Thermal Manufacturing Processes Research Articles

Potentially toxic elements distribution, petrography, and synchrotron characterization in polluted soils around industrial complex, Central Jordan

Industry is the main source of soil pollution in Jordan, where higher concentrations of potentially toxic elements were found in the soil around industrial estates. This study is dealing with an industrial pollution hot spot that is a steel factory in central Jordan that emits various ashes and gases. This area is moderately inhibited, and its soil is increasingly utilized in agricultural activities. High Fe, Cr, Mn, Pb, and V contents were recorded in the soil adjacent to the factory mainly concentrated on the prevailing wind direction. The studied sites bear heavy metalloids concentrations exceeding the permissible limit of WHO/EPA. These concentrations were found in topsoils and they decreased downward because of low mobility due of high soil alkalinity and lower pedogenesis. Moreover, the synchrotron-based XAFS technique was used to understand changes in oxidation states of Fe atom as well as in its structural parameters with depth. EXAFS analysis reveals association of Fe atoms mainly with oxygen (O), which indicates the anthropogenic Fe source. XANES data shows that Fe occurs in divalent (Fe2+) and trivalent (Fe3+) forms, which indicates that magnetite is dominating the topsoil. This Fe-phase is usually formed during oxygenated high thermal manufacturing processes. The topsoils SEM-EDS investigations confirmed the dominance of magnetite spheres, which coincides with the positive correlation between Fe and other elements as indicated from the statistical interpretation of the data.

Evolution of as-solidified and heat-affected microstructures under different thermal manufacturing processes for 316 L stainless steel

In this study, laser-arc welding (LAW), laser welding (LW), and laser cutting (LC) of 316 L stainless steel plates were selected to comparatively study melting-solidifying and heat-affected zones (MSZ, HAZ). Variations of morphology, crystalline orientation, and phase interfaces were systematically investigated from LAW to LW and LC. In the MSZ, δ phase presented a dramatic decrease in fraction and size with degenerated dendritic and increasingly dispersed features while γ grains were gradually refined. Special orientation relationships Bain, K.-S., N.-W. and G.-T. were frequently observed in re-solidified zones and δ coarsening regions of HAZ. Depending on the solidification speed, temperature gradient, and solid/liquid interface instability caused by manufacturing processes, δ and γ refinements in MSZ and HAZ from LAW to LW and LC were attributed to the S/L instability, lowered high-temperature duration，and variable epitaxial growth on previously formed δ (LW) or γ (LC). • Evolution of microstructure and microtexture in as-solidified and heat affected zones were compared. • The fraction and arrangment of δ phase was primarily controlled by the solid precipitation duration. • Grain size and orientation of γ phase was both decided by previously formed δ phase at a low temperature gradient or γ phase at a high one.

Digital twin-driven multi-variable process control of thermal manufacturing processes

Thermal manufacturing processes are complicated to the extent that they require sophisticated performance optimization. However, their implemented form often lacks advanced control strategies. This research proposes digital twins (DTs) that generalize the concept of process control towards multivariable performance optimization. To achieve this, data-driven models are used to describe the mathematical link between the process parameters and the performance indicators (KPIs), while they are all defined based on the spatiotemporal profile of the temperature field. The control strategy is then designed based on time and quality criteria, while the control enforcement is regarded in real-time manner, so that the DT concept is validated. The performance of the process models is examined through aggregation of modelling details from physics-based models from an LPBF process, including delays and dynamics. The current proposed framework seems to close the gap between the theoretical and data driven models with respect to process modelling and control efficiency.

Influence of caramel and molasses addition on acrylamide and 5-hydroxylmethylfurfural formation and sensory characteristics of non-centrifugal cane sugar during manufacturing.

The aims of this study are to (i) evaluate the effects of color enhancers, caramel (C) and molasses (M), on acrylamide and 5-hydroxylmethylfurfural (HMF) formation in non-centrifugal cane sugar (NCS) and to (ii) perform nine-point hedonic scale and evaluation of sensory attributes, encompassing the appearance, flavor, texture and aftertaste, by 71 consumers on NCS, NCS_C, and NCS products made with a blend of molasses and sugar (NCS_MS) and steam processing (NCS_S). With the addition of molasses and caramel at the maximum allowable level of 5 g kg-1 in sugarcane juice, significantly greater acrylamide or HMF did not accumulate in NCS_C and NCS_M during the thermal manufacturing process, while color values of NCS_C significantly changed (P < 0.05). The increases in acrylamide and HMF contents were influenced by pH because they were produced by the Maillard reaction. Hedonic responses showed that NCS_MS was rated with the highest score for overall acceptance, whereas NCS_S, with the lowest content of acrylamide, exhibited the lowest score for every attribute. In addition, the appearance acceptance score of NCS_C was significantly higher than that of NCS (P < 0.05). Significant differences were also found between NCS and NCS_C in the frequency of 9 of 16 items with which consumers selected to characterize the appearance in a check-all-that-apply questionnaire (P < 0.05). The association between hedonic evaluations and sensory profiles in visual attributes of NCS_C indicated that caramel could be a promising addition in Maillard reaction-mitigated NCS products to improve consumer preferences through color strengthening without safety concerns. © 2020 Society of Chemical Industry.

Numerical Investigation on Residual Stresses of the Safe-End/Nozzle Dissimilar Metal Welded Joint in CAP1400 Nuclear Power Plants

The residual stress evolution in a safe-end/nozzle dissimilar metal welded joint of CAP1400 nuclear power plants was investigated in the manufacturing process by finite element simulation. A finite element model, including cladding, buttering, post-weld heat treatment (PWHT) and dissimilar metal multi-pass welding, is developed based on SYSWELD software to investigate the evolution of residual stress in the aforementioned manufacturing process. The results reveal a large tensile axial residual stress, which exists at the weld zone on the inner surface, leads to a high sensitivity to stress corrosion cracking (SCC). PWHT process before dissimilar metal multi-pass welding process has a great influence on the magnitude and distribution of final axial residual stress. The risk of SCC on the inner surface of the pipe will increase if PWHT process is not taken into account. Therefore, such crucial thermal manufacturing process such as cladding, buttering and post-weld heat treatment, besides the multi-pass welding process, should be considered in the numerical model in order to accurately predict the distribution and the magnitude of the residual stress.

Plasma Arc Cutting Dimensional Accuracy Optimization employing the Parameter Design approach

Plasma Arc Cutting (PAC) is a thermal manufacturing process used for metal plates cutting. This work experimentally investigates the influence of process parameters onto the dimensional accuracy performance of the plasma arc cutting process. The cutting parameters studied were cutting speed (mm/min), torch standoff distance (mm), and arc voltage (volts). Linear dimensions of a rectangular workpiece were measured after PAC cutting following the full factorial design experimental approach. For each one of the three process parameters, three parameter levels were used. Analysis of means (ANOM) and analysis of variances (ANOVA) were performed in order for the effect of each parameter on the leaner dimensional accuracy to be assessed.

Crush resistance and insufflation potential of poly(ethylene oxide)-based abuse deterrent formulations

ABSTRACTObjectives: This study was conducted to evaluate suitable methods of testing crush-resistant tablets composed largely of thermoplastic polymers. The objectives were, i) to evaluate the effect of thermal processes on crush resistance, ii) to develop test method(s) to indicate whether a crush-resistant tablet is susceptible to tampering by insufflation based on generated particle sizes, and iii) to find an appropriate analytical tool for discriminatory studies.Methods: We investigated the crush-resistance properties of poly(ethylene oxide) (PEO) tablets using three manual and four electrical devices. PEO tablets were directly compressed or further heat-treated to mimic thermal manufacturing processes (i.e. hot-melt extrusion, sintering). Differential scanning calorimetry was also utilized to evaluate effect of thermal processes on polymer properties.Results: Non-heat treated tablets were easily crushed by all methods. Heat-treated tablets were only susceptible to cryogenic grinding and high-powered domestic blender. Our results confirm that manual methods are not suitable for discriminatory study.Conclusions: Testing methods for crush resistance may not be applicable to all products nor allow control over all process factors. Notwithstanding, the use of high-powered electrical devices may be an effective discriminatory tool for testing heat treated PEO-based ADFs.

Suitability of Simplified (Ir,Ti)Ox Films for Characterization during Electrocatalytic Oxygen Evolution Reaction

Simplified IrOx electrodes lacking typical mud crack structure have been produced on polycrystalline Ti cylinders with spin-coating using an iridium acetate solution and are compared to thicker samples in terms of stability, composition, and suitability as a model system. The spin-coating process forms smooth, thin islands of IrOx with limited cracking and decreases the surface-to-bulk ratio to allow a more intimate study of the growth, composition, and stability of the layer without the complications of the mud crack morphology. XPS and XRD measurements show a resulting (Ir,Ti)Ox surface (x near 2) with OH − groups and H2O. Cyclic voltammetry measurements indicate the expected high catalytic activity for the oxygen evolution reaction as well as a dry IrOx phase resulting from the thermal manufacturing process, although evidence of hydrous phases are found in XPS. Both films required only small overpotentials for the oxygen evolution reaction, with the spin-coated sample showing a slightly lower activity. CO temperature desorption spectroscopy analysis showed CO → CO2 oxidation and, in combination with XPS, an unstable surface. The oxidation of CO was not due to the TiOx, and the absence of any evidence of an Ir-suboxide phase indicates the presence of near-surface active species present after synthesis or an active surface termination.

Enhanced Requirements for Surface Quality of Outer Car Body Shells According to Thermal Manufacturing Processes

Challenging automotive design in the interaction of modern lightweight strategies to reduce car body weight as well as legislative regulations, impose higher requirements for future car body development. This trend leads to thinner sheet metal blanks and indicates higher requirements for narrow process windows in the entire manufacturing process to ensure the surface quality of outer shell panels. Especially, thermal loads within the coating process might cause local shape deviation in the startup phase of a new product. Further developments in multi-material-design for car body components induce material configurations with a complex deformation behavior due to different thermal expansion characteristics of the materials involved. For these reasons, there is a need to improve the prediction of the surface quality in the early car development process using numerical simulation methods. The influence of process parameters affecting the surface quality is shown and integrated into the process simulation.

Applications of KinetiSol® Dispersing for the production of plasticizer free amorphous solid dispersions

Thermal manufacturing methods for the production of solid dispersions frequently require the addition of a plasticizer in order to achieve requisite molten material flow properties when processed by unit operations such as hot melt extrusion. KinetiSol Dispersing, a rapid high energy thermal manufacturing process, was investigated for the ability to produce amorphous solid dispersions without the aid of a plasticizer. For this study itraconazole was used as a model active ingredient, while Eudragit L100-55 and Carbomer 974P were used as model solid dispersion carriers. Triethyl citrate (TEC) was used as necessary as a model plasticizer. Compositions prepared by KinetiSol Dispersing and hot melt extrusion were evaluated for solid state properties, supersaturated in vitro dissolution behavior under pH change conditions and accelerated stability performance. Results showed that both manufacturing processes were capable of producing amorphous solid dispersions, however compositions produced by hot melt extrusion required the presence of TEC and yielded a glass transition temperature (T(g)) of approximately 54 degrees C. Plasticized and unplasticized compositions were successfully produced by KinetiSol Dispersing, with plasticizer free solid dispersions exhibiting a T(g) of approximately 101 degrees C. Supersaturated in vitro dissolution testing revealed a significantly higher dissolution rate of plasticized material which was attributed to the pore forming behavior of TEC during the acidic phase of testing. A further contribution to release may also have been provided by the greater diffusivity in the plasticized polymer. X-ray diffraction testing revealed that under accelerated stability conditions, plasticized compositions exhibited partial recrystallization, while plasticizer free materials remained amorphous throughout the 6-month testing period. These results demonstrated that KinetiSol Dispersing could be used for the production of amorphous solid dispersions without the aid of a plasticizer and illustrated the enhanced solid state stability that can be achieved by producing solid dispersions with higher glass transition temperatures.

Optimization of a thermal manufacturing process: Drawing of optical fibers

The optimization of thermal systems and processes has received much less attention than their simulation and often lags behind optimization in other engineering areas. This paper considers the optimization of the important thermal manufacturing process involved in the drawing of optical fibers. Despite the importance of optical fibers and the need to enhance product quality and reduce costs, very little work has been done on the optimization of the process. The main aspects that arise in the optimization of such thermal processes are considered in detail in order to formulate an appropriate objective function and to determine the existence of optimal conditions. Using validated numerical models to simulate the thermal transport processes that govern the characteristics of the fiber and the production rate, the study investigates the relevant parametric space and obtains the domain in which the process is physically feasible. This is followed by an attempt to narrow the feasible region and focus on the domain that could lead to optimization. Employing standard optimization techniques, optimal conditions are determined for typical operating parameters. The study thus provides a basis for choosing optimal design conditions and for more detailed investigations on the feasibility and optimization of this complicated and important process.

An experimental investigation of microresistor laser printing with gold nanoparticle-laden inks

This paper presents an experimental investigation of the novel thermal manufacturing process of printing and laser curing of nanoparticle-laden inks that can produce functional microstructures such as electronic microresistors and interconnections for semiconductors and other devices. Of specific interest are the complex and interweaved transport phenomena involved, focusing on the absorption and diffusion processes of irradiated laser energy influencing solvent vaporization, the nanoparticle curing process, the substrate, and the final quality of the produced resistor. Parametric studies of the thermal process together with extensive microscopy analysis of the topography and resistivity measurements piece together a better understanding of the underlying physics and aid the development of the technology.

Distributed parameter thermal controllability: a numerical method for solving the inverse heat conduction problem

AbstractThis paper addresses the inverse heat conduction problem encountered in thermal manufacturing processes. A numerical control algorithm is developed for distributed parameter conduction systems, based on Galerkin optimization of an energy index employing Green's functions. Various temperature profiles of variable complexity are studied, using the proposed technique, in order to determine the surface heat input distribution necessary to generate the desired temperature field inside a solid body. Furthermore, the effect of altering the iterative time step and duration of processing time, on the convergence of the solution generated by the aforementioned method is investigated. It is proved that despite the variations in numerical processing, the iterative technique is able to solve the problem of inverse heat conduction in the thermal processing of materials. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Robust Multivariable Control And Simulation Of Time-Varying Thermal Manufacturing Processes

In a variety of thermal manufacturing process, the need for si-multaneous regulation of multiple thermal quality features requirea distributed-parameter control of the temperature field in the product. However, aa such infinite-dimensio nal sensing, actuation, and control techniques are not yet perfected, in this article we propose an alternative multivariable formulation of the thermal distribution. An efficient quasilinear simulation model of the temperature field is developed by Green's function analysis, in which the process nonlinearities, disturbances, and alterations are reflected as time variation of its parameters. Thus, a design methodology for a robust stabilising controller is developed and validated by both computational simulation and experimental tests on a plasma processing setup with infrared thermometry feedback. Several applications of this MIMO thermal regulator and enhancements of its performance are also explored.

Distributed-Parameter Control of the Heat Source Trajectory in Thermal Materials Processing

In thermal manufacturing processes performed by a localized, sequentially moving heat source, simultaneous regulation of multiple thermal quality characteristics requires real-time control of the temperature field developed through the distributed heat input on the part surface. Such control of the thermal field to a desired distribution employs infrared sensing and feedback of the surface temperature hill, to modulate the torch power and motion in-process. The torch trajectory is guided in real time by an efficient optimization algorithm based on the concept of moving complexes. This distributed-parameter control strategy is developed using a numerical simulation model of thermal processing, and its performance is evaluated experimentally in heat treatment of thin stainless steel plates. The thermal controller is applied to the new scan welding process, in which it drives the torch in a reciprocating motion along the weld, yielding a uniform and smooth temperature field, and thus a favorable material structure and mechanical properties. Application of such thermal control to various other material processing methods is also investigated.

Thermal Manufacturing Process Control by Lumped Mimo and Distributed-Parameter Methods

A variety of geometric, material structure, and stress/distortion attributes are needed to characterize the quality of thermally manufactured products. Because of in-process sensing difficulties and transportation lags, these features must be regulated in real time through appropriate thermal outputs, measured by non-contact infrared pyrometry. In thermal processes with a localized, sequentially moving heat source, the necessary heat input distribution on the part surface is supplied by an innovative timeshared or scanned torch modulation, in a raster or vector pattern. A unified lumped multivariable and a distributed-parameter quasilinear modeling formulation provide a design methodology and real-time reference for the development of finite- or infinite-state adaptive thermal control systems. These controllers modulate the power and motion of a single torch, supplying distinct concentrated heat inputs or a continuous power distribution on the part surface, so as to obtain the specified thermal characteristics or the entire temperature field. These regulation strategies are computationally tested and implemented experimentally in arc welding, but their applicability can be extended to a variety of thermal manufacturing processes.

Knowledge-based system for the computer aided design of ingot casting processes

The complexity of the design in thermal manufacturing processes stems from the need to simulate complicated heat transfer, fluid flow and phase change phenomena and couple the results with the design rules and knowledge available of these processes to obtain satisfactory designs. In this regard, the ability of expert systems to use heuristic reasoning has proved to be a powerful tool in the computer-aided-design of thermal manufacturing systems.