxx series Al-alloys. It has been confirmed by our experiments that the MC-DC process can produce billets and slabs with fine and uniform microstructure, uniform chemical compositions and much reduced cast defects, such as porosity and cracks.

scholarly journals Petrogenetic and Compositional Features of Rare Metal Pan-African Post-Collisional Pegmatites of Southwestern Nigeria; A Status Review

2018 ◽  
Vol 7 (2) ◽  
pp. 166-187
Author(s):  
Abiola Oyebamiji ◽  
Adeniyi JohnPaul Adewumi ◽  
Tehseen Zafar ◽  
Adegbola Odebunmi ◽  
Philips Falae ◽  
...  
Keyword(s):  
Mineral Chemistry ◽  
Rare Metal ◽  
Border Zone ◽  
Chemical Compositions ◽  
Molten Material ◽  
Southwestern Nigeria ◽  
Pan African ◽  
Opening And Closing ◽  
High Degree ◽  
Rare Metal Pegmatite

Abstract This research reviews the geology, petrogenesis, compositional trends and geochronology of the rare-metal pegmatite of southwestern Nigeria. The source of these pegmatites is still presently debated which have been explained as either product of highly fractionated molten material or anatexis of the local crust. However, published works of past authors have been compiled to give a detailed understanding of the formation of the mineral deposits. The basement complex of southwestern Nigeria comprises of Precambrian rocks of amphibolite, the hornblende gneiss and the granite gneisses which were formed as a result of the opening and closing of the ensialic basin with significant, extensive subduction during the Pan-African orogeny. The pegmatites in this region have shown internal zoning and a high degree of evolution from the border zone to the core zone during the crystallization and solidification of the felsic granite to pegmatite melt. The rare-metal pegmatites have distinct chemical compositions and mineralogy, containing quartz, biotite, muscovite, microcline, garnet with localized tourmaline, tantalite and columbite. These pegmatites vary significantly by their bulk-rock and mineral chemistry which indicates a more peraluminous attribute and enrichments of lithophile elements of Rb, Cs, Ta and Ba. Previous K/Ar isotopic ages (502.8±13.0 Ma and 514.5±13.2 Ma) suggest that the pegmatites are related to the post-collisional phase of intensive metasomatism. Adopted from previous studies, a five-stage conceptual model of evolution which is widely accepted have been proposed for the origin of the pegmatites.

scholarly journals Use of Electrosprayed Agave Fructans as Nanoencapsulating Hydrocolloids for Bioactives

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 868 ◽  
Author(s):  
Jorge Ramos-Hernández ◽  
Juan Ragazzo-Sánchez ◽  
Montserrat Calderón-Santoyo ◽  
Rosa Ortiz-Basurto ◽  
Cristina Prieto ◽  
...  
Keyword(s):  
Uv Light ◽  
Particle Morphology ◽  
Bioactive Compound ◽  
Processing Parameters ◽  
Degree Of Polymerization ◽  
Spherical Particles ◽  
Sem Images ◽  
High Degree ◽  
Thermal Stability Of ◽  
Β Carotene

High degree of polymerization Agave fructans (HDPAF) are presented as a novel encapsulating material. Electrospraying coating (EC) was selected as the encapsulation technique and β-carotene as the model bioactive compound. For direct electrospraying, two encapsulation methodologies (solution and emulsion) were proposed to find the formulation which provided a suitable particle morphology and an adequate concentration of β-carotene encapsulated in the particles to provide a protective effect of β-carotene by the nanocapsules. Scanning electron microscopy (SEM) images showed spherical particles with sizes ranging from 440 nm to 880 nm depending on the concentration of HDPAF and processing parameters. FTIR analysis confirmed the interaction and encapsulation of β-carotene with HDPAF. The thermal stability of β-carotene encapsulated in HDPAF was evidenced by thermogravimetric analysis (TGA). The study showed that β-carotene encapsulated in HDPAF by the EC method remained stable for up to 50 h of exposure to ultraviolet (UV) light. Therefore, HDPAF is a viable option to formulate nanocapsules as a new encapsulating material. In addition, EC allowed for increases in the ratio of β-carotene:polymer, as well as its photostability.

Effect of Processing Parameters on Microstructure and Properties of Continuously Cast Al-Mg Sheets

2005 ◽  
Vol 482 ◽  
pp. 279-282 ◽  
Author(s):  
Margarita Slámová ◽  
P. Sláma ◽  
Petr Homola ◽  
Miroslav Karlík
Keyword(s):  
High Strength ◽  
Cost Effective ◽  
Processing Parameters ◽  
Direct Chill ◽  
Continuously Cast ◽  
Chill Cast ◽  
Direct Chill Cast ◽  
Twin Roll Cast ◽  
Twin Roll ◽  
Al Mg Alloys

Inner panels of modern ecological cars are nowadays manufactured from Al-Mg alloys. Continuously twin-roll cast sheets are a cost effective substitution for direct-chill cast sheets. The effect of composition and down-stream processing on sheet properties should be well understood in order to produce high quality products, which exhibit good formability and high strength. Finegrained microstructure and well-balanced texture are the necessary pre-requisites. Results of the investigation of twin-roll cast AlMg2Mn0.8 and AlMg3 alloys are reported. Sheets of 1.0 mm gauge were prepared using different processing routes. The route involving homogenisation results in grain coarsening and anisotropy, however, deep-drawing ability is affected only a little.

Effects of Processing Parameters on Microstructure and Properties of Aluminum-Silicon Alloy ADC12

2018 ◽  
Vol 777 ◽  
pp. 300-305
Author(s):  
Kasem Charoenrut ◽  
Chaiyasit Banjongprasert
Keyword(s):  
Mechanical Properties ◽  
Die Casting ◽  
Processing Parameters ◽  
Shrinkage Porosity ◽  
Process Conditions ◽  
Chemical Compositions ◽  
Silicon Alloy ◽  
Aluminum Silicon Alloy ◽  
Casting Pressure ◽  
Aluminum Silicon

Aluminum-Silicon Alloy, ADC12 is one of the most popular alloys for pressure die casting due to its high castability and high productivity. ADC12 is a hypoeutectic aluminum-silicon alloy that contains 10-12wt% of Si and has an occasional problem for a mechanical properties failure such as crack and shrinkage porosity. This study presents the investigation of the microstructure of ADC12 parts produced by pressured die casting with different process parameters and chemical compositions. The microstructure was observed using optical microscopy (OM) and scanning electron microscopy (SEM) with energy – dispersive X-ray (EDX) and electron backscatter diffraction (EBSD) to determine phases, grain, and crystallographic information in order to understand the microstructural evolution after die casting with different process conditions. Changes in casting pressure and a reduction of iron content contributed to enhanced mechanical properties and less shrinkage porosity. This was due to different processing parameters, mainly casting pressure. The average grain size of aluminum matrix was also reduced due to a higher pressure during casting with a moderately fast cooling rate.

scholarly journals Pultrusion of Micro-Braided GF/PA6 Yarn

1999 ◽  
Vol 8 (6) ◽  
pp. 096369359900800
Author(s):  
G. Bechtold ◽  
M. Sakaguchi ◽  
K. Friedrich ◽  
H. Hamada
Keyword(s):  
Bending Strength ◽  
Polyamide 6 ◽  
Processing Parameters ◽  
Experimental Investigations ◽  
Mechanical Characterisation ◽  
Reinforced Composite ◽  
Preheating Temperature ◽  
New Type ◽  
Commingled Yarns ◽  
Fibre Matrix

The present paper reports about experimental investigations on a new type of thermoplastic intermediate material (TP-prepreg). Today, most processes for producing fibre reinforced composite parts with thermoplastic matrices require expensive prepregs like pre-impregnated tapes or hybrid yarns (commingled yarns or powder impregnated yarns). The microbraiding technique offers some advantages compared to existing prepregs: Microbraided yarns can be produced directly by the user by a microbraiding process requiring only glass rovings and polymer rovings, and at the same time, the user is free of any restrictions on fibre/matrix combinations or reinforcement fibre content. Glass Fibre/Polyamide 6 (Nylon 6) microbraided yarn was compared to commercially available GF/PA6 tape concerning the use in a pultrusion process. For mechanical characterisation, shear strength and bending strength were determined. The processing parameters such as preheating temperature, heated die temperature and pulling speed were varied.

Physical Model of Aluminium Refining Process in the Batch and Continuous Reactors

2010 ◽  
Vol 654-656 ◽  
pp. 1553-1556 ◽  
Author(s):  
Mariola Saternus ◽  
Jan Botor
Keyword(s):  
Liquid Metal ◽  
Batch Reactor ◽  
Gas Bubbles ◽  
Physical Modelling ◽  
Processing Parameters ◽  
Refining Process ◽  
Continuous Reactor ◽  
Gas Dispersion ◽  
Uniform Dispersion ◽  
Over Dispersion

Both primary and secondary aluminium need to be refined. The most popular methods of aluminium refining is barbotage. This method is based on the introduction of refining gas bubbles into liquid metal. It can be done in batch or continuous reactors. The refining gas can be introduced to the metal by lances, ceramic porous plugs or rotary impellers. The gas bubbles generated in this way are then mixed with the liquid metal and the level of mixing depends on the processing parameters such as the flow rate of refining gas or the impeller speed. Five patterns of the refining gas dispersion in the liquid metal are known: no dispersion, minimal dispersion, intimate dispersion, uniform dispersion and over-dispersion. Physical modelling is the best way to visualize these kinds of dispersion. It also helps to choose the adequate processing parameters. However, it is also important to keep the dynamic and geometrical similarities to the refining process. In the paper the physical modelling of the aluminium refining process is presented. Two reactors: URO-200 batch reactor with a rotary impeller and URC-7000 continuous reactor with ceramic porous plugs were taken into consideration.

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