JOURNAL OF NEW MATERIALS
Year:2018 | Volume:8 | Issue:3 (31) |Papers Count:14

The aim of this study is to provide a method of making ultralight open cell copper foam with high surface area using chemical procedures. Among the various methods of making open-cell metal foams, electrodeposition method is selected because it can be done in a clean way and is cheaper than other methods. In this method, an open cell polyurethane sponge was used as substrate. Then by choosing appropriate chemical solutions with specific technical knowledge, first polyurethane surface has activated and then by electroless-deposition method, polyurethane activated surface covered with a thin layer of copper. In the final stage, with the aid of electrodeposition the thickness of copper layer was increased to the desired thickness with a minimum required strength. The results show that electrodeposition can increase the thickness of copper layer from 3-5 microns that is obtained in electroless-deposition method to above100 to 150 microns. SEM results show that the micro structure of the deposited layer is globular. By controlling the thickness of deposited copper in electroplating, the surface area of the copper foam can be increased. According to results optimum time for electroless-deposition is between 5 to 7 minutes and for electrodeposition is 1 hour. The open-cell copper foam that is produced in this research is ultralight and due to it high surface can transfer heat with high rates.

One of the ways to improve the mechanical properties and product new compounds with good quality is the use of combination of polymer and thermoplastic elastomers. In addition to the use of nano clay particles can affect the properties of polymer composites. One of the most renowned elastomers is nitrile butadiene rubber (NBR). The thermoplastic elastomer NBR/PP is applied for oil resistance and high temperature. Therefore, in this paper are discussed the recovery characteristics of thermoplastic elastomer NBR / PP with the addition of clay nanoparticles. By a laboratory mixer, ratios of 2, 3 and 5 wt% nano clay particles with thermoplastic elastomer NBR/ PP was mixed. The results of the profile of the structure using X-ray diffraction (XRD) showed that the formation of flake structure, the clay is used in related samples. The results of Nano composite structural effect on mechanical properties such as tensile strength, stretch to the point of rupture, hardness and thermal analysis TGA and DTA for each of the samples were studied.

This research report investigated investigates the causes and mechanisms of copper pipes clogging used in gas chlorination systems of drinking water. Clogging of the chlorine gas transmission pipes causes incomplete water disinfection process and may put the human health in dangerous. Comprehensive examinations of the destroyed copper pipes in some stations revealed that, the reason of frequent clogging of the pipes is corrosion phenomenon. The reasons and mechanism of the frequent clogging of the pipes were investigated in the present work. For this purpose, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were applied to deduce the reasons and mechanism of the frequent clogging. The investigations of pipe clogging mechanism revealed that, the unwanted presence of the water inside the pipe when the system is out of service lead to pipes clogging in two stages (formation and growth of corrosion products). The simultaneous presence of water and chlorine inside the pipes cause the formation of corrosive electrolyte (Hydrochloric acid) which provides corrosion conditions inside the pipes. The XRD results identified the presence of the porous and voluminous corrosion product of paratacamite (Cu2(OH)3Cl). The SEM images demonstrated by providing the corrosive environment inside the pipe and as result, formation of porous corrosion products cause the rapid growth of non-protective layer of corrosion products. The growth of corrosion products scale and aggregation of separated parts of corrosion products in some parts of the pipes led to pipes clogging and as result the incomplete injection of sufficient amount of chlorine in drinking water.

Prediction of mechanical properties for different alloys is an appropriate way to design alloys with adequate properties. One of the methods is Quench-Factor Analysis (QFA). The technique is used to predict mechanical properties of heat treated alloys. However, there is not yet any study concentrated on superalloys. In the present study, the efficiency of the method for the prediction of hardness of the Ni-based superalloy GTD-111 was evaluated. For this reason, some specimens were quenched in different quenching media. After measuring the hardness values of the samples, they were fitted to the data obtained using classical equations of quench factor analysis. Values k2 to k3 for GTD-111 were determined as 12´10-11 s and 68 j.mol-1, respectively using the cooling curves and measured hardness values. Moreover, the Time-Temperature-Property curve of the superalloy GTD-111 was obtained using the k2 to k5 constants. The results showed that, QFA is an appropriate method for hardness prediction of the Ni-based superalloys.

In this study, core-shell structure Fe3O4/SiO2/TiO2-Ag Nano composites were synthesized in several stages. At first the Fe3O4 magnetic particles were obtained using the carbon reduction method. Then the Fe3O4/SiO2 composite was synthesized using Tetraethyl orthosilicate (TEOS) precursor via sol-gel method. In the following a shell of TiO2 was coated directly on it. Finally, Ag particle was deposited on the surface of TiO2 nano-shell by an in situ wet chemistry route. Prepared Nano composites were characterized by environmental scanning electron microscopy analysis (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Vibrating Sample Magnetometer (VSM). The results revealed Fe3O4/SiO2/TiO2–Ag Nano composites have been successfully synthesized. The average size of Fe3O4 particles was about 300-400 nm and the size of Fe3O4/SiO2 particles is averagely between 400-450 nm and the average size of Fe3O4/SiO2/TiO2-Ag particles was calculated between 450-480 nm. Saturation magnetization (Ms) of nanocomposite showed a decreasing from 80emu/g to 37emu/g. Further coating of SiO2 and TiO2decreases the saturation magnetization.

In this study, the laser surface processing of H13 hot-work tool steel was successfully carried out by TiC powder deposited through laser surface engineering process using a pulse Nd:YAG laser. The deposition process has been done at laser scanning speed of 2, 7 and 12 mm/s and pulse width of 6, 8 and 10 ms and operational distance of 4, 5 and 6 mm. Characterization of the composited area was done using field emission scanning electron microscope (FESEM), scanning electron microscope (SEM), X-ray diffraction (XRD) analysis and energy dispersive X-ray spectroscopy (EDX). Hardness of the composited surfaces was measured with a microhardness tester. Through taking advantage of response surface methodology (RSM), the experimental results were fed into Design Expert software which then mutual relationships between three independent variables were established. Prediction of model at the experimental range using systematic data enables us to provide a better understanding of the simultaneous effect of variables on the properties of composed area. Moreover the optimum value of variables was predicted. In order to applying composite surface with optimized microstructure, the optimal condition for scanning speed, pulse width and operational distance is 12 mm/s, 9.96 ms and 5.94 mm respectively and at this term, microhardness is 1606.49 Vickers. Characterization results of optimized samples showed a composited zone without any crack and porosity, with appropriate incorporation and uniform distribution of TiC particles in the matrix.

Magnesium and its alloys due to their unique properties, much attention has been aerospace and automotive industries. Important properties of these alloys can be cited to relatively low density that about two-thirds aluminum and high strength to weight ratio and good vibration absorption. In this paper, effect of heat treatment and hot working on vibrational properties, Mechanical and microstructure of magnesium alloy AZ91was studied. Thus, some samples that were identical in shape and weight were made of magnesium alloy AZ91.Then Solution, Solution-aging, Extrusion Process and stress relieved also rolling process and then stress relieved applied. Mechanical properties and vibration of samples heat treated and hot working along with the cast samples are measured. The microstructure of the samples analyzed by optical microscope. The results are shown solution and aging heat treatment to deposit the second phase boundaries and with increasing influence of deposition to the border, Power locks on the border increases. As a result of this process is to increase the mechanical properties and reduce the vibrational properties. While the sample is rolled had the best frequency response and damping ratio. Increased mechanical properties of aging sample Reduces the damping ratio.

The most recent studies have shown, due to high specific strength, and modulus, low density, low fabrication cost, and easy production processes, the raw material used is polymer. Thermosets are the most studied polymers during recent researches, they generally have higher chemical and thermal resistance than thermoplastics. Despite these important advantages, there are also some disadvantages, the most important imperfection of thermosetting polymers is their brittleness. In this study Epoxy/(up to 1.5 wt%) silica nanocomposites fabricated by casting method and then mechanical and thermal properties of nanocomposites are evaluated and Fourier Transform Infrared Spectroscopy (FT-IR) was implemented to study molecular bonding . Mechanical tests results showed 43%, 12% and, 40 % increase in strength, flexural strength and, toughness, respectively. Thermal gravimetric analysis results showed 22% decrease in Reduction of mass and Dynamic mechanical analysis results illustrated an increase in Glass transition temperature of Epoxy/0.3 wt% nanosilica from 74.5oC to 75.4oC, and an increase in storage modulus from 1.8Gpa to 2.3Gpa at 30oC.

Nowadays, soft magnetic materials such as nanocrystalline and amorphous alloys with unique physical, mechanical and magnetic properties have attracted much attention. Recently, Fe-based amorphous alloys have been greatly developed due to their excellent magnetic properties and relatively low cost. In this study, effect of milling time on microstructure of Fe-C-Ta alloy prepared by mechanical alloying was studied. Besides, the possibility of glass formation was investigated according to thermodynamic calculations, performed based on advanced Miedema model. The X-ray diffraction (XRD) results proposed that the fraction of amorphous phase enhances by increasing milling time up to 70 h, and then it becomes unchanged up to 90 h milling. Moreover, the differential scanning calorimetry (DSC) results confirmed the formation of amorphous phase with a crystallization temperature of 678 K, after 70 h of milling. The thermodynamic calculations with respect to the advanced Miedema model revealed that the Gibbs free energy changes for glass formation (-42.35 kJ/mol) are larger than those of solid-solution formation (-28.5 kJ/mol) and consequently, the amorphous phase has a larger tendency to form after milling.

One of the mechanisms of degradation of the wear parts is considered. In this study, Al-SiC-B4C composite with B4C various rate prepared on surface of AA332 alloy. For make surface composite, all the samples were surface melted. Microstructural investigation with optical and electron microscope shows, SiC and B4C placed in proximity to the grain boundaries. Increasing of B4C content is cause of increase tendency formation of Al3B4C and Al4C3 phases. Hardness of composite layer increase up to 182 HV has more than doubling the number. Unlike the hardness, wear resistance with increasing B4C showed different behavior. The results of Pin on disk wear test showed that B4C in each case leads to a decrease in the rate of wear. But after 1000 meters, the wear rate increased with increasing B4C. Check of the worn surfaces by SEM showed that the wear mechanism from adhesion to abrasive with increasing B4C changes.

In this study by applying plasma electrolytic oxidation (PEO) coating on titanium alloy Ti-6Al-4V its fatigue behavior was studied. The results were compared in the presence or absence of the coating. Scanning electron microscopy (SEM) were used to determine the chemical composition of different phases as well as analyzing the microstructure and cracks’ nucleation and propagation and the coating hardness was measured by micro hardness tester. Fatigue test results showed that the fatigue life of the uncoated specimens was longer than the coated specimens. Comparing the images of the fracture surface of the coated specimens and the uncoated specimens in the same surfaces showed that the nucleation of fatigue cracks was appeared in one area in the uncoated specimens while the nucleation of fatigue cracks in coated specimens appeared in multiple areas. According to the microscopic images the coated surface had many pores which causes the nucleation to begin with the coating. The results of the test micro surveys of coverage shows that the hardness of the coating over the layer below it and makes it crack initiation of coverage to begin.

Excellent features including high elastic modulus and thermal expansion coefficient associated with low weight and the ability to manufacture with conventional techniques were developed Aluminium composites reinforced with cremic particles at recent decades. In this work, Al2024/SiC composites with different SiC percentages (1,2,3%) were produced by Accumulative Roll Bonding (ARB) process. In order to produce composite samples 60% reduction rolling were applied to the samples firstly and then rolled strips cutted out into two parts and again subjected to 50% reduction for 3 passes. Mechanical properties of samples were investigated. Creep tests were done at temperature and stress range about 250-350oC and 30-40 MPa respectively. According to the results, Al2024+1%SiC composite had higher hardness degree than the other composites because of appropriate adhesion of raw strips together due to lower volume of SiC powder in this composite and acceptable consistency of particles into the matrix. Moreover, creep life of this sample was higher than the other. It is obvious that the creep life of All composites produced were several times less than the Al2024-T3 original raw sample.

To investigate the behavior of the superalloy deformation behavior of GTD 111 casting, the hot-pressure tests were carried out at a temperature range of 950-1100oC and strain rates of 1- 0.001 s-1. All of the flow curves showed a relatively linear tension increase to one peak point and then its descent to a strain of 0.5, and the region of steady state deformation with constant stress was not observed. This process was attributed to the control of dislocations by the dendritic structure and their amplification at peak point. Microstructural investigations showed that the hot work would break the structure of the dendritic network and create separate cells. An increase in the temperature of the hot work, resulted an increase in the decomposition of the structure and the achievement of larger cells coused by dissolution of broken dendritic particles. Also, with the increase in the rate of deformation at a given temperature, the decomposition rate of the dendritic network decreased and its elongation increased in the direction of the deformation. Using the fundamental constants of material, n, b and a were determined at the peak point. Also, with the help of the fundamental relationship of sinuses hyperbolic, the amount of activation energy at the peak and the strain of 0.4 samples was 947 kJ / mol and 890 kJ / mol, respectively. These results showed that the deformation activation energy decreases with increasing strain and breaking the dendritic structure into distinct cells.

The magnetic photocatalyst Fe3O4/SiO2/ZnO was synthesized by sol-gel method. For this purpose, in the first stage, Fe3O4 particles were prepared as the magnetic core of this composite and using the carbon recovery method. In the second stage, the coating of the SiO2 shell was performed using the tetraethyl orthosilicate (TEOS) precursor. In the end, the zinc oxide shell was deposited using a zinc hydrate nitrate precursor on the Fe3O4/SiO2 composite. The as-prepared nanostructures were characterized by environmental scanning electron microscopy analysis (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Energy Dispersive X-ray (EDX). FESEM and TEM results confirmed the coating of silica and zinc oxide on core particles and the Fe3O4/SiO2/ZnO magnetic photocatalyst was successfully prepared. The particle size mean of Fe3O4 was 300 nm approximately. The silica shell thickness was 25 nm, and the thickness of the zinc oxide shell was about a few nanometers approximately. The VSM results showed that coating of silica and zinc oxide shells reduced the saturation magnetization (Ms) of Fe3O4 powder so that the saturation magnetization decreased from 80.8 emu/g to 48.8 emu/g, which It is suitable for Magnetic Recovery. Photocatalytic properties of Fe3O4/SiO2/ZnO composite were studied on methylene orange degradation under UV light irradiation. Destruction of orange methylene was achieved 70%.