Corrosion is a harmful processes which by definition is a chemical or electrochemical reaction between a substance (usually a metal) and the environment which leads to a change in the properties of ...the substance and has destructive effects. In this study, new composites consisting of Al/WS2/ZnTerp-2TH with 5 and 10 wt.% ZnTerp-2TH were prepared and the results were fully compared. Al/WS2 played the role of matrix and ZnTerp-2TH played the role of reinforcement. In other words, as a novelty to prevent the corrosion of Al/WS2, ZnTerp-2TH is designed and synthesized and showed good results when the corrosion ratio was reduced by the existence of ZnTerp-2TH. Furthermore, the NMR and mass analysis of ZnTerp-2TH were carried out, and the thermal properties, X-ray diffraction, Fourier-transform infrared (FTIR) spectroscopy, morphology, energy-dispersive X-ray spectroscopy (EDX) analysis and corrosion behavior of the composites were also discussed in detail. The crystal size values of composites were calculated by the modified Scherrer method 34, 26 and 27 nm for Al/WS2, Al/WS2/5 wt.% ZnTerp-2TH and Al/WS2/10 wt.% ZnTerp-2TH, respectively. The microstructural examination of the specimens showed that the reinforcing phase (ZnTerp-2TH) has a favorable distribution on the surface of Al/WS2 when it covers the cracks and holes. In addition, the corrosion investigation results showed that the addition of ZnTerp-2TH to Al/WS2 can improve the corrosion resistance when the Ecorr and Icorr values of Al/WS2/10 wt.% ZnTerp-2TH were recorded in tandem −724 mV/decade and 5 uA cm−2.
Recently, researchers have focused on the biocompatibility and mechanical properties of highly porous structures of biomaterials products. Porous composites are a new category of bioengineering that ...possess excellent functional and structural properties. In this study, the physical and mechanical properties of prepared doped silver (Ag)-hydroxyapatite (HA) by the mechanochemical and spark plasma sintering (SPS) methods were investigated. The influence of dopant on phase formation, structural properties, mechanical properties and morphological characteristics was investigated. Furthermore, in this case, as a new approach to produce a porous scaffold with an average size of >100 µm, the hair band was used as a mold. According to the Monshi–Scherrer method, the crystal size of scaffold was calculated 38 ± 2 nm and this value was in the good agreement with average value from transmission electron microscopy (TEM) analysis. In addition, the stress–strain compression test of scaffold was considered, and the maximum value of compressive strength was recorded ~15.71 MPa. Taking into account the XRD, TEM, Fourier-transform infrared (FTIR), scanning electron microscope (SEM) and energy dispersive X-Ray analysis (EDAX) analysis, the prepared scaffold was bioactive and the effects of doped Ag-HA and the use of polyvinyltrimethoxysilane (PVTMS) as an additive were desirable. The results showed that the effect of thermal treatment on composed of Ag and HA were impressive while no change in transformation was observed at 850 °C. In addition, PVTMS plays an important role as an additive for preventing the decomposition and creating open-microporous in the scaffold that these porosities can be helpful for increasing bioactivity.
The synthesis of nanostructured fiuorapatite （FA; Calo（PO4）6F2） was explored from the starting materials of CaHPO4, Ca（OH）2, CaO, P205 and CaF2 via a mechanochemical process. In this research, the ...suitability of using the mechanochemical process to prepare a high crystalline phase of FA was studied. The characterization and structural features of the synthesized powders were evaluated using powder X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR）, energy dispersive X-ray spectroscopy （EDX）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM） techniques. The results from the structural studies indicate that the maximum lattice disturbance in the apatite structure after the mechanochemical process was at the （0 0 2） plane. Furthermore, the maximum particle size was below the crystallite size after 60 h of milling and subsequent thermal treatment at 600 ℃ for 1 h （heated up to 600 ℃ and kept for 1 h at this temperature）. We determined that this method gives rise to the single-crystal FA with an average size in the range of 25 ± 5 to 29 ± 9 rim. The present findings suggest that the solid-state reaction and appropriate thermal process simultaneously lead to the formation of nanostructured FA with spheroidal shape.
Mg-based alloys have several suitable properties for biomaterials, but they have major problems of being less antibacterial and have a low mechanical strength. To solve these problems, a new ...combination of Ag/Zn/Mg was prepared in this study, where the presence of Zn and Ag can help to increase the bioactivity. The use of 5 wt.% polymers consisting of PolyCaproLactone (PCL), PolyHydroxyButyrate (PHB) and PolyVinylTriMethoxySilane (PVTMS) is also investigated. DSC, XRD, TEM, FTIR, SEM, and EDAX analysis, as well as mechanical and bioactive behavior, were investigated to characterize the prepared composites. In the comparison, the best behavior was found when PHB was used. The results show that the strength values ranged from ~201 to 261 MPa.
The effect of bonding temperature and bonding time on the microstructure of transient liquid phase (TLP) bonding named GTD111 and IN718 superalloys, using a commercial Ni–B–Cr filler alloy (BNi-2) ...interlayer were evaluated. The sandwich assembly was kept in a vacuum furnace at temperatures of 1050, 1100, and 1150 °C for 1, 15, 30, 45, 60, and 80 min until the TLP process occurred. Microstructural characterization was carried out via optical microscopy, scanning electron microscopy (SEM) equipped with field emission energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Microstructural assessments displayed those in little bonding times, the joint microstructure includes continuous eutectic intermetallic phases and longer times cause eutectic free microstructure. The bonding temperature affects the isothermal solidification rate, while, at low bonding temperatures microstructure of the joint centerline is controlled by diffusion of melting point depressant (MPD) elements. Despite, at high bonding temperature effect of base metal alloying elements on the joint microstructure development was more marked. The results showed that athermally solidified zone (ASZ) size reduces with increasing bonding temperature and time due to diffusion of boron into the base metal.
In this work, hydroxyapatite-20%wt titanium (HAp-20%.wt Ti) nanocomposite was produced by novel solid state method. The effect of one step mechanochemical process on the formation, structural, and ...morphological features of HAp-based nanocomposite was explored. Characterization of the products was accomplished by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Phase analysis indicated that the milling time and thermal annealing process at 650 °C affected phase stability and structural features of products. The crystallinity degree of mechanosynthesized powders increased after thermal treatment at 650 °C. Morphological evaluation exhibited that the average particle size of resultant powder with ellipse-like morphology reached about 25 ± 15 nm after 20 h of milling. The prepared nanopowders which have an acceptable purity are able to improve the biomedical performances of the calcium phosphate-based nanocomposites owing to possess appropriate morphological and structural features.
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In the present investigation the effects of milling parameters (time, atmosphere, and media) and chemical composition of raw materials on the mechanochemical synthesis of nanocrystalline ...hydroxyapatite (n-HAp) were studied. For a comparative study of the mechanically activated samples versus thermally treated specimen (natural origin), n-HAp was also produced via annealing of bovine bone at 800°C for 2h. The gained powders exhibited average sizes about 32 and 27nm under air atmosphere, and about 32 and 34nm under argon atmosphere. TEM images confirmed the formation of n-HAp with various morphologies under different experimental conditions.
Nanostructured SiC was synthesized by magnesiothermal reduction of silica derived from zeolite ZSM-5 with a Si/Al ratio of about 80 and four carbons from different sources. The carbons were carbon ...black and three carbons synthesized by impregnating furfuryl alcohol or sucrose into three porous templates (ZSM-5, clinoptilolite and MCM-48). Magnesiothermal reduction was carried out by reacting mixtures of silica, carbon and magnesium powder at 600–800°C in a flowing argon atmosphere. The starting materials and final products were characterized by X-Ray diffraction, thermogravimetric analysis, scanning electron microscopy and BET analysis. The results indicated that the synthesis of nanostructured SiC is influenced by the chemical nature of the carbon and its surface area.
Boron carbide (B4C) is an advanced engineering ceramic with properties that are improved in highly densified materials. A possible alternative to the use of sintering additives may be the use of ...nanostructured B4C powders. This paper reports the synthesis of nanostructured boron carbide by magnesiothermic reduction of boron oxide and porous carbons derived from synthetic ZSM-5 zeolite, mesoporous SBA-15 silicate or mesoporous MCM-48. The syntheses were carried out under argon with different mass ratios of boron oxide, carbon and magnesium. The ZSM-5, SBA-15 and MCM-48 templates and the corresponding porous carbon products were characterized by BET, XRD, TGA, SEM and EDX. The effect of the type and content of the carbon reactant on the boron carbide synthesis suggests that in addition to the type of carbon, the nature of the template is an important factor in the synthesis of nanostructured boron carbide.
In this study, mechanochemical reactions in the ternary system of Al–B2O3–C were investigated. The starting materials were activated in a planetary ball mill under Argon atmosphere at different ...times. X-Ray diffraction and scanning electron microscopy (SEM) methods were used to characterize the products. The results showed that B4C, AlB12, and Al2O3 were formed at least after 4 h of milling. Furthermore, an aluminum borate (9Al2O3.2 B2O3) compound was formed during an aluminothermic reaction, as a by-product that could be diminished substantially by increasing the milling time to 20 h. SEM and TEM micrograph showed that the products were agglomerated and the range of particle size was within 100 nm. A high hardness value of 88 BHN with a compaction strength of 313 MPa can be achieved for the bulk sample sintered at 560°C for 90 min.
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