Suitable Processing Conditions Research Articles

A theoretical model to estimate steam and CO2 gasification rates based on feedstock characterization properties

An improved model for the estimation of gasification rate constants using CO2 and steam as gasifying agents is presented in this work. The theoretically deduced model only considers the micropore surface area and catalyst (alkali) content of the raw feedstock as inputs for the gasification rate estimation. The main advantage compared with other models is its simplicity in determining the rate constant with only one regression parameter, which is a result of introducing, for the first time, theoretical limits to the activation energy of the main gasification reactions (steam gasification and Boudouard reactions).Experiments were carried out in a setup that reduces the most common problems associated with laboratory gasification procedures, such as misinterpretation of a maximum gasification rate, adverse effects on the char properties during the pyrolysis phase, and interparticle diffusion. Statistical analysis showed that the model fitted well with experimental data, since the determination coefficient was higher than 0.96 for 13 coal samples with a broad range of ash contents (6.4% to 74.8%).The new model gives an accurate mixing rule that is useful in determining gasification rates of different feedstock mixtures. The new concepts presented in this research can be used for simulating and determining suitable process conditions for industrial gasifiers operating with different feed mixtures.

Microwave-assisted extraction of phenolic acids and flavonoids and production of antioxidant ingredients from tomato: A nutraceutical-oriented optimization study

Abstract The production of natural extracts requires suitable processing conditions to maximize the preservation of the bioactive ingredients. Herein, a microwave-assisted extraction (MAE) process was optimized, by means of response surface methodology (RSM), to maximize the recovery of phenolic acids and flavonoids and obtain antioxidant ingredients from tomato. A 5-level full factorial Box–Behnken design was successfully implemented for MAE optimization, in which the processing time (t), temperature (T), ethanol concentration (Et) and solid/liquid ratio (S/L) were relevant independent variables. The proposed model was validated based on the high values of the adjusted coefficient of determination and on the non-significant differences between experimental and predicted values. The global optimum processing conditions (t = 20 min; T = 180 °C; Et = 0%; and S/L = 45 g/L) provided tomato extracts with high potential as nutraceuticals or as active ingredients in the design of functional foods. Additionally, the round tomato variety was highlighted as a source of added-value phenolic acids and flavonoids.

Ultrasound assisted extraction and nanofiltration of phenolic compounds from artichoke solid wastes

Artichoke wastes from the canning industry are rich in phenolic compounds, which can be used as food additives. This study aims to evaluate the potential of sequential process based on the use of ultrasound extraction and membrane technology for phenolic recovery. In the extraction step, solvent composition and ultrasound power were evaluated to understand their impact on phenolic content and antioxidant capacity. The highest yields were observed for extracts with higher ethanol content (50 and 75%). Therefore, these extracts were selected for concentration by nanofiltration in a tangential module, using differents membranes (NF270, DK and DL). The flux decrease and the phenolic retention were evaluated. Hermia's models and membrane surface characterization were used to investigate the fouling. The highest flux was observed for extracts with 50% of ethanol with a retention of chlorogenic acid higher than 95%. DK membrane showed to be less susceptible to fouling, although the cake formation occurred in all evaluated membranes. The most suitable process condition to obtain the highest phenolic yields was extraction with 50% ethanol and an ultrasound power of 240 W and extracts nanofiltration using DK membrane.

Analysis of Cutting Glass Sheets by Laser-Induced Thermal Stress

Scribing, or the full-body cutting of glass substrates, can be achieved by thermal stress that is induced by laser heating. In such processing, the substrate’s temperature distribution is controlled by scanning the heat source or a pair of heat and cooling sources for generating sufficiently high tensile stress to propagate a crack. As a result of crack propagation that follows the laser beam, the substrate can be divided along the laser beam scanning path. By analyzing the temperature and the thermal stress in the numerical simulations, we can estimate suitable processing conditions. How the crack propagates can also be estimated by analyzing the stress intensity factors. Numerical simulations supported clarifying the mechanism of crack propagation and devising new processing methods for controlling crack propagation.

Atomic layer deposition of Pd and Pt nanoparticles for catalysis: on the mechanisms of nanoparticle formation

The deposition of Pd and Pt nanoparticles by atomic layer deposition (ALD) has been studied extensively in recent years for the synthesis of nanoparticles for catalysis. For these applications, it is essential to synthesize nanoparticles with well-defined sizes and a high density on large-surface-area supports. Although the potential of ALD for synthesizing active nanocatalysts for various chemical reactions has been demonstrated, insight into how to control the nanoparticle properties (i.e. size, composition) by choosing suitable processing conditions is lacking. Furthermore, there is little understanding of the reaction mechanisms during the nucleation stage of metal ALD. In this work, nanoparticles synthesized with four different ALD processes (two for Pd and two for Pt) were extensively studied by transmission electron spectroscopy. Using these datasets as a starting point, the growth characteristics and reaction mechanisms of Pd and Pt ALD relevant for the synthesis of nanoparticles are discussed. The results reveal that ALD allows for the preparation of particles with control of the particle size, although it is also shown that the particle size distribution is strongly dependent on the processing conditions. Moreover, this paper discusses the opportunities and limitations of the use of ALD in the synthesis of nanocatalysts.

Melt compounding of poly (Lactic Acid) and talc: assessment of material behavior during processing and resulting crystallization

The influence of talc incorporation by melt compounding on a commercial grade of poly (lactic acid) (PLA), and the choice of the optimal compounding conditions were investigated. Two types of talc, having micrometric and submicrometric distribution, were adopted. Since the compounding itself has a dramatic influence on the properties of PLA, a study was carried out aimed at assessing the effect of processing on this resin and choosing the most suitable processing conditions. It was found that the incorporation of talc increases the viscosity during the compounding and helps the stability of the viscosity during the mixing. Furthermore, the talc, acting as a nucleating agent, enhances crystallization kinetics, so that crystallization half time can be reduced by one order of magnitude with respect to the pure PLA processed in the same way.

Processing and characterization of conductive composites based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) and carbon additives: A comparative study of expanded graphite and carbon black

Electrically conductive polymer composites (ECPCs) based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) and expanded graphite (EG) or carbon black (CB) were prepared through melt blending using a torque rheometer equipped with a mixing chamber. Variations in parameters such as temperature, rotation speed and mixing time were investigated in order to define the most suitable processing conditions. The processing parameters investigated did not exert significant influence on the electrical conductivity for SEBS/EG composites, except for the mixture processed at 230 °C and 150 rpm for 15 min. On the other hand, it can be stated that the conductivity of the SEBS/CB depends on the processing temperature and mixing time. The electrical conductivity, morphology, dynamic mechanical, dielectric and rheological properties as well as electromagnetic interference shielding effectiveness (EMI-SE) of the SEBS/EG and SEBS/CB composites prepared under the same processing conditions were evaluated and compared. The insulator–conductor transition of SEBS/CB was very sharp and the electrical percolation threshold at room temperature was about 5 wt.% of CB, which was significantly lower than that of 9 wt.% for SEBS/EG composites. It was also observed that EMI SE value depends on its electrical conductivity. The EMI SE acceptable value for SEBS/CB composite with 15 wt.% of CB indicates that this materials are promising candidates for shielding applications.

Enhancement of static strength and long term durability of steel/epoxy joints through a fiber laser surface pre-treatment

The aim of this work is to investigate the effectiveness of laser irradiation on steel substrates for adhesive bonding. The evolution of surface topography and wettability for various pulse fluencies was investigated. The most suitable processing conditions were then selected and adhesive bonded steel/epoxy single-lap and T-peel joints were prepared for static testing. Moreover, in order to assess joint strength against environmental attack, an additional batch of samples was subjected to hydrothermal cycling before testing. The obtained results were compared with baseline samples fabricated using degreasing and sand blasting surface pre-treatments. Post-failure SEM analyses of fracture surfaces were undertaken to survey the locus of failure within the joint bond-line. Results indicated that laser irradiation effectively enhances the overall mechanical behavior of the joint under shear and peel loading. In addition, it allows to retain joint strength after exposure to aggressive environmental conditions.

Formation of indium tin oxide film by wet process using laser sintering

Indium tin oxide (ITO) films were prepared via a very simple and low-cost preparation technique based on a wet process using a continuous wave (CW) laser and an indium tin (In–Sn) alloy nanoparticle ink. The formation of continuous transparent conductive films using a laser sintering method and micropatterning of the ITO films using a laser direct writing method were investigated. This process is simpler than the conventional two-step heat treatment method and other wet processes that use ITO nanoparticles as starting materials. In addition, the optical and electrical properties of the ITO films were improved. Notably, the conductivity and transmittance were remarkably influenced by the processing parameters, including the laser power and scan speed. Suitable processing conditions were thus investigated and optimized, and ITO micropatterns with accurate linear and sharp edge profiles were obtained by controlling the laser power and focusing conditions in the laser direct writing process.

Computational Analysis of the Interaction between Impregnation, Forming and Curing in Pultrusion

Numerical and analytical models dealing with different physics involved in pultrusion are combined in the optic of an integrated analysis of the process. The impregnation stage is simulated by means of a CFD multiphase model, evaluating the pressure and velocity field in the liquid resin. Composite temperature and degree of cure are inferred using 3D thermo-chemical models. Finally, contact conditions, stresses and strains are derived applying computational simulation and analytical models, in order to predict the final pulling force. Different product sizes are considered, simulating suitable processing condition.

Static and dynamic percolation of phenoxy/carbon nanotube nanocomposites

The electrical conductivity of a carbon nanotube/phenoxy nanocomposite fabricated by melt-processing is presented. A low percolation threshold (pc∼0.20wt.%) for carbon nanotubes in phenoxy, a thermoplastic epoxy, is reported. The dispersion of the nanofillers within phenoxy matrix was examined by scanning electron microscopy, showing good levels of dispersion without aggregates. The temperature dependence of nanotube network formation is described and explained by a dynamic percolation process. Suitable processing and annealing conditions are provided to achieve low percolation thresholds based on observed electrical and rheological results. Since these phenoxy resins are dissolvable into epoxy, these findings open up possibilities to deliver carbon nanotubes into composites based on such epoxy resin, creating hierarchical nanoengineered composites.

Numerical and experimental investigations of hydro-mechanical deep drawing process of laminated aluminum/steel sheets

The application of hydro-mechanical deep drawing (HMDD) process on laminated sheets combines advantages of both process and material to improve the forming condition of poor formable light-weight metals such as aluminum alloys. In this research, the HMDD process of anisotropic laminated bimetallic sheets has been analyzed using a 3D finite element simulation with implementing Fortran based code for accurate modeling of non-uniform oil pressure distribution. To verify FE results, experimental works were conducted on the widely used laminated aluminum/steel sheets. Based on the developed FE model, parametric studies were performed to investigate the effect of material parameters such as layers thickness and lay-up arrangement on the forming condition, process window and formability of aluminum sheet as key process parameters. Results demonstrated that suitable process condition to attain a successful forming of bimetallic aluminum/steel sheets can be predicted by developed FE model reasonably. Also, It shown that wider working zone was achievable with decrease in drawing ratio, reduction in thickness of sheet with lower strength layer and also when aluminum sheet is in contact with punch (A/S lay-up). In addition, the higher limiting drawing ratio (LDR) and lower thinning in low formable aluminum sheet would be achievable in A/S lay-up than S/A lay-up.

Expanded Gluten-Free Extrudates Made from Rice Grits and Bandinha (Bean) Flour Mixes: Main Quality Properties

The effect of extrusion operating conditions on main quality properties of gluten-free expanded snack-type products, developed from rice grits and bandinha flour formulations, was studied. The protein content in the extrudate varied from 9.44 to 14.74 g/100 g for formulations containing 13 and 47% bandinha flour, respectively, processed at 85C and 15% feed moisture. Apparent density and the radial expansion index of the extrudate were significantly (P < 0.05) affected by bean flour content, moisture content, temperature and the interaction between moisture content × temperature. The most suitable extrusion conditions were 30 g/100 g bean flour content, 14 g/100 g moisture content and 80C die temperature, which resulted in a product with a high radial expansion index and crude protein of 9.5 and 13 g/100 g, respectively, and a low apparent density of 0.20 g/cm3. Practical Applications There is a dynamic growth trends taking place in the gluten-free market due to its relationship to celiac disease, wheat allergy, gluten intolerance and gluten sensitivity. To date, most gluten-free products in the market are in the form of pasta and bakery products. However, there is an open niche for gluten-free foods in the form of expanded snack-type products. The flours of underutilized broken rice and beans (“bandinha”), processed under the selected range of extrusion conditions in this study, have great potential for the development of value-added, protein-rich, gluten-free foods in the form of expanded, low-density, snack-type products. The factorial design used to determine the relationship between the independent and the response variables aided to determine the most suitable processing conditions to generate a quality end product.

Comparison of some morphological and absorption properties of the nanoparticles Au/TiO2 embedded films prepared by different technologies on the substrates for application in the plasmonic solar cell

The nanoparticle Au/TiO2 embedded system plays a very important role in the plasmonic solar cell. The features of the nanoparticle embedded system will determine light enhancement, light absorption, scattering and localized surface plasmon resonance (LSPR), aiming to enhance the efficiency of the plasmatic solar cell. The characterizations of nanoparticles Au/TiO2 embedded system consist of many parameters: the sizes of nanoparticles (Au, TiO2), the weight ratio of Au to TiO2, the thickness of the single layer or multilayer of Au/TiO2, the arrangements of Au and TiO2 nanoparticles in integrated-matrix system, the light absorption, scattering and LSPR capacities of the Au/TiO2 system. These parameters, however, depend on the technological conditions, the structure of plasmonic solar cell as well as the used substrate materials. This paper presents some technological developments for nanoparticles Au/TiO2 embedded systems by different methods, including the preparation of the mixer Au/TiO2 solutions and fabrication of the nanoparticle Au/TiO2 systems with different Au percentages on several substrates (glass/ITO and AAO(Al)/Si…), and measured results of the morphological, structural and optical properties using FESEM, EDX, UV–vis spectroscopy. The comparisons of experiment results between different technology conditions and substrates (glass/ITO, AAO(Al)/Si…) are also shown and discussed with the aim of choosing the suitable technological process and technological conditions for application in the plasmonic solar cell.

1004 The study of the ultra-precision finishing process by using a plane magnetic abrasive finishing

A lot of highly precise surfaces are needed at the semiconductor and the medical field. For removing the machining traces of plane surfaces, magnetic abrasive finishing (MAF) is an effective method in which magnetic brush that formed by magnetic particles and magnetic force. In this reseach, to achieve super-precise surface, the influence exerted on finishing characteristics was considered, and the most suitable processing conditions were considered to figure out the finishing properties of MAF, three elements are set as objects in this study, including the size of abrasive particle, the types of magnetic pole and the clearance between workpiece and pole. In this study, the three elements have been studied and their best conditions have been found. At the same time, the magnetic flux densities of magnetic poles are investigated by electromagnetic simulation. At last, a new multistep finishing has been proposed that can finish plane surface into nanometer-scale. The surface roughness has been improved from 381.32 nm Ra into 12.02 nm Ra.

Reasearch and Application of Basic Tundish Covering Flux in Continuous Casting Process in WISCO

Fundamental theory of functions of basic tundish coving flux is analyzed at the first step. Several types of the flux used in deferent steel grade include ultra-low carbon steel, low carbon steel and micro-alloyed steel are involved . The result shows that the basic flux with CaO/SiO2 to be 3~5 can help to control the SiO2 be reduced by Al in steel within ±2%, and whole cleaness keeps stable with suitable component and proper process condition, marked with the T[O] content change ranged within 3ppm. But the basicity should be variable considering the productivity for different steel grade.

Semen quality parameters, their inter-relationship and post-washing sperm attributes of Rhode Island Red roosters

Aim: The present experiments were conducted (a) to evaluate the semen attributes of older Rhode Island Red (RIR) roosters and the inter-trait relationships, (b) to test sperm washing and storage duration suitable for gene transfer experiments. Materials and Methods: The semen characteristics of older RIR roosters were studied, and Pearson correlation analysis was done to demonstrate the inter-trait relationships. Progressive motility and percent live sperms were tested at different post-washing intervals to identify suitable sperm processing conditions for gene transfer experiments. Results: The volume, appearance score, initial motility, sperm count and percent live and abnormal spermatozoa were 0.38 ml, 3.58, 80.34%, 4.03 × 109 sperms/ml, 83.18% and 4.52% respectively. Positive correlation was observed among appearance score, motility, live sperm and sperm count. Semen volume is negatively correlated with all the other characters except live sperms, whereas, percent abnormal sperms negatively associated with all the other traits. Significant (p<0.05) decrease in terms of motility and live sperm was recorded at 60 min post-washing. Conclusion: The semen attributes of RIR roosters compares well with the other breeds of chicken. The appearance score can be used to assess fertility where microscopic evaluation facilities are limited. The sperm washing protocol tested in the experiment is suitable for gene transfer experiments.

The effect of plasma nitriding temperature on the electrochemical and semiconducting properties of thin passive films formed on 316 L stainless steel implant material in SBF solution

In this study, 316L stainless steel samples were nitrided plasma at temperatures of 350, 400 and 450°C for 2h under a gas mixture of 50% N2–50% H2. The effect of plasma nitriding temperature on the corrosion performance and semiconductor properties of the passive film on the 316L stainless steel was evaluated in simulated body fluid (SBF) using electrochemical test and Mott–Schottky analysis. In literature study, the effect of plasma nitriding temperature on corrosion behavior of 316L stainless steel was evaluated in solutions of NaCl, H2SO4 and acidic for biomedical applications. However, corrosion studies are more suitable to test in simulated body solution. Also, there are no enough studies on the effects of plasma nitriding temperature on semiconductor properties of the passive film obtained on film 316L stainless steels in SBF solution. So, in this study the effects of plasma nitriding temperature on the electrochemical and semiconducting properties of thin passive films formed on 316L stainless steel implant material in SBF solution at 37°C were investigated. The effects of microstructure and phase structure on corrosion properties of samples were determined. The results showed that the phase composition and microstructure of the treated samples were affected from the nitriding temperatures. It was obtained that s-phase formed at the lower temperature than 400°C. According to electrochemical test results, the plasma nitriding process at 350°C was the most suitable process condition for improving the corrosion resistance in SBF. All oxide films showed p-type (acceptor) semiconductor behavior at low potentials and n-type (donor) behavior at high potentials.

Hot deformation characteristics and processing map of nickel-based C276 superalloy

The hot compression tests for the nickel-based C276 superalloy were carried out on a Gleeble-1500D simulator in the temperature range of 950–1250°C with the strain rate range of 0.01–10.0s−1. The high-temperature deformation behaviors of C276 superalloy were analyzed based on the true stress–true strain curves. The results show that during the hot deformation process of C276 superalloy, under the same temperature, the flow stress rises with the increasing of strain rate. At the same strain rate, the flow stress decreases with the increasing of the temperature. As the strain rate is less than 1.0s−1, there exist peak stress and steady flow stress, and only peak stress appears at 10.0s−1. The processing maps of C276 superalloy in different strains were constructed according to DMM model. A small area where the power dissipation efficiency is higher than that in others areas exists in the maps. In this area the deformation temperature and strain rate is 1050–1150°C, 0.01–0.1s−1, and the fully dynamic recrystallization has been completed. There exists a small area of rheological instability in the processing map where the temperature is low, while the strain rate is high, and the dynamic recrystallization grains are distributed along the adiabatic shearing zone. According to the microstructure evolution and the processing maps of the C276 superalloy, its suitable processing condition can be summed up as that the temperature range is between 1050°C and 1150°C, and the strain rate range is between 0.01s−1 and 0.1s−1.

The effect of laser irradiation on peel strength of temporary adhesives for wafer bonding

Thin silicon wafers are usually used for many devices and electronic fabrication development. But handling thin wafers are not easy since thin wafers may lose the supporting strength and crack. Using adhesives is the one of the possible solutions for thin wafer handling, and how to synthesize adhesives materials and investigate debonding behaviors for temporary bonding and debonding are an important research. In this work, laser irradiation is considered for debonding temporary adhesives in a 3D multi-chip package process because of its very fast debonding time about few seconds and irradiation stability than thermal or chemical debonding. The thermal curable adhesives were fast cured on high temperature by the laser irradiation. The emphasis is the choice of the specific laser process parameters such as the out-focusing length, the line spacing, and the scan speed. The surface morphology with various sets of these parameters is examined by optical microscopy. Also, peel strength before/after the laser irradiation is investigated. Based on this study, suitable process parameters and conditions are proposed for clean surface of silicon wafers and lower peel strength for easy debonding.