Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Hardness


Characterization and Mechanical Properties of the ZA-12 Hybrid Composites Reinforced with Nano Ceramic Particles

Aveen K. Yawer; Niveen J. Abdulkader; Dr. Ahmed A. Zainalaadbeen

Engineering and Technology Journal, 2021, Volume 39, Issue 4A, Pages 642-652
DOI: 10.30684/etj.v39i4A.1945

In this work, nanosized Boron nitride and silicon carbide reinforced ZA - 12 matrix hybrid composites were produced using stir casting technique with using of aluminum scrap (AA 2024), pure Al (electrical wires) and zinc scraps. Microstructure Observation was revealed by using scanning electron microscopy, and the analysis showed a uniform distribution of (SiC and BN) hybrid nanoparticles for the Zn-Al matrix. Also, an optical microscope was used to display the dendritic structure and reinforcement particles that dispersed uniformly in the matrix. Mechanical tests results confirmed that the hardness and the compression was increased with increasing the hybrid nanoparticle's percentage, whereas the wear rate decreased as the reinforcing materials increased. Since nanoparticles restrict dislocation movement, the mechanical properties are enhanced. The improvement ratio in hardness after addition was 26%., and in wear rate was 24% and for the compression strength the improvement was (19%).

Effect of Oil – Corrosion on Tensile and Fatigue S-N Curve Properties of AA6061-T6

Hussain J.M. Al-Alkawi; Ghgada A. Aziz; Shmoos R. Mazel

Engineering and Technology Journal, 2021, Volume 39, Issue 3A, Pages 407-414
DOI: 10.30684/etj.v39i3A.298

The present study described the effect of shot peening on mechanical properties and rotating corrosion –fatigue behavior (strength and life) of AA6061-T6. Ultimate tensile strength (UTS) and yield stress (YS) were reduced by 4.6% and 1.24% when immersing the tensile samples in crude oil for 60 days. The values of (UTS) and (YS) were raised from 307 to 316 MPa and from 248 to 254 MPa respectively when treated for 10 min. shot peening (SP). Hardness of oil corrosion samples dropped due to pitting corrosion and slightly raised for SP prior to corrosion samples. Oil corrosion reduced the fatigue strength by (-1.25%). This percentage was enhanced due to SP to 2.377%. SP significantly increased the rotating fatigue life by a factor of 1.19 and 1.3 at (UTS) and (Ys) loads respectively. (SP) technique improved corrosion-fatigue resistance due to producing compressive residual stresses at surface layers.

Mechanical Properties of Martensitic Stainless Steel (AISI420) Subjected to Conventional and Cryogenic Treatments

Hareer S. Mohamed; Ali H. Ataiwi; Jamal J. Dawood

Engineering and Technology Journal, 2020, Volume 38, Issue 8, Pages 1096-1105
DOI: 10.30684/etj.v38i8A.517

Martensitic Stainless Steel (AISI420) MSS are vastly used because of their properties conventional which mix good mechanical and corrosion resistance. Cryogenic up to -196°C for different soaking time and heat treatments at (1000,500,200°C) for 15 minutes is one of the ways that used to enhance mechanical properties of these steels by means transformation of retained austenite, deformation regarding martensite then carbide refinement. the result showed an increase in tensile strength of samples that were treated cryogenically and tempered at 500°C was 933 (MPa) compared to samples that just treated conventionally in austenitizing and tempering at the same temperature that was 880 (MPa). The hardness values increased considerably to 414HV and 321 HV for the specimen that tempered at 200°C and 500°C respectively, precipitation of small carbides was observed that this is responsible for the improvement in the mechanical properties of the material.

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 Compression, Hardness and Density properties of PMMA Reinforced by Natural Powder Used in Denture Base applications

Jawad Oleiwi; Q. A. Hamad; N. N. Kadhim

Engineering and Technology Journal, 2019, Volume 37, Issue 12A, Pages 522-527
DOI: 10.30684/etj.37.12A.5

 This research had been done to investigate the effect of adding natural powder of Pistachio Shell to PMMA, which popularly used in denture applications. The powder added in different weights fraction (3%, 6%, 9%, and 12%), and different average particle size (53µm, 106 µm, 150 µm, and 212µm %), and studying Compression Strength, Surface Hardness, and Density properties. Hand Lay-Up represented the method used to prepare the specimens in this research. The results were statistically analyzed by SPSS (one-way ANOVA) to determine the mean value and showed a significant difference for each particle size. The highest value of compression strength and surface hardness of PMMA composite specimens happened at (9%wt.) of the filler particles. Also the results represented that the density values for the composite specimens are increased with increasing the weight fraction of the filler particles.

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

Study the Mechanical and Physical Properties of Polyester Composite Reinforced by Multi Layers

Fadhil Abbas Hashim; Mohammed Sellab Hamza; Reham Raad Abdulla

Engineering and Technology Journal, 2016, Volume 34, Issue 9, Pages 1834-1843

In this research, a laminate composite has been prepared, using unsaturated polyester resin (UP) as a matrix reinforced with Kevlar fibers in different number of layers, glass fibers were added to the optimum product, by replacing one of the layers of Kevlar Fibers with a layer of Glass Fibers. Hand Lay-up method was used to prepare the test samples. To evaluate the composite material properties, tensile, hardness, impact, optical microscope tests were done.
The results of composite made of polyester reinforced with Kevlar Fibers show that the mechanical properties (Tensile strength, Modulus of elasticity, Hardness, Impact strength) increase with increasing the number of reinforced layers.
The best experimental values ofthe mechanical properties (Tensile strength, Modulus of elasticity, Hardness, Impact strength) were (190 MPa, 1.72 GPa, 79.25, and 68.75KJ/m2) respectively, for composite with three layers of Kevlar Fibers and then followed by composite with the sequence of layers (kevlar-glass-kevlar) and its mechanical properties (Tensile strength, Modulus of elasticity, Hardness, Impact strength) were (175.5 MPa, 1.69 GPa, 80, and 59.1 KJ/m2) respectively, Optical microscope shows welldistribution ofreinforcedlayers in composite.

Effect of Thermally Sprayed Ceramic Coating on Properties of Low Alloy Steel

Fadhil A. Chyad; Abdalkalaq F. Hamood; Lamees S. Faiq

Engineering and Technology Journal, 2014, Volume 32, Issue 10, Pages 2568-2575

Thermal spraying technique was employed for coating low alloy steel specimens that have been used in a derrick oil well frames.
Two types of ceramic materials were used as a coating material and two groups of steel samples were prepared for coating process.
The first group was coated by zirconia while the second group was coated by alumina. Ni-Al composite powder was used forbonding the coating material on the substrate surface of the steel specimens.
The hardness, adhesion strength of the coating layers as well as wear rateswere studied for the two steel group samples and compared with as received steel.
The results showed an increase in the mechanical properties with a decrease in wear rate values for coated samples as compared to those of uncoated samples.

Studying Some Of Mechanical properties Of (sawdust/Un Saturated Polyester) Composite in salt solution

Sanaa A. A. Hafad

Engineering and Technology Journal, 2010, Volume 28, Issue 16, Pages 5238-5245

Commercial sawdust is the most common wood filler used for polyster
thermosetting and is produced from graduated particles of different sizes which has in general has a lower aspect ratio than wood and other natural fibers. Wood additives include a mixture of sawdust and short chopped fibers. To study how characteristics of fibers and sawdust influence the mechanical properties of unsaturated polyester composites .Investigations were made by studying the effects of different volumetric fractions from sawdust and fiber fillers (up to limit
of 1.4mm), then these results were compared with the properties of sawdust –fiber filled composites immersed for different periods in a salt solution of (2 N) . wood volume fractions {(20, 30, 50) vf %} selected to be added for un saturated polyester were studied which gave improvement in their selected studied mechanical properties for all reinforced composites -(only impact is decreased)- and particularly at higher values of volume fractions ,were hardness showed an improvement by (15% ) , compressive strength gave obvious Improvement by
(38% ) ,while impact resistance decreased by (16%) with the reinforcement of (50 vf %) sawdust . The above values were reduced when the items were immersed in asalt solution for (60days).

The Mechanical Properties of Aluminum Matrix Composites

Engineering and Technology Journal, 2009, Volume 27, Issue 15, Pages 517-523

This work is production of aluminum matrix composite by powder metallurgy method .The samples have done when aluminum powder was used as a matrix in purity of (9.99%) and silicon carbide(α-SiC) as reinforcement material, the particle sizes were used which (125μm) at weight percentage (7.5% - 10% - 15%) from silicon carbide for each particle size. The purpose is to improve the hardness and wear properties of matrix .It was found that the hardness is increased with increment of the amount of added particles, due to the hardness of silicon carbid particles. From the wear test, it is found that the wear resistance increase with increasing the weight percentage of SiC particles, but the wear rate increase when the applied load increase for all the particles size and additional percentage. Also, it is found that when the sliding velocity increases, the wear rate also increases, but the best results were found in samples reinforced with (SiC) particles

Effect of Some Processing Parameters on Arc Sprayed Coating

Ali Hussein Ataiwi

Engineering and Technology Journal, 2008, Volume 26, Issue 12, Pages 1550-1562

In this work, arc spray coating of 13% Cr-steel (BS403S17) has been used in
repair of nodular cast iron journals. This study discusses the processing factors
effecting the roughness, hardness,and wear resistance of coating produced by
arc spraying. The studied factors are applied voltage, wire feed rate, spraying
distance (distance between gun nozzle and substrate) and coating thickness. All
coated samples were tested using pin on ring wear testing machine.
The final results showed that the best voltage in this application is between 28
and 30 V. With this voltage a reduction in wear rate of about 8% can be
obtained. The research reveals that the wear rate decreases by 46% with
increasing in wire feed rate from 68 to 122 mm/s and it is found that the best
spraying distance is about 10 to15 cm to get a good coating surfaces with
reduction by about 58% in wear rate. It is also approved that coating thickness
has positive effect on reducing wear rate by 43%.