Search

Antimony and arsenic are recognized to be toxic carcinogens. With the development of chemical industry, antimony and arsenic pollution problems are becoming more and more serious in soil. This paper described speciation analysis of antimony and arsenic in soil in the latest technical progress. Speciation analysis of arsenic and antimony which use joint techniques and non joint techniques are summarized. This paper also introduced various remediation technologies for antimony and arsenic contaminated soil. Finally, the trend for future technical development in remediation of antimony and arsenic in contaminated soils and speciation analysis is prospected.

It’s generally accepted that the transport of lithium ions in solid polymer electrolytes exists mainly in the amorphous regions, thus the research has focused on reducing the crystallinity to obtain high conductivity at room temperature. However, the point has been challenged: crystalline systems can provide a better ionic conductivity. In this paper, PEO/LiClO4polymer electrolytes with different lithium-oxygen ratios were prepared by melt-blending. The results show that [EO]/ [Li+] = 3 system has higher ionic conductivity, 4.26×10-6S/cm, more than twice as that of [EO]/ [Li+] = 4 system. DSC and XRD results show PEO3:LiClO4crystalline phase present in both systems, the crystallinity of [EO]/ [Li+] = 3 system is higher. It illustrates the generally accepted mechanism is not suitable for these systems, suggesting the high conductivity of [EO]/ [Li+] = 3 system is due to the unique crystal structure of PEO3:LiClO4. Besides, as the crystallinity increases, the tensile strength of [EO]/ [Li+] = 3 system increases greatly, to 1.43 MPa. In addition, because of the high melt temperature of PEO3:LiClO4, the electrolytes will gain excellent heat resistance. In summary, this paper provides a new idea to prepare polymer electrolytes with high ionic conductivity, improved strength and excellent heat resistance in large scale.

With Raney nickel catalyst and aniline solvent, the reaction kinetics of catalytic hydrogenation of isophthalonitrile (IPN) for meta-xylenediamine (MXDA) preparation is studied in this paper. The experiment is conducted in a 1L büchiglas high-pressure hydrogenation reactor under the condition of the reaction temperature (100°C) and the reaction pressure (35 bar). The results shows that the kinetics equation proposed in this paper can be used to predict the response speed of IPN accurately.

This paper is devoted to one of the most urgent problems in the automation of fluorine production (FP) processes: the development of a dynamic model of the hydrodynamic regime. The paper suggests a dynamic model represented in the form that provides the effective use of up-to-date methods of synthesis and analysis for control algorithms. The model is a set of dynamic models of individual units and devices that have a significant impact on the processes in the technological scheme.

This paper presents the results of a numerical calculation of beryllium poisoning of an IRT-T reactor and its effect on the excess reactivity and neutron flux density in the beam ports. Also, the prediction of 6Li and 3He poison concentrations in the beryllium reflectors of the IRT-T reactor is presented. The results are based on MCU Monte Carlo calculations. The part of reactor history was taken into account to predict reliable values of parasitic isotope concentrations. The impact of shut-down time and operating time on the excess reactivity is shown. The results presented in this paper could be used to perform the safety analysis of an IRT-T reactor.

The character of one refractory gold copper mine located in the west of the Sichuan province is so complex, that the valuable element of the ore cannot be recovered by the traditional beneficiation processing. In this paper, a series of tests were conducted to optimize the suitable collector and develop a new beneficiation processing to recover the valuable associated minerals as while as the copper minerals. The results of the tests showed that the bulk-concentrate with 14.73% of Cu grade, 40.59×10-6 of Au grade and 2360.00×10-6 of Ag grade can be obtained from the recommended bulk flotation processing. The recommended processing showed in this paper could greatly improve the copper mineral recovery and reduce emissions of copper tailings, which is very important for the copper beneficiation technology development and the protection of the environment.

As an important part of energy industry, power grid plays a pivotal and irreplaceable role in promoting low-carbon development. In this paper, the carbon emission reduction potential of power grid corporation was systematically analyzed from qualitative and quantitative perspectives respectively. First, this paper discussed the pathways of power grid corporation’s carbon emissions reduction, including decreasing line loss, promoting clean energy development, and so on. Then, a quantitative evaluation model for carbon emissions reduction potential of power grid corporation was developed. Based on the model, the carbon emission reduction benefits that promoted and achieved by State Grid Corporation of China (SGCC) in 2010 and 2015 were calculated. The results show that the carbon emission reduction benefits of SGCC is 138 million tons in 2010, and will be 481.8 million tons in 2015.

Copper alloys with high strength and high conductivity are a serial of materials with excellent comprehensive performance. However, the strength and the conductivity are a pair of conflicting factors. To resolve this contradiction, Cu-1.0Cr-0.12Zr alloy was studied in this paper. With optical microscope, scanning electron microscope, Brinell hardness and the arms bridge, effects of heat treatment on microstructure and properties of such alloys was studied,and we strived to find a heat treatment processing to achieve the best match between the conductivity and the strength of the alloy. This paper focused on the study of conductive properties of the alloy. The main factor infuencing the conductivity of the alloy was the content of the soluting elements. The higher the content,the lower the conductivity, and vice versa. The results showed that the best comprehensive properties were obtained after solid solution at 920°C and then aging at 450°C for 180 min.

This paper developed a composite indicator for evaluating the performance of low-carbon economy for the cities in Jiangsu province, China. The empirical results show that the performance of low carbon economy of cities in Jiangsu province may be divided into three levels. The first level include Yangzhou, Zhenjiang, and Nanjing, that the performance is below the province average level; the second level including Huaian, Suqian, Lianyungang, and Nantong which, that the performance is similar with the province average level; the rest of the cities in Jiangsu are set as third level. At same time, this paper analyze some cities’ performance of low carbon economy.

This paper summarized the measure methods which include both Chinese national standards and international standards of how to determine the concentration of Non-methane Hydrocarbons (NMHC).Some problems and suggestions were discussed in this paper to improve the level of the measure methods and prompt the establishment of relative Chinese national standard.

This paper construct the index decomposition model of carbon dioxide and decompose China's current total of carbon dioxide emissions into 11 factors based on the relevant statistical data of 1997-2010 and LMDI. Then, obtain that positive factors such as the economic output, per capita GDP and the level of urbanization play a catalytic role in the growth of carbon dioxide emissions, conversely negative factors such as energy consumption intensity of various departments, the proportion of the rural population and the proportion of the provincial department structure play an inhibitory effect in the growth of carbon dioxide emissions by analysis and calculation; Further, the paper briefly summarizes the results of the above study.

This paper introduced the fundamental principle of the simultaneous desulfurization and denitrification by combining ozone oxidation and the NaOH double alkali method. And the total chemical reaction equations were achieved by analyzing the process of the absorption of the productions of ozone oxidation by NaOH double alkali method. Then, based on thermodynamic principle, the partial pressure of SOx, NOx and CO2 when reactions reached equilibrium were calculated respectively. This paper also studied the reaction mechanism of the absorption of SOx and NOx and analyzed the absorption characteristic of SOx and NOx in absorption solution. The results showed that the simultaneous desulfurization and denitrification by combining ozone oxidation and NaOH double alkali method was feasible. Not only the elimination ratio of SOx and NOx were almost up to 100%, but also CO2 was removed on a considerable scale. The partial pressure of SOx and NOx was very important to the pH value of the absorption solution which affected the elimination ratio of SOx and NOx greatly.

With the continuous development of distributed solar, wind power and other renewable energy sources, renewable energy sources which has its own features, such as intermittent and randomness volatility, brings great challenges to the stable operation of power grid. Aiming at meeting the requirement of balancing the fluctuating renewable energy sources of micro grid, this paper proposes the operating control strategies of the zinc bromine flow battery storage. Firstly, the equivalent mathematical model based on the working principle of the zinc bromine flow battery is established; Secondly, a dual closed-loop strategy for the DC/DC converter is proposed, of which the inner loop is peak current control on zinc bromine flow battery side inductance while the outer loop is a switch control by constant active power and trickle current. By resorting the DC/AC grid side converter, the stability of DC bus voltage is maintained; Then, this paper proposes the optimization power control strategies of zinc bromine battery energy storage system as a constraint of state of charge and DC bus voltage; Finally, a 50kW zinc bromine flow battery energy storage system test platform is built, and the charging and discharging characteristics of zinc bromine energy storage system (ZESS) is researched in grid-connected mode, the test results have shown that the proposed power optimization control strategies for zinc bromine energy storage system could smooth renewable energy sources power fluctuation.

The paper analyses problems of a lead-zinc ore from Yunnan with a sink and float test. In the paper, we explored the possibility of pre-discarding about the ore by dense-media process. Dense liquids with the specific gravity of 2.6, 2.7 and 2.8 were used in the test, respectively. -12mm crudes were taken into the test. Finally, it revealed that pre-discarding by dense-media separation can be used in the ore. 2.7 was taken as the best specific gravity of separation. 12~1mm was used as the optimal fraction of pre-discarding by dense-media separation. Pre-discarding rate was 45.53%. The light product with a lead grade of 0.29% and a lead recovery of 4.29% was pre-discarded in which the grade and recovery of zinc were 0.22 and 5.84, respectively.

The paper presents the results of experimental research on the wear mechanism of the tool-electrode as a result of machining metal materials by applying electric discharges in pulse. It examines several phenomena noticed on the tool - electrode surface, exactly, the oxide layer formation and the modification of the micro geometry of the tungsten tool electrode surface. The paper presents the experimental results on the behavior of the tool electrode made of stainless steel after the metal parts have been machined. It also presents the phases of mass transfer in the gap between electrodes.

This paper investigates the influence of natural pre-ageing time on T6 peak hardness of rheo-high pressure die cast (R-HPDC) 6xxx series aluminium alloys. Natural pre-ageing has a negative effect on the 6xxx series Al-Mg-Si alloys that contain higher quantities of Mg2Si (typically > 0.90%). However, a positive effect is observed in alloys with lower quantities of Mg2Si. The negative effect can be attributed to the clustering of solute atoms that form at room temperature because the precipitates which develop directly from clusters formed at room temperature are coarser than those developed in alloys artificially aged immediately after quenching. The opposite occurs in alloys where a positive effect of natural pre-ageing is found. The effects of the duration of natural pre-ageing on the subsequent T6 properties are of importance. In this study the T6 (190oC-4h) hardness values of various R-HPDC 6xxx series alloys were determined after natural pre-ageing times ranging from 0h to 3240 hours. Alloys that show either the positive or the negative effect of natural pre-ageing are used. This paper also compares the influence of natural pre-ageing time on Cu-containing and Cu-free alloys. The addition of copper to the 6xxx series aluminium alloys lessens the negative effect of natural pre-ageing in the higher strength alloys.

This paper describes the synthesis of Yttrium Aluminum Garnet (YAG), Y3Al5O12 nanoparticles (NPs) and their application in Enhanced Oil Recovery (EOR). YAG NPs were synthesized by using sol-gel method. These NPs were then synthesized by using Thermal Gravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The monophasic YAG having crystallites size of 40.98 nm and 40.91 nm were obtained at annealed temperature of 1100 °C and 1200 °C as determined by XRD. Magnetic measurement results show that initial permeability of YAG increased and relative loss factor decreased at high frequency. In this paper, the feasibility of application of YAG nanofluid in EOR was determined by measuring oil-nanofluid interfacial tension and also viscosity of the nanofluid. YAG with 0.5 wt% yielded the lowest IFT. It can be concluded that the synthesized YAG nanoparticle has great potential in EOR applications in the near future.

Nitrile butadiene rubber (NBR) comes into widespread applications due to the excellent performances, but it is susceptible to aging during its storage and usage periods. This paper surveys the external factors that act on the aging process of NBR. The aging of NBR in liquid environment, and non-liquid environment such as thermo-oxidative aging, ozone aging, stress aging and radiation aging, are considered. The emphasis of present works is test of physical and mechanical properties of NBR, and the micro analysis should gain special attention. One direction of future research on NBR aging is the coupling effects of various factors included in this paper.

Increased focus on reducing CO2 emissions has created growing interest in CO2 capture from industrial processes for storage in underground formations. New technical solutions, costs and energy requirements for ship-based transport of CO2 are presented. All elements in the transport chain, namely liquefaction, storage, loading system, dedicated CO2 ship (s), onshore loading and unloading, and offshore unloading systems are included in the paper. Over 80 % from the primary energy consumed all over the world is obtained from fossil oil and natural gas. The last researches have shown the energy dependences of these types of fuels. The transition to the economy based on the low influence of the carbon, the carbon capture technology, is the main means to reconsider the fossil fuels for meeting the needs for reduction of negative emissions. This is necessary for keeping the world temperature at normal levels. The main target of this paper is to put highlight the negative effect of CO2 emissions and the interest in recovery of carbon dioxide from flue gases trough multiple factors: the merchant CO2 market, renewed interest in enhanced oil recovery, and the desire to reduce greenhouse gas emissions. It also takes in account modalities of transport and storage of CO2. Solutions for CO2 capture and injection into caverns instead of natural deposits were found worldwide. These solutions are not applicable however all over the world and they are not a priority in the environment protection activity.Another important aspect calls for all merchant ships requirements regarding CO2 emissions through index calculation and development of Management Plan. Also, to increase the control of CO2 it would be useful to identify the caverns where it is possible to deposit the CO2, to build new special ship for CO2 transport or replace natural deposits through CO2 injection.

The microwave differential thermal analysis (MW-DTA) is a new procedure to evaluate the materials, barium ferrite type M in this paper, according to the phenomena appeared during the material heating. The paper presents a new evaluation technique which is faster and with low energy consumption. The microwaves are used to heat the material, two infrared pyrometers for monitoring the temperatures on the material surface and a temperature regulator where the data are recorded for evaluation. The material, a homogeneous mixture of Fe2O3+BaCO3, is a ceramic material with good absorbance properties, so the heating will be pure microwave heating. The results and the DTA graphic is automatically generated by the temperature recording device based on the data sensed by the infrared pyrometers. The paper presents technical aspect regarding to the microwave heating and temperature measurement in microwave field and how to make differential thermal analysis in microwave field.

The effects of grain sizes and oxygen impurities on thermal conductivity in aluminum nitride (AlN) ceramics has been calculated by density functional perturbation theory (DFPT) and quasi-harmonic approximation (QHA) combined with Debye theory in the paper. From 300K up to 1000K, the predicted thermal properties are compared with experimental data. The agreements with experiment suggest that the theoretical method used in the paper is an effective approach. From our theoretical study, the reduction of thermal conductivity is greater between grain sizes of 1μm and 5μm, while it’s smaller between 8μm and 10μm. Oxygen defects bring about greater influence on thermal conductivity at low temperature than at high temperature. The influence of the oxygen defect is not as significant as the grain sizes when the oxygen concentrations are less than 0.70 at. %, so it’s more important to increase the grain sizes than reduce the oxygen contents in the preparation process to achieve high thermal conductivity AlN ceramics.

Elimination gasoline vapor in oil tank by mechanical ventilation has disadvantages of long vent time poor safety, and low efficiency, however, those shortcomings can be better conquered if combusted gas is used in the process of the mechanical ventilation. Based on former studies, the research on the effects of inlet location on gasoline vapor’s inert replacement in oil tank by combusted inert gas is studied experimentally in this paper. The conclusions in this paper can provide some useful guidance for the field project of gasoline vapor’s inert replacement in oil tank.

In this paper, a conjugate interference filter which could be used in gas sensing is presented .The filter consists of two large spot collimators and a gas etalon which has two separate cells:absorption gas chamber and non-absorption gas chamber. When cascading the broadband light to the filter , only light absorbed by the target gas can pass through the filter and the spectrum of output light matches well with the absorption spectrum of target gas.By changing the target gas in the absorption chamber ,filter for various kind of gases can be implemented. In this paper, acetylene is selected as the target gas and the spectrum of light through the filter completely matches the absorption peak of acetylene after parameter adjustments.

This paper presents work on improving piezoelectric energy harvesters. Harvesting energy from vibrations has received massive attention due to it being a renewable energy source that has a wide range of applications. Over the years of development, there is always research to further improve and optimise piezoelectric energy harvesters. For this paper, the piezoelectric specimen is made of PZT (Lead Zirconate Titanate), brass reinforced and has 31.8mm length, 12.7mm width and 0.511mm thick. An external beam is implemented to provide deflection amplification which in turn increases the output of the energy harvester. Depending on the configuration of the external beam, it can amplify output voltage from 100% to 300%.

Composite materials are the most advanced class of materials invented and produced by humans in modern times as well as a challenge for the future in the field of scientific and technological performance. They are made up of at least two phases of different nature which are so combined to form a new material with a superior combination of properties. They are generally materials with unusual performances on the relationship between properties and specific gravity. Composites are multiphase materials with distinct and well-defined interface between the constituent phases ensuring a transfer of property but can lead to obtaining a product with exceptional performance from the starting material. In this paper we have focused research on Al-Mg alloys with magnesium and silicon carbide (SiC). Stabilized Aluminium Foams (SAF) are new class of materials with low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They offer potential for lightweight structures, for energy absorption, and for thermal management; and some of them, at least, are cheap. Metal foams offer significant performance gains in light, stiff structures, for the efficient absorption of energy, for thermal management and perhaps for acoustic control and other, more specialized, applications. They are recyclable and nontoxic. They hold particular promise for market penetration in applications in which several of these features are exploited simultaneously. The paper presents some results related to the research of metallic foams based on AlMg10 metallic alloy obtained by melt bubbled C4H10 addition of SiC particles. Microsrtucture of these foams is analyzed by using (SEM) Scanning Electron Microscope, laying out the network of pores imbued into each others developed around SiC particles and other issues microstructural characteristics.

Heavy metal pollution has raised a lot of concerns because of its bioaccumulation and non-degradability. A variety of methods have been applied in removal of heavy metals. This paper focused on the method of biosorption using biopolymer-based adsorbents in removing heavy metals from waster water. Cellulose and chitin/chitosan are abundant in supply and contain reactive functional groups. Cellulose-based adsorbents prepared from direct chemical modification or graft copolymerization are proved to show chelating ability to bind heavy metals. Chitin-and chitosan-based adsorbents have improved mechanical strength and better resistance to chemical conditions after physical or chemical modification. The regeneration and reusability of biopolymer-based adsorbents were also discussed in this paper.

The purpose of this paper is to study the impact of furnace temperature and load after blending in lignite, based on CFD software FLUENT-6.3,this paper choose the appropriate geometry model and the physical and mathematical models, and numerical simulation of the different conditions 600MW supercritical once-through boiler blending lignite furnace combustion process is curried out. And through a 600MW supercritical coal-fired boiler furnace lignite blended performed sections thermodynamic calculation under different conditions, worked out the furnace flue gas temperature, CO, CO2concentration distribute trend and radiant heat each section surface heat load conditions. The specific amount were blended with 5%, 10%, 15%, 20% were not dried lignite and dried lignite 20% after five conditions. And obtained a conclusion is the temperature and radiation heating surface flue gas heat load in the overall trend under the various conditions.

Micro-machining of hard dies and molds for optical parts or precision instruments is required to extend die and mold life. This paper investigates the effect of cutting fluid on diamond tool life under micro V-groove turning of cobalt-free tungsten carbide. Zinc dialkyldithiophosphate fluid (ZnDTP) displayed excellent diamond tool wear resistance in previous experiments. The performance of this cutting fluid is compared to newly developed vegetable oil based cutting fluid with dispersed MoS2 nanotubes. This paper investigates nanopolycrystalline diamond (NPD) tool life with a rake angle of 0° and-30° under continuous micro V-groove turning (i.e. face turning), of cobalt-free tungsten carbide using the developed cutting fluids. Superior diamond tool edge wear resistance is observed when using the dispersed MoS2 nanotubes in vegetable oil and using a NPD tool with a-30° rake angle.

Cutting technology is one of the important methods to fabricate small-sized precision components in the semiconductor, electro-mechanics, and automobile industries. This paper focuses on high efficiency machining of small hole drilling for PPS (Polyphenylene Sulfide). In this paper, drilling experiments were designed to investigate the influence of the depth of cut on the burr formation. The experimental results obtained are as follows, (1) The thrust force and radial force increase with the increase in feed per revolution and depth-of-cut. (2) On the prevention of burr formation, the step feed is better than the non-step feed. Also, the burr formation decreases with the increase in the feed per revolution. (3) The hole straightness increases with the increase in depth-of-cut.

The composite extrusion process, which is investigated at the Institute of Forming Technology and Lightweight Construction (IUL), allows the combination of different materials within an aluminum profile. In contrast to the useage of reinforcing elements, this paper focuses on the embedding of functional elements, such as isolated electric conductors. Results of the experimental and numerical investigations are presented within this paper.

The paper presents the theoretical bases of gas flow, as drowned jets, the device used for viewing the pure gas cone (argon) using a smoke screen infused on the edge of the argon jet and then the results of researches carried out on four sizes of nozzles often used in TIG welding. On each type of nozzle the argon flow parameter was varied and the height of the cone of pure argon was photographed and measured. The paper ends with the mathematical correlations that allow us to maximize the height of pure cone argon in relation to its flow. Keywords: TIG welding, Pure argon cone

The main objective of this paper is to evaluate the mechanical properties, chemical and corrosion resistance of four types of metallic coatings: FeCr, FeCoCr, and FeCoCrNi, FeCrNi sprayed through thermal spraying in electric arc on an anchor substrate type 95Ni5Al or 78.3Ni20Cr1. 4Si0.3Fe. The five layers tested were deposited on carbon steel support low alloyed and the obtained results have provided a picture regarding the possibilities of using of the deposits. Because these types of alloys are used to increase the wear resistance of tools, it is very important to know their behaviour is saline environment, because the contributions brought by this paper would increase the applicability domain of these materials (could be used to recondition by thermal spraying the tools used in naval and petroleum industry). The researches of the obtained deposits have been carried out through several methods to screen their performance. Therefore, there have been done investigations on the microstructural morphology of the deposit, by optical microscopy (OM) and scanning electron microscopy (SEM). The OM and SEM results have sought to determine the degree of uniformity of the deposits and the amount of pores and oxides in layer. The physical properties of coatings were also evaluated by adhesion and porosity quantification. The corrosion resistance was evaluated by exposing samples in saline fog chamber. The corrosion products formed on the surface layers were investigated by scanning electron microscopy (SEM) analysis of the SEM. The intermediate alloy 78.3Ni20Cr1.4Si0.3Fe used as anchoring layer allowed the reducing of the pores and micro cracks frequently found in the ordinary 95Ni5Al alloy. It has been observed that the deposits based on NiCrCo are good enough to be used as an efficient coating of carbon steel in aggressive marine environments.

Grinding aids to increase grinding efficiency in cement production are materials that can produce large amounts of high-quality cement in a short time by reducing surface energy by preventing particle agglomeration and improving fluidity. In the paper, a grinding aid using glycerol-waste antifreeze(GAP) is prepared and its effect on the grinding properties of clinker is investigated in contrast to that without the grinding aid. The results are as follows: The angle of repose of the cement powder added with GAP decreases as the grinding time increases (decreases by 3.8° when the grinding time is 60 minutes), indicating that it increases the flowability of the powder. On the contrary, the residual amount of 45µm sieve is also significantly reduced (4.6% decrease) and the specific surface area increases (30.5m2/kg), which results in an increase in the grinding efficiency. In the size range of 3 to 32µm, it increases the particle content, makes the particle size distribution uniform, the 7d and 28d activity index of the powder is improved by 5% and 6%, respectively, and increases the compressive strength of the cement. In addition, it is confirmed that the performance of the TEA grinding aid and the grinding aid are similar, and are very effective in terms of economy.

The sudden emergence of novel coronavirus CoVID-19 in China during the end of last year and its outburst all around the globe thereafter have raised serious questions about their instant management and diagnostic measures as it is infecting humans around in an exponential manner. The implementation of nanotechnology could perhaps ingenerate the rising distress due to the spread of the disease as the conventional antiviral drugs just control the symptoms. Nanoparticles drug delivery systems are engineered technologies that use nanoparticles for targeted drug delivery and controlled release of therapeutic agents. Nanoparticles based approach can replace the treatment with a more promising one that could meet these challenges. Understanding molecular pathogenesis of CoVID-19 infection is very important to exploit the nanoparticles to fight against it. A lot of nanostructures have been developed with antiviral and antibacterial properties for a variety of drug delivery and biomedical applications. The need of the hour is to exploit nano research to develop effective diagnostics tools, drugs, vaccines to treat and prohibit infection. In this paper an attempt has been made to understand the role and potential of various nanoparticles to inhibit CoVID-19 infection and its toxicity effects.

The paper presents a series of experimental researches performed using the design of experiments method RSD (Response Surface Design) for modeling and optimizing the welding process of PE 100 pipelines, used in natural gas distribution. In this sense, the aim was to analyze the influence of controllable factors such as pressure, temperature and time on the objective functions, aiming to obtain certain characteristics of the welded joint. By modeling the welding process, based on the results obtained, an optimal welding procedure was established and validated to meet the conditions imposed on the objective functions.

Microchannel heat sink plays a vital role in removing a considerable amount of heat flux from a small surface area from different electronic devices. In recent times, the rapid development of electronic devices requires the improvement of these heat sinks to a greater extent. In this aspect, the selection of appropriate substrate materials of the heat sinks is of vital importance. In this paper, three boron-based ultra-high temperature ceramic materials (ZrB2, TiB2, and HfB2) are compared as a substrate material for the microchannel heat sink using a numerical approach. The fluid flow and heat transfer are analyzed using the finite volume method. The results showed that the maximum temperature of the heat source didn’t exceed 355K at 3.6MWm-2 for any material. The results also indicated HfB2 and TiB2 to be more useful as a substrate material than ZrB2. By applying 3.6 MWm-2 heat flux at the source, the maximum obtained surface heat transfer coefficient was 175.2 KWm-2K-1 in a heat sink having substrate material HfB2.

TiC – Fe composite coating was produced on AISI 1020 steel by the tungsten inert gas (TIG) cladding process to increase the hardness and wear resistance properties of the substrate. In this paper authors have investigated the effect of process parameters on the microstructure and hardness value of the coated layer. In this TIG cladding process the variable parameter is only current, whereas the other parameters such as scanning speed, standoff distance, and voltage and gas flow rate are fixed. Fe and TiC powders were mixed in the proper ratio of 80wt% - 20wt% and 90wt% - 10wt% respectively. The microstructure and micro-hardness value of the samples were investigated by the scanning electron microscope (SEM) and Vickers micro hardness tester. The result of SEM shows the distribution of the coating powder in the cladded zone. Micro hardness profile shows the variation of the hardness value in the cladded zone as well as in the substrate. The hardness value decreases with increase in distance from top surface of the cladded layer, which is due to difference in cooling rate. Also, the hardness value of cladded layer decreases with increase in current from 140A to 150A. The maximum hardness value of cladded layer was achieved as 262 HV0.05with 140A current and composition of 90 wt.% - 10wt% (Fe - TiC), which was nearly two times higher than that of the as received AISI 1020 steel substrate. Keywords TIG, Microstructure, Micro hardness, Titanium Carbide (TiC), Iron (Fe) powder.

The aim of this paper is to perform a study on how the elevated temperature and gradient of temperature affect the natural frequencies of aluminum honeycomb plate. This study is carried out for temperature range between 200K and 800K, and gradient temperature (ΔT) across the thickness direction of the plate between [0-500K]. Different honeycomb plate geometries have been selected for the analysis, by changing the core thickness, skins thickness and cell size. The obtained results show that the effect of the temperature is noticeable. At temperature 800K, the natural frequencies decrease by 16.1% in comparison to their values at ambient temperature (300K). That means, high temperature makes the material suffers from weak rigidity, which furthermore contribute to high decrease of all the frequencies. In addition, investigations carried out in this work relate to the modal analysis of the honeycomb plate, under various gradients of temperature across the core of the plate. The obtained results show that the gradient of temperature has an effect on the modes of vibration of the honeycomb plate. This effect becomes significant when the gradient of temperature is very high. At ΔT equal 500K, the natural vibration modes decrease by 9.5% in comparison to the case where no gradient of temperature (ΔT = 0K) is applied between the two faces of the plate. Keywords: honeycomb panel; aluminum; natural frequency; finite element method; temperature.

In this paper, the hot compression tests were performed to study on deformation-induced pearlite transformation in vanadium microalloyed eutectoid steel. The results showed that volume fraction of deformation -induced pearlite were higher and the pearlite were spheroidized better under lower strain rate and higher strain in vanadium microalloyed steel. Ferrite grains and granular cementites were further refined through vanadium microalloying combined with deformation-induced pearlite transformation .Vanadium dissolved in γmatrix could retard deformation-induced pearlite transformation under low strain, vanadium carbides precipitated due to strain-induced precipitation eliminate the retardation when the strain was increased to a certain extent. Under heavy deformation, ferrite grains and granular cementites in vanadium microalloyed steel were finer compared with vanadium free steel.

This paper examines and present the findings of the physical and mechanical properties of concrete containing rice husk ash (RHA), and the blend of rice husk ash with calcium carbide waste (RHA-CCW). Concrete cubes, cylindrical and beam specimens containing different percentages of RHA and RHA-CCW by weight of cement (5, 10, 15 and 20 %) were cast. Compressive strength test was carried out after the specimens were cured in water for 7, 14, 28 and 56 days. Test for tensile and flexural strength was carried out after 28 days curing. Initial and final setting time test was carried out on mortar specimens with the same percentage of RHA and RHA-CCW. Bogues model was used to determine the elemental and compound composition of cement when blended with the RHA and RHA-CCW. From the results obtained, the compressive strength of RHA-CCW concrete increases as cement is partially replaced with RHA-CCW content, with the maximum strength attained at 5 % replacement. RHA concrete attains it maximum strength at 10 % replacement. The maximum compressive strength results obtained for both RHA and RHA-CCW concrete were higher than the strength of plain concrete (0 % replacement) by 1.1 % and 14.7 % respectively. Interestingly, results obtained for the tensile strength also shows a similar pattern of strength development with that of compressive strength. The flexural strength properties of concrete was improved upon when RHA-CCW was used in concrete compared to RHA. The results of setting time test for RHA mortar showed a decrease in setting time, while the reverse was the case for RHA-CCW mortar. In conclusion, provided adequate curing is maintained, the used of RHA-CCW gives a better performance in concrete than RHA. However, they both perform better in concrete than the plain, and can be used as additives in concrete production.

In this paper, the Mg-Al hydrotalcite-like compound (Mg-Al-HTLC) was synthesized by hydrothermal method at 373K. Structure and morphology of Mg-Al-HTLC was obtained with X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infra-red spectroscopy(FTIR). A series of polar and non-polar molecules were used for probes, surface properties of Mg-Al-HTLC was studied by inverse gas chromatography (IGC) at 353K, 363K, 373K, 383K respectively. The retention volume was utilized for evaluating the free energy of adsorption (-ΔGSP), the dispersive component of the surface energy(γsD), as well as the enthalpy and entropic component(ΔHSP, -ΔSSP). XRD results reveal that the Mg-Al-HTLC has high crystallinity and perfect layered structure. The results of IGC show that Mg-Al-HTLC would adsorb straight-chain alkanes spontaneously, and the values of γsDwere similar at all temperature. It reveals Mg-Al-HTLC is a material with particular characteristics of both acid and base. This study illustrates that, as a method to evaluate the surface properties of material , IGC method is dependable and significant.

Zirconium alloys are solid solutions of zirconium or other metals. Zirconium has very low absorption cross-section of thermal neutrons. Zirconium has high corrosion resistance, ductility and hardness. Zirconium is mainly used as a good refractory metal. Zirconium can be manufactured by using standard fabrication techniques. In the present scenario zirconium alloys are used in water reactors for the cladding of fuel rods in nuclear reactors in nuclear technology. We use the composition of zirconium alloys as more than 94.5 weight percentage of zirconium and less than 2.45 weight percentage of copper which are added to improve mechanical, thermal properties and corrosion resistance. This paper first focuses on the study of thermal properties of Zirconium. And this particularly concentrated on variation of Coefficient of Thermal Expansion by varying temperatures by using Dilatometer and as well as ANSYS

The paper presents the results of a mathematical model of the material flow during Friction Stir Welding (FSW) of aluminium alloys using a Finite Element Analysis. The authors presented their work on a two-dimensional visco-plastic model, using User Define Functions (UDF) in a commercial CFD code (FLUENT). The model developed was validated by microstructural investigations on experimental FSW joints and by a comparative analysis of temperature distribution field of the experimental FSW joint and numerical simulated model. The results confirmed that the mathematical model describes with a good precision the material flow and temperature field during FSW process.

Welding copper and its alloys is usually difficult to achieve by conventional fusion welding processes because of high thermal diffusivity of the copper, which is at least 10 times higher than most steel alloys, in addition to this, there are the well-known disadvantages of conventional fusion welding represented by necessity of using alloying elements, a shielding gas and a clean surface. To overcome these inconveniences, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is being explored as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (TIG) which generates and adds heat to the process. The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The process parameters that varied were the rotational speed of the tool [rpm] and the welding speed [mm/min] while the compressive force remained constant. The purpose of this paper is to correlate the evolution of temperature, tensile strength, elongation and microscopic aspect with the linear position on the joint (local process parameters) for each experimental case and then make comparisons between them, and to identify and present the set of process parameters that has the best mechanical properties for this material.

During Friction Stir Welding (FSW) process materials to be joined will be subject of intense mechanical and thermal processes, characteristic to this solid state welding process. As a result, the welded materials will suffer quick heating and cooling cycles that will be overlapping on large plastic deformation/flow of the materials, which will produce their phase and structural transformation as well as modification of their properties. The paper investigates the structural transformation of the materials and will analyse the influence between the FSW process and these transformations.

Friction Stir Welding, abbreviated FSW is an innovative joining process. The FSW is a solid-state welding process with a lot of advantages comparing to the traditional arc welding, such as the following: it uses a non-consumable tool, it results of good mechanical properties, it can use dissimilar materials and it have a low environmental impact. First of all, the FSW process was developed to join similar aluminum plates, and now, the technology was developed and the FSW process is used to weld large types of materials, similar or dissimilar. In this paper it is presented an experimental study and the results of it, which includes the welding of three dissimilar aluminum alloy, with different chemical and mechanical properties. This three materials are: AA2024, AA6061 and AA7075. The welding joints and the welding process were analyzed considering: process temperature, micro-hardness, macrostructure and microstructure.

This paper designed and completed the different polymer dosage of recycled concrete, was prepared by adding amount was 7%, 14%, 21%, 14% styrene butadiene latex recycled concrete, recycled rubber powder recycled concrete and ordinary concrete block, the cube compressive strength and damping performance test. The cube compressive strength of concrete test according to the ordinary concrete mechanics performance test methods, specimen is 150×150×150 mm cube specimens, pressure testing machine loading speed is 0.5 MPa per second. The concrete damping performance test is carried out according to the free attenuation method, with the hammer vibration test device, the test piece is T type. Based on the damage form of specimens, the compressive strength and damping performance analysis, and compared with ordinary concrete as the benchmark analysis test results show that the polymer recycled concrete cube compressive strength failure process and failure pattern basic consistent with common concrete. In the water/cement ratio, sand ratio, and amount of material per unit volume is the same, under the condition of polymer recycled concrete cube compressive strength is lower than normal concrete, damping performance is higher than that of ordinary concrete, the compressive strength is inversely proportional to the damping sexual relations.

The objective of this research work was to study the influence of the iron oxide phase resulted during steam oxidation of the sintered steels specimens obtained by powder metallurgy (P/M) route. Steam oxidation is a surface treatment applied to sintered iron parts, as an economic way to reduce the interconnected pores. In powder metallurgy products, the networks of pores are specific, who can be stress concentraions and can produce cracks in material. By steam oxidation treatment the interconnected porosity is closed by sealing them with iron oxides phases. Also, other properties of sintered PM steels are improved. The specimens analyzed in this paper were produced from atomised iron powders, compacted at room temperature at pressures of 600 MPa, sintered for 120 minutes at 1150o C in a laboratory furnace and then subjected to a continuous steam oxidation at 550o C for 60 minutes. Investigations on the structural, mechanical and abrasive wear properties were performed. The microstructure and the pore morphology of the sintered and steam oxidation samples were studied on using optical microscope.

Ground granulated blast furnace slag, red mud, wheat straw ash are secondary material which after alkaline activation can be used in the construction materials’ domain. Their disposal poses a threat to the environment, whereas by reusing them we would be able to reduce this negative impact. This paper describes the research carried out in order to synthesise some geopolymer recipes, which are based on ground granulated blast furnace slag, red mud and wheat straw ash, alkaline activated with sodium hydroxide or a solution made with sodium hydroxide and sodium silicate. Factors that influence the compression strength have been studied such as: the nature of the alkaline activator, the chemical composition of solid materials in the recipes and the curing time. The geopolymer samples have been dried at room temperature for 7 and 28 days, respectively, and after the compressive strength tests has been made. Following this research it has been found out that NaOH/Na2SiO3 activated geopolymer samples have shown a higher resistance in the compressive strength. From the SEM analysis it has been found out that the samples with a higher amount of ground granulated blast furnace slag in their composition had a more homogeneous and less porous design than those with a smaller amount of ground granulated blast furnace slag.

Galvanic sludge resulting from wastewater treatment is a hazardous waste that can be removed by disposal only after neutralization process. A chemically complex sludge is a mixture of hydroxides of the many heavy metals such us: copper, iron, nickel, chromium, cadmium and zinc. There is worldwide, a concern to develop methods and techniques for extraction and recovery of the metal compounds from sludge out of treatment processes of wastewater from metal plating works (washing wastewater and technological solutions) in order to reinsert them into existing industrial flows or to capitalize them in other industries, leading to a significant reduction of environmental pollution.This paper presents the results of the scientific activity in the laboratory with a view to recover Cr (VI, III) from two types of galvanic sludge: a fresh sludge from wastewaters treatment by Lancy technique and an old sludge, stabilized by disposal for many years. Chromium extraction was performed by alkaline sludge oxidation to obtain salts of chromium. The extraction efficiency was 84.20 % from fresh sludge (in one stage) and 93.19% from old sludge (in two stages).