Showing 177 results for Cr
Tamilanban Thangaraju, Thirupandiyur Selvanambi Ravikumar, Sivaraman Kanthasamy,
Volume 18, Issue 4 (12-2021)
Abstract
The effect of pouring temperature while preparing Al SiC metal matrix composites, with additional benefits of magnesium and copper through stir casting technique were investigated. The composites were fabricated by mixing 12 wt% of SiC reinforcements, 4 wt% magnesium and 2 wt% copper into 6061 aluminium alloy melt at different pouring temperatures (630 ºC, 670 ºC and 710ºC). The addition of magnesium will enhance the wettability of the SiC particles with Al matrix and subsequently increase its interface bonding strength. The inclusion of copper has considerable improvement in strength and hardness of the composite. The microstructure and mechanical properties (tensile strength and hardness) of the Al MMC are evaluated with the corresponding processing parameter, specifically pouring temperature of the cast composite. The metallurgical characterization utilizing optical and scanning electron microscope were observed for the prepared composites. The coarse microstructure and homogenous distribution of alloying elements along with SiC particles were appeared within dendrite structures of the Al SiC composites. The SiC particles has effectively distributed and produced better bonding strength in composites prepared with 670ºC pouring temperature. Higher tensile strength and maximum hardness have occurred in composite at pouring temperature of 670ºC as compared to other composites. The mechanical properties were lower in composites prepared using lesser pouring temperature (630ºC) and significantly decreased for higher pouring temperature (710ºC) of the composites.
Dillibabu Surrya Prakash, Narayana Dilip Raja,
Volume 18, Issue 4 (12-2021)
Abstract
Hybrid composites consisting of AA6061 matrix reinforced with TiB2 (2, 4, 6, and 8 wt. %), Al2O3 (2 wt. %) particles were produced by the sintering process. In comparison to the base material AA6061, the composite produced had improved mechanical properties. The sintered composites' mechanical properties, such as tensile strength and hardness, are measured and compared to the wear-tested specimen. Optical micrographs reveal that composites were riddled with defects like blowholes, pinholes, and improper bonding between the particulates before sintering. However, the post-sintered optical micrograph showed that the defects were greatly suppressed. Micrographic images revealed the changes in surface characteristics before and after wear. Until a sliding distance of 260 m, the wear rate of the hybrid composites was kept lower than that of the base material. The coefficient of all the composite materials produced for this study was noted to be less than that of the base material. The results reveal that the hardness of hybrid composites having 4 wt. % and 6 wt. % of TiB2 particulates increased by 5.98 % and 1.35 %. Because of the frictional heating during the wear test, the tensile properties lowered by up to 49.6%. It is concluded that the hybrid composites having 4 wt. % and 6 wt. % of TiB2 particulates exhibited less wear rate for extended sliding distance, good hardness, moderate tensile strength, and decent elongation percentage compared to its counterparts.
Mala Siddaramappa, Haraluru Kamala Eshwaraiah Latha, Haraluru Shankaraiah Lalithamba, Andi Udayakumar,
Volume 18, Issue 4 (12-2021)
Abstract
Indium tin oxide (ITO) nanoparticles were synthesized by green combustion method using indium (In) and tin (Sn) as precursors, and Carica papaya seed extract as novel fuel. This paper highlights effect of tin concentration (5%, 10% and 50%) on microstructural, optical and electrical properties of ITO nanoparticles (NPs). The indium nitrate and tin nitrate solution along with the fuel were heated at 600 °C for 1 h in muffle furnace and obtained powder was calcinated at 650 °C for 3 h to produce ITO NPs. The above properties were investigated using XRD, FTIR, UV-Vis spectroscopy, SEM, TEM and computer controlled impedance analyser. The XRD, SEM and TEM investigations reveals the synthesized NPs were spherical in shape with an increase in average grain size (17.66 to 35 nm) as Sn concentration increases. FTIR investigations confirms the In-O bonding. The optical properties results revealed that the ITO NPs band gap decreased from 3.21 to 2.98 eV with increase in Sn concentration. The ac conductivity of ITO NPs was found to increase with increase in Sn concentration. These synthesised ITO NPs showed the excellent properties for emerging sensor and optical device application.
Sara Ahmadi, Bijan Eftekhari Yekta, Hossein Sarpoolaky, Alireza Aghaei,
Volume 18, Issue 4 (12-2021)
Abstract
In the present work, monolithic gels were prepared through different drying procedures including
super critical, infrared wavelengths and traditional drying methods. Dense and transparent glasses
were obtained after controlled heat treatment of the dried porous xerogels in air atmosphere.
The chemical bonding as well as different properties of the prepared gels and the relevant glasses
were examined by means of Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmitt-
Teller (BET) and UV-Vis spectrometer. Based on the obtained results, different drying conditions
affect the average pore size and the total pore volume of the studied gels. The mean pore size was
found to be 8.7 nm, 2.4 nm and 3.2 nm for super critical, IR radiation and slow drying in air
atmosphere, respectively. The glass network structure was significantly changed by heat treatment temperature so that the B-O-Si bonds were formed only after 450 °C. It was found that the gel dried under super critical condition was unable to reach to its full density all over the selected sintering temperature interval.
Muhammad Muzibur Rahman, Shaikh Reaz Ahmed,
Volume 18, Issue 4 (12-2021)
Abstract
This paper reports the wear behavior of Cu, high Cu-Sn alloy, high Cu-Pb alloy and high Cu-Sn-Pb alloy under dry sliding at ambient conditions. These four materials were chosen for the wear resistance characterization of SnPb-solder affected old/scraped copper (high Cu-Sn-Pb alloy) to explore its reusing potentials. Wear tests were conducted using a pin-on-disk tribometer with the applied load of 20N for the sliding distance up to 2772 m at the sliding speed of 0.513 ms-1. The applied load was also changed to observe its effect. The investigation reveals that the presence of a little amount of Sn increased the hardness and improved the wear resistance of Cu, while a similar amount of Pb in Cu reduced the hardness but improved the wear resistance. The general perception of ‘the harder the wear resistant’ was found to match partially with the results of Cu, Cu-Sn alloy and Cu-Sn-Pb alloy. Coefficient of friction (COF) values revealed non-linearly gradual increasing trends at the initial stage and after a certain sliding distance COF values of all four sample materials became almost steady. SnPb-solder affected Cu demonstrated its COF to be in between that of Cu-Pb alloy and Cu-Sn alloy with the maximum COF value of 0.533.
Ata Abdi, Mehrdad Aghaie-Khafri,
Volume 19, Issue 1 (3-2022)
Abstract
Hot Workability and Processing Map of High Gd Content Mg-Gd-Zn-Zr-Nd Alloy Hot deformation behavior of homogenized Mg-4Sn binary alloy was studied using compression tests at the temperature range of 300-500
and strain rates of 0.001-1s
-1. The material showed typical single peak flow behavior followed by a steady state flow as a plateau, which is more evident at the high value of Zener-Hollomon parameter. Constitutive analysis showed that in spite of the original Johnson-Cook (J-C), conventional strain compensated Arrhenius model based on Sellars-McTegart model has a reasonable agreement with the experimental data. Moreover, the well-known hyperbolic sine function fits the experimental data for predicting of the peak stress with a fair degree of accuracy.
Morteza Hadi, Omid Bayat, Hadi Karimi, Mohsen Sadeghi, Taghi Isfahani,
Volume 19, Issue 1 (3-2022)
Abstract
In this research, the effect of initial microstructure and solution treatment on rollability and crystallographic texture of a Cu-Mn-Ni-Sn alloy has been investigated. The initial tests indicated that the rolling of the alloy at different temperature conditions is not possible due to formation of second phases. Herein to eliminate the segregated phases, according to DTA analysis, proper temperature for solution treatment was selected as 750°C applied at different periods of time. The obtained results showed that after 15-hour solution treatment, the complete elimination of Sn, Mn, Ni, and Fe-rich phases can be achieved. Also, the peaks of XRD shifted to the higher angles indicating that the alloying elements are dissolved. Meanwhile, the intensity of the texture reduced and the dominant texture changed from Goss and Brass-texture to Copper-texture. Accordingly, the amount of maximum total reduction at the rolling process increased from 16.37 to 109.46 after solution treatment.
Zahra Rajabimashhadi, Rahim Naghizadeh,
Volume 19, Issue 1 (3-2022)
Abstract
ꞵ-tricalcium phosphate (ꞵ-TCP) and anorthite are the main crystalline components in bone china bodies. The difference in their thermal expansion coefficients causes a decrease in the thermal shock resistance of the body. In this study, anorthite was replaced with bone ash at the bone china body, and the effect of this new composition on different properties of bone china, after curing at 1260 °C for 3 hours, was investigated. The results showed that the physical and mechanical properties of the sample containing 50 wt% anorthite compared to the typical bone china improved and only 8.7% of the whiteness index diminished. Also the microstructure of samples containing Anorthite were observed without thermal crack and almost uniform distribution of Anorthite and quartz crystals in the heterogeneous glass matrix.
Parviz Parviz Mohamadian Samim, Arash Fattah-Alhosseini, Hassan Elmkhah, Omid Imantalab,
Volume 19, Issue 1 (3-2022)
Abstract
In this study, CrN/ZrN multilayer nanostructured coatings with different bilayers (10, 20, and 30) were created by the cathodic arc evaporation. The electrochemical behavior of samples was evaluated by polarization and impedance spectroscopy tests in the Ringer medium and the pin on disk test was used to investigate the tribological behavior of the samples. The results of measurements showed that the electrochemical and tribological behavior of the coatings depends on the number of bilayers and by rising the number of bilayers, the coating shows higher corrosion resistance and better tribological performance. Field emission scanning electron microscopy (FE-SEM) images of the specimens after exposure to the corrosion medium showed that the number of surface cavities were formed by the coating that had the highest number of bilayers comparing with other coatings were quite fewer in number and smaller in diameter. The results of the pin on disk test showed that by increasing the number of bilayers from 10 to 30, the coefficient of friction and wear rate decreased and the 30L coating showed better wear resistance.
Puneeth Puneeth, Gangarekaluve J. Naveen, Vishwanath Koti, Nitrahalli D. Prasanna, Litton Bhandari, Javaregowda Satheesh, Parthasarathy Sampathkumara,
Volume 19, Issue 1 (3-2022)
Abstract
Hybrid composite finds wide application in various fields. In this present study, the hybrid composites are developed using stir casting technique as per Taguchi’s L9 orthogonal array. Hybrid composites were fabricated using Aluminium Al6082 as the base material and reinforced with the combinations of reinforcements Al2SiO5 and B4C at three levels (4%, 8% and 12%).The developed composites were analyzed for micro structural investigations and mechanical tests were done as per ASTM standards. The micro structural analysis was done using optical Microscope and Scanning electron microscope while composition studies were done using X-ray diffraction and EDAX. Mechanical test like tensile, impact and flexural were conducted and their damage assessment was done using Scanning electron microscope. The fatigue characteristics like high cycle fatigue and fatigue crack propagation was studied both experimentally and numerically. The experimental data and numerical modeling analysis data obtained for the hybrid composite system, agree with each other.
Saleheh Abbaspoor, Farhang Abbasi, Samira Agbolaghi,
Volume 19, Issue 2 (6-2022)
Abstract
Single crystals of double crystalline block copolymers of poly(ethylene glycol) (PEG)-b-poly(ε-caprolactone) (PCL) and PEG-b-poly(L-lactide) (PLLA) were grown from dilute solution in homo- and mixed-brush systems. Crystallization behavior of biodegradable one end-restricted crystallizable PCL and PLLA chains in homo- and mixed-brush nanostructures were investigated. Chemical and physical circumstances of crystallizable brushes were altered. Physical environment was adjusted by amorphism/crystallinity and rigidity/flexibility of neighboring brushes. Chemical environment was manipulated by interaction and miscibility of various brushes. Distinct single crystals were grown with mixed-brushes of amorphous-crystalline (polystyrene (PS), poly(methyl methacrylate) (PMMA), PCL and PLLA, double crystalline (PCL/PLLA), and rod-crystalline polyaniline (PANI)/PCL or PLLA. Surrounding was only effective on hindrance or nucleation commencement of crystallization for crystallizable brushes and had no effect on crystallization features. Novel three-layer fully single crystalline nanostructures, whose characteristics were fixed via changing the crystallization temperature, were also developed. For long crystallizable tethers, crystallization increased both brush and substrate thicknesses.
Tashi Tenzin, Amrinder Kaur,
Volume 19, Issue 2 (6-2022)
Abstract
Green synthesis refers to the synthesis of nanoparticles using plants and microorganisms. It is preferred over conventional methods as its sustainable, eco-friendly, cost effective and rapid method. The phytochemicals and enzymes present in plants and microorganisms respectively acts as the reducing and capping agent for the synthesis of nanoparticles. Phytochemicals and enzymes have the ability to reduce precursor metal ions into nanoparticles. As the conventional methods involve the use of high energy and toxic chemicals which are harmful to both environment and organisms, these synthesis methods are discouraged. Of the nanoparticles, gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have gained lots of attention owing to their multiple applications and less toxicity. In addition, various in-vitro studies have reported the antimicrobial activity of AgNPs and AuNPs against various microbes. This particular review portrays the methods of nanoparticles synthesis, components of green synthesis, mechanism of green synthesis, antimicrobial activity, other applications and various factors affecting the green synthesis of AgNPs and AuNPs.
S. Giridhar Reddy,
Volume 19, Issue 2 (6-2022)
Abstract
Sodium alginate (SA), brown seaweed algae, and Lignosulphonic acid (LS), a plant product, are biodegradable polymers extensively investigated for drug-controlled release. The Hydroxychloroquine sulphate (HCQ) drug, an antimalarial drug, was extensively used in the initial periods of COVID situations. The HCQ drug release from SALS beads is investigated for its control release in a simulated medium (pH1.2 and pH7.4) using different crosslinking agents such as Calcium chloride, Barium chloride and Aluminum chloride. The HCQ release has better controlled in Barium crosslinked beads. They are found to be relatively intact and stable and release the drug for more than 180 minutes in the simulated medium. Further drug entrapment studies prove very high for Ba crosslinked SALS beads. Whereas Aluminum crosslinked beads showed, inferior crosslinking and drug retention in beads is very low and starts degrading in simulated fluids. Drug release kinetics were analyzed using various kinetic model equations to discuss the order of reaction and drug-polymer mechanism. FT-IR investigations of beads show chemical interactions between crosslinking ion and alginate blends.
Behzad Pourghasemi, Vahid Abouei, Omid Bayat, Banafsheh Karbakhsh Ravari,
Volume 19, Issue 3 (9-2022)
Abstract
It has long been thought-provoking and challenging as well for researchers to design and produce a special low-modulus β titanium alloy such as Ti‐35Nb‐7Zr‐5Ta, representing optimal mechanical properties that is needed to successfully simulate bone tissue. In order to identify the key effects of processing pathways on the development of microstructure, Young’s modulus, and strength, a nominal Ti-35Nb-7Zr-5Ta alloy was made via casting, hot forging, homogenizing, cold rolling and finally annealing. Results from tensile test alongside microscopic and XRD analysis confirm the importance influence of processing method on fully β phase microstructure, low elastic modulus and high strength of the alloy. The specimen with post-deformation annealing at 500 °C demonstrated the Young’s modulus of 49.8 GPa, yield strength of 780 MPa and ultimate tensile strength of 890 MPa, all of which are incredibly close to that of bone, hence suitable for orthopedic implants. At temperature above 500 °C, a sharp fall was observed in the mechanical properties.
Zainab J. Shanan, Huda M.j. Ali, H.f. Al-Taay,
Volume 19, Issue 3 (9-2022)
Abstract
The objectives of this work is to synthesize TiO2/MgO nanocomposites using a pulse laser deposition technique. At a vacuum pressure of 2.5 10-2 mBar, TiO2/MgO nanocomposites were synthesized on substrates with a laser power of 600 mJ and a wavelength of 1064 nm. This search utilizes various pulses (500, 600, and 700) at a 6-Hertz repetition rate. X-ray diffraction was utilized to investigate crystallography of the phases in the samples, as well as average crystallite size (XRD). An increase in the average crystal size was observed with an increase in the number of shots (from 35.15 to 38.08) nm at (500 to 700) shots respectively. The impact of the number of laser shots on the surface characteristics of TiO2/MgO nanocomposites was also evaluated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM). Finally, optical characteristics were evaluated using UV-Vis spectroscopy. Increasing the number of shots increased the absorbance and thus reduced the energy gap.
Erfan Lotfi-Khojasteh, Hassan Elmkhah, Meisam Nouri, Omid Imantalab, Arash Fattah-Alhosseini,
Volume 19, Issue 4 (12-2022)
Abstract
This paper aims to study the tribological and electrochemical properties of the CrN/AlCrN nano-layer deposited on H13 tool steel. Arc physical technique was employed to deposit multilayer coating. X-ray diffraction technique, thermionic and field emission scanning electron microscopy and energy dispersive spectroscopy have been used to determine the characteristics of the samples. To study the samples' wear behavior, coating adhesion, and surface hardness, reciprocating wear test, Rockwell-C test, and microhardness Vickers tester were employed, respectively. The measured values of the coefficient of friction and the calculated wear rates showed that the CrN/AlCrN multilayer coating has a much higher wear resistance than the uncoated sample. The coefficient of the friction of the coated sample was 0.53 and that of the uncoated sample was 0.78. Moreover, the wear rate of the coated H13 steel was about 127 times lower than the bare H13 steel sample. The results obtained from electrochemical impedance spectroscopy and polarization tests demonstrated that the corrosion current density of the H13 steel sample was 8 μA/cm2 and that of the CrN/AlCrN multilayer-coated sample was 3 μA/cm2. In addition, the polarization resistance of the treated and the substrate specimens was estimated at 4.2 and 2.7 kΩ.cm2, respectively.
Mozhgan Hirbodjavan, Arash Fattah-Alhosseini, Hassan Elmkhah, Omid Imantalab,
Volume 19, Issue 4 (12-2022)
Abstract
The principal goal of this research is to produce a CrN/Cu multilayer coating and a CrN single-layer
coating and also compare their electrochemical and antibacterial behavior. In this investigation, the coatings were
applied to the stainless steel substrate by cathodic arc evaporation a sub-division of physical vapor deposition
(CAE-PVD). The present phases were characterized and the thickness of the coatings was measured using X-ray
diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. Rockwell-C tester was
used to evaluate the adhesion quality. Also, to evaluate the mechanical properties of the coatings such as modulus
of elasticity and hardness, a nanoindentation test was used and the indentation effect and coating topography were
evaluated using atomic force microscopy (AFM). Studying the electrochemical behavior of the coatings was done
using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests in Ringer's
solution. The results of EIS tests showed that the CrN coating had higher polarization resistance in comparison to
the CrN/Cu coating and an increasing trend of polarization resistance related to both coatings was identified by
rising the time of immersion. Also, using the PDP curves, the CrN and CrN/Cu coating current densities were
estimated at 1.835×10-8 and 2.088×10-8, respectively. The antibacterial activity of CrN and CrN/Cu coatings was
evaluated by the spot-inoculation method. The results of the antibacterial test indicated that compared to CrN
coating, CrN/Cu coating had a better impact on the control of the bacteria growth.
Davar Rezakhani, Abdol Hamid Jafari,
Volume 19, Issue 4 (12-2022)
Abstract
In this work, the addition of a combination of Graphene Oxide Nanoplatelets (GONPs) and Ground
Granulated Blast Furnace Slag (GGBFS) was studied as admixture in concrete. Tests on physical and mechanical
properties and chloride permeability were conducted. GGBFS was replaced with Ordinary Portland Cement (OPC)
and it was determined that GGBFS Up to 50% by weight improves the physical and mechanical properties of
concrete. GONPs with an optimal amount of 50% by weight of GGBFS were added to the concrete and the physical
and mechanical properties of the samples were determined. It was observed that the addition of GONPs was effective
in improving the mechanical strength and physical properties of specimens. The results indicated that addition of
0.1 wt.% GO and 50 wt.% GGBFS would increase the compressive strength of the concrete sample up to 42.7%
during 28 days and 46% during 90 days compared to OPC. Concrete with a combination of 0.1 wt.% GONPs and
50 wt.% GGBFS witnessed an increase in its flexural strength up to 58.5% during 28 days and 59.2% during 90
days. The results indicated that by adding 0.1 wt.% GO and 50 wt.%, concrete chloride permeability decreased
substantially 72% for 90 day cured samples compared to OPC. GONPs as an alternative to cement up to 0.1% by
weight can accelerate the formation of C-S-H gel, thereby increasing the strength and improving the resistance of
water absorption and chloride permeability. The effects of pozolanic reaction in the concrete leading to the filling
of the pores were significant factors in the proposed curtailment mechanism
Sravanthi Gudikandula, Ambuj Sharma,
Volume 19, Issue 4 (12-2022)
Abstract
The lean duplex stainless steels (LDSS) have excellent features due to the microstructural phase
combination of austenite and ferrite grains. These steels have low Ni and Mo contents which can reduce the cost
and stabilize the austenite fraction in the microstructure. In recent years, welding is used to enhance the
microstructural behaviour of LDSS. In this paper, Gas tungsten arc welding (GTAW) was performed on LDSS
S32101 with different heat energy inputs and varying welding currents. The influence of heat inputs (0.85 and 1.3
kJ/mm) on welded samples was investigated to study the microstructural behaviour, phase balance, and mechanical
& corrosion performance. The microstructures studies were carried out using an optical microscope, scanning
electron microscope and X-ray diffraction. The effect of Heat input led to the significant microstructural evolution
in weld metals with high austenite reformation. The microstructure of weldments consisted of inter-granular
austenite (IGA), grain boundary austenite (GBA) and Widmanstatten austenite (WA). Important mechanical
properties such as tensile strength and micro-hardness were investigated to understand the performance of
weldments. The polarization method was used to understand the corrosion behaviour of weldment in a 3.5% NaCl
solution. The experimental results showed enhanced properties of welds that could be suitable for industrial
applications.
Hussein Ali Jan Miran, Zainab Naji Abdullah, Mohammednoor Altarawneh, M Mahbubur Rahman, Auday Tariq Al-Bayati, Ebtisam M-T. Salman,
Volume 20, Issue 1 (3-2023)
Abstract
This contribution evaluates the influence of Cr doping on the ground state properties of SrTiO3 Perovskite using GGA-PBE approximation. Results of the simulated model infer agreement with the previously published literature. The modification of electronic structure and optical properties due to Cr3+ doping levels in SrTiO3 has been investigated. Structural parameters infer that Cr3+ doping alters the electronic structures of SrTiO3 by shifting the conduction band through lower energies for the Sr and Ti sites. Substituting Ti site by Cr3+ results the energy gap in being eliminated revealing a new electrical case of conducting material for the system. Furthermore, it has been noticed that Cr doping either at Sr or Ti positions could effectively develop the SrTiO3 dielectric constant properties. Consequently, Cr3+ is an effective dopant due to enhancing the optical absorption properties, thus opening up new prospects for optoelectronic applications.
