Salma Bessalah, Jebahi Samira, Amel Raoufi, Asim Faraz, Mouldi Zagrouba, Mohamed Hammadi,
Volume 19, Issue 2 (6-2022)
Abstract
Abstract
Gelatin (GEL) is most extensively used in various fields, particularly in therapeutics and pharmaceuticals. GEL was extracted from goat skin using hot temperature extraction process and compared with that of commercial GEL. The physico-chemical characterization and functional properties were investigated by using temperature denaturation (Td), water-holding and fat-binding capacities (WHC and FBC), colour measurement and UV-light spectrum. In vitro biocompatibility was studied for the first time and was evaluated by blood coagulation index (BCI) and haemolytic tests for using as wounds dressing. The results revealed thermal stability of goat GEL at Td 37°C. WHC and FBC capacities represented 2.5 and 1.2 g/ml, respectively. The hunter colour spaces a*, b* and L* showed a -0.27, -1.97 and 25.23 values, respectively. UV-Vis absorption spectrum of the goat GEL showed a maximum absorption peak at 280 nm. The in vitro anticoagulant activities of extracting GEL were higher than 70% after incubation for one hour. After being in contact with red blood cells for 1 h, the haemolysis ratio increased from to 0.46 to 1.4 when the concentration of goat GEL increased from 1 to 50 mg/ml suggesting the safety of the tested samples. These results suggest that thromboresistivity and hemocompatibility of this biopolymer retained the biological activity of our samples for biomaterial applications. According to this, goat GEL successfully competes with, and significantly could be useful for substitution of bovine in wound healing.
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.
Amirhossein Kazemi, Arash Fattah-Alhosseini, Maryam Molaei, Meisam Nouri,
Volume 19, Issue 2 (6-2022)
Abstract
In this study, for the first time, the Forsterite (Mg2SiO4) nanoparticles (NPs) with the size of about 25 nm were added to the phosphate-based electrolyte, and the characteristics and properties of the obtained plasma electrolytic oxidation (PEO) coating on AZ31 Mg alloy was investigated. The results of the potentiodynamic polarization measurements revealed that after one week of exposure to simulated body fluid (SBF) solution, the coating with Mg2SiO4 NPs possessed 12.30 kΩ cm2 polarization resistance, which was more than two times greater than that of the coating without NPs. The thicker coating layer, lower wettability, and also presence of Mg2SiO4 NPs inside the pores were responsible for enhanced corrosion protection in the Mg2SiO4 NPs incorporated coating. After three weeks of immersion in SBF solution, the in-vitro bioactivity test results indicated the ability of the NPs-containing coating to form apatite (Ca/P ratio of 0.92) was weaker than the coating without NPs (Ca/P ratio of 1.17). This could be attributed to the lower wettability of the coating with NPs and supports that the addition of the nanoparticles is not beneficial to the bioactivity performance of the coating.
Hannaneh Ghadirian, Hamid Golshahi, Sara Bahrami, Farhood Najafi, Allahyar Geramy, Soolmaz Heidari,
Volume 19, Issue 2 (6-2022)
Abstract
Quaternary ammonium compounds (QACs) are among the most commonly used antibacterial agents. The aim of this study was to synthesize a dimethacrylate monomer functionalized with a QAC and to study its effect on the properties of an orthodontic adhesive primer. Urethane dimethacrylate monomer functionalized with a QAC (UDMAQAC) was synthesized and then characterized by nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). 5, 10, 15 and 20 wt% of UDMAQAC was added to an orthodontic adhesive primer (control group). FTIR analysis was used to measure the degree of conversion (DC). The bond strength of dental brackets was measured by shear bond strength (SBS) test and adhesive remaining index (ARI) was evaluated by stereomicroscope. Agar diffusion test and MTT assay were used to evaluate the antibacterial property and cell viability, respectively. Statistical analysis included one-way ANOVA with Tukey’s post hoc test and Kruskal-Wallis nonparametric test (P˂0.05). Although the obtained data did not show significant differences between the SBS and DC of different groups, but the highest values were obtained by adding 10 wt% monomer. Adding more than 10 wt% UDMAQAC resulted in significant increase in antibacterial property. The 15 and 20 wt% groups showed significantly lower cell viability
Farnaz Dehghani Firoozabadi, Ahmad Ramazani Saadatabadi, Azadeh Asefnejad,
Volume 19, Issue 2 (6-2022)
Abstract
Fabrication of fully optimized tissue-engineered materials in order to simulating the natural structure, and enhancing the biological properties of damaged tissue is one of the major challenges in biomedical engineering and regeneration medicine. Although polymeric based membranes have revealed noticeable advancements in bone regeneration, their mechanical stiffens, electrical conductivity and bioactivity need to be tolerated.
Therefore, the present study is designed to generate a multifunctional biomaterial based on polylactic acid (PLA)/ polycaprolactone (PCL)/hydroxyapatite (HA) nanocomposite containing zinc oxide (ZnO) and Graphene (Gr) nanoparticles employing solvent casting combined with die cast techniques for using as absorbable joint implants in bone tissue regeneration. The physical, chemical, mechanical and biological properties of the produced nanocomposite biomaterials were analyzed in vitro. A detailed experimental evaluation between the nanocomposite coatings was carried out to shed light on the effect of ZnO and Gr nanoparticles on the properties.
It was found that the nanocomposite contained 1% ZnO and 1% graphene with a Young's modulus of 1540.5 ± 169.426MPa and the pure sample had a Young's modulus of 1194.81±215.342MPa. The rate of elongation at break of the nanostructure contained 1% graphene was 5.1±0.816%. This value was 3.8±0.944% for the pure sample. The improvement in elongation at break is due to the presence of polycaprolactone in the polymer matrix. The optimal sample with 1% zinc oxide and 1% graphene had antibacterial properties more than other samples. Also, the survival rate of fibroblasts cell in the vicinity of the optimal matrix was significantly different from other samples.
The obtained results revealed that the incorporation of the nanoparticles improved physico-chemical features and mechanical strength with enhanced biological properties and its anti-bacterial performance makes this material a promising candidate for further bone regeneration studies.
Israa Khahtan Sabree, Batool Abd Aladel Jabar,
Volume 20, Issue 3 (9-2023)
Abstract
Abstract. Hydroxyapatite (HA) scaffold is commonly used in the applications of bone tissue engineering due to its bioactivity and equivalent chemical composition to the inorganic constituents of human bone. The present study focused on the fabrication of porous 3D hydroxyapatite scaffold which was modified by polymer coating as a successful strategy to improve the mechanical properties. A 3D porous hydroxyapatite scaffolds were fabricated by gel-casting method by using freshly extracted egg yolk (EY) with (50 and 60)wt% of HA powder. To enhance the mechanical properties, composite PVA/ HA scaffolds were produced by using dip coating in Polyvinyl alcohol (PVA). Fourier transform infrared spectroscopy (FTIR) was used to recognize the functional group associated with the hydroxyapatite scaffolds before and after PVA coating. The physical (density and porosity) and mechanical (compressive strength and elastic modulus) properties were investigated before and after coating. SEM was used to inspect the surface morphology and pore modification of the scaffolds. Wettability was determined by using a water contact angle to analyze the scaffold hydrophobicity. Surface roughness was studied by atomic force microscopy (AFM). It was revealed that the scaffold porosity decreased with increase solid loading of HA powder in the gel and after PVA coating. The findings showed that PVA coating improved mechanical strength of scaffold to be double by covering the small pores and filling microcracks sited on the scaffold strut surfaces, inducing a crack bridging mechanism. The scaffolds’ strength was in the range of trabecular bone strength. This indicates non-load bearing applications.
Mohammad Badaruddin, Ahmad Kurniawan Purga, Dwi Asmi, Sugiyanto Sugiyanto, Slamet Sumardi, Andreas Luki Indratmoko,
Volume 21, Issue 0 (3-2024)
Abstract
The investigation of SUP9 steel under the hot-rolling conditions for applications to leaf spring suspension focused on its tensile and fatigue crack growth (FCG) properties. In order to investigate the tensile properties, tensile specimens were fabricated in the longitudinal-transverse (LT) direction. Furthermore, in order to evaluate fatigue crack growth (FCG) behaviour, compact tensile (CT) specimens with different crack plane orientations in both the LT and transverse-longitudinal (TL) directions were employed. Microstructural and fractographic analyses were conducted using optical microscope (OM) and scanning electron microscopy (SEM). The hot-rolling process reduced the interlamellar spacings of Fe3C, enhancing the tensile properties through strain hardening. A high yield-to-ultimate strength ratio (~0.623) indicates excellent plastic deformation capability and resistance to fatigue crack growth, making SUP9 steel suitable for the leaf spring suspension system. Furthermore, the exponential crack growth rate constant, m, was found to be 3.066 in the TL direction and 3.265 in the LT direction, indicating that cracks propagate more rapidly in the LT orientation. Additionally, non-metallic inclusions, such as spherical oxides and MnS precipitates in LT specimens, were observed to facilitate faster crack growth in the transverse direction.
Ram Chhavi Sharma,
Volume 21, Issue 0 (3-2024)
Abstract
The effect of different Nd and PT compositions on the electrical and ferroelectric properties of (1-y)Bi1-xNdxFeO3-yPbTiO3 solid solutions, where x = 0.05, 0.10, 0.15, 0.20 and y = 0.1, 0.2, 0.3, and 0.4, was investigated to optimise material performance. Nd doping enhances the frequency-dependent dielectric properties of produced solid solutions. However, an anomaly in the dielectric loss tangent, which is consistent with the Debye relaxation process, is observed for compositions with x˂0.10 and y≥0.2 values in the frequency range of 1 KHz to 1 MHz. Dielectric anomalies were more noticeable around the transition temperature in temperature-dependent dielectric characteristics plots, suggesting stronger magnetoelectric interactions. The decrease in the dielectric constant for solid solution compositions with y ≥0.3 indicates the presence of MPB with BFO due to an increase in the tetragonal phase of the PbTiO3 compound. As Nd content increases, temperature-dependent dielectric permittivity predicts relaxor-type ferroelectric performance for y=0.4 composition of solid solutions. A ferroelectric investigation showed that saturation polarisation, remnant polarisation, and coercive field of all prepared solid solutions decrease with increased Nd doping. However, for y˃0.3 composition, a substantial rise in these parameters was observed, which is a result of electric order dominating over magnetic order in solid solutions. The study reveals that Nd doping reduces leakage current, making it a promising contender for future applications
Payam Tayebi, Ramin Hashemi,
Volume 21, Issue 0 (3-2024)
Abstract
This study presents the manufacturing of Al 1050/Mg AZ31B bimetallic sheets using the cool roll bonding process, followed by an investigation of the effect of annealing temperature on mechanical properties and microstructural features. Annealing treatment was performed at 200, 300, and 400 degrees Celsius. Mechanical testing includes tension, micro-hardness, three-point bending, and fracture toughness. Scanning electron microscopy equipped with energy-dispersive X-Ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD) were used to investigate the microstructure in the infiltration zone. Mechanical testing shows that increasing the annealing temperature decreases the tensile strength of the two-layer specimens. Micro-hardness, XRD, and SEM-EDX investigations confirm the presence of intermetallic particles in the penetration zone. The Micro- hardness test showed that with the increase of the annealing temperature, the hardness in the penetration zone of Al 1050/Mg AZ31B increases. This increase in micro-hardness result confirms the presence of harder intermetallic phases with increasing annealing temperature in the penetration zone.
Adil Kadum Shakir, Ebrahim Ghanbari-Adivi, Aref S. Baron Baron, Morteza Soltani,
Volume 21, Issue 0 (3-2024)
Abstract
Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties, which result from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles have attracted considerable interest because of their diverse applications.
In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO.
The calcination time had a minimal effect on the crystal structures and also morphology of the nanocomposites, which gave rise to its negligible impact on optical properties and biological activities of the samples. Optical properties assessed by means of UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties.
The sample prepared at 1 hour not only showed the most favorable optical properties, but also demonstrated significant antibacterial, antifungal, and cytotoxic activities, which make it suitable for various applications. In this regard, a reduction of more than 99.9% occurred in the number of Escherichia coli and Staphylococcus aureus bacteria and also Candida albicans fungus by using TiO2-ZnO nanocomposite. Besides, addition of 500 µg/ml of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity.
Eswaran Kamaraj, Kavitha Balasubramani,
Volume 21, Issue 2 (6-2024)
Abstract
Heterostructure photocatalyst of CuWO4 modified SnO2 (CuWO4/SnO2) was fabricated by in simple wet-impregnation process and evaluated via degradation of rose Bengal (RB) under visible light irradiation. The samples had been completely characterized by Ultraviolet-visible diffuse reflectance spectroscopy (UV-vis-DRS), X-ray diffraction (XRD), Scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), High-resolution TEM (HR-TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett and Teller surface analysis (BET). The result divulged that amongst the catalysts, CuWO4/SnO2 displayed higher photocatalytic activity than CuWO4 or SnO2. The enhanced photocatalytic efficiencies are attributed to the charge transfer from SnO2 to CuWO4 nanoparticles, which efficiently decrease electron-hole recombination energy level. The time required for maximum degradation of rosebengal (RB) under visible light over CuWO4/SnO2 was 180 min. The other parameters such as pH (pH=8), photocatalyst dosage (0.2 g/L) and dye concentration (20 µM) were optimized to achieve high degradation efficiency (98.5%). The excellent photocatalytic activity of CuWO4/SnO2 is due to efficient separation of photogenerated electron-hole pairs. The holes (h+) and superoxide radicals (O2•-) are the reactive species involved in photocatalytic mechanism for gdegradation of RB.
Mohammad Derakhshani, Saeed Rastegari, Ali Ghaffarinejad,
Volume 21, Issue 2 (6-2024)
Abstract
In this research, a nickel-tungsten coating as a catalyst for hydrogen evolution reaction (HER) with different current densities was synthesized and the resulting electrocatalytic properties and morphology were assessed. Linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry in 1 M NaOH were used to evaluate the electrocatalytic activity for HER. By increasing the current density of electrodeposition up to 500 mA/cm2, a columnar morphology was observed. The cyclic voltammetry test (CV) revealed that when the plating current density increases, Cdl has increased from 248 to 1310 µF/cm2 and the active surface area increases 5 times. The results showed that by modifying the coating morphology, the current density of the hydrogen evolution increased up to two times.
Muhammad Shahzad Sadiq, Muhammad Imran, Abdur Rafai, Muhammad Rizwan,
Volume 21, Issue 2 (6-2024)
Abstract
With increasing energy demand and depletion of fossil fuel resources, it is pertinent to explore the renewable and eco-friendly energy resource to meet global energy demand. Recently, perovskite solar cells (PSCs) have emerged as plausible candidates in the field of photovoltaics and considered as potential contender of silicon solar cells in the photovoltaic market owing to their superior optoelectronic properties, low-cost and high absorption coefficients. Despite intensive research, PSCs still suffer from efficiency, stability, and reproducibility issues. To address the concern, the charge transport material (CTM) particularly the electron transport materials (ETM) can play significant role in the development of efficient and stable perovskite devices. In the proposed research, we synthesized GO-Ag-TiO2 ternary nanocomposite by facile hydrothermal approach as a potential electron transport layer (ETL) in a regular planar configuration-based PSC. The as synthesized sample was examined for morphological, structural, and optical properties using XRD, and UV-Vis spectroscopic techniques. XRD analysis confirmed the high crystallinity of prepared sample with no peak of impurity. The optimized GO-Ag-TiO2 ETL exhibited superior PCE of 8.72% with Jsc of 14.98 mA.cm-2 ,Voc of 0.99 V, and a fill factor of 58.83%. Furthermore, the efficiency enhancement in comparison with reference device is observed which confirms the potential role of doped materials in enhancing photovoltaic performance by facilitating efficient charge transport and reduced recombination. Our research suggests a facile route to synthesize a low-cost ETM beneficial for the commercialization of future perovskite devices.
Risa Suryana, Nida Usholihah, Markus Diantoro,
Volume 21, Issue 2 (6-2024)
Abstract
Modifying photo-anode structures in DSSC devices is still challenging in improving efficiency. This study focused on the ZnO rod growth on several porous silicon substrates using the hydrothermal method and determining which porous silicon is appropriate for DSSC applications. The materials used for the growth solution were Zn(NO3)26H2O 0.05 M and C6H12N4 0.25 M. The hydrothermal process was carried out at 90°C for 6 h and then annealed at 450°C for 30 min. SEM revealed that PSi pore influences the structure, diameter, and density of ZnO rods. ZnO structures formed in ZnO rods with a dominant vertical growth direction, ZnO rods with an intersection direction, and flower-like ZnO rods. The diameter of the PSi pore affected the density of ZnO rods grown on the PSi. The average diameter size and the density of ZnO rods vary from 747.66-1610.68 nm and 0.22-0.90 rod/μm2. XRD confirmed the presence of ZnO hexagonal wurtzite, Si cubic, and SiO2 monoclinic. UV-Vis spectrometry characterization results showed that sample reflectance was influenced by ZnO rod density and PSi pitch. The larger density of ZnO rods and the smaller pitch of the PSi pore will lead to lower reflectance. In addition, band gap values were obtained in the 3.06-3.75 eV range. FTIR identified the existence of a ZnO vibration bond, indicating that ZnO was successfully grown on all PSi substrates. The ZnO rods grown on P15S1180 are expected to have more appropriate properties among all five samples for DSSC photoanode.
Seyed Farzad Dehghaniyan, Shahriar Sharafi,
Volume 21, Issue 2 (6-2024)
Abstract
Mechanical alloying was employed to synthesize a nanostructured alloy with the chemical formula of (Fe80Ni20)1-xCrx (x= 0, 4). The microstructural and magnetic properties of the samples were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and a vibrating sample magnetometer (VSM). Additionally, theoretical calculations were performed using density functional theory (DFT) under the generalized gradient approximation (GGA). Simulations have demonstrated that an appropriate quantity of chromium (Cr) can dissolve within the BCC-Fe (Ni) structure, resulting in a favorable enhancement of the magnetic moment of the lattice. The XRD results indicated that after 96 hours of milling, Fe (Ni) and Fe (Ni, Cr) with a body-centered cubic (BCC) structure were formed. With increasing milling time, the grain size decreased while the microstrain increased. The saturation magnetization (Ms) of Fe80Ni20 composition increased up to 32 hours of milling, but further milling (up to 96 h) resulted in a decrease in the saturation magnetization However, for the (Fe80Ni20)96Cr4 powders, milling up to 64 h caused a reduction in Ms. The coercivity (Hc) trend was different and increased with longer milling times (up to 96 h) for both compositions.
Lakshmiprasad Maddi, Srinivas R Gavinola, Atul Ballal,
Volume 21, Issue 2 (6-2024)
Abstract
High thermal conductivity, low coefficient of thermal expansion makes P92 a candidate material for Ultra Super Critical (USC) power plant piping. Microstructural features viz., high dislocation density, lath martensitic microstructure, fine precipitates of M23C6 and MX (X=C, N) contribute towards the high rupture strength. However, most components are typically subjected to multiaxial stress conditions; either metallurgical (weldments), or mechanical (change in the dimension). The present work involves stress rupture testing of circumferential 60° V- notch specimens in the range of 300 – 375 MPa at 650 °C. Notch strengthening effect was observed; with rupture times ranging from 200 – 1300 h. Scanning electron microscopy (SEM) fractography revealed mixed mode of fracture with brittle fracture observed at notch root, while ductile fracture was seen at the centre of the specimen.
Fathi Brioua, Chouaib Daoudi,
Volume 21, Issue 2 (6-2024)
Abstract
We have modeled theoretical incident photon-to-current electricity (IPCE) action spectra of poly(3-hexylthiophene) (P3HT) and [6,6]-Phenyl C61 butyric acid methyl ester active layer bulk-heterojunction. By the two-dimensional optical model of a multilayer system based on the structure of Glass substrate / SiO2 /ITO/ PEDOT: PSS /P3HT: PCBM(1:1)/Ca/Al, the optical responses of the device have been computed for different photoactive layer and Ca layer thicknesses to found an optimal structure which allows obtaining the maximum absorption localized in the active layer and high device performance. The electric field intensity, energy dissipation, generation rate, and IPCE have been computed to enhance the device's performance. The finite element method executes the simulation under an incident intensity of 100 mW/cm2 of the 1.5 AM illumination. It was found that the optimum structure is achieved by a 180 nm photoactive layer and 5 nm Ca layer thicknesses.
Rakhesh V, Sreedev P, Ananthakrishnan A,
Volume 21, Issue 2 (6-2024)
Abstract
Organic and Perovskite solar cells have attracted a lot of attention recently since they can be used with flexible substrates and have lower manufacturing costs. The configuration and materials employed in their construction, including the Electron Transport Layer (ETL), active layer, electrode contact, and hole transport layer greatly influence the stability and performance of these solar cells. This research focuses on the simulation of solar cells, specifically utilizing zinc oxide (ZnO) as the electron transport layer. A 0.1 molar ZnO thin film was prepared from Zinc acetate salt and was deposited on a glass substrate using the cost effective Successive Ionic Layer Adsorption and Reaction (SILAR) method. In-depth investigations were carried out on several factors, including structural, surface, optical and numerical analysis. The obtained parameters were utilized in the General-Purpose Photovoltaic Device Model (GPVDM) software to perform numerical simulations of the organic solar cell and Perovskite solar cell. Both Organic solar cells and Perovskite solar cells were designed numerically and through careful observations, electrical parameters like Open circuit Voltage (Voc), Short circuit current (Jsc), Fill Factor (FF), and Power Conversion Efficiency (PCE) were identified. The studies indicate the promising performance of simulated solar cells with SILAR-synthesized ZnO thin film as the ETL.
Padmanaban Ramasamy,
Volume 21, Issue 2 (6-2024)
Abstract
The present investigation delves into the friction stir welding of AA5052 and AZ31B alloys, examining the effects of three distinct parameter configurations. A face-centered central composite design, structured to incorporate full replications for comprehensive and reliable analysis, was employed. A pivotal element of this study is implementing an advanced deep neural network (DNN) model. Characterized by its varied activation functions, structural parameters, and training algorithms, this DNN model was adeptly configured to precisely predict the tensile strength and microhardness of the welded joints. This comprehensive examination also included a quantitative assessment of the parameter effects on joint microstructure and mechanical properties. Flawless welds with exemplary surface characteristics were attained through a meticulously optimized set of parameters: a tool rotation speed set at 825 rpm, a tool traverse speed of 15 mm/min, and a shoulder diameter of 18 mm. During the welding process, the formation of intermetallic compounds, specifically Al12Mg17 and Al3Mg2, was observed. An exceptionally refined grain size of 2.23 µm was observed in the stir zone, contributing to the joint's enhanced tensile strength, measured at 180 MPa. The hardness of the specimen fabricated at the high rotational speed is more elevated due to the brittle intermetallic compounds. The better mechanical properties are related to the reduction and distribution of intermetallic compounds formed in the interface zone.
Alireza Zibanejad-Rad, Ali Alizadeh, Seyyed Mehdi Abbasi,
Volume 21, Issue 2 (6-2024)
Abstract
Pressureless sintering was employed at 1400 °C to synthesize Ti matrix composites (TMCs) reinforced with in-situ TiB and TiC reinforcements using TiB2 and B4C initial reinforcements. The microstructure and wear behavior of the synthesized composites were evaluated and compared and the results showed that B4C caused the formation of TiB-TiC in-situ hybrid reinforcements in the Ti matrix. Also, TiB was in the form of blades/needles and whiskers, and TiC was almost equiaxed. Moreover, the volume fraction of the in-situ formed reinforcement using B4C was much higher than that formed using TiB2. In addition, although the hardness of the B4C-synthesized composites was higher, the composite synthesized using 3 wt.% TiB2 exhibited the highest hardness (425 HV). The wear test results showed that the sample synthesized using 3 wt.% TiB2 showed the lowest wear rate at 50 N, mainly because of its higher hardness. The dominant wear mechanism in the samples synthesized using 3 wt.% B4C was abrasive and delamination at 50 N and 100 N, respectively while in the samples synthesized 3 wt.% TiB2, a combination of delamination and adhesive wear and adhesive wear was ruling, respectively.