In this research the effect of cooling rate and mold type on mechanical properties of the eutectic
and hypoeutectic (Al-Si) alloys has been studied. The alloys used in this research work were (Al- 12.6%Si
alloy) and (Al- 7%Si alloy).The two alloys have been melted and poured in two types of molds with
different cooling rates. One of them was a sand mold and the other was metal mold. Mechanical tests
(hardness, tensile test and impact test) were carried out on the specimens. Also the metallographic
examination was performed.
It has been found that the values of hardness for the alloys(Al-12.6%Si and Al-7%Si) which poured in
metal mold is greater than the values of hardness for the same alloy when it poured in a heated metal
mold at different temperatures or in sand mold. The strength and impact resistance for the alloys (Al-
12.6%Si and Al-7%Si) are greater when these were poured in a metal molds than that when it poured in a
sand mold.
Furthermore, the higher cooling rates enhance the strength, hardness and impact resistance for the
two alloys, while the low cooling rates reduces these mechanical properties.
The percentage of elongation and the amounts of formed porosity decreased when the cooling rates
increased
The development of a future mechanism for sustainable development in Iraq to meet the current and future challenges requires an analysis of the indicators of sustainable development. This research aims at presenting and analyzing the social care aspect and highlighting the important role of taxes with a focus on social sustainable development to determine the extent and direction of changes. Level of progress, the researcher concludes the weakness of the financial allocations to the Ministry of Labor and Social Affairs and in line with the large number of people who apply the conditions and controls, and recommends the researcher the necessity of participation of all segments of society between the public and private sector In terms of o
... Show MoreVarious assays are used to determine the toxic effects of drugs at cellular levels in vitro. One of these methods is the dye exclusion assay, which measures membrane integrity in the presence of Trypan blue. Trypan blue the dye which was used in this study to investigate cytotoxic effect of a new Cis –dichloroplatinum (II) complex [(Qu)2PtCl2] on the viability of polymorphonuclear cells (PMNs). Three concentrations of platinum complex were prepared (70, 35and 17.5 µg/ ml) and the results revealed that the percentage of cell viability decreased as the platinum complex concentration increased in comparison with control.
... Show MoreThis research investigates manganese (Mn) extraction from Electric Arc Furnace Steel Slag (EAFS) by using the Liquid-liquid extraction (LLE) method. The chemical analysis was done on the slag using X-ray fluorescence, X-ray diffraction, and atomic absorption spectroscopy. This work consisted of two parts: the first was an extensive study of the effect of variables that can affect the leaching process rate for Mn element from slag (reaction time, nitric acid concentration, solid to liquid ratio, and stirring speed), and the second part evaluates the extraction of Mn element from leached solution. The results showed the possibility of leaching 83.5 % of Mn element from the slag at a temperature of 25°C, nitric acid co
... Show MoreCommercial banks represent the main pivot in financing national economic activity and its development. The capital represents safety margin to depositors and represents a defense line that protects bank work from dangers. Basel committee requirements represent protection and comprehensive supervision to bank activities for depositors, debtors and the bank. It provides trust in bank dealings and tackles activities of high dangers. The most prominent of these requirements are capital adequacy that concerns bank management and supervision and auditing bodies such as the central bank and protecting banks that suffer weakness in its vital important borrowing activity that reflects weakness in implementing borrowing policy .The purpose
... Show MoreA new class of higher derivatives for harmonic univalent functions defined by a generalized fractional integral operator inside an open unit disk E is the aim of this paper.
The research aims to measure the relationship and impact of the operations of the knowledge of management of the six dimensions (diagnosis knowledge, define knowledge objectives, knowledge generation, knowledge storage, distribution of knowledge, application of knowledge) in the fiscal performance of the General Authority for taxes of the four dimensions (financial, customers (taxpayers), Operations Interior, learn and grow), the research aims also to the use of computerized programs for training and career development of the Authority that helps to add knowledge workers in the Authority, and to reach an appropriate arrangement for knowledge management processes in the Authority, as well as analysis of the reality of the Authority to get
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Natural convection in an annular space provided with metal foam fins attached to the inner cylinder is studied numerically. The metal foam fins made of copper were inserted in different axial sections with three fins in each section. The temperature of the inner cylinder is kept constant while the annular outer surface is adiabatic. The thickness effect of the inner pipe wall was considered. Naiver Stokes equation with Boussinesq approximation is used for the fluid regime while Brinkman-Forchheimer Darcy model is used for metal foam. In addition, the local thermal non-equilibrium condition in the energy equation of the porous media is presumed. The effect of Rayleigh numb |