română RĂZVAN LISNIC, SORIN ION JINGA
Abstract
Coal-fired power plant represents the major source of sulphur dioxide emissions in Romania. This study presents the influence of a wet FGD system applied to an energetic block from Rovinari power plant in Gorj county over SO2 dispersions regarding air quality. Sulphur dioxide emissions were modelled using AERMOD software considered a state-of-the-art dispersion model for industrial sources.
The results were plotted to Google Earth Pro showing a decrease of 95.6% for SO2 hourly maximum concentrations and a decrease of 92.7% for SO2 daily maximum concentrations.
Keywords
wet flue gas desulfurization, efficiency, SO2, emission modeling, software dispersion model, AERMOD.
RADU MIREA, GIMI RÎMBU, MIHAI IORDOC,, ANDREI TIBERIU CUCURUZ
Abstract
The experimental investigation of hydrogen adsorption capacity in Ruthenium doped nano-structured carbonic materials, by using two methods has been carried out within this paper. It is well known that carbonic materials along with metal hydrides are considered to be one of the most promising materials to be used for hydrogen storage by using adsorption method, specifically based on "spill-over" phenomena. These materials have different applications and one of the most important is considered to be fuel cells technology for mobile applications, namely onboard automotive hydrogen storage. By using transitional metals in order to dope carbonic materials, their adsorption capacity increases, thus approaching “the target” of 4,5% weight ratio of H2 adsorbed in a substrate, according to US Office Of Energy Efficiency And Renewable Energy [1]. Within this paper carbon based nanomaterials: multi-wall nanotubes (MWNT) and poly-aniline (PANI) have been used as substrates for Ruthenium doping and their hydrogen storage capacity has been determined. PANI has been firstly prepared and after that doped in laboratory, while MWNT have been purchased from the market and afterwards doped in laboratory. The doping procedure consists of a physical-chemical method which involves Ru salts and the use of ultrasounds in order to activate the carbon based substrate for doping.
The adsorption and storage capacity of carbonic materials has been determined by using spill-over phenomena in a PCT Pro-User apparatus, provided by SETARAM and also calculated from cyclic voltametry, by using VoltaLab-40 apparatus. In order to investigate the adsorption capacity of the nano-structured carbonic materials, the experiments have been carried out at different pressures (ranging from 10 to 30 bar). Both substrates have been characterized in order to determine their porosity, BET surface and XRD before and after doping.
Keywords
Hydrogen adsorption, weight ratio, doped carbonic materials, poly-aniline, and carbon nanotubes.
AHMET GÖKDEMİR, TALAT YATKIN
Abstract
Throughout history, the Anatolian Peninsula, with its many fertile lands and many settlements of civilization, has seen a bridge between civilizations due to its position on commercial and military roads. Ankara, the capital, since the establishment of the Republic of Turkey; is a witness to many political, administrative and military events that have been up to date. For this reason, the city has a rich cultural heritage. Ankara Castle, which has always been in the same place since the Hittites, repaired many times during the Roman, Byzantine and Seljuk periods. It is very important that the materials used in the restoration work are compatible with the existing structure. In this; an analysis of the existing material was carried out which could shed light on the restoration work to be done on the Ankara castle.
Therefore, from Ankara Castle were taken samples from the materials used in the areas where structural deterioration occurred on the east, west, north and south facade walls. On the samples, material characteristics were analyzed by using methods such as SEM, EDS, F-TIR. In addition, density, water absorption, compressive strength and thermal conductivity properties of the samples were measured.
As a result, the physical, mechanical and thermal properties of the materials used in the construction of the Ankara Castle have been revealed. As a result, it is possible to apply materials compatible with the existing structure that can be used in the restoration works of the Ankara Castle.
Keywords
Ankara Castle, Restoration, Materials, Strength, SEM, EDS
A.VISHNU, P. ARULMURUGAN, V. PONMALAR
Abstract
The structural recital of axially loaded concrete containing Nano metakaolin (NMK) in filled steel composite columns is investigated. The ratio of height and breadth of the specimens are kept constant as 6.25 and M20 grade of concrete is used. The width to depth ratio is assumed to be taken as 1.00, 1.25, 1.50, 1.75 and 2.00. The foremost constraint of the task is to study the effectiveness of concrete in filled steel hollow sections with bolted connection incorporating NMK as cementitious substantial. The columns examined are different in cross-sectional dimensions. The axial load is provided to the core concrete alone and the behaviour of the confined cold form steel is studied, and axial load of reinforced concrete column and confined columns are compared. The optimal percentage at which cement can be substituted with Nano-Metakaolin is found to be 4 % and XRD analysis is carried out to predict the pozzolanic activity of cementitious materials. Also, consequences show that the column with greater cross-sectional area had higher load carrying capacity of about 33 kN while comparing to reinforced columns.
Keywords
Metakaolin (MK), Nano Metakaolin (NMK), Cold-formed steel (CFS), Hat section, In-filled, Columns, Axial load
CRISTIAN DOBRESCU, SÂNZIANA ITTU, NICOLAE CONSTANTIN, BOGDAN FLOREA, VALERIU RUCAI, DRAGOȘ FLORIN MARCU
Abstract
The goal of this paper was to analyze the industrial behavior of CENOTERM coating powders used in continuous casting of steel. CENOTERM powder is made using thermal power plant ash in the manufacturing recipes. The thermal power plant ash is part of the range of industrial waste. In the context of this paper, CENOTERM coating powder was used for continuously casting steel under industrial conditions. Industrial experiments with powder recipes for the thermal power plant ash-based dispenser were carried out at MECHEL Târgoviște.
Testing of coating powders at an economic agent where continuous casting of steel is carried out has been carried out with a view to finalizing these powders’ manufacturing technology. The paper presents the analysis of the behavior in industrial conditions of coating powders made from indigenous raw materials, some of which are even landfilled waste. The research carried out revealed the functions of the powder on the surface of the liquid steel and the final effects of the powders on the quality of the steel.
Keywords
coating powder, secondary materials, thermal power, fly ash, steel, continuous casting.
VASILE ADRIAN SURDU, ECATERINA ANDRONESCU
Abstract
Configurational entropy has been recently used to develop innovative materials with multiple different cations or anions, belonging to different crystallographic systems. Fluorite oxides exhibit chemical stability, thermal stability and thermal insulating properties and therefore are of interest in high temperature applications. Entropy engineering via compositional considerations proved to be beneficial in increasing hardness and decreasing thermal conductivity coefficient. Several aspects need to be considered and investigated in order to understand the mechanisms involved in the functionality of such materials.
Keywords
ceramics, entropy, fluorites, oxides
YASSINE BELAICHE, ABDELHAMID KHELEF, SALAH EDDINE LAOUINI, ABDERRHMANE BOUAFIA, MOHAMMED LAID TEDJANI, AHMED BARHOUM
Abstract
Artemisia herba-alba is a medicinal plant, and its essential oil is used as an antiseptic and antispasmodic. In this study, green synthesis of silver/silver oxide (Ag/Ag2O) nanoparticles was successfully synthesized from Artemisia Herba-Alba aqueous leaves extract. The effect of temperature, reaction time, the concentration of AgNO3, the quantity of plant extract, and pH on the synthesis process of Ag/Ag2O was optimized. More interesting, the results showed that only 5 min were required for reducing 1 mM AgNO3 into Ag/Ag2O NPs at room temperature. The crystalline nature of Ag/Ag2O NPs with an average crystallize size of 10.7-36.8 nm. The green synthesizing Ag/Ag2O NPs having in general a spherical morphology with particle/aggregate size less than 100 nm. The maximum UV-Vis absorption peak of Ag/Ag2O NPs was observed at the range of 418- 435 nm giving optical band gaps of 2.05-2.30 eV. The TGA/DTA analysis shows significant organic contents (18 wt%) were physically and chemically adsorbed on the dry weight Ag/Ag2O NPs. Artemisia herba-alba is a source of phytochemicals for effective and prompt fabrication of Ag/Ag2O NPs with relevant insecticidal and anti-bactericidal activity against species of high public health importance.
Keywords
silver /silver oxide nanoparticles; Artemisia Herba-Alba; Silver nitrate AgNO3; Green Synthesis, XRD
İSMAİL HOCAOĞLU
Abstract
Today, materials are produced with nanotechnology, which are new products as a result of the development of technology. For cement-based composites, porosity is very important in terms of the strength and durability of the material after the material hardens. Today, with the innovations in technology, new materials are produced in the construction sector. New generation materials are produced on nano-meter scale using nanotechnology. These materials are used in cement-based composites to reduce porosity and improve durability properties. This research is aimed to reduce the porosity of the mortars by adding the nanomaterial graphene oxide (GO) to cement-based mortars whose sizes are 4cm x 4cm x 16cm. To investigate the effect of graphene oxide on porosity, series were produced as water/cement ratios are 0.55, 0.70, 0.90, and 1.00, by substituting 0.025 % GO in the mortars instead of cement. Besides, to investigate the effect of DC stress intensity on porosity, 25 V DC current is applied to all series. Mortar internal temperatures were measured from the beginning of hydration reactions in fresh mortars. Various comparisons have been made by calculating the maturity values of the mortars. Hardened mortars were cured for 7 and 28 days, then current passes on the mortars were measured by using an ampere meter. It has been investigated whether a relationship can be established between flow transfer and porosity. As a result of this study, the porosity of mortars can be reduced and maturity values can be increased by adding GO to cement-based mortars and applying DC current. In addition, porosity of cement-based materials can be estimated by using electrical methods.
Keywords
Nanomaterial; Graphene oxide; DC current; Porosity; Electrical measurement
ALINA MELINESCU, ENIKŐ VOLCEANOV , MIHAI EFTIMIE, ADRIAN VOLCEANOV, LAVINIA POPESCU, ROXANA TRUȘCĂ
Abstract
Electroless nickel is applied to many types of substrates to take advantage of the coating`s properties. The final electroless nickel-based deposit quality is only as good as the quality of the base substrate metal since the coating`s ability to level or hide imperfections in the base material is poor. In fact, any defect in the substrate will be more visible after the part is plated with electroless nickel. A variety of contaminants include machining oils, drawing lubricants, buffing compounds, sulfurized oils, chlorinated oils, waxes, etc. Experimental work was carried out in order to establish the effectiveness of the method for degreasing thin low carbon steel strips before chemical coating. One alkaline (Solution A) and two acidic based on deoxidants (Solution B and Solution C) were tested at a temperature of 750C.
Before the chemical deposition of Ni-P și Ni-P-Al2O3 coatings, water break test was performed on steel substrate to evaluate the presence of hydrophobic contaminants, which can be detrimental to adhesion of coatings. Nickel sulphate hexahydrate was used as the source of nickel and sodium hypophosphite was used as the reducing agent, which also serves as the source of phosphorus in the coating. Sodium acetate, ammonium sulphate, sodium citrate, sodium dodecyl sulphate and lead acetate were used as additives in the plating bath, to accelerate the rate of deposition of the coating or as stabilizers to prevent the decomposition of the plating bath. During plating (45 minutes), the temperature of the bath was maintained at 80 oC using a constant temperature bath and the pH of the bath was maintained at 5.2.
The waterbreak test has been used to evaluate how clean a surface may be. The test is based on the ability of a properly cleaned surface to retain an unbroken film or sheet of water. Normally, dirty surfaces show a water break.
The samples of thin steel strip before and after deposition electroless Ni-P and Ni-P-nano - Al2O3 layers were characterized regarding the chemical composition, layer thickness, macroscopic appearance, uniformity and adhesion.
The chemical composition of steel substrate and of the layers was determined by X-ray Fluorescence. In order to investigate the morphology and microcomposition of metallic substrate and of deposition layers and thickness coating for the samples were studied by using Scanning Electron Microscope coupled with Energy-Dispersive X-ray Spectroscopy
Keywords
electroless plating, steel surface pretreatment, Ni-P and Ni-P-Al2O3 composite coating
ENIKŐ VOLCEANOV, MIHAI EFTIMIE , ALINA MELINESCU, ADRIAN VOLCEANOV, ADRIAN SURDU
Abstract
This work emphasizes on the development of electroless nickel composite coatings with the incorporation of oxide nanosized hard particles embedded in Ni-P matrix to improve their performance. The preparation of electroless nickel composite coating bath, methods to introduce hard particles in the bath, factors that affect the particle incorporation in the coating and its effect on coating structure is discussed in detail. The nickel-phosphorus coatings alloy layer was deposited by an autocatalytic process, without external power input is from this point of view an major advantage over electrolytic nickel plating technology. However, the autocatalytic Ni-P coatings deposition has a drawback, namely the low speed of layer deposition. Our investigations were focused on enhancing the deposition speed and homogeneity of the Ni – P –XO coatings, where XO is a mixture of Al2O3 + ZrO2, nanoparticles (ratio of 95: 5 by weight) deposited on low carbon content steel strip substrates
The chemical cell (bath) was formulated for 10/L oxides admixture and then connected by immersing the pre-treated steel substrate in the electroless bath solution for 15, 30, 45 and 60 minutes, respectively. The pH of the solution was kept between 4.58 and 6.23. The temperature was controlled in the bath in 60 oC -98oC range. Different stirring intensities in 50 - 400 rpm range were tested. There was almost no difference between Ni-P coating adherence versus Ni-P-(Al2O3+ZrO2) coating obtained by electroless plating. Moreover, electroless plating have nearly constant coating thickness across all surfaces, including edges and complex interior geometry. Nodularity of the Ni-P globules is reduced due to incorporation of second phase oxide nanoparticles.
Keywords
Electroless Composite Coatings, Nickel, Nano-sized oxide powders, Process Parameters