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Skin wounds caused by burns, physical injuries, and diseases such as diabetes can lead to amputation and even death of people due to infection and lack of proper angiogenesis. In this research, a wound dressing was made using the electrospinning method from a blend of poly-caprolactone and gelatin polymers which Ciprofloxacin and Vitamin C were loaded in the polymers separately. The morphology of the structure was observed by scanning electron microscope followed by evaluation of hydrophilicity, swelling, degradation rate, tensile strength, and drug release pattern Fibroblast cell response was also considered using cytotoxicity test method. Results showed that the wound dressing fibers without drugs and containing drugs were uniform with a diameter of 1039.246 ± 96 and 1403± 406 nm, respectively. The wound dressing showed a suitable wide range of swelling ability and durability within 35 days. The tensile strength increased up to 3.5 times by addition of ciprofloxacin and vitamin C due tothe morphological changes. The presence of drugs in the system did not indicate any adverse effect on the cell's viability, and suitable proliferation and adhesion of skin fibroblast cells were observed on the surface of the sample. In addition, a combination of gelatin and polycaprolactone polymers could provide an appropriate degradation rate and release pattern without any crosslinking process, while preserving the mechanical properties and flexibility. [ABSTRACT FROM AUTHOR]

The present research has aimed to investigate the effect of Ti3AlC2 reinforcing MAX phase on the electromagnetic behavior of TiC matrix composites. In this case, the milling process and secondary heat treatment were used for the synthesis of the composite. The resulting structures were examined by scanning electron microscope, differential thermal analysis, and X-ray diffractometer. Electromagnetic behavior was investigated by vector network analyzer. The investigations showed that it is possible to create a TiC/Ti3AlC2 composite structure in situ after milling. Electromagnetic investigations revealed that the electromagnetic absorption behavior of TiC/Ti3AlC2 ceramic matrix composite was improved compared to the original TiC. So that the lowest reflection loss of the milled composite was equal to -19.46 dB in the frequency range of 1 to 18 GHz band. After annealing at 1400 °C, it was found that the Ti3AlC2 phase resulting from the milling process was not stable and turned into the single phase solid solution of TiCx. Electromagnetic investigations of the annealed sample showed that after removing the MAX phase, the electromagnetic absorption behavior was weakened. Thus, the lowest reflection loss of the annealed sample was equal to -9.82 dB. [ABSTRACT FROM AUTHOR]

Cast AZ91 alloy is one of the most used magnesium alloys, which is sensitive to liquation in the fusion weld method's and friction stir spot welding due to low eutectic temperature and the presence of the intermetallic compound in eutectic temperature. In this research, the liquation behavior of AZ91 alloy during friction stir spot welding was investigated. The process was carried out at two rotation speeds of 1000 and 2500 rpm and a dwell time of 1 second on the plate of AZ91 with a 10 mm thickness. Microstructural characterization was carried out using optical and scanning electron microscopes. The results showed that at low rotation speed (1000 rpm), mechanical grinding redistribution and dissolution of precipitates occurred. While at high rotation speed (2500 rpm), the predominant phenomenon was liquation. In this condition, the liquation initiated around the stirred zone. Also, the presence of liquid film along grain boundaries resulted in decreased grain boundary strength and liquation cracking. [ABSTRACT FROM AUTHOR]

Metastable beta titanium alloys have the ability to achieve different microstructures as a result of various heat treatment cycles. The aim of the present study was to create a combination of fine spherical and needle-shaped alpha phase in a metastable beta Titanium alloy (Ti-3Al-8Mo-7V-3Cr) using two-phase solution annealing and aging to improve tensile properties. In this regard, one strip of the alloy was solution annealed in the two-phase region (α+β) at 750°C. Then, some of the solution treated specimens were aged in one step and the others in two steps. The microstructural observation and phase analysis were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively followed by investigating tensile properties using tensile test. The results exhibited that the microstructure of the alloy after annealing in the two-phase region (α+β) consisted of a spherical primary alpha phase of 1 μm in the beta matrix. One-step aging at 600°C resulted in a microstructure without secondary alpha layers. This heat treatment cycle resulted a yield strength of 980 MPa and fracture strain of 13.9%. Two-step aging at 300°C and 600°C led to formation of the secondary alpha layers with 0.1 μm thickness and increased the yield strength and fracture strain to 1007 MPa and 15.8%, respectively. [ABSTRACT FROM AUTHOR]

In this research, the effect of temperature and time on the properties of AISI420/SAF2507 dissimilar joint produced by transient litpd phase bonding process was investigated. A BNi-2 interlayer witb 25 pm thickness was inserted between two dissimilar steel samples. The bonding process was performed at 1050 oC and 1100 oC for different bonding times. The microstructures of the joints were studied using optical microscope, scanning electron microscope and energy dispersive X-ray spectroscopy. Microhardness and tensile shear strength of bonded samples were investigated. Isothermal solidification was completed for the joints bonded at 1050 oC and 1100 oC for 45 min and 30 min, respectively. ASZ and ISZ areas of the bonding zone at the bonding temperature of 1050 oC indicated the highest (520 HV) and the lowest (300 HV) microhardness values, respectively. Sample bonded at 1050 oC for 1 min indicated the lowest tensile strength (196 MPa) and sample bonded at 1100 oC for 60 min indicated the highest tensile strength (517 MPa). [ABSTRACT FROM AUTHOR]

Amorphous steel slag was blended with different concentrations of waste glass (20, 40, 50, 60, 70 wt.%) and SiC to obtain a composite. According to Hot Stage Microscopy images, slag-glass composite contractions started at 1050 ºC. scanning electron microscope micrographs of slag-SiC (foaming agent) composite revealed tunnel-like porosities of 500 to 1000 microns. Gaseous products of carbide decomposition led to the formation of these tunnel-like porosities. By adding up to 50 wt. % of waste glass to this composite and sintering at 1200 ° C, the size of cavities decreased by 10 times and achieved 50 microns to form spherical cavities. By increasing glass content, the total porosity of slag-glass-SiC increased to 80 wt.% followed by a decrease in the strength to 3.2 MPa. Having an overall density of 0.8 g/cm3, the slag-glass composite could be classified as a porous foam material. Pseudo Waltonite phase was also detected in this composite after sintering. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effect of glycyrol (tri-dentate, GLY) and ethylenediamine (doubledentate clay, en) chelating agents on phase and morphology changes of spinel nanoparticles synthesized by sol-gel method. Characterization of samples was performed by X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray spectrometer (EDX). The results showed that both samples synthesized with GLY and en contain cubic spinel phase. The sample synthesized with ethylenediamine has a pyramidal morphology with particle size in the range of 20-25 nm whereas the specimen prepared with glycerol is spherical with particle size in the range of 20-25 nm. Finally, suggested mechanism for morphological changes of spniel nanoparticles was discussed. [ABSTRACT FROM AUTHOR]

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In this study, the effect of platinum-aluminide coating parameters on surface roughness of nickel-based superalloy Rene®80 was evaluated. For this purpose, different thicknesses of Pt-layer (2, 4, 6 and 8µm) were plated on the Samples. Then diffusion aluminide coating in two types, high tempeature-low activity and low temperature-high activity was performed. The results of structural investigations by scanning electron microscope and X-Ray diffraction indicated a three-zone structure of coating in all thicknesses of platinum layer, as well as in the two methods of aluminizing. Surface roughness of coatings was measured in three steps: 1-after Pt plating, 2-after Pt diffusion, and 3-after aluminizing and final aging. The results showed that the thickness of Pt and the final thickness of the coating directly affected the surface roughness. The minimum surface roughness was created by high temperature low activity with 2µ of Pt-layer (2.6µm) and the maximum of surface roughness was obtained in low-temperature high activity with 8µ of the Pt-layer (8.8 µm). [ABSTRACT FROM AUTHOR]