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The effect of hydrodynamic cavitation on performance of the alkaline aluminosilicate coatings for metal structures
Get PDFLoad-bearing metal structures working in atmospheric conditions are exposed to corrosion. Known-in-the art paint-and-lacquer protective coatings can provide protection of metal for rather short period of time (5…10 years). These structures can be effectively protected by more advanced coatings of new generation, namely: alkaline aluminosilicate binder-based coatings of barrier type. These binders differ from the known-in-the-art binding materials by formation in their hydration products of zeolite-like minerals and feldspathoids. The paper discusses principles laid down in formulating the binder composition in the (хК, уNa)2OAl2O3nSiO2mH2O system, target synthesis of hydration products of the binder matrix under influence of dynamic of the binder matrix in cavitation, optimal parameter order to synthesis of cavitation treatment aimed at nanostructuring of zeolite-like and hydromica phases after solidification. These coatings exhibit high corrosion resistance, high adhesion to metal substrate and durability results of restoration works that had been carried out in December 2010 of the Big Bell Tower of the Kiev Petchersk Lavra in order to protect corroded metal surfaces by applying the aluminosilicate binder-based coatings, the major constituent (binder) of which was represented by (0.72Na2O+0.28K2O)1.5Al2O3(4.56)SiO217.5H2O are discussed in details. In 2016, after 6 years of service in high humidity conditions and other aggressive exposures, the coated metal structures were examined and no sign of corrosion of metal substrate and damage of the applied coating was found
Hydrocarbon Reservoir Evaluation: a case study of Tymot field at southwestern offshore Niger Delta Oil Province, Nigeria
Get PDFAbstract: Aim: This study presents the log analysis results of a log suite comprising gamma ray (GR), resistivity (LLD), neutron (PHIN), density (RHOB) logs and a 3D seismic interpretation of Tymot field located in the southwestern offshore of Niger delta. This study focuses essentially on reserves estimation of hydrocarbon bearing sands. Well data were used in the identification of reservoirs and determination of petrophysical parameters and hydrocarbon presence. Three horizons that corresponded to selected well tops were mapped after well-to-seismic tie. Structural depth maps were created from the mapped horizons. The structural style is dominated by widely spaced simple rollover anticline bounded by growth faults, and this includes down-to-basin faults, antithetic faults and synthetic faults. The petrophysical values – the porosity, net-to-gross, water saturation, hydrocarbon saturation that were calculated yielding an average porosity value of 0.23, water saturation of 0.32 and an average net-to-gross value of 0.62. Three horizons H1, H2 and H3 were mapped. The three horizons marked the tops of reservoir sands and provide the structures for hydrocarbon accumulation. Hydrocarbon in-place was estimated. The total hydrocarbon proven reserves for the mapped horizons H1, H2, and H3 were estimated to be 39.04MMBO of oil and 166.13BCF for sand E.
The structure and properties of laser seam stepper system (LSS) welded the low alloy high strength steel DOCOL 1200M with martensitic structure
Get PDFThis paper will present the influence of joining process parameters on the structure and properties of overlapped welded joints of 1.8 mm DOCOL 1200M steel. The obtained welded joints were subjected to micro- and macroscopic metallographic examination and hardness measurement. The visual inspections and non-destructive testing made it possible to develop the field of welding parameters to allow obtaining full penetration joints (depending on requirements) or partial penetration joints. For present welding parameters, i.e. feed rate and weld length, which are constant, the actual length of weld is determined by welding frequency. In each case, the microscopic examinations revealed martensitic structure in the weld area, and with the increase in linear welding energy the size of martensite needles became larger, especially in relation to the base material. In HAZ, the martensitic structure is tempered. It has been shown that with appropriately selected parameters the Laser SEAM Stepper method is suitable for welding the DOCOL 1200M steel. With the increase in welding power, the penetration depth increases
Cooling Rate, Hardness and Microstructure of Aluminum Cast Alloys
Get PDFThis experiment investigated the cooling curve behavior, hardness and microstructure of two aluminum alloys produced by casting process. There are Al-1.37Zn-1.19Si and Al-1.66Si-1.35Zn derived from melting and alloying a pure aluminum with ADC12 (Al-Si) ingot. Cooling curve recorded from both those two alloys with pouring temperature at 710 oC and the mold temperature kept constant at 220 oC. The result shows, a freezing range of Al-1.37Zn-1.19Si alloy is 643–348 oC and Al-1.66Si-1.35Zn alloy is 621–401 oC. Then cooling rate obtained for Al-1.37Zn-1.19Si is 55.56 oC/S, and Al-1.66Si-1.35Zn is 30.09 oC/S. TThe higher hardness is 40.42 BHN at Al 1.66 Si-1.35Zn, while the lower value is 34.62 BHN on Al-1,37Zn-1,19Si alloy. The hardness value found higher when cooling rate is shorted. The number of silicon present on microstructure is highest in Al-1.37Zn-1.19Si alloy but the hardness value decreases. This is caused by the distribution of the silicon content in the alloy is irregular. It was found that the solidification rate had an effect on hardness, where the freezing rate obtained a high hardness value
3D Monte Carlo simulation modeling for the electrical conductivity of carbon nanotube-incorporated polymer nanocomposite using resistance network formation
Get PDFHigh electrical and thermal conductivity associated with high stiffness and strength offer tremendous opportunities to the development of a series of carbon nanotube incorporated composite materials for a variety of applications. In particular, a small amount of carbon fibers or carbon nanotubes in a non-conductive polymer will transform a composite into a conductive material, which reveals superb potential of their future application in electronic devices. The relation between the amount of carbon nanotubes in a polymer and the electrical conductivity of it can be studied experimentally as well as theoretically with various simulation models. A three-dimensional (3D) Monte Carlo simulation model using resistance network formation was developed to study the relation between the electrical conductivity of the polymer nanocomposite and the amount of carbon nanotubes dispersed in it. In this model, carbon nanotubes were modeled as curvy cylindrical nanotubes with various lengths and fixed tube diameter, all of which were randomly distributed in a non-conductive constrained volume, which represents polymer. The model can be used to find the volumetric electrical resistance of a constrained cubic structure by forming a comprehensive resistance network among all of the nanotubes in contact. As more and more nanotubes were added into the volume, the electrical conductivity of the volume increases exponentially. However, once the amount of carbon nanotubes reached about 0.1 % vt (volume percentage), electrical percolation was detected, which was consistent with the experimental results. This model can be used to estimate the electrical conductivity of the composite matrix as well as to acquire the electrical percolation threshold
Optimization of DPC Process Applied by Electroless Copper Plating
Get PDFWith the continuous improvement of chip power, the area is shrinking and the integration is getting higher and higher. The LED package puts higher requirements on the heat dissipation substrate. Direct plated copper (DPC) is fabricated on a ceramic substrate by a thin film process. It has stable chemical properties, high thermal conductivity, fine wiring, and a coefficient of thermal expansion (CTE) matching the chip material. The important development direction of power LED package heat sink substrate. However, due to the high price of DPC substrates, there is no corresponding quality and testing standards, which limits its application in high-power LED packaging. In this thesis, electroless copper plating on ceramic surface is used as the seed layer of DPC substrate, which reduces the costly equipment and process such as magnetron sputtering, and reduces the manufacturing cost of DPC substrate. Pulse plating instead of DC plating thickens the copper layer line, which not only improves the efficiency. At the same time, the quality of the coating is optimized; the silver layer is replaced by the gold layer as the soldering layer and the protective layer to reduce the material cost; and compared with other types of ceramic substrates, some test methods for the performance of the DPC substrate are proposed to further standardize the DPC substrate quality standard. Explored. The relationship between the current density of pulse copper plating and the plating rate was analyzed. The results show that the two are proportional to each other within a certain range. At the same current density, pulse plating can significantly reduce the formation of the tumor-like structure and optimize the quality of the coating compared to DC plating. The current density of 3ASD not only improves the plating efficiency, but also obtains a well-formed circuit layer
Latitudinal dependence of supergranular Area and Fractal dimension
Get PDFAbstract: A dependence of the area of supergranular cells with respect to the Latitude is studied and it is found that the cells are situated symmetrically about the ±250 latitude.Fractal dimension of the supergranular cells also shows a marginal latitudinal dependence, variation being in the range 1.6–1.7 in the latitudinal limits of ±300. Fractal dimension D for supergranulation is obtained according to the relation P ∝ AD/2 where ‘A is the area and ‘P’ is the perimeter of the supergranular cells. A difference in the fractal dimension between the active and quiet region cells is noted which is conjectured to be due to the magnetic activity level.Supergranular cells are essentially a manifestation of convective phenomena. They can shed light on the physical conditions in the convection zone of the Sun. Moreover, supergranules play a key role in the transport and dispersal of magnetic fields as it is an important step in our quest to understand the solar cycle
Metallic nanoformulations: Green synthetic approach for advanced drug delivery
Get PDFAn important reason for investigation using plants for nanotechnological research is due to their easy availability as well as applications in various ailments. Silver nanoformulation can be synthesized using whole plant extract or bioactive of that particular plant. In addition, plant extracts or bioactive of the plant may act both as reducing agents and stabilizing agents in the synthesis process of nanoformulation. The therapeutic effect of plant extract is hindered because of its instability, poor solubility, and low bioavailability. So, nowadays, researches have been carried out for improving all these properties including sustainability through silver nanotechnological approach. The major advantage of green synthesis using plant extracts is that, organic solvents and other excipients are not used because the plant phytochemicals are involved directly in the reduction of the ions and formation of silver nanoparticles. The present review provides an updated knowledge on mechanism of green synthesis of silver nanoparticle and their mechanism of action as antibacterial and anticancer activities
Machining millimeter-scale deep holes in SiCf/SiC material using femtosecond laser filamentation effect
Get PDFA 3.5 mm thick SiCf/SiC material was drilled in air environment using a femtosecond laser filament effect. The surface morphology of deep micropores was observed by scanning electron microscopy and the depth and profile of the pores were observed using μm-CT. The variation of entrance diameter, exit diameter and depth variation with laser focus position and processing time was further analyzed. The results showed that as the processing time of femtosecond laser increases, the ablation threshold of the material reached saturation. The exit and entrance diameter also stopped increasing and the aperture tend to saturate. The focus entered the interior of the material, allowing the location of the peak power near the surface of the material. So the entrance aperture was of good quality and the exit aperture was round
The Association for the Accreditation of Human Research Protection Programs: 15 years of emphasizing research safety, ethics, and quality
Get PDFThis year marks the 15th anniversary of the founding of the Association for the Accreditation of Human Research Protection Programs (AAHRPP), an organization that has been instrumental in strengthening protections for research participants. AAHRPP was established by seven Founding Members in response to a series of high-profile incidents that shook the foundation of the U.S. research enterprise. The Founding Members viewed voluntary accreditation as one way to strengthen research protections and restore and preserve public trust. Today, AAHRPP accreditation is widely regarded as the gold standard for research protections. To attain accreditation, organizations must demonstrate that they adhere to rigorous standards covering three domains: The Organization, The Institutional Review Board or Ethics Committee, and Researcher and Research Staff. The emphasis is on system-wide policies and procedures that strengthen an organization’s commitment to participants and help ensure a more consistent, more effective approach to protecting them. Because AARHPP accreditation is considered an objective indicator of quality, the benefits to accredited organizations can be considerable. Their accreditation status sends a signal — to potential research partners, to sponsors and other funders, and to research participants — that the organization has the systems in place to conduct research in a scientifically and ethically sound manner