Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : microstructure


Evaluation of the Microstructure and Mechanical Properties of Al / Fe3O4 Nanocomposites

Suaad M. Jiaad; Khansaa Salman; Ahmed A. Hussein

Engineering and Technology Journal, 2021, Volume 39, Issue 11, Pages 1632-1638
DOI: 10.30684/etj.v39i11.2080

The goal of this research is to study the microstructural analysis and mechanical properties of an aluminum matrix reinforced with different amounts of nano Fe3O4 at (2, 4, 6, 8, and 10wt. %). Al/ Fe3O4 nanocomposites specimens were prepared using the powder metallurgy route. Many examinations, including Field Emission Scanning Electron Microscopy (FESEM) and X-Ray Diffraction (XRD) analysis, were performed on the specimens in this study to determine the microstructure and phases of the nanocomposites. Mechanical tests, such as compressive, microhardness, and wear tests, were also performed to assess the mechanical properties of the nanocomposites. The results of this study show that Fe3O4 nanoparticles have been homogeneously dispersed in the Al matrix by FESEM and XRD examination. While the mechanical tests show improving the compressive strength at 6 wt.% by 5.36%, the highest microhardness was at 10% by 101.6% compared with the pure Al, and improving the wear rate.

Investigating The Effect of Magnetite (Fe3O4) Nanoparticles on Mechanical Properties of Epoxy Resin

Ehab Kaadhm; Khansaa D. Salman; Ahameed Hameed Raja

Engineering and Technology Journal, 2021, Volume 39, Issue 6, Pages 986-995
DOI: 10.30684/etj.v39i6.2063

In this paper, study the effects of magnetite nanomaterial Fe3O4 on the mechanical properties of epoxy. Dispersion of Fe3O4 nanoparticles in the epoxy resin was performed by ultrasonication. The samples of the nanocomposites were prepared using the casting method. The nanocomposites contain epoxy resins as a matrix material incorporated by different weight percentages of magnetite Fe3O4 that varies from 0wt.% to 15wt.% as a reinforcing material. The epoxy with the additive reinforcement materials Fe3O4 was slowly mixed in a sonication bath for 15 minutes, then the mixture poured into silicon molds. Field Emission Scanning Electron Microscopy FESEM and X-ray diffraction spectra XRD were used to characterize the morphological and structural properties of preparing samples and the distribution of Fe3O4 nanoparticles to the epoxy resin. Mechanical testing consists of tensile, hardness shore, and three-point flexural tests were performed on the samples at room temperature according to ASTM standards. The results showed that reinforcement by 15wt.% of Fe3O4 nanoparticles maximizes these mechanical properties of nanocomposites compared with pure epoxy except for the young modulus's preferred weight at 9 wt.%, this is due to aggregation of the additives nanomaterials in epoxy resin above 9 wt.%.

Effect of ZrO2 Addition on Microstructure and Mechanical Properties of Al-Zn-Mg Alloy Matrix Composite

Israa A. Aziz; Russul S. Bedien

Engineering and Technology Journal, 2020, Volume 38, Issue 12, Pages 1751-1757
DOI: 10.30684/etj.v38i12A.336

Aluminum – based metal matrix composite are widely used in industrial applications compared with conventional and unreinforced alloy. The composite materials usually exhibit a higher strength both at elevated and ambient temperature, as well as wear resistance. The production of composite materials which contain different weight percentage of ZrO2 (0.5, 1.5 and 2.5wt %) by stir casting process. The mechanical properties of the base alloy and composite were evaluated by using tensile and hardness tests. The microstructure inspection by optical microscopy, scanning electron microscope and energy dispersive spectroscopy (EDS) were utilized to study the fracture surface topography. The results represent that the hardness, strength of yield and tensile strength increased with increasing the weight % of ZrO2 to 2.5 % while the elongation decreased. The microstructure inspection by optical microscope shows that the dendrites structure and the particles distribution in matrix without any voids. Furthermore, the grain size refining with the weight percentage of weight reinforcement elevated.

Effect of Filler Metals on Microstructure and Mechanical Properties of GTAW Welded Joints of Aluminum Alloy (AA2024-T3)

Muna K. Abbass; Jihad G. Abd Ul-Qader

Engineering and Technology Journal, 2020, Volume 38, Issue 8, Pages 1236-1245
DOI: 10.30684/etj.v38i8A.1277

This study presents an appropriate filler metal or welding electrode to join aluminum alloy (AA2024-T3) sheet of 3.2 mm thickness with a square butt joint using Gas Tungsten Arc Welding (GTAW) process. This process was carried out at three different welding currents with three various filler metals: ER4047 (12% Si), ER4043 (5% Si), and ER5356 (5% Mg). Experiments were conducted to investigate the microstructure and the mechanical properties. The effect of various filler metals upon the weld joints quality were analyzed via an X-ray radiographic and tensile test. Hardness test, microstructures, SEM, and XRD also conducted to the welded specimens. It was found that the best result was at 100 Ampere with using filler metal (ER5356) which produced the highest strength of 240 MPa in comparison with welded joints with utilizing fillers (ER4043) and (ER4047) having values of 235 MPa and 225 MPa, correspondingly. The hardness results showed that the highest hardness values were at the weld metal for ER4047 and ER4043, then decreased to HAZ and increased in the base metal. While in the case of ER5356, the highest hardness was in HAZ and decreased in the weld metal. The fractography of the fracture surface of the welded joints after the tensile test was analyzed using SEM

Studying Wear Behavior of Ni-Ti- Ag Shape Memory Alloy Synthesized by P/T

Suad A. Shihab; Khansaa D. Salman; Laith J. Saud

Engineering and Technology Journal, 2020, Volume 38, Issue 6, Pages 846-853
DOI: 10.30684/etj.v38i6A.463

Because of the unique properties, Ni-Ti based shape memory alloys (SMAs) are increasingly attractive for a wide variety of engineering applications such as actuators, biomedical, or robot coupling. In this work, a third alloying element, namely nanoparticles of Ag (which is insoluble in Ni-Ti matrix), is added by powder technology to the Ni-Ti alloy to produce a Ni-Ti-Ag alloy. The Nanoparticles of the Ag element are added at 3, 5, 7, and 10 wt. % to produce four alloy specimens with different mixtures .The mixing process was done by a horizontal mixer for 120 min with a speed of 350 rpm, and then the mixture was compacted by using a compacting pressure of 600 MPa. Afterward, the compacted specimens were sintered at 600 /min for 6 hrs. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to evaluate the microstructure and phases of the products. DSC examination was used to characterize the phase transformation temperatures in heating and cooling. Wear behavior was defined by using the pin-on-disc technique, and the hardness of the samples was calculated using Vickers's hardness apparatus. The results of this work showed that the nano-Ag added at 7 and 10 wt. % were distributed homogeneously in the Ni-Ti matrix, and that Ag slightly decreased hardness and increased the wear rate. The value of shape memory effect (SME) for the produced alloy was about 89.9% and the phase transformation in heating was at a temperature of about 186.48 and in cooling of about 140.3 for the specimen that contains 10 wt.% Ag nanoparticles.

Study the Microstructure and Mechanical Properties of High Chromium White Cast Iron (HCWCI) under Different Martempering Quenching Mediums

Ali H. Ataiwi; Zainab A. Betti

Engineering and Technology Journal, 2019, Volume 37, Issue 4A, Pages 112-119
DOI: 10.30684/etj.37.4A.1

The aim of this study is to find an alternative quenching medium for the ordinary nitrate mixture that is cheaper and more available in Iraqi markets. So to obtain the suitable medium , the  effect of different quenching mediums used in martempering treatment on the microstructure and mechanical properties of  high chromium white cast iron was studied  . This type of cast iron is used in mining ,crushing and cement plants as mill liners so it is subjected to extreme conditions of wear and impact that eventually cause failure . In this study, two types of quenching mediums were used in martempering treatment: (50% Sodium hydroxide + 50 % potassium hydroxide) mixture and (50% Sodium nitrate + 50 % potassium nitrate) mixture with different quenching intervals. It is  also found that both of the quenching mediums produce higher hardness values at 350°C martempering temperature for 4 hr quenching time ,but there were several advantages and disadvantages associated with using these two different mediums

Strength Evaluation of CO2-Cured Cellulose Date Palm Fiber Reinforced Cementitious Boards

Maan Salman Hassan; Shakir Ahmed Salih; Isam Mohamad Ali

Engineering and Technology Journal, 2016, Volume 34, Issue 6, Pages 1029-1046

In recent years there has been an increasing demand to recycle wastes produced by the agricultural and industrial processing. The aim of this paper is to investigate the suitability of date palm (Phoenix dactylifera) as lignocellulosic materials for the production of wood-cement composite boards, in addition to enhance their compatibility with cement using physical pretreatment processes and accelerated carbonation curing.
Experiments were performed to assess the physical properties (as density, flexural strength, toughness and E-modulus), and micro structural properties (as determined by scanning electron microscopy) of the produced cement boards. The results show an improvement in the physical and microstructural properties of cellulosic fiber-cement composites by using accelerated CO2 curing method. In addition, excessive carbonation rate associated with pure gas carbonation does not necessarily lead to high strength and even detrimental strength development was found, which was shown by cement paste.

The Influence of Microstructure on the Corrosion Rate of Carbon Steels

Sami I. Al-rubaiey; Eman A. Anoon; Mahdi M. Hanoon

Engineering and Technology Journal, 2013, Volume 31, Issue 10, Pages 1825-1836

This paper presents the influence of carbon steel microstructure on the corrosion rates. Four types of microstructures have obtained by quenching and tempering and iso-thermal annealing. These microstructures are:
banded ferrite/pearlite microstructure, fine ferrite/pearlite microstructure, coarse ferrite/pearlite microstructure and tempered martensite microstructure.
General corrosion and localized corrosion (penetration rates) were determined via mass loss and optical microscopy. The different microstructures of steels investigated in this paper revealed corrosion rate variations of 0.8– 3.2 mm y-1 and 3.3–6.4 - mm y-1 for the general and localized forms, respectively. The corrosion stability of the various microstructures may arise from variations of phases within the steel. A banded ferrite/pearlite microstructures have worse general corrosion properties, while tempered martensite worse microstructures have localized pitting corrosion properties. Coarse ferrite/pearlite microstructures have better localized pitting corrosion resistances compared to others investigated microstructures This paper has demonstrated that, microstructure is an important consideration when selecting carbon steel for an industrial corrosion resistance application.

Microstructure and Hardness Effects on Behavior of Copper Alloy under Creep – Fatigue Interaction

Mairb R. Abdul Hassan

Engineering and Technology Journal, 2011, Volume 29, Issue 9, Pages 1641-1650

The microstructure and hardness of copper alloy after fatigue-creep interaction
testing have been investigated. Experiments were carried out in the temperature
range from room temperature to 300oC. Attention has been paid to the role of the
microstructure and hardness on the fatigue-creep strength of copper alloy. It has
been shown that, there is a little effect of microstructure in the cyclic response of
copper alloy, while the hardness has a significant effect on the fatigue-creep
strength. The relation between strength and hardness were described by the
following equation:
σE.L. = 5.345 H0.6217

Effect of Pb and Sn Adding on Dry Sliding Wear Behavior of á-Brass (70/30)

Engineering and Technology Journal, 2009, Volume 27, Issue 7, Pages 258-268

This work is concerned with a study of dry sliding wear of α–Brass (70/30) with
addition of lead and tin(3%wt) for each one alloy. Three brass alloys were prepared by
melting and pouring in steel molds. A Pin -on-Disc technique was used. The effect of
applied loads and sliding times on wear rate were examined. The results show that the
wear rate increases with increasing applied loads and with increasing sliding time at
constant sliding speed (2.7m/s) while hardness of steel disc was 35 HRc .
The results also show that the brass alloy containing 3% tin has more
wear resistance than that of other brass alloys.