scholarly journals The Role of Acoustic Pressure during Solidification of AlSi7Mg Alloy in Sand Mold Casting

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 490 ◽  
Author(s):  
H. Puga ◽  
J. Barbosa ◽  
V. H. Carneiro
Keyword(s):  
Acoustic Pressure ◽  
Melt Processing ◽  
Cast Aluminum ◽  
Sand Cast ◽  
Cast Aluminum Alloys ◽  
Mold Casting ◽  
Acoustic Radiator ◽  
The Face ◽  
Numerical Approaches

New alloy processes have been developed and casting techniques are continuously evolving. Such constant development implies a consequent development and optimization of melt processing and treatment. The present work proposes a method for studying the influence of acoustic pressure in the overall refinement of sand cast aluminum alloys, using and correlating experimental and numerical approaches. It is shown that the refinement/modification of the α-Al matrix is a consequence of the acoustic activation caused in the liquid metal directly below the face of the acoustic radiator. Near the feeder, there is a clear homogeneity in the morphology of the α-Al with respect to grain size and grain circularity. However, the damping of acoustic pressure as the melt is moved away from the feeder increases and the influence of ultrasound is reduced, even though the higher cooling rate seems to compensate for this effect.

Ductility–Fatigue Life Relationships in Aluminum Alloy Castings: Role of Structural Quality

2019 ◽  
Author(s):  
Murat Tiryakioğlu ◽  
Hüseyin Özdeş
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Aluminum Alloys ◽  
Tensile Properties ◽  
Quality Factor ◽  
Structural Quality ◽  
Cast Aluminum ◽  
Cast Aluminum Alloys ◽  
Alloy Castings

The relationships between tensile properties and fatigue life in cast aluminum alloys have been reviewed. Strong relationships were found between fatigue life and the quality factor, QT, that uses tensile ductility to characterize structural quality for a number of cast aluminum alloys. The model developed by the authors to estimate the Basquin parameters as a function of QT is introduced along with a step-by-step guide on how to apply it to cast aluminum alloys. This model provides much more reliable estimates for cast aluminum alloys than other models available in the literature.

scholarly journals The Comparison of the Microstructure and Corrosion Resistance of Sand Cast Aluminum Alloys

2016 ◽  
Vol 61 (1) ◽  
pp. 209-212 ◽  
Author(s):  
A. Dobkowska ◽  
B. Adamczyk – Cieślak ◽  
J. Mizera ◽  
K. J. Kurzydłowski ◽  
A. Kiełbus
Keyword(s):  
Corrosion Behavior ◽  
Passive State ◽  
Chinese Script ◽  
Secondary Phases ◽  
Cast Aluminum ◽  
Sand Cast ◽  
Cast Aluminum Alloys ◽  
Different Types ◽  
Solid Solution Matrix ◽  
Solution Matrix

The influence of different types of precipitation on the corrosion behavior was investigated in three aluminum-siliconmagnesium alloys. The microstructures of the alloys were studied through optical (OM) and scanning electron microscopy (SEM). The structures consisted of an α-Al solid solution matrix, Si eutectic crystals, secondary phases AlFeSi and AlMgFeSi (Chinese script), as well as Mg2Si. The corrosion behavior was examined with the use of a potentiodynamic polarization test followed by a SEM surface analysis. The results indicate that all the analyzed samples were in the passive state and AlSi10Mg was less reactive in the corrosive environment.

The Role of Roller Speed on Solidification of Al-Mg-Si Alloy during Twin Roll Strip Casting

2015 ◽  
Vol 819 ◽  
pp. 15-19
Author(s):  
Hussain Zuhailawati ◽  
Masyitah Mt. Yusof ◽  
Anasyida Abu Seman ◽  
Indra Putra Almanar ◽  
Brij Kumar Dhindaw
Keyword(s):  
Induction Furnace ◽  
Low Cost ◽  
Strip Casting ◽  
Cast Aluminum ◽  
Casting Technique ◽  
Cast Aluminum Alloys ◽  
Strip Cast ◽  
Packaging Industry ◽  
Twin Roll

In the production of aluminum alloy strips for packaging industry twin roll strip casting technique is now being extensively employed. The twin roll caster has advantage of the energy saving, low cost equipment and rapid solidification. The present research aimed to investigate the microstructure and hardness of twin roll strip cast aluminum alloys strips by varying the speed of roller cast. Al-Mg-Si ingot was melt in an induction furnace. Once it melted, the liquid was poured into a crucible attached to a twin roller cast to maintain the liquid temperature at 700°C. Molten alloy was poured in the gap between the copper rollers to produce the strips. The rotational speed of the cast rolls was varied from 60-30 rpm. During this process, the melt solidified to form strips. A specimen of 50 mm length cut from the cast strips was subjected to physical and mechanical characterization. Variation in hardness and microstructure of the produced trip were discussed.

Questions on the role of biofilms for the adaptation of microorganisms to unfavorable environmental factors by the example of P. aeruginosa

2020 ◽  
Vol 99 (4) ◽  
pp. 379-383
Author(s):  
Vasily N. Afonyushkin ◽  
N. A. Donchenko ◽  
Ju. N. Kozlova ◽  
N. A. Davidova ◽  
V. Yu. Koptev ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Environmental Factors ◽  
Barrier Function ◽  
Infectious Agent ◽  
Antagonistic Activity ◽  
The Body ◽  
Main Function ◽  
Pathogenic Potential ◽  
The Face

Pseudomonas aeruginosa is a widely represented species of bacteria possessing of a pathogenic potential. This infectious agent is causing wound infections, fibrotic cystitis, fibrosing pneumonia, bacterial sepsis, etc. The microorganism is highly resistant to antiseptics, disinfectants, immune system responses of the body. The responses of a quorum sense of this kind of bacteria ensure the inclusion of many pathogenicity factors. The analysis of the scientific literature made it possible to formulate four questions concerning the role of biofilms for the adaptation of P. aeruginosa to adverse environmental factors: Is another person appears to be predominantly of a source an etiological agent or the source of P. aeruginosa infection in the environment? Does the formation of biofilms influence on the antibiotic resistance? How the antagonistic activity of microorganisms is realized in biofilm form? What is the main function of biofilms in the functioning of bacteria? A hypothesis has been put forward the effect of biofilms on the increase of antibiotic resistance of bacteria and, in particular, P. aeruginosa to be secondary in charcter. It is more likely a biofilmboth to fulfill the function of storing nutrients and provide topical competition in the face of food scarcity. In connection with the incompatibility of the molecular radii of most antibiotics and pores in biofilm, biofilm is doubtful to be capable of performing a barrier function for protecting against antibiotics. However, with respect to antibodies and immunocompetent cells, the barrier function is beyond doubt. The biofilm is more likely to fulfill the function of storing nutrients and providing topical competition in conditions of scarcity of food resources.

The Modern Aristotle: Michael Polanyi’s Search for Truth against Nihilism

2018 ◽  
Author(s):  
Ronald Hoinski ◽  
Ronald Polansky
Keyword(s):  
Philosophy Of Science ◽  
Modern Science ◽  
Michael Polanyi ◽  
Contemporary Philosophy ◽  
The Face ◽  
Human Desire ◽  
The Mind ◽  
Theoretical Science

David Hoinski and Ronald Polansky’s “The Modern Aristotle: Michael Polanyi’s Search for Truth against Nihilism” shows how the general tendencies of contemporary philosophy of science disclose a return to the Aristotelian emphasis on both the formation of dispositions to know and the role of the mind in theoretical science. Focusing on a comparison of Michael Polanyi and Aristotle, Hoinski and Polansky investigate to what degree Aristotelian thought retains its purchase on reality in the face of the changes wrought by modern science. Polanyi’s approach relies on several Aristotelian assumptions, including the naturalness of the human desire to know, the institutional and personal basis for the accumulation of knowledge, and the endorsement of realism against objectivism. Hoinski and Polansky emphasize the promise of Polanyi’s neo-Aristotelian framework, which argues that science is won through reflection on reality.

Expansion of borders in the Kurdistan region and local and regional positions

2019 ◽  
Vol 3 (11) ◽  
pp. 1
Author(s):  
Harith Qahtan Abdullah ◽  
Abbas Fadel Atwan
Keyword(s):  
Middle East ◽  
Central Government ◽  
Kurdistan Region ◽  
War On Terrorism ◽  
National State ◽  
The Face ◽  
In The Beginning

The borders of Kurdistan represent an important point in Kurdish thought. They represent the hope of establishing their national state. The circumstances of the war on terrorism in Iraq and Syria have led to the emergence of what is known as a "propaganda" and the formation of a global front in its struggle. And with the signs of the collapse of the Syrian state and the weakness of the Iraqi state in the face of the "dashing" in the beginning. These circumstances led to the emergence of the role of the Kurdistan region in the confrontation "ISIS" and maintain the administrative border in the three provinces of Kurdistan in addition to the province of Kirkuk. That the circumstances of the war on terrorism created new international conditions on the Middle East arena, which will generate many problems between the Kurdistan region and the central government of Baghdad, as well as other problems between the region, Syria, Turkey and Iran. The war on terrorism has made countries free to fight the opposition groups under the name Terrorism by their classification. The Turkish side is fighting the PKK within the borders of the Kurdistan region, and this war can develop in a post-"warlike" phase. The war in Syria is also contradictory to vision and not resolved to a specific side and Iran's position on developments is encouraging.

FAITH–BASED COMMUNITIES AND POLITICS IN DULLSTROOM-EMNOTWENI: LOCAL STORIES OF IDENTITY

2016 ◽  
Vol 1 (1) ◽  
pp. 45-57 ◽  
Author(s):  
Christina Landman
Keyword(s):  
Higher Education ◽  
Service Delivery ◽  
Special Focus ◽  
Traditional Role ◽  
Cultural Conflicts ◽  
Local Identities ◽  
Political Interests ◽  
Local Municipality ◽  
The Face

A majority of the black community of Dullstroom-Emnotweni in the Mpumalanga highveld in the east of South Africa trace their descent back to the southern Ndebele of the so-called ‘Mapoch Gronden’, who lost their land in the 1880s to become farm workers on their own land. A hundred years later, in 1980, descendants of the ‘Mapoggers’ settled in the newly built ‘township’ of Dullstroom, called Sakhelwe, finding jobs on the railways or as domestic workers. Oral interviews with the inhabitants of Sakhelwe – a name eventually abandoned in favour of Dullstroom- Emnotweni – testify to histories of transition from landowner to farmworker to unskilled labourer. The stories also highlight cultural conflicts between people of Ndebele, Pedi and Swazi descent and the influence of decades of subordination on local identities. Research projects conducted in this and the wider area of the eMakhazeni Local Municipality reveal the struggle to maintain religious, gender and youth identities in the face of competing political interests. Service delivery, higher education, space for women and the role of faith-based organisations in particular seem to be sites of contestation. Churches and their role in development and transformation, where they compete with political parties and state institutions, are the special focus of this study. They attempt to remain free from party politics, but are nevertheless co-opted into contra-culturing the lack of service delivery, poor standards of higher education and inadequate space for women, which are outside their traditional role of sustaining an oppressed community.

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