Function Of Process Parameters Research Articles

Stable DC vacuum arc plasma generation from a 100 mm TiB2 cathode

Titanium diboride exhibits outstanding properties for hard and wear resistant coatings. However, efficient physical vapor deposition (PVD) processing through DC vacuum arc, with a deposition rate unreachable for any other PVD technique, is comparatively unexplored for TiB2 thin films due to challenges associated with the film synthesis process. In this work, we used an industrial scale arc plasma source having a plane cathode of 100 mm in diameter and a permanent magnet on its back side. We present analysis of the cathode surface, plasma generation/composition, as well as analysis of collected macroparticles. The cathode weight loss and the amount of generated macroparticles were measured as a function of process parameters (arc current and pressure, in both Ar and N2 gas). Plasma analysis shows average ion energies around 120 and 25 eV for Ti and B, respectively, and plasma ion composition of approximately 50 % Ti and 50 % B. The cathode weight loss was around 0.3–0.5 g/min, of which at least 25 % is estimated to be macroparticles. Notably, the intensity of the macroparticle generation was reduced with an increase in N2 pressure. Altogether, the results show a stable and reproducible plasma generation process and a high potential for the use of the cathodic arc as an efficient and useful method for deposition of metal borides.

Recycling of glass waste and spent alkaline batteries cathodes into insulation materials

Expanded glass with thermal and acoustic insulation properties are obtained from a foaming blend composed of 97% glass waste and 3% expanding agent. This latter is a blend of carbon and manganese oxides, recovered from exhausted alkaline batteries. The samples are produced after heating the mixture in a ventilated furnace at temperatures between 850 and 950 °C, for times between 15 and 60 min. Mechanical, thermal and acoustic properties are characterized as a function of process parameters. The glass foam samples have densities in the range of 290–350 kg/m3, porosity of 86–90%, thermal conductivity values of 107–120 mW m−1 K−1, noise reducing factors of 0.2–0.3 and compressive strengths up to 4.6 MPa. Although the resulting insulating performances are not as outstanding as those of polymer foams or mineral wool, these materials can emerge as competitive candidates for applications requiring low weight and moderate thermal and acoustic insulation properties, in combination with non-flammability and high temperature load bearing-capacity. Moreover, the use of 100% recycled raw materials limits the energy and the resource required for their production, if compared to those needed for the extraction, transportation, and processing of primary raw materials, making these foams attractive also in terms of environmental impact.

Evolution of microstructure and properties of CoCrFeMnNi high entropy alloy fabricated by selective laser melting

Abstract CoCrFeMnNi high entropy alloy was prepared by selective laser melting as a function of processing parameters by adopting the single factor variable method. The influence of process parameters on the microstructure and mechanical properties was investigated in detail. The results show that the alloy maintained a single-phase fcc structure, the microstructure is anisotropic and shows the presence of a high density of dislocations accumulated and entangled inside the grains. The ductility has a significant influence on the level of porosity, which in turn depends on the process parameters. Especially with the variation of hatch spacing, the elongation at break differs by at most 20.9 %.

Process-Structure-Property Relationships of Laser Powder Bed Fusion Lattice Structures

Abstract Lattice structure metamaterials offer a variety of unique and tailorable properties, yet industrial adoption is slowed by manufacturability and inspection-related difficulties. Despite recent advances in laser powder bed fusion additive manufacturing, the sub-millimeter features of lattices are at the edge of process capabilities and suffer from low geometric quality. To better understand their complex process-structure-property (PSP) relationships, octahedron structures were manufactured across a power spectrum, inspected, and mechanically tested. X-ray computed tomography was used to characterize lattice geometry, and demonstrated that lattice strut geometry measures, increased significantly as a function of laser power. Furthermore, lattices are shown to exhibit a direct correlation between laser power and mechanical performance metrics. Performance variations up to 60% are shown as a function of process parameters despite nominally identical geometry. Significant geometry variations are found to be the cause of performance variation, while material properties as measured by microindentation hardness are constant across the studied parameter range. PSP relationships are modeled, and the limitations of these models are explored. It was found that resulting models can predict mechanical performance based on geometric characteristics with R2 values of up to 0.86. Finally, mechanistic causes of observed performance changes are discussed.

A comprehensive study of A357 alloy printability via laser metal deposition

Laser metal deposition (LMD) is one of the most important techniques in additive manufacturing (AM) thanks to the high flexibility of the process, which makes the production of free-form shapes possible. However, working with some materials presents some challenges. This is the case with aluminum alloys due to their reflectivity and their very high thermal conductivity. On the other hand, aluminum and its alloys are quite important in several industrial fields, including aerospace, among others, due to their mechanical properties with low density. In this work, LMD is applied on an A357 aluminum alloy. The techniques are investigated moving from a single-track approach up to multi-pass and multi-layer strategies. Densities, microstructures and mechanical performance are investigated as a function of process parameters. Porosities are reduced, resulting in overall densities of over 97% and microhardness values are in the range of 80–100 HV. Differences in mechanical performance are analysed considering different building directions, showing a dependency on loading direction and the distance from the substrate. Tensile tests reveal a promising performance for further investigation with the LMD technique. The obtained evidence is interesting for future trends where large and light components are required while maintaining the mechanical performance of traditional manufacturing methods. Moreover, a comprehensive study is done for the first time on A357 alloy that is deeply used in the aerospace and automotive fields. The investigation and definition of the best process parameters open the possibility of exploiting LMD technology in the production of wide components or for adding features to already existing components overcoming some limits of other AM technologies.

Understanding Causalities in Organic Photovoltaics Device Degradation in a Machine-Learning-Driven High-Throughput Platform.

Organic solar cells (OSCs) now approach power conversion efficiencies of 20%. However, in order to enter mass markets, problems in upscaling and operational lifetime have to be solved, both concerning the connection between processing conditions and active layer morphology. Morphological studies supporting the development of structure-process-property relations are time-consuming, complex, and expensive to undergo and for which statistics, needed to assess significance, are difficult to be collected. This work demonstrates that causal relationships between processing conditions, morphology, and stability can be obtained in a high-throughput method by combining low-cost automated experiments with data-driven analysis methods. An automatic spectral modeling feeds parametrized absorption data into a feature selection technique that is combined with Gaussian process regression to quantify deterministic relationships linking morphological features and processing conditions with device functionality. The effect of the active layer thickness and the morphological order is further modeled by drift-diffusion simulations and returns valuable insight into the underlying mechanisms for improving device stability by tuning the microstructure morphology with versatile approaches. Predicting microstructural features as a function of processing parameters is decisive know-how for the large-scale production of OSCs.

A new control parameter to predict micro-warping-induced job failure in LPBF of TI6AL4V titanium alloy

Laser powder bed fusion (LPBF) includes a few printing techniques widely used, in recent years, concerning the additive manufacturing of Ti6Al4V alloys. These produced parts, typically utilized in sectors such as aerospace and biomedical, are characterized by very high added value. It is therefore fundamental to identify the influence of process parameters typical of LPBF technology on the occurrence of warping leading to process failure. This study deals with the characterization of single-track and “micro-scale” level warping phenomena which may lead to protrusion of material over the powder bed and process failure before normal termination. This phenomenon was investigated as a function of process parameters, referring also to the strength and ductility characteristics of the manufactured samples. With this purpose, several samples were printed using variable process parameters both in terms of line energy density (LED) values and in terms of laser power and speed combinations such as to guarantee constant LED values. For the samples that did not show significant micro-warping phenomena, in addition to the transversal and longitudinal geometric characterization of the single track, tensile tests were performed to determine both the resistance of the material and the ductility characteristics. The single tracks, for given process parameters, were printed on a homogeneous material substrate. For every single track, a microstructural and morphological transverse and longitudinal characterization has been carried out and the measured geometrical features were correlated to the process parameters. The obtained results allowed the identification of a new threshold parameter, indicating the limit operating conditions beyond which significant warping phenomena and process failure occur.

Correlation between Processing Parameters, Morphology, and Properties of Injection-Molded Polylactid Acid (PLA) Specimens at Different Length Scales.

Polylactic acid (PLA) is one of the most promising bioplastic representatives that finds application in many different areas, e.g., as single-use products in the packaging industry, in the form of mulch film for agriculture, or in medical devices. For the development of new areas, especially in terms of long-term applications and the production of recyclable products, the material properties controlled by processing must be known. The state of the art is investigations at the global scale (integral values) without consideration of local structure inhomogeneities and their influence on the material properties. In this work, morphological, thermal, and mechanical properties of injection-molded PLA tensile bars are investigated at different length scales (global and local) as a function of processing parameters. In addition to the processing parameters, such as melt temperature, mold temperature, and cooling time in the mold, the influence of the D-isomer content on the crystallization behavior and the resulting material properties are investigated. The material was found to form crystalline structures only when cooled in a mold tempered above Tg. In addition, PLA with a lower content of D-isomer was found to have a higher degree of crystallinity. Since the mechanical properties obtained by tensile tests could not be correlated with the degree of crystallinity, detailed analysis were performed showing a characteristic inhomogeneous morphology within the tensile bars. By means of micromechanical investigations on samples with different microstructure ranges, the relationship between local morphology and failure behavior could be explained.

Food aeration: Effect of the surface-active agent type on bubble deformation and break-up in a viscous Newtonian fluid: From single bubble to process-scale

Two continuous whipping devices, a rotor–stator (RS) and a narrow angular gap unit (NAGU), were used to produce aerated food with a 25% (v/v) gas fraction target. The liquid phase was a Newtonian model-solution containing 2% (w/w) of either whey proteins (WPC), sodium caseinate (SCN), or tween 20 (TW20). Strong differences emerged regarding gas incorporation and bubble size as a function of process parameters: namely, rotation speed and residence time. To improve understanding of the results obtained at pilot-scale, a second investigation consisting in the observation of the deformation and break-up of single gas bubbles has been undertaken using successively a Couette device and an impeller close to NAGU. For proteins, the observation of single bubble deformation and break-up showed that bubble break-up occurred by tip-streaming above a well-defined critical Capillary number Cac of 0.27 and 0.5 for SCN and WPC, respectively, whereas no break-up was observed with TW20 even though Ca reached 10. The poor foaming ability obtained with TW20 could be explained by a poor break-up mechanism, promoting coalescence and gas plugs at high shear instead of gas incorporation. Conversely, protein promote tip-streaming as the major break-up mechanism at low shear rate, explaining why rotation speed is not a key process parameter. Differences observed between SCN and WPC can be attributed to diffusion limitation for SCN when a much larger surface area is generated during aeration.

Thickness variation in contoured composite parts by vacuum infusion

Contoured laminates were produced by vacuum infusion (VI), and thickness variations were monitored dynamically as a function of process parameters. Process simulations were performed using finite element software (PAM-RTM), and predictions of thickness along the length of the laminate were compared with dynamic measurements. Initial simulations approximated the effects of corners on preform deformation and fabric draping behavior. Subsequent modifications to the simulation geometry and material properties were implemented to increase accuracy and more closely match experimental measurements. User-defined geometry (UDG) simulations were used to predict both the maximum corner deviation and the area of corner deviation with greater accuracy. The present study demonstrates a workflow for use of analytical tools to design and control vacuum infusion processes. The workflow leverages process monitoring and modified process simulation tools to provide insight into parametric effects and to guide process modifications to reduce product variability.

Effects of Processing Parameters on the Microstructure and Mechanical Properties of Intermetallic Matrix Composites

In the realm of advanced materials, Intermetallic Matrix Composites (IMCs) have garnered significant attention due to their potential for high-temperature applications. This study systematically investigates the influence of various processing parameters on the microstructure and mechanical properties of IMCs. Utilizing a combination of powder metallurgy and subsequent heat treatments, samples were prepared under varied conditions. The microstructural evolution was meticulously examined using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), revealing distinct morphological changes as a function of processing parameters. Quantitative analysis demonstrated a direct correlation between processing conditions and the distribution, size, and morphology of the reinforcing phases. Mechanical testing, including tensile, compression, and hardness tests, was conducted to evaluate the resultant properties. The findings indicate that specific processing conditions can be optimized to achieve a desirable balance between ductility and strength. Notably, a unique set of parameters was identified that yielded an unprecedented combination of high strength and ductility, challenging the conventional trade-off paradigm in composite materials. This research underscores the critical role of processing in tailoring the microstructure and, consequently, the mechanical performance of IMCs, paving the way for their application in demanding environments.

XANES Studies of Zinc Tin Oxide Films Deposited by Atomic Layer Deposition: Revealing Process-Structure Relationships for Amorphous Oxide Semiconductors

Amorphous oxide semiconductors have grown in technological relevance in displays, information technology, energy, and catalysis. Recent research efforts have converged on the need to develop design principles for the electronic structure of these materials. Here, we systematically vary the cation composition and annealing temperatures of zinc tin oxide films using atomic layer deposition (ALD) and study their process-structure relationships with synchrotron X-ray absorption near-edge spectroscopy (XANES). Measurements of the O K-edge, Sn M-edge, and Zn L-edge are analyzed with ab initio and nonlinear statistical modeling to understand the changes in geometric and electronic structure of the films. A key finding from this approach is the ability to measure the changes in the relative contribution of the Zn and Sn s orbitals to the density of states near the conduction band minimum. Furthermore, we identify and delineate critical process-structure design principles when working with amorphous oxide semiconductor (AOS) material systems: (1) use of complementary diffraction and absorption spectroscopy techniques to characterize the as-deposited coordination environment; (2) accounting for gradual and abrupt changes in coordination environment as a function of processing parameters (stoichiometry, annealing, etc.); (3) revealing and exploiting the relevant knowledge and interdependence of coordination environments, orbital hybridizations, the density of states, and band structures. In the future, this multimodal X-ray analysis and modeling framework can be applied to understand the process-structure relationships needed to optimize AOS performance in devices.

Microstructure and mechanical properties of laser metal deposited Ti6Al4V alloy with near equiaxed β grain structure

Ti6Al4V alloy produced by additive manufacturing are generally characterized by their columnar β grain structure and the resulting anisotropy in mechanical properties as a critical challenge in engineering applications. In the present work, a near equiaxed β grain structure is obtained in the Ti6Al4V alloy thin-wall specimens produced by laser metal deposition through tailoring laser power and interlayer dwell time. Microstructure, texture, and mechanical properties of the as-deposited alloys are investigated as functions of processing parameters. When the interlayer dwell time is fixed at 10 s, the columnar β grain structure changes to a near equiaxed morphology, and the grain width (size) decreases with increasing laser power from 1200 W to 1500 W. Recrystallization of the previously deposited layers during processing is suggested to be responsible for the formation of the near-equiaxed β grain structure. All the as-deposited alloys consist of a weakly textured α phase and the β phase at room temperature. The as-deposited alloys with the near-equiaxed β grains show superior mechanical properties, as evidenced by large elongation values up to 14%.

Heavy Oil Fly Ash as an Adsorbent for Methylene Blue Removal from Aqueous Solution

The industry produces a large amount of solid waste that has very bad effects on the environment. The application of waste material adsorbents for waste materials treatment has become of greater interest. Heavy oil fly ash (HOFA) is hazardous industrial solid waste which produces from the combustion of heavy fuel oil in power plants. The work aims to investigate using waste material heavy oil fly ash (HOFA) after modification to activated carbon (AC) as an adsorbent of methylene blue (MB) in an aqueous solution. Chemical and physical analyses were conducted to characterize the HOFA produced as a by-product of an electrical power station. BET analysis showed the surface area was 1.6 m2/g and the surface area was enhanced by the activation process to 63.7 m2/g and the pore width to 553.5A. SEM showed a change in the nature of the surface of the martial by increasing the porosity. Adsorption studies were performed by batch experiments as a function of process parameters. The removal percentage increased with the increase of the adsorbent to 1.5g, the amount was selected as the optimum dosage. The removal percentage decreased with an increase the entail dye concentration and limited difference in pH variables. The experimental adsorption data was represented with Langmuir, Freundlich, and Tempkin isotherms. The data fitted well to the Freundlich model as multilayer adsorption.

A physics-based modeling framework to assess the cost scaling of additive manufacturing, with application to laser powder bed fusion

Purpose This study presents a framework to estimate throughput and cost of additive manufacturing (AM) as related to process parameters, material thermodynamic properties and machine specifications. Taking a 3D model of the part design as input, the model uses a parametrization of the rate-limiting physics of the AM build process – herein focusing on laser powder bed fusion (LPBF) and scaling of LPBF melt pool geometry – to estimate part- and material-specific build time. From this estimate, per-part cost is calculated using a quantity-dependent activity-based production model. Design/methodology/approach Analysis tools that assess how design variables and process parameters influence production cost increase our understanding of the economics of AM, thereby supporting its practical adoption. To this aim, our framework produces a representative scaling among process parameters, build rate and production cost. Findings For exemplary alloys and LPBF system specifications, predictions reveal the underlying tradeoff between production cost and machine capability, and look beyond the capability of currently commercially available equipment. As a proxy for build quality, the number of times each point in the build is re-melted is derived analytically as a function of process parameters, showcasing the tradeoff between print quality due to increased melting cycles, and throughput. Originality/value Typical cost models for AM only assess single operating points and are not coupled to models of the representative rate-limiting process physics. The present analysis of LPBF elucidates this important coupling, revealing tradeoffs between equipment capability and production cost, and looking beyond the limits of current commercially available equipment.

Deformation based additive manufacturing of a metastable high entropy alloy via Additive friction stir deposition

Additive friction stir deposition (AFSD) is a novel solid-state additive manufacturing process which offers unique capability of producing 3-D parts with no solidification related defects and having homogeneous, equiaxed microstructure. However, to fulfill the full potential of the process for structural applications, AFSD needs intense process optimization for a wide range of alloys with excellent mechanical properties. The present study explored AFSD of a novel metastable high entropy alloy (HEA), CS-HEA (Fe 40 Mn 20 Co 20 Cr 15 Si 5 (at.%)), enabled with transformation and twinning induced plasticity during deformation. Intense shear deformation at elevated temperature and strain rate during AFSD led to the operation of restoration mechanisms such as recovery, recrystallization, and grain growth which resulted in refined grains with excellent strength and work hardenability. The average grain size for as-deposited CS-HEA is 3.0 ± 0.5 µm, and the average tensile yield strength of as-deposited CS-HEA is 450 ± 20 MPa. The microstructural variation and mechanical response of the alloy as a function of process parameters were correlated to the AFSD process variables, phase transformation, and recrystallization kinetics. Further, the interaction between recrystallization kinetics and transformation kinetics on microstructural evolution of the material was explored. Additionally, the microstructure and stacking fault energy of the alloy were used to predict the mechanical response of the deposited material using a five parameter work hardening model. • A Metastable high entropy alloy, CS-HEA is additively manufactured using a deformation based additive manufacturing process – additive friction stir deposition. • Operation of discontinuous dynamic recrystallization during AFSD deposition of CS-HEA led to formation of refined equiaxed grain structure in as deposited state. • Variation in AFSD processing parameters affected the microstructure of the alloy, higher heat input resulted in larger grain size with higher fraction of high temperature γ phase. • γ→ε transformation and twinning in ε phase provided excellent strength-ductility combination in as deposited state.

Predicting particle orientation: Is an accurate flow field more important than the actual orientation model?

Analytical orientation prediction models (OPMs) are widely applied to efficiently predict the orientation of particles in suspensions or pastes. One application of these prediction models are extrusion processes where the model is used to identify combination of process and paste parameters that yield anisotropic orientation within the extruded filament. The accuracy of these predictions mainly depends on two elements that are the correct choice of the orientation model itself and the rheology model. The rheology of a paste is commonly modeled with the help of the Herschel Bulkley (HB) rheology model. The optimal OPM is still topic of today’s research. Which of the two elements, however, has a stronger influence on the orientation has not been addressed, yet. We make use of a wide range of HB parameters reported in literature with a particular focus on data that is reported for varying paste compositions. Based on this data, we use the HB model to predict the velocity and shear rate profile within a pipe and perform orientation predictions with the help of the models by Jeffery and Folgar and Tucker (FT). These predictions are used to estimate the sensitivity of the final orientation on the HB parameters and on the OPM. For our study, we assume that the paste can be described by the standard Herschel Bulkley rheology model. We assume no-slip boundary conditions and no influence of the particle orientation on the rheology. Second, we assume that the initial particle orientation before entering the pipe is random. Our results suggest that capturing the rheology model correctly is generally more important than capturing the OPM correctly. This applies in particular when densely filled states are approached. We also provide universal relations for predicting the degree of particle alignment and the mean flow velocity as functions of process parameters and material properties. • A suitable rheology model is found to be more important than the actual orientation prediction model in terms of particle orientation. • Normalized diagrams enable quick estimations of the evolution of particle orientation based on process parameters and paste properties. • The derived methodology is applied to a large set of published rheology data.

Electrical Discharge Coating a Potential Surface Engineering Technique: A State of the Art

Electrical discharge coating (EDC) process is used to deposit material on workpiece surface from sacrificial or green compact tool electrode in an electrical discharge machine. The paper presents the mechanism of EDC using green compact electrode and powder mixed dielectric methods. The tool electrode material, electrode size, process parameters, and type of dielectrics can directly affect the surface integrity of workpiece. Here, a process map of EDC as a function of process parameters, its classification, advantages, and applications for a wide range of engineering materials offers a proper template for the evaluation of coating phenomena. This study shows that EDC is an economic process as compared to other costlier techniques. Additionally, the effect of various EDM and EDC parameters on surface integrity and tribological behavior of deposited coatings is studied with their pros and cons. Finally, the current research trends of EDC and its challenges are elaborated.

An experimental investigation and neuro-fuzzy modeling to ascertain metal deposition parameters for the wire arc additive manufacturing of Incoloy 825

Additive manufacturing is critical to repair, rebuild, and rapidly manufacture major components in today's manufacturing environment. Wire arc additive manufacturing technique using metal inert gas welding, which is a better way to produce large-scale parts at a subsidized cost was experimented on Incoloy 825 due to its many industrial applications in the construction of large structures. As bead deposition is vital for wire arc additive manufacturing, single bead depositions were performed. Metrological features of all deposited beads are evaluated using the CNC Video Measuring System by capturing the macrostructures. The effects of input parameters on bead geometry are statistically analyzed, and regression models are derived to forecast bead geometry. An adaptive Neural Fuzzy Inference System was implemented to predict geometrical characteristics, and the results were compared with experimental results. Subtractive clustering fuzzy inference model obtained the lowest percentage error difference in predicting deposited bead geometry as a function of process parameters. Further, the multi-objective optimization technique determined optimal input parameters for the best bead geometry. Finally, using identified optimum parameters, wire arc additive manufacturing of a single-pass multi-layer wall of Incoloy 825 was successfully constructed for validation, which revealed that the microstructure of the built structure was of appreciable quality without cracks and porosity.

Effects of processing conditions on the solidification and heat-affected zone of 309L stainless steel claddings on carbon steel using wire-directed energy deposition

Directed energy deposition and laser cladding technologies are suitable advanced manufacturing techniques for applying corrosion-resistant claddings to large carbon steel components. In this work, we clad 309L stainless steel wire onto carbon steel substrates and examine the effects of processing parameters (laser power and travel speed) on metallurgical bonding and microstructures. Wire dripping defects correlate to excessive heat input, while cracking, stubbing and delamination defects are linked with insufficient heat input. Spectroscopic scans of the weld microstructure show the amount of base metal mixing in the weld is a function of processing parameters and the number of cladding layers. In the first cladding layer, the weld metal is diluted with base metal ranging from 1.7 to 45.6 %; this amount dramatically decreases in the second layer (0–8.6 %), promoting primary ferrite solidification, which decreases solidification cracking susceptibility. Martensite forms in the heat-affected zone from the high cooling rates associated with laser processing. Subsequent laser passes temper the martensite and carbon diffuses from the substrate into the first cladding layer. Cladding two or more layers is beneficial for mitigating defects, lowering dilution, and producing a highly alloyed surface suitable for corrosion protection.