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The aim of this research was to produce three-layer Medium Density Particleboard (MDP), with the addition of impregnated paper, in the inner layer, in proportions of 1; 5 and 20%. In this study, MDP was composed with particles of small size in outer layers, and larger particles in internal layer. After panel manufacturing, physical and mechanical tests based on Brazilian Code ABNT NBR 14.810 were carried out to determine moisture content; density; thickness swelling; water absorption; modulus of rupture (MOR) and modulus of elasticity (MOE) in static bending and internal adhesion. Test results were compared to commercial panels, produced with 100% Eucalyptus, considering the requirements specified by Brazilian Code. Properties presented values close to normative specifications, indicating positively the possibility of production of MDP using addition of waste paper impregnated.

The construction industry is responsible for high energy and raw materials consumption. Thus, it is important to minimize the high energy consumption by taking advantage of renewable energy sources and reusing industrial waste, decreasing the extraction of natural materials. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing to the thermal comfort and reduction of the use of heating and cooling equipment, using only the energy supplied by the sun. The simultaneous incorporation of PCM and fly ash (FA) can reduce the energetic consumption and the amount of materials landfilled. However, the addition of these materials in mortars modifies its characteristics. The main purpose of this study was the production and characterization in the fresh and hardened state of mortars with incorporation of different contents of PCM and FA. The binders studied were aerial lime, hydraulic lime, gypsum and cement. The proportion of PCM studied was 0%, 20%, 40% and 60% of the mass of the sand. The content of fly ash added to the mortars was 0%, 20%, 40% and 60% of the mass of the binder. It was possible to observe that the incorporation of PCM and fly ash in mortars caused differences in properties such as workability, microstructure, water absorption, compressive strength, flexural strength and adhesion.

Studies have been conducted to investigate biomass accumulation of earthworms (Eisenia fetida andrei), cultivated in the soil media under various concentrations of the slaked lime. The group, which is cultivated on the media with lime concentration 0.1% is characterized by maximum biomass accumulation (average – 120 %). As a result we have discovered two phase kinetic dependence between biomass accumulation of earthworms and the amount of the slaked lime.

In this research the aim was produce a particleboard with alternative materials and evaluated its physical and mechanical characteristics. The raw materials used are residues from sucarcane bagasse (SC) (Saccharum officinarum) and stem leaves of bamboo (B) (Dendrocalamus giganteus), bonded with a bi component adhesive based on castor oil. It was produced particleboards with five different traces: 100% SC, 75% SC+25% B, 50% SC+50% B, 25% SC +75%B and 100 % B. Their physical and mechanical characteristics were evaluated accordingly to Brazilian standard NBR 14810-3. Regarding the results obtained, it can be detached that for physical and mechanical evaluation it is evident a negative relation among the amount the sugarcane bagasse and their physical and mechanical characteristics, that is particleboards with low concentrations of sugarcane bagasse had better results. However all particleboards could be recommended for use as sealing particleboards in the segment of civil construction.

The problem of proper disposal of solid waste generated in different industrial processes is one of worldwide environmental concerns nowadays. Thus, this study aimed to establish a new alternative for the disposal of two agro-industrial residues employing them to produce particleboard for different purposes in building construction. The focus was given to the reuse of the sugarcane bagasse (SB) originated during the processing ofSaccharum officinarumfor sugar and ethanol production, and bamboo stem leaves ofDendrocalamus giganteus(BB). For this, six particleboards were produced in the following compositions: with 100% SB, 75% SB + 25% BB, 50% SB+50% BB, 40% SB +60 BB, 25% SB+ 75% BB and 100% BB in the total mass of the composites. The particleboards physical characterization followed Brazilian Standard ABNT NBR 14810-3 to density, moisture content and water absorption. Results showed these raw materials are compatible to particleboard production.

A green method to synthesize the reduced graphene oxide using supercritical fluid has been developed, which is an environmentally friendly and efficient route. The reduced graphene oxide has been examined by X-ray diffraction, Raman spectroscopy. We have also studied the effects of reduction temperatures and supercritical fluids on the electrical properties of reduced graphene oxide. It was found that ethanol has higher reducing capability than CO2at all temperatures (200 - 400°C) examined in this study for graphene oxide reduction. As a result, reduced graphene oxide (6300 S/m) from supercritical ethanol treatment has 5 times as high conductivity as that from supercritical CO2treatment at the reduction temperature of 400°C. This green process is applicable for large scale production of reduced graphene oxides for various practical applications.

The dyeing of cotton fabrics using mulberry leaves (Morus alba L.) as a natural dye has been studied in both conventional heating and ultrasonic techniques. The extractability of Mulberry leaves dye from natural origin using power ultrasonic was also evaluated in comparison with conventional heating. The mulberry leaves extract to provided brown-green to green color, depending on the pH concentration. The results of dye extraction indicate that power ultrasonic is rather effective than conventional heating at low temperature and short time. The effects of dye bath pH, dyeing time, dyeing temperature and mordants were studied and the colorimetric parameters L*, a*, b* of dyed fabrics with ultrasonic and conventional techniques were compared.

The mining districts located in the western mountain range in the south of Ecuador have gold minerals with refractory characteristics, which do not allow gold recovery by traditional methods used in Ecuador. Therefore, it is necessary to apply some technology that permits to obtain greater metal recovery. Bio-oxidation, as treatment of refractory ores that contain low grade of gold, offers an economic and sustainable alternative for this purpose. The objective of this research was to evaluate the effect of particle size, pulp density and concentration of inoculum and inducer (Fe+2) on the bio-oxidation of refractory gold minerals in order to maximize gold recovery of the bioleached minerals by means of a cyanidation process. The microbial consortium used in this work was collected and isolated from the Portovelo mining district corresponding mostly toAcidithiobacillus ferrooxidansandLeptospirillum ferrooxidansspecies. The Eh, final concentration of ferric ion, total iron and sulfates were measured. Finally, the bio-oxidized material was tested using cyanidation to determine the gold recovery. The results after the cyanidation tests showed that the highest gold recovery was obtained when the bio-oxidation step was conducted with 68-91 µm particle size, 15% pulp density, 20% v/v inoculum and 2 g/L of Fe2+as inducer. At those conditions, gold recovery was 68% compared to 26% obtained when no bio-oxidation step was performed, demonstrating that this process was favorable compared with traditional gold recovery processes

As the trend for lighter more efficient structures continues, the requirement for alternative materials follows. One material that has gained attention more recently is porous metallic foam. One drawback to these materials is that there is limited pedigree and understanding of their performance. As with all materials, the use of metallic foam for structures requires knowledge of its mechanical properties; including at high-strain rates. The focus of this paper is to determine the compressive mechanical properties and the influencing parameters for AISI 4340 steel closed-cell foam under high-strain rates (776s-1 to 3007s-1). ANSYS commercial finite element code is used to simulate a closed-cell sample under a split Hopkinson pressure bar test. In this paper the pores are considered to be spherical in shape for simplification while various parameters such as the pore size, the number of pores, the distribution of pores, and the strain rate are varied. Each of these parameters gives this material a unique response which is presented in this paper.

Prediction and optimization of quality characteristics is an important means to improve the quality of laser cutting. Kerf width (KW) and material removal rate(MRR) are selected as the quality characteristics in this paper. The fitting response surface models (RSM) of KW and MRR are considered as the optimization objective function in pulsed Nd: YAG laser cutting of alloy steel for multi-objective optimization. An improved Pareto genetic algorithm is used in the optimization, and the significant factors have been found. The predicted results are basically consistent with the experimental. Therefore, the method used in this paper can be used for optimization of KW and MRR in pulse Nd: YAG laser cutting. The study can provide theoretical basis for the prediction and optimization of quality in laser cutting. Keywords-laser cutting; multi-objective optimization; RSM; improved Pareto genetic algorithm

Magnetoacoustic Tomography (MAT) is a new imaging method. MAT combines the good contrast of electrical impedance tomography with the good spatial resolution of ultrasound imaging. Magnetoacoustic Tomography includes Magnetoacoustic Tomography with magnetic induction and Magnetoacoustic Tomography with injecting current. In this paper we researched the later imaging method mainly; in paper we studied the parameters of AC power supply, which was injected to the imaging sample. At the same time, the waveforms of experiment were given and analyzed, which provides theoretical basis for the selection of power supply used in the subsequent experiments.

This paper presents some research results of the application of finite element method and molecular dynamics in the simulation of grinding surface creation. The comparison of these two methods shows that both methods could illustrate the material removal phenomena and provide useful information of grinding mechanics, but they have different feasible application arranges depending on the level of size scales. The investigation demonstrated that rubbing hypothesis of grinding material removal mechanism is valid at all size level even down to nanometre level. Further investigation areas are identified in the paper.

This paper presents a review of developing of creep damage constitutive equations for high chromium alloy (such as P91 alloy). Firstly, it briefly introduces the background of creep damage for P91 materials. Then, it summarizes the typical creep damage constitutive equations developed and applied for P91 alloy, and the main deficiencies of KRH (Kachanov-Robatnov-Hayhurst) type and Xus type constitutive equations. Finally it suggests the directions for future work. This paper contributes to the knowledge for the developing creep damage constitutive equations for the specific material.

This paper presents a brief review, followed by some new results from recent diffusion simulations in Ni-base superalloy systems, performed by means of a thermodynamic and kinetic modeling approach as taken in the commercial finite-difference code DICTRA. The DICTRA code solves the multi-component diffusion equations, combining assessed thermodynamic and kinetic data in order to determine the full composition dependent interdiffusion matrix. The link between fundamental physics based models and critically assessed data allows simulations to be performed with realistic conditions on alloys of practical importance. Emphasis in this paper is on modeling and simulation of interdiffusion occurring between NiAl coatings and Ni-base superalloy substrates. For this purpose we have used the so-called homogenization approach to diffusion in multi-phase systems, recently implemented into the DICTRA software. The simulation results have been validated against experimental data and the agreement is very satisfactory given the complexity of the problem.

Main works on microstructure prediction on superalloys during hot forming processes deal with close die forging of 718 alloy. In this paper, we focused our interest towards incremental hot forming process. In that case, matters become more complex, due to the partially recrystallized microstructure we have to take into account at the beginning of each pass. An original method is presented in this paper, still using a phenomenological approach, according to Avrami formulation, with two main additional assumptions, in order to carry out computation on microstructure evolution during the process. Examples with comparisons between real and computed microstructure (recristallyzed fraction, different populations of grain size) enable us to valid our model for bar forging.

A method for achieving better dimensional control for composites based on deformation compensation in mold design is presented in this paper. The process-induced deformation of a general angled part, i.e. spring-in, was studied statistically to account for the processing-related uncertainties. The part geometry was modified based on the results from the statistical analysis for offsetting the deformation. The modified part geometry was used to design the mold for resin transfer molding and the mold was made by the CNC wire electrical discharge machining (WEDM) process. Five sample parts were fabricated using the mold and the spring-in angles were measured. The results show that the process-induced deformation is significantly reduced through deformation compensation. This method presented in this paper provides an approach to minimizing the overall process-induced deformation of resin transfer molded parts.

The objective of this paper is measurement of the surface roughness of tensile specimens under different tensile speed. In the test, the tensile specimens were loaded by tensile testing machine. The roughness of the surfaces was measured by digital holographic interferometric system (DHI). From the results, it was confirmed that DHI could measure the roughness of the various types of the specimen surface. In this paper, as the tensile speed was faster, the roughness of specimen surface was smaller.

By changing gel and electrode shape, many different actuators could be invented. In the previous papers, we have reported that Maxwell stress generated in the PVC gels was expected as the results of polarization response of charges, and it mainly took place between the gel and the anode due to the accumulated negative charges on surface of the PVC gel near anode. Due to the existence of the Maxwell force, the PVC gel will be deformed asymmetrically and resulted in creep deformation along the anode. In this paper, we conducted some mechanical experiments and investigated the modulus of PVC gels with varied contents of plasticizer DBA. It was found that PVC gels were separated to two layers obviously after applied an electrical field. Near the anode, the layer (L1) was thinner and softer than other layer (L2) due to the transfer of plasticizer to the anode. This phenomenon was also confirmed by a fluorescence microscope. The displacement of gel in both sides near electrodes was different, and then a bending force was generated due to the force of electrical field. On the other hand, the recovery time of the deformed gel depended on the contents of plasticizer. The longer recovery time was observed for the lower content of plasticizer. The Young’s modulus of PVC gels in tensile becomes small after applied an electrical field and the gels became to be deformed easily.

In the world of MEMS processing today, fabrications of membrane are performed using bulk micromachining (BMM). However these techniques not easiest to integrate with CMOS standard process due to not compatible of the processing flow. An attractive alternative deployment of surface micromachining (SMM). There is a trend to use surface micromachining to their advantage of simplicity in design and fabrication process compatibility. This paper presents process development of thin layer membrane for very low capacitive pressure sensor application. The structure of the membrane consists of parallel plate which both top and bottom electrodes were fixed at both sides. Utilizing CMOS MEMS process compatible fabrication of the thin layer membrane involved in three stages; i) hole opening etch, ii) sacrificial intermediate oxide release etch and iii) closing of etch holes. Therefore seals-off process characterization and optimization experiment are presented in this paper, will spur advancement in the development of a CMOS MEMS product for very low capacitive pressure sensor.

This paper presents the results of investigations on topology optimizations in extrusion dies. The change of material viscosity of finite elements in the numerical model is utilized to allow or to block the material flow through the finite elements in simplified two-dimensional extrusion models. Two different optimization procedures are presented. In the first part of the paper dead zones in a flat and in a porthole die were improved by enhance the streamlining of the extrusion die. In the second part an evolutionary optimization algorithm has been used to optimize the extrusion die topology in order to reduce the difference between the strand exit velocities in a multi extrusion process. Finally, both methods were sequentially combined.

On a global market, new products are subject to rising requirements regarding strength and quality. Simultaneously, the conservation of the environment and natural resources has become a key priority. One approach to these demands is the weight reduction of mechanical components by lightweight construction. The Transregional Collaborative Research Center (TR 10), funded by the German Research Foundation (DFG), is therefore working on the “Integration of forming, cutting and joining for the flexible production of lightweight space structures”. The use of light metals, like aluminium and composite materials is a main part in the TR10 process chain. This paper deals with the challenges of welding of light weight components made out of EN AW-6060. It shows the use and potentials of two innovative joining processes, particularly suited for welding aluminium. Especially developed for the fusion welding of aluminium components, BHLW (Bifocal Hybrid Laser Beam Welding), combines a Nd:YAG and a high power diode laser. The paper will give insight into the findings of the achieved results so far and line out the further proceedings with regard to critical parameters and their effect on the overall laser welding process. For the welding of aluminium composite materials, which play a big role in the TR10 process chain, Friction Stir Welding (FSW) is evaluated. As a solid state joining process, it can be used for the welding of materials that are hardly weldable with fusion welding techniques. In this paper, results of basic experiment for the joining of reinforced aluminium and the resulting process forces are presented.

Turbine and generator rotors and shafts undergo high stresses during regular working life and, from a safety and operational aspect, are the most significant components of a power generation system. Depending on the appropriate operating conditions, like temperature and/or corrosion the, shafts can be fabricated out of low/high alloy heat resistance material or of low alloyed, highly toughened material for different application. Despite known good practice and developed operation procedures, the failures of shafts sometimes occur. The right and well-defined failure analysis is the basis for feasibility analysis of repair method in the power generating industry. The analysis of direct and indirect costs of repair after the failure analysis as well as the analysis of the repair and post-repair conditions of the repaired element is the vital for decision on the key question. Is it possible to repair this element and what is the optimal repair strategy? This paper compares and analyses two approaches, by weldability analysis and weld cycle simulation, in order to determine welding feasibility analysis of cracked hydro turbine shafts.

Knowing temperatures at the tool-chip interface is extremely important to optimize the machining condition and to improve the machining performance, furthermore to design high performance materials. In order to grasp the temperature distribution at the tool-chip interface, this study has devised an indexable insert with seven pairs of built-in micro Cu/Ni thermocouples on the rake face near the cutting edge. This paper shows the performance of the indexable insert with built-in micro thermocouples developed. The thickness of each element of the micro thermocouple is approximately 15 μm. The result of unsteady heat conduction analysis employing FEM shows that the temperature difference by installing the micro thermocouples is less than 10 K or 1.2 %. The temperature measurement experiments by cutting of aluminum alloy were carried out by changing the cutting speed. The results provided the evidence that the temperature distribution at the tool-chip interface can be grasped with the indexable insert with built-in micro thermocouples developed.

Buildings are responsible for more than 40% of the energy consumption and greenhouse gas emissions. Thus, increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials could constitute the most effective way of reducing heat losses in buildings by minimising heat energy needs. These materials have a thermal conductivity factor lower than 0.065 (W/m.K) while other insulation materials such as aerated concrete can go up to 0.11. Current insulation materials are associated with negative impacts in terms of toxicity. Polystyrene, for example contains anti-oxidant additives and ignition retardants. In addition, its production involves the generation of benzene and chlorofluorocarbons. Polyurethane is obtained from isocyanates, which are widely known for their tragic association with the Bhopal disaster. Besides current insulation materials releases toxic fumes when subjected to fire. This paper presents experimental results on one-part geopolymers. It also includes global warming potential assessment and cost analysis. The results show that only the use of aluminium powder allows the production mixtures with a high compressive strength however its high cost means they are commercially useless when facing the competition of commercial cellular concrete. The results also show that one-part geopolymer mixtures based on 26% Ordinary Portland Cement (OPC)+58.3% Fly Ash (FA)+8% Calcined Stuff (CS) +7.7% Calcium Hydroxide (CH) and 3.5% hydrogen peroxide constitute a promising cost efficient (67 euro/m3), thermal insulation solution for floor heating systems with low global warming potential of 443 KgCO2eq/m3.

Present paper relates to the field of “smart textiles” and demonstrates the results of research carried out on the development of a new type of knitted sensing elements (knitted resistive fabric (KRP)) which can be integrated in the garment applied for health monitoring. KRP produced from conductive resistive, nonconductive isolating and nonconductive elastomeric yarns. Elastomeric yarn is used as the base yarn and is knitted in the whole fabric, but isolating and resistive yarns (functional yarns) are used as face yarns and knitted in specific sequence. Proposed knitted resistive fabric has high sensitivity to strain deformation and can be used as sensing element to control deformation of the human body parts, joint motion, respiration etc.

This paper describes the numerical investigation on the adsorption () of nanoparticles (NPs) scale inhibitor (SI) using Eulerian Computational Fluid Dynamics (CFD) solver ANSYS/FLUENT® based on a scaled down flow model. The simulation were done to investigate theof normal and nanoscaled Calcium-phosphonate. The phosphonate used was 1-hydroxyethylidene-1, 1-disphosphonic acid (HEDP) SI in order to determine the enhancement in adsorption achieved by the nanoscaled SI. This was done by looking at the change in concentration of the SI particles throughout the simulation time. It was found that the two sizes (normal and nanostructured) of the SI particles result in different change in concentration, hence indicates that the two yields different adsorption to the active sites. For the normal SI, the concentration distribution throughout the column remains almost the same as its initial concentration () of 2000 ppm except for very narrow regions in the vicinity of the wall boundaries. This suggests that the rate of process (of the SI onto the wall) is very slow. Consequently, it will take longer time for the SI to be adsorbed to the column wall, hence indicates that it is less efficient. Meanwhile, the nanoscaled Calcium-HEDP SI rapidly shows a significant change in concentration. At 200 s its concentration has distributed evenly in the range of 1960 ppm to 2000 ppm. This shows a really high rate. The results from this study indicates that the nanoscaled Calcium-HEDP SI has better which shows that it is more efficient than normal-scaled Calcium-HEDP SI.

This paper presents the effect of Jatropha curcas biodiesel on the wear properties of mild steel, which was coated by preplacement of TiC particulate and melting it using a conventional TIG torch arc heat source. The aim of the study is to investigate the wear behaviour of surface modified AISI 4340 steel and the uncoated AISI 4340 steel which were performed using CSM tribometer at four different temperatures viz., 100 °C, 120 °C, 140 °C, and 160 °C, with the presence of jatropha biodiesel. At the end of the tests, wear characteristics was investigated by weight loss measurements and changes of the exposed metal surface. Surface morphology was examined by scanning electron microscope and surface profilometry. EDX analysis was performed on the samples’ surface. Results showed that wear of alloy steel increases with increasing temperature. TiC coated alloy steel showed improved wear resistance as this alloy steel demonstrated lower wear volume loss as compared to the uncoated steel in presence of jatropha biodiesel at higher temperature.

In the ZnO based varistor, the improvement of nonlinear coefficient (α) and prevention of evaporation of Bi2O3 during heat treatments can be achieved by the addition of MnO2 or Co3O4. In this conjunction, it is proper to see the effect of these additives at different low mol percentage and sintering conditions to nonlinear coefficient improvement of the varistor ceramics. In this paper, the investigation regarding to the α variation of Co3O4 doping on ZnO-Bi2O3-TiO2 system is discussed. Here, the crystalline phases were identified by an XRD (PANalytical (Philips) XPert Pro PW3040/60) with CuKα radiation and the data were analyzed by using XPert High Score software. The density of varistor ceramics was measured by the geometrical method. The current-voltage characteristics of the varistor ceramics were evaluated. The average grain size (d) was determined by lineal intercept method. The α of ZnO doped with 0.5 mol% of Bi2O3, 0.5 mol% of TiO2 and x mol% of Co3O4 was calculated from data analysis of current-voltage characteristics obtained through a Source Measure Unit (Keithley 236). The calculation of α is done by using Origin Pro8.0 software. The value of α at low concentration at 1170 °C has the value 5.36 and 3 at 45 and 90 min sintering time, respectively, and then decreases to 4.99 and 2.98 at 0.8 mol% Co3O4 concentrations. When the amount of dopant is increased then the value of α increase up to 0.4 mol% and then the value are slightly dropped after further addition. The addition of Co3O4 dopant in Zn-Bi-Ti oxide ceramics sintered at 45 minutes cause the value of α to increase up to 0.4 mol% and decrease after further addition.

RETRACTED PAPER: The fabrication of nanospinel zinc chromite (ZnCr2O4) crystals by the means of thermal treatment method from an aqueous solution containing metal nitrates, polyvinyl pyrrolidone (PVP), and deionized water was described in this study. The samples were calcined at various temperatures ranging from 773 to 973 K for the decomposition of the organic compounds and crystallization of the nanocrystals. PVP was used as capping agent to control the agglomeration of the particles. The characterization studies of the fabricated samples were carried out by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), energy dispersed X-ray spectroscopy (EDX) and electron spin resonance spectroscopy (ESR). The corresponding peaks of Zn, Cr and O were observed in the EDX spectrum of the sample which confirms the formation of ZnCr2O4. The XRD patterns also confirmed the formation of the single faced nanocrystallines of spinel ZnCr2O4 with a face-centered cubic structure. The average particle size of the synthesized crystals was also determined from the XRD patterns using the Scherers formula which shows that the crystallite sizes increases with increase in calcination temperature and was in good agreement with the TEM images which shows cubical ZnCr2O4 nanocrystals with uniform morphology and particle size distributions. The ESR spectra confirmed the existence of unpaired electron in the fabricated samples and the increase in g-factor and decreases in resonant magnetic field (Hr) were observed as the calcination temperature increases.

The design of layers for multilayer flame-resistant glass is a vital task in terms of upgrading fire resistance of window glass units. This paper describes chemical modification of flame-proof acrylate hydrogel layers and shows experimentally how a cross-linking agent — hexamethoxymethylmelamine ether – influences the kinetics of hydrogel polymerization and the enhancement of carbonated structures yield. It has been determined that adding HMMM to the hydrogel composition raises the coke residue yield from 10 % to 35 % and increases the 19 mm thick glass flame resistance class from EI30 to EI50.

The paper is dedicated to the research of calcium-phosphate coatings formed on the surface of the polymer layers (copolymer tetrafluoroethylene with vinylidene fluoride) by pulsed laser deposition. The calcium-phosphate coatings were formed using two different by composition targets. The morphology of the obtained coatings was analyzed by Scanning Electron Microscopy, the elemental composition was analyzed by Energy Dispersive Analysis, and the chemical composition was analyzed by Fourier Transform Infrared Spectroscopy.

Since squeeze casting process is considered as a new technology for light alloys like aluminum and magnesium, more basic research is required for a scientific understanding of the practice. In distinct, as a cost-effective and resource-efficient tool, advanced numerical modelling in conjunction with dynamic boundary conditions and capabilities of predicting the formation of casting defects have to be fully developed for the optimization of squeeze casting processes. In squeeze casting, an external pressure is applied to molten metal before, during and after its solidification, which makes the condition at the casting die interface different from other typical casting techniques. In this paper, Finite Difference Method (FDM) is used to investigate the effect of heat transfer during squeeze casting process and the relationship between casting temperature and solidification on Al-Si alloys.

Debinding is one of the most critical and time consuming stage in metal injection moulding (MIM). German and Bose (1997) reported that early debinding practice relied on thermal binder degradation, requiring up to 300 hours for complete binder removal. Today multi-stage debinding techniques are introduced cutting down the debinding time to as little as 2 hours. This work investigates solvent debinding variables prior to thermal debinding. Solvent debinding is carried out in n-heptane. Wax and stearic acid are the target binder components being leached out from the green bodies, with wax as the major constituent in the binder formulation. Debinding is conducted at 50, 55, 60 and 65°C for 1-4 hours at each temperature. Weight loss measurements were done. For porosity and surface appearance, scanning electron microscope (SEM) analysis and visual inspection were done. Samples de-bound at 65°C showed an appreciable amount of mass loss; however, surface cracks and warping were observed. A 60°C temperature and time of 4 hours demonstrated best results i.e. a satisfactory mass loss, absence of surface cracks and no warping. Mass loss is directly proportional to temperature and time. SEM results are discussed in the paper.

An important step of a new process being developed for the beneficiation of the mineral zircon (Zr (Hf)SiO4) to produce nuclear grade zirconium (Zr) metal, is the separation of the Zr from the hafnium (Hf). Zr ores typically contain between 1 and 3% Hf , whereas the use of Zr metal in the nuclear industry requires a Hf content 2•SiO2) with ammonium bifluoride (ABF). The separation involves the selective sublimation of the two tetrafluorides in an inert atmosphere under controlled conditions, and subsequent similarly selective desublimation. An accurate estimation of the sublimation rates the zirconium tetrafluoride (ZrF4) and hafnium tetrafluoride (HfF4) as a function of temperature is required since this forms the basis of the development of a sublimation model to determine whether the concept under consideration is theoretically possible. The sublimation kinetics of ZrF4is reported in this paper.

Lasers have the potential for the micromachining of germanium (Ge). However, the thermal damages associated with the laser machining process need to be properly controlled. To minimize the thermal damages, a hybrid laser-waterjet ablation technology has recently been developed for micromachining. This paper presents an experimental study to assess the machining performances in microgrooving of Ge by using a nanosecond laser and the hybrid laser-waterjet technology. The effects of laser pulse energy, pulse overlap and focal plane position on the groove geometry and heat affected zone (HAZ) size are analyzed and discussed. It is shown that the hybrid laser-waterjet technology can give rise to narrow and deep microgrooves with minimum HAZ.

Delivery of polymer melts into the mold cavity is the most important stage of the injection molding process. This paper shows the influence of cavity surface roughness and technological parameters on the flow length of rubber into mold cavity. The fluidity of polymers is affected by many parameters (mold design, melt temperature, injection rate and pressures) and by the flow properties of polymers. Results of the experiments carried out with selected types of rubber compounds proved a minimal influence of surface roughness of the runners on the polymer melt flow. This considers excluding (if the conditions allow it) the very complex and expensive finishing operations from the technological process as the influence of the surface roughness on the flow characteristics does not seem to play as important role as was previously thought. Application of the measurement results may have significant influence on the production of shaping parts of the injection molds especially in changing the so far used processes and substituting them by less costly production processes which might increase the competitiveness of the tool producers and shorten the time between product plan and its implementation.

Little research was done to investigate possible utilization of irradiated materials after the end of their lifetime. This research paper deals with the possible utilization of irradiated high-density polyethylene (HDPEx) after its service life. Irradiated HDPE was used as filler into the virgin low-density polyethylene (LDPE). Three material combinations were investigated (powder/powder, granules/powder and granules/grit) and influence of the filler on optical behavior was measured. Terahertz spectroscopy at wide range of frequencies was used for refractive index determination. According to measured data there is significant influence by the amount of the filler. Moreover influence of particle size was also observed. All three combinations have similar curve courses; however the most consistent results were achieved at the powder/powder combination. Behavior of virgin LDPE and virgin HDPE is in correlation with previous findings.

In this paper we investigated the influence of vibratory stress relieving technique, which is widely used for stress relaxation of weld and casting components/structure, on machining residual stresses in a ring-component of 12%Cr-steel. It was shown that the employed vibratory treatment, without significantly altering the microstructure, turned the surface layer from tension into compression but retained the compressive residual stresses in the subsurface. In comparison, a stress relieving heat treatment, included as a reference in the study, removed completely the surface tensile residual stresses and reduced the subsurface compressive residual stresses to a low level. Significant microstructural changes in the form of recrystallization also occurred in a thin surface layer of the machining affected zone after the heat treatment.

A two-level homogenization approach is adopted in order to predict the stress state of deformed polycrystals in correlation with the microstructure. This study is devoted to complex loading paths behaviour of cubic material. A mechanical description of the grain is developed through a micro-meso transition based on elastoplastic Kroner's model. The meso-macro transition using a self-consistent approach is applied to deduce the global behaviour. Mechanical tests and neutron diffraction measurements are used to validate and assess the model. Classic one transition level models were developed to predict the influence of the local mechanical behavior to the global one. The grain is considered as an uniform region neglecting the formation of the dislocation microstructure. These approaches permit to predict correctly the yield surface, the crystallographic texture linked to the plastic deformation, the intergranular stresses due to initial and induced anisotropy during monotonic loadings. Nevertheless, this kind of description fails to reproduce the mechanical behaviour during changing strain paths. These methods do not, or weakly, take account of the formation, the evolution and the stability of induced dislocation microstructures which are strongly path dependent. In this work, a two-level homogenization approach is developed for the micromechanical modelling of the elastoplastic material behavior (1). This study is particulary devoted to complex loading paths. At the microscopic scale, the mechanical behavior is described by the Kroner model. The grain is considered as two-phase material: dislocations walls (with high density dislocation) and cells (with low density dislocation). The intragarnular heterogeneities are highlighted by a non- local work-hardening, which is linked to the two-phase description. At the global scale, the mechanical behavior is deduced from the mesoscopic one by an elastoplastic self-consistent model. To validate our numerical approach and explain the Bauschinger mechanisms, we conclude this paper by a confrontation between the simulation results with those from neutron diffraction (ND). This will allow to get a complete analysis at different levels: diffraction volume scale and macroscopic one.

For X-Ray Diffraction Measurement of Depth Profiles of Residual Stress, Step-Wise Removal of Materials has to be Done to Expose the Underneath Layers to the X-Rays. this Paper Investigates the Influence of Layer Removal Methods, Including Electro-Polishing in Two Different Electrolytes and Chemical Etching, on the Accuracy of Residual Stress Measurement. Measurements on Two Shot-Peened Steels Revealed Large Discrepancy in Subsurface Distributions of Residual Stress Obtained with the Respective Methods. Especially, the Chemical Etching Yielded much Lower Subsurface Compressive Stresses than the Electro-Polishing Using a so Called AII Electrolyte. the Difference was Explained by the Influence of the Different Layer Removal Methods on the Microscopic Roughness.

Laboratory X-ray diffraction is commonly used for surface residual stresses determination. Nevertheless, the in-depth residual stress gradient also needs to be known. Chemical or electro-polishing method is generally used for material removal. However, material removal may seek a new equilibrium and stress field may change in such a way that experimental residual stress values must be corrected. Different methods exist to account for the residual stress relaxation associated with the material removal operation and will be discussed in this paper.

Selectively induced compressive residual stress depth profiles are gaining increasing importance as design tool for internally pressurized components. Hydraulic Autofrettage (AF) is a well-known manufacturing process to induce pronounced compressive residual stresses. However, AF does not stand alone in the technical process chain. In this paper, results from neutron diffraction experiments performed on thick-walled cylinders are presented and compared to finite-element simulations with Abaqus/CAE. The impact on the final residual stress depth profile after pre-machining, Autofrettage and post-machining is discussed.

Titanium aluminide (TiAl) is a lightweight intermetallic compound with a range of exceptional mid-to-high temperature mechanical properties. These characteristics have the potential to deliver significant weight savings in aero engine components. However, the relatively low ductility of TiAl requires improved understanding of the relationship between manufacturing processes and residual stresses in order to expand the use of such components in service. Previous studies have suggested that stress determination at high spatial resolution is necessary to achieve better insight. The present paper reports progress beyond the current state-of-the-art towards the identification of the near-surface intragranular residual stress state in cast and ground TiAl at a resolution better than 5 μm. The semi-destructive ring-core drilling method using Focused Ion Beam (FIB) and Digital Image Correlation (DIC) was used for in-plane residual stress estimation in ten grains at the sample surface. The nature of the locally observed strain reliefs suggests that tensile residual stresses may have been induced in some grains by the unidirectional grinding process applied to the surface. © (2014) Trans Tech Publications, Switzerland.

The use of short process chains for the realization of complex and high performance components is a reasonable approach to achieve sustainable products and to reduce energy consumption. In the Collaborative Research Center SFB/TR TRR30 which is supported by the German Research Foundation DFG this approach is investigated applying thermo-mechanically forming processes. In this way, combining hot metal forming and heat treatment steps in a single process, tailored materials properties together with appropriate geometries are achieved [1, 2] . However, still additional machining operations, e. g. turning operations in case of shafts, are needed to achieve proper workpiece finish. Due to locally varying mechanical properties, undesired changings of the process conditions occur, leading to varying surface and subsurface properties, e.g. the residual stress state. It is well known that residual stresses have a major impact on the components properties during service [3]. In this paper, a survey is given about near surface residual stress states after exterior dry turning of differently heat treated cylindrical workpieces made of steel AISI 6150.

Strain is routinely used in state-of-the-art semiconductor devices in order to improve their electrical performance. Here we present experimental strain measurements obtained by different transmission electron microscopy (TEM) based techniques. Dark field electron holography, nanobeam electron diffraction (NBED) and high angle annular dark field scanning electron microscopy (HAADF STEM) are demonstrated. In this paper we demonstrate the spatial resolution and sensitivity of these different techniques on a simple calibration specimen where the accuracry of the measurement can easily be assessed. Introduction. Although the effects of introducing strain in semiconductor devices is well known from an electrical point of view, little is known about the distribution of strain. Indeed, it is only in the last few years that methods that can measure the strain with the required level of spatial resolution have been developed. Dark field electron holography (1), NBED (2) and HAADF STEM (3) are different TEM based techniques that have been developed in order to solve this problem. A calibration specimen was designed so that the different strain mapping techniques could be tested and compared to accurate simulations that would account for the relaxation of the thin TEM specimen. The calibration specimen that was examined was grown by reduced pressure chemical vapour deposition and comprised from top to bottom, a 150-nm-thick capping layer, then four 10- nm-thick SiGe layers with Ge concentrations of 45%, 38%, 31% and 20%, each separated by 30nm of silicon on a silicon substrate. As the growth is epitaxial, the lattice spacing in the in-plane (x- direction) does not change. However, in the growth (z-direction) the lattice parameter is expanded relative to the unstrained substrate due to the presence of Ge and it is this relative expansion which is measured. The dark holography experiments were performed using a probe corrected FEI Titan operated at 200 kV, the precession NBED (PED) and the HAADF STEM experiments were performed using a double corrected FEI Titan operated at 200 kV. All of the data was processed using software written at CEA.

Dye-sensitized solar cell (DSSC) is part of the thin film family that consists of a TiO2 electrode coating which acts as a photo electrode, sensitizer from dye molecules soaked in the TiO2 film, electrolyte layer and a counter electrode. This paper focuses on the usage of a sensitizer from the rose flower and will review some of the research conducted on dye sensitizers from other researcher. Rose flower also known as woody perennial of the genus Rosa, within the family Rosaceae is extracted and were used as sensitizer to fabricate dye sensitized solar cell (DSSC). The photoelectrochemical performance of Rose sensitized solar cell shows parameter of open circuit voltage, VOC,short circuit current, (ISC), fill factor (FF), solar cell efficiency (η), and peak absorbance rate as much as 0.13 V, 57.58 µA, 0.58, 0.85% and 3.5 at 550nm respectively. The photoelectrochemical performance of DSSC and the usage of natural sensitizer from Rose flower dye demonstrate good potential to be applied as a sensitizer yet detail investigations are essential in terms of its applicability for long term application.

This paper investigates experimentally and numerically the degree to which the stress relaxation in shot-peened simple geometric features of steel turbine materials can be modelled by using an understanding of simple eigenstrain distributions. The residual stress is determined as the elastic response of whole component when the plastic strains caused by shot peening is incorporated as an eigenstrain in an appropriate finite element (FE) model. The application of a subsequent live load is then modelled as an additional load step in the FE model which will superpose the effect of this loading on the residual stress field. The results show that the eigenstrain approach is particularly useful in predicting residual stress relaxation in shot-peened components.

Layer removal method is an experiment method which is used to calculate the average stress indirectly by deformation of the specimen. However, in the experiment, some certain predeformation can be caused after each clamping, which can affect the accuracy of the test data, and make the deformation data larger. Based on the comparison of the simulation calculation, this paper builds an amended function by fitting the deformation error, which solves the deviation caused by larger deformation on stress calculation while the specimen is milled by layer, that is to say, the stress calculation model can be compensated by this function. This method can make the experimental calculation model more accurate.

Ultrasonic impact treatment (UIT) is a remarkable post-weld treatment, which reduce not only in external stress concentration, but also in residual stress in a welded joints. Internal and surface stresses were investigated on UIT treated welded joints by neutron and X-ray diffraction method. This paper discuses the effect of internal and surface residual stress and surface stress concentration after UIT on fatigue resistance by the comparison of fatigue experiments to predictions calculated with the results of the experimental investigations.

9th European Conference on Residual Stresses, ECRS-9, Troyes, France, july 7-10, 2014, session 3.5 - Acoustics and Electromagnetics, paper 194; International audience; For amorphous materials such as glass, the fragility of the material can be limited using surface reinforcement by chemical tempering. The principle of chemical tempering consists in forming a superficial compression layer on the surface by immersing the glass in a solution of molten potassium nitrate. In this study, dispersion of surface ultrasonic waves caused by the presence of residual surface stresses was studied. The thickness and the level of the stressed cortical zones were estimated using an inverse method.