Search

The aim of this study was to study the morphology and structural characteristic of NCC hydrolyzed from filter paper. The NCCs were extracted by acid hydrolysis at 50°C for 1 hour, using 55% conc. H2SO4 under vigorous mechanical stirring, centrifugation at 12000 rpm in distillate water and followed by homogenizing at 7000 rpm. The morphology and surface profiles of the NCC suspension was characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The crystalline structure of the NCC was evaluated by using X-ray diffraction (XRD) technique. As a result, hydrolysed NCC was found to have a rod liked shape with diameter in the range of 100-300nm length and 10-50nm width, with the aspect ratio value of 10.3 nm. According to XRD investigations, the semi-crystalline cellulose was observed with the presence of an amorphous broad hump and crystalline peaks at 2θ of 15o and 22.7o, respectively. The crystalinity index of the raw filter paper was calculated as 86.7 % and increased to 94.4 % as it was extracted to NCC. Crystallite size of raw filter paper and NCC was calculated as 20.6 nm and 11.4 nm, respectively

The use of agricultural wastes and natural materials in new technologies is a novel subject. Consequently, an attempt has been made to formulate a synthetic fluid using an organic water, Water Extract from Fermented Ground Maize (WEFGM) and compare its performance with water-based sample in turning operation using a mild steel as workpiece. Two samples of synthetic fluids were formulated from each of deionized WEFGM, ordinary WEFGM and deionized water as base-fluids at two composition (5 and 10%vol) levels of selected additives. The results of experimental analysis of heat transfer properties of these synthetic fluids exist, hence the need to ascertain the actual performance output. Temperature-Time Gradient (TTG) which is a rate of temperature drop (heat withdrawn) from the work zone was used as evaluation parameters. The result showed that deionized WEFGM is the most efficient of the entire samples at both compositions with an average TTG of 3.61 and 2.16 °C/min at 10 and 5% additive concentration respectively. At lower additive concentration which is more economically advantageous, the performance rating is deionized WEFGM>>WEFGM>>deionized Water. This implies that WEFGM is more effective than water as a base fluid for synthetic fluid in performance as it has been previously so reported in properties. Meanwhile, T-test statistical analysis (using IBM SPSS 23) shows that there is highly significant difference in TTG at each time of application of individual fluid (p0.05) implying that the fluids can all work as coolants and relatively have comparable performance output.

Oil Palm Empty Fruit Bunch (OPEFB) contributes more than 50% of oil palm biomass wastes in Malaysia. This provides tremendous opportunities for value-added product generation from recycling and utilizing its latent capacity. In this work, the performance of physically-pretreated OPEFB fibers without any chemical treatment for Pb2+ removal from aqueous system was evaluated. Three different size ranges (1-5 cm, 0.5-2 mm and 0.005-0.02 mm) of raw sorbent, pH (4-10) and contact time (2-150 min) for Pb2+ batch adsorption were tested. The kinetic data were evaluated by the pseudo-first-order, pseudo-second-order and intra-particle diffusion model. The experimental data were well described by the pseudo-second-order model with r2=0.997. Adsorption efficiency was size-dependent with about 38% sorption increase at 0.005-0.02 mm, and reached 94% efficiency, achieved 47.49 mg/g capacity with 500 ppm Pb2+ at pH 7.5, in 60 min. The eco-friendly, low cost sorbent can be applied as green, effective adsorbent in waste water remediation.

Oil contamination has caused more public anxiety than other waste or spilt materials into the marine environment. Oil sorbents of high sorption capacity, biodegradable, readily available and low cost, are important for protection of water environment, especially from oil spillage. This work deals with raw and modified corn silk, an agricultural waste, as a low cost sorbent for oil-products spill cleanup in the aquatic environment. Corn silk was modified using fatty acid (oleic acid) to improve its sorption capacity. The chemical functional groups of raw and modified corn silk were analyzed by Fourier transform infrared (FTIR) spectroscopy. Kinetic tests were conducted with a series of contact times. The kinetic studies showed good correlation coefficients for a pseudo-second-order kinetic model. The oleic acid treated corn silk (OTCS) showed high degree of hydrophobicity and oil sorption capacity of approximately 10.7 and 11.90 g oil/g sorbent for Tapis and Arabian crude oil, respectively. Corn silk is a cheap waste material that can be treated to have an acceptable sorption capacity which can be used as an alternative to the commercial synthetic sorbents such as polypropylene.

Dyeing cellulosic fibres with reactive dyes wastes great quantities of salt and water. The objective of this work is to dye cellulosic fibers using colored nanoparticles (CNPs) as an alternative to dyeing with reactive dyes, without salt and without washing off at the end of dyeing. Samples of cotton were dyed by exhaustion with CNPs at medium to dark colours. Build-up of colour compared to samples from previous work is given and shows a big improvement. Washfastness results are given. Washing-off after dyeing was not necessary for the red and yellow colours. The blue colour needs some washing off since the fastness is lower than for the other colours even though soaping is not necessary, saving energy and time relative to dyeing with reactive dyes.

The series resistance (Rs) controls the device performance significantly and for organic diode, the typical value of Rs is quite high. There are not many reports on the investigation of the high value of resistance in organic diodes. In this paper, we report that the trapping of charge carriers which is an important parameter to control the charge transport mechanism in organic solids is responsible for this high value of series resistance. In this paper effect of trap energy on Rs has been studied in the presence of TiO2 and ZnO nanoparticles on Phenosafranine (PSF) dye-based organic diode. It is already reported that by incorporating nanoparticles, trap energy is reduced which in turn increases the conductivity and efficiency of the device. So it is expected that trap energy has a strong influence on Rs. In this work we have measured Rs by using the Cheung Cheung method and the trap energy is also measured by analyzing the dc current. The value of Rs is related to trap energy. The extracted values of Rs are about 250.8 KΩ, 108.0 KΩ, and 98.4 KΩ respectively for only PSF, PSF+ZnO, and PSF+TiO2. It is also been observed that by incorporating nanoparticles the trap energy is reduced. The estimated values of the trap energy are about 0.090eV, 0.078eV ,0.072eV respectively for only PSF, PSF+ZnO, and PSF+TiO2. It has been observed that lowering of trap energy by incorporating TiO2 and ZnO reduces the value of Rs.

Research conducted aimed to compare the hybrid ultrasonic-thermal cutting technology with the classic thermal cutting one. The experimental program was carried out on the ISIM designed hybrid equipment, operating at a frequency of 35 KHz, with a cutting geometry of the ultrasonic horn - sonotrode and the thermal anvil designed specifically for the task at hand; the first phase of the experimental program was developed on the thermal cutting module, the second one was performed on the US-thermal hybrid module, both modules being part of the hybrid cutting equipment designed and patented by ISIM Timisoara. The research performed in this present paper, intends to highlight the benefits of the hybrid cutting technology when compared to classical thermal cutting, in order to process two types of materials with different specifications and dimensions. After visually inspection cut materials have been then compared with automotive seatbelt quality standard IATF - International Automotive Task Force 16949. Experiments highlighted that hybrid ultrasonic-thermal cutting process has a significant influence on the quality of processed materials when compared to classic thermal cutting process, which in some cases makes the materials unsuitable for use in the automotive industry. The paper further presents two types of technology data sets suitable for 2 types of materials and up to automotive industry requirements.

The purpose of this research is to analyse the technological and economical aspects of making 3D print pieces to produce functional parts and subassemblies for abrasive waterjet processing equipment. The authors of this paper intend to make a clarification on the technological and economic approaches of material that can be used to make such a reference in terms of economic efficiency and technology. In the paper are analysed all the aspects involved in generating the necessary elements on the mechanical side of them by FDM (Fused Deposition Modelling). The paper is structured in a five chapters in which it is presented in a logical order the analysis of the materials that can be used in the mentioned technological field, the technological parameters specific to the analysed process, the method of generating the parts and their realization from a practical point of view and presenting the main economic aspects that involve the manufacturing costs of specific parts through 3D printing technology for components of water jet processing equipment with suspension abrasive media.

The nanocrystalline (NC) and ultrafine-grained (UFG) structures of metallic materials can lead to their extraordinary high strength. However, most of the papers on this topic consider deformation parameters of NC and UFG materials only for the case of quasi-static tensile tests. Characteristics of dynamic strength and fracture of such materials remain unexplored. This paper presents a study of the mechanical behavior of pure titanium Grade 4 with a coarse-grained (CG) and UFG structure under uniaxial compression with different strain rates. The UFG structure was provided using the method of equal-channel angular pressing. The dynamic compression was carried out on a setup with the Split-Hopkinson pressure bar. It is found that in the observed range of strain rates 10–3-3×103 s–1, the yield stress of the CG titanium increases by 20%, and does not exceed the yield stress of the UFG titanium. However, the yield stress of the UFG titanium remains close to a quasi-static value. It is shown that these strain-rate dependencies of the yield strength can be predicted by the incubation time approach. The calculated curves show that at strain rates above 104 s–1 the yield stress of the CG titanium becomes higher than the yield strength of the UFG titanium.

This paper is concerned with the selected aspects, which are discovered during a design stage of cable and membrane structures, known as “form-finding” process. The aim of this paper is the understanding of the basic principles of the form-finding process and their explanation of the very simple examples. The use of the finding a shape of a tension membrane that is in static equilibrium as an analogy with the search condition of minimal surfaces is explained. The basic principles are demonstrated on simple 2D example, in which the finding a stable minimal surface passes in the finding a stable minimal length.

The paper focuses on some properties of concrete with fly ash after 55 years in operation. Among other things this topic refers to still current issue of sustainable development. In this case, it is saving of cement by using of substitution of fly ash. Another researched topic in the paper is the durability of structures and building materials. For obtaining important data, samples of concrete were extracted from the body of the dam Orlík, which has been in operation since 1961 and fly ash was used in a mixture. The results of the measurement of carbonation and frost resistance of concrete with fly ash addition are presented and analyzed in this paper.

Clay is a traditional construction material which has got to background with introduction of modern materials to building practice. There is not proper material available for clay constructions design due to a lack of proper examination of its mechanical properties. This article focuses on tensile bending strength of rammed earth. The mechanical properties depend on the amount of mixture water and on the amount and type of clay minerals. The clay minerals play role of the binder similarly like a cement in concrete. This paper is focused on the tensile bending strength and its dependence on the composition and quantity of clay mineral and its dependence on the amount of mixture water. Five earth mixtures were tested. Mechanical properties were examined on small test bodies made of these mixtures. The mechanical properties of the five mixtures are compared at the end of the paper.

The paper presents some aspects regarding the wetting conditions in aluminium – graphite composite. The wettability depends on several factors like the presence of the oxide skin at the melt surface, formation Al4C3 at the interface between Al and particles, temperature, pressure etc. In this paper, the conditions of perfect wettability of carbon by molten Al achieved under MCl–K2TiF6 molten salts (fluxes), alloying of the melt with surface active elements, heat treatment of reinforcement material and coating of the particles with a metallic thin layer.

In this paper is describe the influence of the deformation degree on the mechanical properties and microstrucure of the blanks obtained by tube and wire drawing. The materials used for this study are represented by two different samples: hot rolled wire rod and wire for concrete reinforcement with periodic profile (drawn wire) with three dimensions of obtained diameter ( d1 = 5.00 mm, d2= 4 mm and d3= 3,5 mm). The results reveal that the strength properties of the samples are increasing with an increase in the degree of deformation, while the plasticity properties are lowering.The purpose of this paper is to evidence the changes in the structure, the strength and plasticity properties depending on the deformation degree and section reducing of the metallic material.

In this paper is analyzed the behavior of parameters that characterize the process of a dynamic crack growth along the interface between the two orthotropic materials. The emphasis is placed on the application of the fracture mechanics concept for the interfacial crack that propagates dynamically, at high speed. In this work is considered the behavior of the oscillation index, the traction resolution factor and the energy factor depending on the crack tip speed and the stifnesses ratio. The oscillatory index increases with the crack tip speed and tends to infinity when the crack speed approaches the Rayleigh wave speed of the less stiff of the two materials. The traction resolution factor depends strongly on the crack speed but weakly on the stiffness ratio. The behavior of the energy factor is completely different from the behavior of the traction resolution factor. Results provided in this paper can be used as a guide for micromechanical modeling of materials.

The general idea of this paper is to produce TiB2 (ceramic particles) reinforced steel matrix composites. These ceramic particles are the best reinforcements for steel matrix composites because of their high thermal stability at higher temperature, high modulus of elasticity, good wetability, low density and their relative stability with steel matrix. This type of new composite family has received much attention as potential structural materials for their high specific strength and stiffness. Therefore, there is a significant interest in developing iron and steel matrix composites and evaluating dynamic behaviours due to their potential usage in automotive industry in future. Final purpose of this paper is to use of the steel sheet for the manufacturing of the lighted structure and manufacturing processes of this sheet. Titanium carbide and titanium diboride TiB2 reinforced steel matrix composites was therefore characterised by optical and scanning electron microscopy. Dynamic behaviours of the base metal and welded specimens have been tested to simulate under the impact-crash test conditions.

The technology of Laminated Object Manufacturing (LOM) is not very new. For hundreds of years wooden parts are built by stacking layers together. Nowadays also paper, plastic, ceramic composite and metal sheets are treated in layers. For the manufacture of prototypes and especially technical tools, e. g. moulds for gravity casting, die casting or injection molding, out of metallic foil however the low self stiffness of this material is a great challenge. In this case it is useful to produce the parts in a two step process. The first subprocess is the stacking of the layers, which can be realised by laser beam spot welding to determine the position of the layer in combination with generating the defined contour by a laser beam cutting process. This procedure is done in a fully automated machine where the CAD-file of the desired part and the building parameters like the laser parameters and the cutting velocity are needed as input. However the stability of the produced green part is insufficient for most kind of application. Hence, a second sub-process to enhance the mechanical properties of the part is necessary. This can for example be realised by high temperature soldering or by diffusion welding in a furnace with inert gas or vacuum. During these kinds of joining processes the green part is homogeneously pressed with the help of a powder bed and at the same time it is tempered for a defined term. In this paper the principle of sheet metal LOM is described as well as the process chain of Laminated Object Manufacturing of metal foil. For each sub-process of metal foil LOM the results of the experimental work for qualifying and optimizing the sub-process are shown. Finally some examples of possible applications especially in the field of Rapid Tooling and Rapid Manufacturing are discussed.

In this paper, the post ballistic impact behaviour of kevlar-glass fibre hybrid composite laminates was investigated against 9×19 mm projectile. Eight different types of composite laminates with different ratios of kevlar woven fibre to glass fibre were fabricated using hand lay-up with epoxy matrix. Ballistic behaviour like ballistic Limit (V50), energy absorption, specific energy absorption and Back Face Signature (BFS) were studied after bullet impact. The results indicated that as the Percentage of glass fibre is increased there was a linear increment in the ballistic behaviour. Addition of 16% kevlar fabric, composite sample meets the performance requirement of NIJ0101.06 Level III-A. Since the maximum specific energy absorption was observed in Pure Kevlar samples and the adding of glass fibre increases the weight and Areal Density of the sample, further investigations need to be carried out to utilize the potential of glass fibre for ballistic applications.

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.

The paper aims to report researches in microbonding process of composite magnetic materials using as thermal source the heat produced in base materials by the conversion of the electromagnetic waves with high frequency into thermal energy. This technology can be applied by targeting the base materials with microwaves and taking into account that composite magnetic materials based on ferrites, present good absorbance and conversion properties of the microwaves into heat. For experimental research, the base materials were sintered sampled of raw products obtained from stoichiometric mixtures of 6Fe2O3 + BaCO3. The raw products were obtained by milling and alloying processes using planetary ball mills. The milling and alloying processes have been perfomed in dry environement for homogeneous mixtures and wet environment for mixtures obtained using mechanical alloying. In terms of eutectic alloys used for microbonding, there have been used lead free Sn96,5%+Ag3%+Cu0,5% with melting point around 2170 C. The microbonding process have been perfomed in two steps: first step was focused on prepairing the base materials by cleaning and deposition of eutectic alloys on their surfaces; the second step was the heating of the base materials in microwave field. A microwave generator with adjustable input power from 0 W to 6000 W with a WR340 waveguide have been used as thermal sources. The researches have shown that the base materials were bonded using less than 10 % of microwave power and the eutectic alloys reached the melting temperature în less than 3 seconds when the magnetron was set to full power. A matching load impedance automatic tuner up to 6000 W have been used for increasing the level of absorbed power from nicrowave generator to samples and decreasing the level of rejected power from composite magnetic material to microwave generator. The temperature have been measured using IR pyrometers with range measurement between 0 and 7000 C. The process can be succesfully applied to a large scale for small parts of electrical engines with permanent cermic magnets.

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.

In this paper, the specific wear rate (SWR) and the coefficient of friction (CoF) of steel embedded glass/epoxy hybrid composites were examined and compared. Experiments were carried on the pin-on-disc machine on different types of composite materials like plain composite (steel volume 0%) and hybrid composites (steel volume 5% and 10%) pressed against a rotating steel disc (EN 31). Composites were fabricated using the hand-lay-up method. The volume percentage of steel pin/pipe varied from 0 to 10% and glass fiber from 50 to 60%, while the percentage of epoxy was kept 40% stable. The experiments were carried out on a group of samples for duration 20 minutes for different loads of 70N, 80N, 90N, 100N, and 110N with a varying sliding distance of 1000 m, 1250 m, 1500 m, 1750 m, and 2000 m. The results show that the SWR and CoF vary with different load and sliding distance. In general, CoF rises for some time of rubbing, and then it remains constant for the rest of the testing time. The results obtained show that the SWR and CoF increase with increasing sliding distance and load for all the composites. However, SWR and CoF decrease as an increase in the volume percentage of steel. An SWR of hybrid composite is observed to be reduced by 28.02% and 45.98% with an increasing percentage of steel by 5% and 10% respectively. CoF of hybrid composite is observed to be reduced by 14.11% and 24.02% with an increasing percentage of steel by 5% and 10% respectively. At last, the worn surfaces of the hybrid composites were studied through a Scanning Electron Microscope (SEM). Shallow and fine grooves appeared on the worn surfaces of hybrid composites at low loads and cracks were found in large quantities at high load which increased weight loss.

Lattice structures can be highly complex imitating natural cellular materials. By the wide adoption of additive manufacturing technologies, lattice structures are a popular design element with many advantages for lightweight and highly functional parts. A detailed examination and an intense inspection of this type of new design element and this new production method is necessary to enable a broad industrialization. In this study we demonstrate how to use x-ray based industrial CT to measure lattice structures in additive manufacturing. This paper shows certain challenges and approaches for metrology on lattice structures. The results show significant deviations between designed and built parts, highlighting the need for quantification and non-destructive inspection.

High strength concrete (HSC) characterized by high compressive strength but lower ductility compared to normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. Nanomaterials have gained increased attention because of their improvement of mechanical properties of concrete. In this paper we present an experimental study of the flexural behavior of reinforced beams composed of high-strength concrete and nanomaterials. Eight simply supported rectangular beams were fabricated with identical geometries and reinforcements, and then tested under two third-point loads. The study investigated the concrete compressive strength (50 and 75 N/mm2) as a function of the type of nanomaterial (nanosilica, nanotitanium and nanosilica/nanotitanium hybrid) and the nanomaterial concentration (0%, 0.5% and 1.0%). The experimental results showed that nano particles can be very effective in improving compressive and tensile strength of HSC, nanotitanium is more effective than nanosilica in compressive strength. Also, binary usage of hybrid mixture (nanosilica + nanotitanium) had a remarkable improvement appearing in compressive and tensile strength than using the same percentage of single type of nanomaterials used separately. The reduction in flexural ductility due to the use of higher strength concrete can be compensated by adding nanomaterials. The percentage of concentration, concrete grade and the type of nanomaterials, could predominantly affect the flexural behavior of HSRC beams.

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 the present scenario, the automobile industry, and aerospace industries are considerable scuffles to strive for innovative lightweight materials among manufacturing industries. They preserve their place by reducing the cost of their products and services. For this tenacity, the demand for lightweight material, low cost, and high-performance material are needed. Aluminum matrix composite is developed to fulfill and becomes an engineer’s material. Aerospace & Automobile industries are eager to introducing compound aluminum metal matrix composites due to their excellent mechanical & tribological properties which makes a reduction in the weight of the component. In this project the LM13 as the matrix material while SiC and B4C have been considered as dual reinforcement. Stir casting is the modest and inexpensive method of fabricating an aluminum matrix composite. For the Evaluation of Mechanical &Tribological behavior of DRP composite castings (LM13/B4C/SiC) selection for experimentation tests. In this paper different specimens of the MMC with LM13 Al Alloy 2wt% SiC and 2wt% B4C, 2wt% SiC and 4% B4C, 4wt% SiC, 2wt% B4C, 4wt% SiC and 4wt% B4C are taken for carried to invention out the increase in DRP in the composites will intensification the mechanical properties of the LM13 Al Alloy SiC and B4 C composite formed.

The impact-echo method is commonly used for detection of flaws in concrete elements based on the shift in the thickness frequency of a plate-like member. However, there is a need to develop this efficient technique for other applications. This paper investigates the feasibility of using the impact echo-method for identifying corrosion of steel reinforcement in concrete structures. For this purpose, 180 reinforced concrete cubes were cast and tested. The main parameters studied were the amount of recycled aggregate (i.e. 0%, 25%, 50% and 100%), nanosilica (1.5% and 3%) and the steel bar diameter (12 and 20mm). Different levels of corrosion were electrochemically induced by applying impressed voltage technique for 2, 5, 10 and 15 days. The impact-echo results were correlated against the actual corrosion levels obtained by the mass loss method. The experimental results showed that the response of impact echo in terms of frequency peaks is found to be sensitive to the high and moderate levels of corrosion. However, no clear trend was observed at the initial stage of corrosion. It is demonstrated that the impact-echo testing can be effectively used to qualitatively detect the damage caused by corrosion phenomenon in reinforced concrete structures.

In the present paper (1-x)Pb (Zr1-yTiy)O3 – xPb (Mn1/3Sb2/3)O3 – z at%E system, with E = Pr3+, Nd5+ and Gd3+ where x = 0.12; y = 0.48; z = 0 and 0.02 ceramic synthesized by solid state reaction technique is analysed. The investigation aims studying of the effect of dopants on the dielectric and piezoelectric properties of such piezoelectric ceramic. The prepared powders have been uniaxially pressed into discs with diameter of 10 – 12 mm and thickness of 1.2 mm. Sintering has been carried out in air atmosphere at temperatures of 1150°C and 1200°C, respectively, for 2 hours each, followed by a controlled cooling at a rate of 200°C /h. The piezoelectric properties have been investigated after a suitable preparation, including polishing, metallization. The structure of the samples has been determined by X-ray diffractometry (XRD), while the morphology and grains size have been investigated by the scanning electron microscopy (SEM). The piezoelectric properties have been studied by the resonance - antiresonance method. XRD analysis reveals a perovskite tetragonal structure and, as expected for ceramic materials, SEM analysis indicates that the average grain size increases as sintering temperature increases. The dielectric and piezoelectric properties have been determined measuring the ceramic discs, and properties, as dielectric permittivity (εr), dielectric loss (tg δ), and the electromechanical coupling factor (kp) have been obtained. The acquired results indicate a significant effect of the dopants on the dielectric and piezoelectric properties of such materials.

The paper presents technologies for the manufacturing of modulated bi-metal elements, used as interchangeable reinforcement, according to patent RO129865. The bi-metal was developed by surface build-up of functional layers that have increased hardness, on a low alloyed steel substrate, so as to ensure maximum lifespan in exploitation. Welded layers deposited on active areas has a thickness of 3 mm and have high hardness (about 50-60 HRC) in order to ensure a good resistance to wear by abrasion, possibly combined with fatigue, erosion or corrosion. The modulated elements sizes are equal to or higher than the wear additions, up to 10%, being dimensioned on the principles of preventive-repetitive maintenance. The interchangeable bi-metal elements are welded on the steel components of machines, used for hot or cold processing of parts and semi-finished products manufactured in series.

Inconel 718 is a very difficult metal for machining because of its high plasticity. Lately, more and more researchers are interested in using it for cavitation parts, such as the plugs and drawers of the valves. For this purpose, thermal volumetric treatments have been initiated to facilitate mechanical machining, aiming simultaneously to obtain good compression and cavitation resistance results. Therefore, this paper presents the results of cavitation erosion behavior and cavitation resistance of ICONEL 718, subjected to two thermal treatment regimes, differentiated by the duration (temperature 800 °C and residence times 5 hours, and respectively 10 hours). The assessment of the cavitation resistance provided by each heat treatment regime is based on the average durability cavitation parameter, as defined by K. Steller. The research is achieved by using the standard vibrator device with piezo - ceramic crystals from the Cavitation Laboratory of the Politechnica University of Timisoara.

The results of impact testing of welded joint specimens taken from a welded plate made of P460NL1 steel are presented in this paper, and analysed with regards to the cooling time t8/5, that was previously calculated. The aim was to determine how the cooling times that were measured, some of which were below the minimum required values, affected the toughness, in terms of total impact energy and its components, crack initiation and crack propagation energy. In addition, this analysis included the effects of temperatures measured at the opposite ends of the plate during the welding process, since this had also affected the cooling times for each welding pass. After observing the differences in total, crack initiation and propagation energy between the tested specimens taken from different parts of the welded plate, it was determined that the specimens from the part where the higher temperatures were measured had shown better, more uniform results, whereas the average total impact energy for specimens from both groups were very similar. It was also noticed that the ratio of crack propagation to crack initiation was more favourable (greater) in the case of specimens from the second group (with higher temperature), as the values of crack initiation energy decreased slightly and the crack propagation energy increased.

With the evolution of society new materials or classes of materials must be developed. The metallic alloys with amorphous structure have exceptional physical properties due to the spatial order of the atoms in structure and the absence of crystalline defects such as dislocations, grain boundaries, etc. Due to the metastable states in which these alloys are located, obtaining bulk materials from amorphous metal alloys is difficult, being limited to simple geometries and high production cost. This problem can be solved by using the ultrasonic welding of amorphous ribbons for the production of bulk metallic glasses.In this paper, we aimed to produce bulk metallic glasses materials by welding the ribbon packages in ultrasonic field. In order to prove the preservation of the amorphous structure of both the primary welding alloys as well as after the welding of the amorphous ribbons, Differential thermal analysis (DTA), X-ray diffraction (XRD), Scanning electron microscopy (SEM) analysis were carried out. Vickers micro-hardness test was also performed in order to reveal the mechanical properties in the welded joint.

The paper proposes to present the results of the evaluation of glass fiber reinforced plastics (GFRP) used in the construction of wind turbine blades. In a wind turbine, the blades are the most exposed to damages and the defects which appear are various and are connected with the type of manufacture, simple/complex loading, environmental conditions etc. In order to increase the lifetime span and to analyze the degradation phenomena during the materials functioning, destructive evaluation tests are performed to determine the mechanical property, by testing pure shear on specimens Iosipescu, from GFRP with woven reinforcement at [± 45°] and [0°/90°], with the shear fixture, endowment of Technical University Gh.Asachi Iasi.

This paper presents experiments regarding the welding with electron beam of multiple overlapping Ni-based amorphous ribbons produced by "Planar flow casting" method [1]. Welded samples were performed, using the electron beam welding equipment “Chamber Machine EBG 45-150 K14” [2]. The welded joints were analyzed by SEM, EDX, XRD in order to optimize some technological parameters to avoid deterioration of the amorphous ribbons during the welding process [3].

In this paper, heat affected zone characteristics of DP1000 steels was investigated during diode laser beam welding (LBW). A butt-welded joint of specimen in dimension of 300 x 150 mm each (according to EN15614-11:2002) with 1 mm thickness is used for the experimental purpose. The welding thermal cycle and the cooling circumstances in the HAZ was determined by real experiment and the physical simulation. A Gleeble 3500 thermo-physical simulator was used to physically simulate the coarse grain heat affected zone (CGHAZ) on the base material specimens by the utilization of the thermal cycles for t8/5 =2.5 s. The results of the physical simulation were validated by real welding experiments. The properties of the simulated and the real HAZ was examined by optical microscopic, scanning electron microscope and hardness tests.

This paper represents a comparative study of the different weave structures of jute woven fiber reinforced unsaturated polyester resin (UPR) composites. The weave structures were selected as plain (1/1), twill (2/1), twill (3/1) and basket (2/2). Composites (50% fiber by wt.) were prepared by using hand lay-up technique. The mechanical properties such as tensile strength (TS), bending strength (BS) and impact strength (IS) of the composites were evaluated and compared. It was found that basket weave/UPR based composite showed the highest mechanical properties. The optimum value of TS, BS, TM, BM and IS of the composite were found to be 47 MPa, 80 MPa, 1.4 GPa, 4.8 GPa and 27 KJ/m2.To find out the effect of yarn density on mechanical properties of the composites, 2/1 twill structure was selected and found significant improvement in the mechanical properties with the increase of Ends/Inch (EPI) and Picks/Inch (PPI) in the fabric. Water uptake and degradation behavior in aqueous medium of the composites was also observed.

Studies have revealed that wood ash cement concrete just like other pozzolanic cement concrete has lower early strength compared to plain cement concrete. Nanoparticles have been found to improve the early strength of concrete due to its small size and large surface area. This paper reports the findings on influence of nanosilica on the workability and compressive strength of wood ash cement concrete. Wood ash was obtained as a waste product from Ladoke Akintola University of Technology (LAUTECH) bread bakery, Ogbomoso. Biological synthesis of nanosilica using kola pod extract and silica precursor (1:5) was conducted at Nanotechnology research group laboratory at LAUTECH. The chemical composition, specific gravity and grading of wood ash, fine and coarse aggregate used were determined. Concrete with 10% wood ash replacement for cement was produced using 1:2:4 mix proportion and water to binder ratio of 0.5. Nanosilica was added at 0.5, 1.0, 1.5 and 2.0% levels. Concrete with no wood ash and nanosilica served as the control. Workability and compressive strength of the plain and composite concrete were determined. The results showed that concrete workability was enhanced with introduction of nanosilica. The compressive strength also increased with the addition of nanosilica. Maximum compressive strength of 27.53MPa was achieved at 90 days with 1.5% nanosilica addition. It was concluded that nanosilica enhanced workability and improved both early and later strength development in wood ash concrete with 1.5% as the optimum addition.

Existing equipment units in specialized industry market, used to process composite polymeric materials, are made with constructive solutions dedicated to specific applications, actual cutting operation are being achieved by thermal effect often resulting in burns of the material on the working area, the version proposed in this paper, a hybrid technology using ultrasonic energy assisted thermic energy, proved to be an excellent solution.The technical problem solved by solution presented by our technology is represented by real market necessity of providing clean processing – in this case cutting and sealing, of composite polymeric materials, in the form of strips, which must correspond in dimensional and qualitative terms to specifications in product documentation, textile tape, used in the textile, food, medical and army industries.

The paper presents the characteristics of TiO2 coatings realized by HVOF spraying process by two different processing paths, i.e. using the classical method of preparing the substrate by sandblasting and by applying a fast laser texturing of the substrate (instead of sandblasting) before the actual HVOF spraying respectively (a duplex treatment). The obtained coatings’ morphology were characterized by SEM before and after electrochemical measurements in NaCl solution. The textured sample presented better resistance to corrosion compared with classical processing path. Keywords: coatings, fast laser texturing, HVOF spraying, duplex surface treatment, anticorrosive.

This paper presents experiments regarding the welding with electron beam of Ni based amorphous ribbons produced by "Planar flow casting" method with the aid of "Politehnica" University of Timisoara equipment. Welded samples were performed in partnership with Graz University of Technology, Institute of Materials Science, Joining and Forming, using the electron beam welding equipment “Chamber Machine EBG 45-150 K14”. The welded joints were analyzed by SEM, EDX, XRD in order to optimize some technological parameters to avoid deterioration of the amorphous ribbons during the welding process.

In this paper, a mixture of commercial Al2O3 and Y2O3 nanopowders was prepared according to the stoichiometric ratios of YAG (Y3Al5O12) with 0.5 wt% tetraethyl orthosilicate (TEOS) as a sintering aid. The effects of air and vacuum sintering atmosphere were examined on the phase transformation, densification, in-line transmission, microstructure evolution, grain size distribution, sintering trajectories, and grain growth map of the YAG ceramics. The results showed that all samples were pure YAG phase. Nearly pore-free microstructure (99.8%) and narrow grain size distribution (4-10 μm) with an average grain size of 7 μm was obtained for the sample sintered in the vacuum atmosphere, while both inner and inter pores with abnormal grain growth, wider grain size distribution (9-27 μm) with the average grain size of 12 μm were detected in air atmosphere. Also, the results showed that the specimens sintered in vacuum atmosphere had higher relative densities and smaller grain sizes at all sintering temperatures for 6 h. The maximum transmittance at 1064 nm of the YAG ceramics sintered at air and vacuum atmosphere was 26% and 68%, respectively.

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.

Aqueous liquid radioactive waste is generated during nuclear reactor operations and during industrial and institutional application of radioisotopes. The immobilization of radioactive waste in Portland cement matrix is the most used method, applied in the world by the countries developing nuclear energy programs. The conditioning of the radioactive wastes by cementation process imposes the structural investigation by X-ray diffraction (XRD) of the samples prepared with cement and different ratio of concentrate. This paper gives useful information about the influence of complexing agents related to damages produced in concrete microstructures.

— The aim of the present work is to investigate the mechanical properties and water absorption capacity of carbon and basalt fibers mixed with epoxy. At present there is demand for natural friendly products. Basalt reinforced composites developed recently and these mineral amorphous fibres are a valid alternative to carbon fibers for their lower cost and to glass fibres for their strength. The present paper describes briefly on basalt and carbon fibers (unidirectional) which are used as reinforcement material for composites. The matrix epoxy (LY556-HY 951) is taken in to account to access to influence on the evaluated parameters. In order to use reinforced composites for structural applications, it is necessary to perform a mechanical characterization. With this aim experiments like tensile strength, flexural strength, hardness and water absorptions are performed. Later the mechanical properties obtained from experiments are compared with ANSYS software results. Keywords—Carbon fibre; Basalt fibre; Uni-directional fibres; Reinforcement, Mechanical Tests, Water Absorption Tests

The aim of this paper is to investigate the mechanical properties of Banana-Pineapple natural fiber reinforced epoxy hybrid composites. The hybrid combination of fibers with various weight fractions i.e. (40/0, 30/10, 20/20, 10/30 and 0/40) are incorporated into the epoxy LY556 and HY951and hand layup technique is used for fabrication. Initially fibers are cut to a length of 5mm and weight percentagesare determined. Banana fiber was hybridized with Pineapple fiber. While overall fiber weight fraction was fixed as 0.4Wf. Tensile, Flexural and Impact specimens are prepared according to ASTM standards. The Dog-bone shaped specimens are prepared for tensile test. Tensile testing was conducted on 5 ton universal testing machine (FIE Make). Flat bar and V-notch shaped specimens are prepared for conducting Flexural, Impact tests.The results are compared with pure Banana and pure Pineapple. Tensile, Flexural and Impact properties of Hybrid Composites are improved as compared to pure composites. The interfacial relationships between the fiber and matrix, internal cracks, fiber pullout, fiber dispersion into the matrix and the inner surfaces of the specimens are examined through SEM analysis.

Now a day’s eco-friendly natural fiber used as the reinforcement for the fabrication of the light weight, lower cost and biodegradable polymer matrix composites. One of such available natural reinforcement for the composite material is basalt fiber. The present paper gives a review on how the basalt fiber reinforced polymer matrix composite behave when they are adhesively, riveted and hybrid joined with other reinforcements such as aluminum, which is used for the particular or other applications and which joint gives better efficiency , suited for given application were discussed and the three joining techniques were investigated. Behavior of basalt fiber reinforced composites for the frequencies at which frequencies the failures like adhesive failure, light fiber tear, and mixed failure modes will occur. These three types of failure modes are investigated with the help of acoustic emission monitoring system.

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 methods for testing the composite materials using two types of fiber-optic sensors as well as a method for using radiation of the vertical-cavity emitting laser radiation (VCSEL) for checking the material deformation and its performances. The deformation checking sensor is a fiber Bragg grating (FBG) with a spectrum width of 50 pm, which is interrogated by the VCSEL. A new algorithm for modulating the laser diode current is proposed for the FBG interrogation providing a dynamic range of at least 3 nm. A new interrogation method of impulse Fabry-Perot interferometer was proposed. The interrogation method was applied for a fiber-optic acoustic emission sensor manufacturing. The sensor was experimentally investigated by the impact of a 6 mm diameter steel ball and compared to a reference piezoelectric acoustic emission transducer.

This paper investigates both fresh and hardened properties of concrete produced with different particle sizes of coarse aggregate (CA). The CAs with the maximum sizes (Dmax) of 25 mm, 19 mm, 15 mm, 12.5 mm, and 9.5 mm were used to produce concrete samples with a water-to-binder ratio of 0.4. The workability, fresh unit weight, compressive strength, and ultrasonic pulse velocity (UPV) of the concrete were tested. Additionally, some concrete samples were fully immersed in 5% sodium sulfate solution in order to assess the performance of the concrete under sulfate attack condition. The experimental results show that the workability of fresh concrete increased with increasing the particle size of CA used, while the particle size of CA insignificantly affected to the unit weight of fresh concrete mixtures. The concrete mixture produced with Dmax of 12.5 mm obtained the highest compressive strength and UPV values in comparison with those of other mixtures. This study also found that the compressive strength values of concrete samples that fully immersed in sulfate solution reduced about 15% as compared with those of the concrete samples cured in lime-saturated water. All of the concrete samples prepared for this investigation exhibited good durability performance with ultrasonic pulse velocity values of above 4300 m/s. Test results also indicated that the concrete properties can be enhanced if the CA sizes were appropriately selected.