Showing 121 results for Tin
E. Najafi Kani, M. Nejan, A. Allahverdi,
Volume 13, Issue 4 (12-2016)
Abstract
This article addresses the interplay between heat of hydration and physico-mechanical properties of calcium sulfate hemi-hydrate in the presence of retarding additives such as citric and malic acids and sodium citrate. The heat of hydration was measured using a semi-isothermal calorimeter. Results proved that citric and malic acids had superior impact on hydration and mechanical properties. While the concentration of additives was increasing, the maximum heat of hydration was decreasing from 56.15 cal/g.min for blank sample to 33 cal/g.min for high concentrations of citric and malic acids. Consequently, the measured time to this maximum heat of hydration and thus the induction period were increased significantly from 5 to 105 min. Mechanical results indicated that the increase in the amounts of additive led to the reduction of the compressive strength from 16.25 MPa in the blank sample up to 74% for the highest concentration of malic acid
T. Ebrahimi Sadrabadi, S.r. Allahkaram, N. Towhidi,
Volume 13, Issue 4 (12-2016)
Abstract
Porous hollow glass microspheres have many uses, including encapsulation of active materials. In this paper a fast and facile method for fabricating porous hollow glass-microspheres was demonstrated by etching them using dilute hydrofluoric acid. Then, a highly reactive amine was infiltrated into the etched glass microspheres. Scanning electron microscopy was conducted for the hollow glass microspheres prior and post etching process. With regards to the porous hollow glass spherical sample, the spherical nature, morphology, pore diameter and the porosity were studied using scanning electron microscopy. Formation of the intact hollow glass microspheres with an open through wall porosities following phase separation and etching of the boron oxide rich phase was demonstrated using reciprocating shaker as the most suitable agitation method. The BET results indicated that the surface of the porous microspheres contained nano-pores. It is believed that the simplicity of the reported fabrication technique of micro/nano porous structure has the potential to scaling up for large scale production
Z. Valefi, M. Saremi,
Volume 14, Issue 2 (6-2017)
Abstract
In this paper the effect of plasma spray parameters, atomizing gas and substrate preheat temperature on microstructure and phase composition of YSZ coatings produced by SPPS process have been investigated. The experimental results showed that increasing the power of plasma, using hydrogen as the precursor atomizing gas and increasing substrate preheat temperature decrease the amount of non-pyrolyzed precursor in the coatings. At low plasma power most of the deposited precursor is in non-pyrolyzed state, and consequently the applied coatings are defective. The increase in substrate temperature beyond 800oC either by preheating or heat transfer from plasma torch to the substrate, prevent the coating formation. In SPPS coating formation, up to a special spray distance the optical microscopy image of the coatings showed a snowy like appearance. XRD analysis showed that in this situation the amount of un-pyrolyzed precursor is low. Beyond this spray distance, spherical particles, are obtained and XRD analysis showed that most of the precursor is in un-pyrolyzed state.
B.y.r. Surnam, B.s. Audit, A. Soopee,
Volume 14, Issue 3 (9-2017)
Abstract
In this study the use titanium and tungsten as alternatives to the noble metals in the jewellery industry was investigated. The degradation of titanium and tungsten were compared to that of gold, used as reference. Alternate immersion tests were performed in 3.5% sodium chloride and artificial perspiration. The metals’ abrasion resistance with respect to textile fabrics was determined.
In general, there is around 30% difference in pit density for titanium and tungsten as compared to that of gold. Pit depth and pit diameter showed a similar trend. From the abrasive test performed, it was observed that titanium and tungsten had insignificant changes in the surface reflectivity with time. Hence, it was deduced that titanium and tungsten products would have longer maintenance intervals than that of gold. New tools and techniques, however, would be required by jewellers to work with titanium and tungsten.
E. Maleki, K. Reza Kashyzadeh,
Volume 14, Issue 4 (12-2017)
Abstract
Hardened nickel coating is widely used in many industrial applications and manufacturing processes because of its benefits in improving the corrosion fatigue life. It is clear that increasing the coating thickness provides good protection against corrosion. However, it reduces the fatigue life. Thus, applying a thin layer of coated nickel might give an acceptable corrosion protection with minimum loss of the fatigue life. In the present study, the effects of hardened nickel coating with different thicknesses on the fatigue behavior of CK45 mild steel were experimentally investigated. After conducting the experimental tests, we carried out two different modeling approaches of finite element method (FEM) and artificial neural network (ANN). In the FEM modeling, an attempt was made to analyze the fatigue of the components by modeling the interface phase between the base metal and coating more accurately and using the spring elements; ANNs were developed based on the back propagation (BP) error algorithm. The comparison of the obtained results from FEM and ANN modeling with the experimental values indicates that both of the modeling approaches were tuned finely.
N. Aboudzadeh, Ch. Dehghanian, M.a. Shokrgozar,
Volume 14, Issue 4 (12-2017)
Abstract
Recently, magnesium and its alloys have attracted great attention for use as biomaterial due to their good mechanical properties and biodegradability in the bio environment. In the present work, nanocomposites of Mg - 5Zn - 0.3Ca/ nHA were prepared using a powder metallurgy method. The powder of Mg, Zn and Ca were firstly blended, then four different mixtures of powders were prepared by adding nHA in different percentages of 0, 1, 2.5 and 5 %wt. Each mixture of powder separately was fast milled, pressed, and sintered. Then, the microstructure and mechanical properties of the fabricated nanocomposites were investigated. The XRD profile for nanocomposites showed that the intermetallic phases of MgZn2, MgZn5.31 and Mg2Ca were created after sintering and the SEM micrographs showed that the grain size of nanocomposite reduced by adding the nHA. The nano composite with 1wt. % nHA increased the density of Mg alloy from 1.73 g/cm3 to 1. 75 g/cm3 by filling the pores at the grain boundaries. The compressive strength of Mg alloy increased from 295MPa to 322, 329 and 318MPa by addition of 1, 2.5 and 5wt. % nHA, respectively.
V. Lykhoshva, A. Tymoshenko, L. Mosentsova, V. Savin, D. Schitz,
Volume 15, Issue 1 (3-2018)
Abstract
This article studies the particle temperature distribution depending on the laser radiation power and the particle’s trajectory and velocity. The uneven heating of particles moving in the laser radiation field is identified. The regimes of laser heating without melting, with partial melting, and with complete particle melting are considered.
F. Sousani, R. Mozafarinia, A. Eshaghi, H. Jamali,
Volume 15, Issue 1 (3-2018)
Abstract
In this research, Germanium-carbon coatings were deposited on ZnS substrates by plasma enhanced chemical vapor deposition (PECVD) using GeH4 and CH4 precursors. Optical parameters of the Ge1-xCx coating such as refractive index, Absorption coefficient, extinction coefficient and band gap were measured by the Swanepoel method based on the transmittance spectrum. The results showed that the refractive index of the Ge1−xCx coatings at the band of 2 to 2.2 µm decreased from 3.767 to 3.715 and the optical gap increased from 0.66 to 0.72 eV as CH4:GeH4 increases from 10:1 to 20:1.
S. Akbarzadeh, S.r. Allahkaram, S. Mahdavi,
Volume 15, Issue 2 (6-2018)
Abstract
Tin-Zinc alloy coatings have many applications because of their unique properties such as corrosion resistance, solderability and flexibility. In this study, the effect of current density, temperature and pH on chemical composition, cathodic current efficiency, morphology and structures of the coatings was investigated. The results illustrated that, at low current densities (<0.5 mA/cm2), the coatings were relatively pure tin, but Zn content increased with enhancing the current density. At higher currents a relatively pure Zn film was obtained. Temperature and pH also affected chemical composition of the alloy films. Zn content of the coatings was decreased by increasing the temperature, while its variation with pH had ascending-descending trend. Morphological investigation of the coatings revealed that increasing Zn content of deposits led to porous, rough and fine grained films.
F. Farzan, H. R. Shahverdi, F. Malek Ghaeni,
Volume 15, Issue 2 (6-2018)
Abstract
Recently, wear resistant properties of metallic glasses has attracted a lot of interest. Because the surface of metallic glasses are prone to phase transformation, finding the effects of test condition on structure and wear behavior of metallic glasses is important. In this research, by using an automated electrospark deposition (ESD), a layer of Fe
51Cr
18Mo
7B
16C
4Nb
4 was deposited on AISI 316l stainless steel. Metallographic,
scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS) analyses of the coating were conducted for measuring the thickness and analyzing composition of the coating. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) investigations showed that the structure of the coating was amorphous. Ball on disc wear tests were conducted in dry and wet conditions and Ringer’s solution was chosen as the wetting agent. The wear test results showed that the coefficient of friction in dry condition was lower than the wet condition and wear modes were fatigue and corrosive wear in dry and wet conditions respectively. SEM and EDS analyses showed different features and elemental inhomogeneity on the surface of the dry wear track, which were not detectable in wet wear track. In addition, activation of diffusion process and formation of carbides and borides were observed on the wear track in dry condition.
M. Taleblou, E. Borhani, B. Yarmand, A. Kolahi,
Volume 15, Issue 3 (9-2018)
Abstract
Thin films of SnS2 were prepared, as the absorber layer in solar cells, using an aqueous solution of SnCl4 and thiourea by spray pyrolysis technique. Effect of the Substrate temperature on the properties of these thin films was studied. Investigation via XRD showed the formation of polycrystalline SnS2 along (001) in all layers; there was no sign of other unwanted phases. With increasing of substrate temperature from 325 to 400 0C, the crystallinity of the sample was improved, after that, it deteriorated the crystallinity. Layers had granular morphology and Valley- Hills topography. UV-VIS spectra revealed that the transmittance of all layers was lower than 40% in the visible region and the band gap reduced from 2.8 to 2.55 eV with increment in temperature from 350 to 400 0C. Photoluminescence spectra of the prepared film, which was formed at 400 0C showed a dominant peak at 530 nm, caused recombination of excitons. The least electrical resistivity of the SnS2 thin film prepared at 400 0C in dark and light environment were 4.6 ×10 -3 Ωcm and 0.65×10 -3 Ωcm, respectively; which demonstrated 400 0C was the optimum temperature in point of optoelectrical properties in the SnS2 thin film.
N. Maragani, K. Vijaya Kumar,
Volume 15, Issue 4 (12-2018)
Abstract
An attempt has been focused to develop a new aluminum ion conducting non aqueous polymer electrolyte for high power rechargeable batteries having applications in rapidly growing markets, such as laptops, handy tele communication equipments, electric vehicles, camcorders, etc. These features have given a thrust to develop a suitable Nano composite GPE based on PAN as polymer host and Sodium fluoride (NaF) as dopant salt and Al2O3 as nano filler in the form of thin films through solution casting technique consuming N,N-dimethyl formamide (DMF) as a common solvent. NCGPE films have been prepared by solution casting technique. The XRD pattern of 70PAN-30NaF with addition of wt% Al2O3 ceramic filler indicates reducing degree of crystallinity. Using IR studies revealed that the complexation of the polymer poly (acrylonitrle) with NaF. The conductivity of the GPEs was studied with enhancement of nano fillers. The sample containing 3% of Al2O3 exhibits the highest conductivity of 4.82x10-3S cm-1 at room temperature (303K) and 5.96x10-3S cm-1 at 378K. With the help of Wagner’s polarization technique electronic (te) and ionic (ti) values can be determined.To determine profiles of discharge characteristics (70PAN-30NaF-3wt% Al2O3) NCGPE solid-state electrochemical cell was fabricated and various cell profiles were evaluated
S. Kord, M. H. Siadati, M. Alipour, H. Amiri, P.g. Koppad, A. C. Gowda,
Volume 15, Issue 4 (12-2018)
Abstract
The effects of rare earth element, erbium (Er) additions on the microstructure and mechanical properties of Al-15Zn-2.5Mg-2.5Cu alloy have been investigated. This new high strength alloy with erbium additions (0.5, 1.0, 1.5 and 2.0 wt%) was synthesized by liquid metallurgy route followed by hot extrusion. Microstructural characterization was performed using scanning electron microscope and electron probe microanalysis. Significant amount of grain refinement was observed with erbium addition in the hot extruded and heat treated alloy. Tensile test was performed to investigate the effect rare earth on mechanical behavior of alloy in as cast and hot extruded condition before and after T6 heat treatment. The combined effect of erbium addition, hot extrusion and heat treatment significantly enhanced the tensile strength of alloy (602 MPa) when compared to the as cast alloy without erbium addition (225 MPa). The strengthening of the alloy was attributed to grain refinement caused by erbium along with hot extrusion and formation of precipitates after T6 heat treatment. Fractograhic investigations revealed that the hot extruded alloy with erbium addition after heat treatment showed uniformly distributed deep dimples exhibiting ductile behavior.
M. Gholami, M. Divandari,
Volume 15, Issue 4 (12-2018)
Abstract
Centrifugal casting process, in both horizontal and vertical mode, is considered as an efficient method to produce bimetallic components. Al/Cu65Zn35 couples were prepared by the vertical centrifugal casting process. In this study, different volume of molten aluminum having melt-to-solid (m/s) volume ratios (VR) of 1.5 and 2.5, were cast into preheated brass bush rotating at 800, 1600, and 2000 (rpm), respectively. The thickness of the interface, which is composed of three different zones, is depended on the rotational speed and the (VR) and was at least 490µm (at VR=1.5 and 2000 rpm) and at most 1480 µm (at VR=2.5 and 800 rpm). The results of optical microscopy, energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis showed that the interface layers are composed of Al2Cu5Zn4, Al3Cu3Zn, Al2Cu precipitates dispersed in the matrix and finally α-Al/Al2Cu anomalous eutectic structure near the aluminum side. Gas pore entrapment and oxide film entrainment defect was detected within the interface next to the aluminum base metal.
M. Tavakoli Harandi, M. Askari-Paykani, H. Shahverdi, M. Nili Ahmadabadi,
Volume 16, Issue 1 (3-2019)
Abstract
One-step and two-step annealing techniques were used to examine the relationship between microstructure and mechanical properties during compression tests in iron-based ribbons and nanostructured 1- and 2.5mm cylindrical rods. The X-ray diffraction, microstructural, and mechanical results showed that substituting Nb for Fe had a minor effect on glass-forming ability but increased the formability index. The novel two-step annealing process resulted in a remarkable formability index of 16.62 GPa, yield stress of 2830 MPa, ultimate strength of 3866 MPa, and 4.3% plastic strain. A ductile nanosized α-Fe framework and boron-containing nano precipitations, which caused Zener pinning effect, were responsible for these novel mechanical properties.
M. Senthil Kumar , R. V. Managalaraja, K. Senthil Kumar, L. Natrayan,
Volume 16, Issue 2 (6-2019)
Abstract
The present requirement of automobile industry is seeking lightweight material that satisfices the technical and technological requirements with better mechanical and tribological characteristics. Aluminium matrix composite ( AMC ) materials meet the requirements of the modern demands. AMCs are used in automotive applications as engine cylinders, pistons, disc and drum brakes. This paper investigates the effect of particle size and wt% of Al2O3/SiC reinforcement on mechanical and tribological properties of hybrid metal matrix composites (HMMCs). AA2024 aluminium alloy is reinforced with Al2O3/SiC different particle sizes (10, 20 and 40 µm) and weight fractions (upto 10 wt %) were fabricated by using squeeze casting technique. HMMCs were characterized for its properties such asX-ray diffraction (XRD), density, scanning electron microscope ( SEM ), hardness, tensile strength, wear and coefficient of friction. AA2024/5wt%Al2O3/5wt%SiC with 10 μm reinforced particle size showed maximum hardness and tensile strength 156.4 HV and 531.43 MPa and decrease in wear rate was observed from from 0.00307 to 0.00221 for 10N. Hybrid composites showed improved mechanical and wear resistance suitable for engine cylinder liner applications.
M. Karimi Sahnesarayi, H. Sarpoolaky, S. Rastegari,
Volume 16, Issue 2 (6-2019)
Abstract
In this study nanosized TiO2coatings on the 316L stainless steel substrate were prepared by means of dip-coating technique in which thickness of the coating layer increased byrepeating the coating cycles in two different routes: (I) dipping and drying,respectively, were repeated one, three and five times and finally the dried coated sample was heat treated (single); (II) multiple heat treatment performed after each dipping and drying cycle, respectively.The structural, morphological and optical characterizations of coatings as well as thickness of coatings were systematically studied.The photocatalytic activity of the various TiO2 coatings was investigated based on the degradation of an aqueous solution of Methyl orange.Moreover, thecorrosion protective properties of coatings were evaluated in both dark and UV illumination conditions based on the obtained polarization curves. The results indicated 1.75 times improvement in photocatalytic reaction rate constant, a two orders of magnitude decrease in corrosion current density in dark condition and about 140 mV electrode potential reduction under UV illumination with optimum coating preparation procedure, repeating the cycle from dipping to heat treatment three times, than the sample prepared with one time coating and heat treatment since this procedure provided not only high thickness and defect-free coating but also transparent one.
M. Akbarzadeh, M. Zandrahimi, E. Moradpur,
Volume 16, Issue 2 (6-2019)
Abstract
Molybdenum disulfide (MoS2) is one of the most widely used solid lubricants. In this work, composite MoSx/Ti coatings were deposited by direct-current magnetron sputter ion plating onto plain carbon steel substrates. The MoSx/Ti ratio in the coatings was controlled by sputtering the composite targets. The composition, microstructure, and mechanical properties of the coatings were explored using an energy dispersive analysis of X-ray (EDX), Xray diffraction (XRD), and nano indentation and scratch techniques. The tribological behavior of the coatings was investigated using the pin-on-disc test at room temperature. With the increase of doped titanium content, the crystallization degree of the MoSx/Ti composite coatings decreased. The MoSx/Ti coatings showed a maximum hardness of 13 GPa at a dopant content of 5 at% Ti and the MoSx/Ti composite films outperformed the MoSx films. Moreover, the films exhibited a steady state friction coefficient from 0.13 to 0.19 and the main wear mechanisms of the MoSx/Ti coating in air were abrasive, adhesive, and oxidation wear.
A. Khalili, M. Mojtahedi, M. Goodarzi, M. J. Torkamani,
Volume 16, Issue 3 (9-2019)
Abstract
The aim of this work was to synthesize TiC reinforced coating on carbon steel via reduction of ilmenite powder. A mixture of ilmenite and graphite was pre-placed on AISI 1020 steel surface. The effect of the addition of excess graphite amounts on the progress of synthesis of carbide particles was studied. The evolution of phases in different coatings was analysed via X-ray diffraction and scanning electron microscopy. Then again, the initial powder mixtures were mechanically activated for various durations, to accelerate the reactions in transient melt pool. Finally, the Fe-TiC hard coating was successfully synthesized by carbothermic reduction of ilmenite through laser surface treatment. Moreover, it is proved that combination of mechanical activation with additive laser melting effectively improves the level of ilmenite reduction, besides enhancing the distribution of hard particles and the hardness of the coatings to more than 1300 HV.
R. Latifi, S. Rastegari, S. H. Razavi,
Volume 16, Issue 4 (12-2019)
Abstract
In the present study, Zirconium modified aluminide coating on the nickel-base superalloy IN-738LC was first created by high activity high temperature aluminizing based on the out-of-pack cementation method. Then, Zr coatings were applied to simple aluminide coatings by sputtering and heat treatment in order to study the effect of Zr on the coating microstructure and oxide spallation. Microstructural studies were conducted by using scanning electron microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDS), and x-ray diffraction (XRD) microanalysis. The results indicated that zirconium modified aluminide coating, like aluminide coating, has a two-layer structure including a uniform outer layer of NiAl and an interdiffusion layer in which zirconium is in a form of solid solution in the coating. Furthermore, the 300nm Zr-coated NiAl demonstrated an excellent scale adhesion, a slow oxidation rate and lower amounts of some other elements such as Ti and Cr in its oxide layer leading to a pure aluminide oxide layer.
