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In this study, the effect of the surface parameters variation as the symbol of surface condition on the wear behavior was studied. For approaching this issue, the precipitated coating, chromium electroplating was applied on the titanium substrate. The maximum obtained microhardness was 510 HV0.5 and 3 N load was chosen as the applying load within the wear test due to the results of the determination of the load test. The best sample with 0.21 g weight loss obtained which was coated at 30 A/dm2 within 15 min. Also, the analysis displayed that both abrasive and adhesive wear mechanisms were active within the wear test. The precipitated feature of the obtained chromium coating plays an important part in the wear performance. Proposed experimental relation based on obtained results shows that different surface parameters including surface roughness, the height of the asperities, and the height of the peaks has meaningful relation with the measured wear rate. Finally, the friction coefficient was decreased remarkably from 1.12 to 0.56. [ABSTRACT FROM AUTHOR]

Metal-matrix Cu–Ti–B nanocomposites were prepared by SHS method and their corrosion behavior was characterized by XRD, atomic force microscopy, polarization testing, and electrochemical impedance spectroscopy. Microhardness of synthesized composites attained a value of up to 544 HV. The presence of BN, Cu3Ti, and TiO phases leads to formation of Cu/BN, Cu/Cu3Ti, and Cu/TiO galvanic pairs which accelerate corrosion. [ABSTRACT FROM AUTHOR]

Al-Ti-B master alloys (MAs) were SHS-produced from the elements taken in the amounts that would ensure the preparation of final combustion products (MAs) containing about 20, 25, and 30 mol % TiB2. Combustion products and the samples of commercial Al alloy doped with 0.2 wt % combustion-synthesized MAs were characterized by optical microscopy, XRD, SEM, and EDS. The effect of added MAs was explored by optical microscopy using Clemex Vision software to determine the ASTM grain size number (G) and percentage of intermetallic compounds in doped Al alloys. A higher microhardness (97.64 HV 0.05) was observed for the Al specimens doped with MA nominally containing 25 mol % TiB2. [ABSTRACT FROM AUTHOR]

Accurate geological modeling of subsurface structures with all available geophysical data is a challenging task in geo-exploration studies. Concern in precise modeling will increase by increasing geological complexity of subsurface structures such as salt dome. Integrating various sources of geophysical data will reduce uncertainty in geological modeling in complex media. In this study, we introduce an integrated strategy for more appropriate detection of salt boundary in seismic image, by applying the normalized full gradient (NFG) method, used in processing of potential field data. In the proposed strategy, we initially, analyzed sensitivity of the NFG parameters by derivation of a synthetic model. Parameter analysis and optimization showed dependency of geometrical properties of the geological target to the harmonic number in the NFG method. Afterwards, seismic traces were processed by the NFG method. Results showed increase in vertical resolution of seismic envelope compared to the result of the well-known Hilbert Transform. The proposed strategy was applied on a synthetic seismic data contains complex salt model. Results have shown that application of the proposed strategy produced higher resolution seismic image compared to the Hilbert Transform method. The method also was applied on a field seismic data with a complex salt dome from southwest of Kazakhstan. Seismic image obtained by the integration procedure could better exhibit body of the salt dome, as well as better interpretation of faults, layer boundary truncation, salt bottom and subsalt layers. Thus, it was concluded that the proposed strategy could be considered as an alternative to resolve some of ambiguities in geological interpretation of seismic data in complex geological settings. [ABSTRACT FROM AUTHOR]

Aluminum conductors joining is an important issue in electric transportation industry. In some conditions, electric arc welding or friction stir welding could not be used to join these conductors due to environmental conditions, lack of welding tools, etc. In these cases, SHS method can be used as an appropriate process. In this work, two aluminum conductors (with 9.3-mm diameter and 125-mm length) were joined by SHS method. The conductors were made of commercially pure aluminum (Al > 99%) and, to enhance the joint strength, different weight percentages of copper (0.73-2.4 wt %) were added to green blends. The joints were characterized by hardness testing, electrical resistance, and optical metallography. With increasing Cu percentage, the electrical conductivity of the joint was found to decrease while the strength and hardness, to increase. In the presence of copper, the grain size of the join material was found to decrease. [ABSTRACT FROM AUTHOR]

The zirconia stabilized by 3 mol % YO (3YSZ) was applied onto the surface of the magnesium alloy AZ91D using electrophoretic deposition (EPD) from a non- aqueous solvent. An interlayer of aluminum between the substrate and YSZ coating was also prepared by EPD. The preparation, microstructure and corrosion resistance of the coatings were investigated. The surface morphologies of the coatings were studied by scanning electron microscopy (SEM) and their compositions were determined by X-ray diffraction (XRD). The corrosion resistance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The results indicate that the aluminum interlayer has a favorable effect on the densification of the coating by formation of aluminum oxide. In addition, the corrosion resistance of coated AZ91D alloy in chloride solution is significantly improved because of the aluminum interlayer and an increase in charge-transfer resistance of the AZ91D surface in chloride solution was observed which was attributed to YSZ. [ABSTRACT FROM AUTHOR]

Electrophoretic deposition was used in order to apply the zirconia stabilized by 3 mol% YO onto the surface of the magnesium alloy AZ91D. Two different interlayers which were including aluminum layer and Ni-P layer were prepared between the AZ91D surface and YSZ coating and the effect of them on the quality of YSZ coating was investigated. The surface morphologies of the coatings were studied by scanning electron microscopy, and their compositions were determined by x-ray diffraction. The corrosion resistance of the coatings was evaluated by electrochemical impedance spectroscopy in 3.5% NaCl neutral solution. Also, the stability of coating was investigated by the Rockwell C indentation test. The results showed that the YSZ coating applied onto different interlayers on AZ91D improves the corrosion resistance of this alloy due to increase in charge-transfer resistance of the AZ91D surface. Also, the aluminum interlayer has a favorable effect on the densification of the coating by formation of aluminum oxide. Furthermore, the corrosion resistance of AZ91D that coated by YSZ and aluminum layer was improved compared to that of coated AZ91D with YSZ and Ni-P layer. The presence of interlayers can make the stability of the YSZ coating improved on the surface of AZ91D. [ABSTRACT FROM AUTHOR]

In this work, two-step anodizing of commercial aluminum foil in acid oxalic solution was applied for producing alumina film. Then the anodic alumina film was etched in sodium hydroxide (NaOH) solution resulting dense and aligned alumina nanowires. This procedure leads to splitting of alumina nanotubes. Subsequently nanowires are produced. The effects of NaOH solution concentration (0.2-1 mol/L) and etching time (60-300 s) at constant temperature on characteristic of nanotubes and produced nanowires were investigated using scanning electron microscopy. The results show that an increase in NaOH solution concentration increases the rate of nanowires production and in turn the manipulation process will be more specific. [ABSTRACT FROM AUTHOR]

The feasibility of Cu-TiO composite production by SHS method was surveyed. Different weight percentages of CuO and Ti powders were mechanically activated, mixed, and compacted under different pressure. SHS reactions were performed in a stainless steel reactor. Combustion products were characterized by SEM, XRD, DTA, and EDS map analysis. The reaction was optimized using the HSC software results. The dispersion of reinforcing particles and the effect of compaction pressure on the hardness of produced composites were investigated. The maximum hardness value and the best dispersion of a second phase were exhibited by the specimens with an overly stoichiometric weight percentage of Ti. The principles of the process optimization were discussed. [ABSTRACT FROM AUTHOR]

Having similar properties with natural bone, has made porous NiTi shape memory alloy (SMA) a promising material for biomedical applications. In this study porous NiTi SMA has synthesized with 30 and 40 vol.% green porosity by self propagating high temperature synthesis (SHS) from elemental Ni and Ti powders. After synthesizing, the average porosity of specimens reached to 36.8 and 49.8% for green compacts with 30 and 40 vol.% of green porosity, respectively. Combustion products were characterized by XRD, SEM, EDS and electrochemical polarization test. Although desired B2 (NiTi) phase was the dominant phase, other phases like Ti2Ni, Ni3Ti and Ni4Ti3 are found. Electrochemical polarization analysis in simulated body fluids (SBF) shows that, synthesized porous NiTi has better corrosion resistance than solid one and hydroxy apatite coating on porous NiTi worsen electrochemical corrosion resistance which is because of bioactive behavior of hydroxy apatite. [ABSTRACT FROM AUTHOR]

Evaporative rocks are known to have a high susceptibility to dissolution in fresh water. Substantial evidence all over the world has shown that the dissolution of evaporative rocks in the foundations of dams and basins can lead to unfortunate disasters. In a basin located in Iran, owing to dissolution of evaporative rock in the foundation on the south side, some hazardous events, such as unexpected subsidence, ground collapse, and water escape from the reservoir, have been reported. Comprehensive geological and geophysical surveys along with detailed geotechnical investigations were performed in order to assess the reasons. By analyzing the site investigation results, it is recognized that even though the foundation of the basin is composed of impervious marl layer, the dissolution of thin streaks of gypsum embedded inside the marl layer provides interconnected paths for the flow of water into the lower depths of the foundation in order to reach to halite layer located inside the marl. The geophysical survey results indicate that the zone with defects is limited to the specific area of the basin where the halite layer is located relatively near the ground surface. However, if the reservoir is filled completely again, the dissolution front may advance to other zones of the basin, and more area of the basin ground may be affected by subsidence and other relevant phenomena. [ABSTRACT FROM AUTHOR]