Detailed Surface Research Articles

Metal-Free Biomass-Derived Environmentally Persistent Free Radicals (Bio-EPFRs) from Lignin Pyrolysis.

To assess contribution of the radicals formed from biomass burning, our recent findings toward the formation of resonantly stabilized persistent radicals from hydrolytic lignin pyrolysis in a metal-free environment are presented in detail. Such radicals have particularly been identified during fast pyrolysis of lignin dispersed into the gas phase in a flow reactor. The trapped radicals were analyzed by X-band electron paramagnetic resonance (EPR) and high-frequency (HF) EPR spectroscopy. To conceptualize available data, the metal-free biogenic bulky stable radicals with extended conjugated backbones are suggested to categorize as a new type of metal-free environmentally persistent free radicals (EPFRs) (bio-EPFRs). They can be originated not only from lignin/biomass pyrolysis but also during various thermal processes in combustion reactors and media, including tobacco smoke, anthropogenic sources and wildfires (forest/bushfires), and so on. The persistency of bio-EPFRs from lignin gas-phase pyrolysis was outlined with the evaluated lifetime of two groups of radicals being 33 and 143 h, respectively. The experimental results from pyrolysis of coniferyl alcohol as a model compound of lignin in the same fast flow reactor, along with our detailed potential energy surface analyses using high-level DFT and ab initio methods toward decomposition of a few other model compounds reported earlier, provide a mechanistic view on the formation of C- and O-centered radicals during lignin gas-phase pyrolysis. The preliminary measurements using HF-EPR spectroscopy also support the existence of O-centered radicals in the radical mixtures from pyrolysis of lignin possessing a high g value (2.0048).

A Predictive and Generative Design Approach for Three-Dimensional Mesh Shapes Using Target-Embedding Variational Autoencoder

Abstract In this paper, we present a predictive and generative design approach for supporting the conceptual design of product shapes in 3D meshes. We develop a target-embedding variational autoencoder (TEVAE) neural network architecture, which consists of two modules: (1) a training module with two encoders and one decoder (E2D network) and (2) an application module performing the generative design of new 3D shapes and the prediction of a 3D shape from its silhouette. We demonstrate the utility and effectiveness of the proposed approach in the design of 3D car body and mugs. The results show that our approach can generate a large number of novel 3D shapes and successfully predict a 3D shape based on a single silhouette sketch. The resulting 3D shapes are watertight polygon meshes with high-quality surface details, which have better visualization than voxels and point clouds, and are ready for downstream engineering evaluation (e.g., drag coefficient) and prototyping (e.g., 3D printing).

Advanced Imaging Techniques Provide New Near Surface Details in 3D Seismic Exploration Data and an Application to New Energy-Related Offshore Shallow Subsurface Investigations

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Phononic quadratic nodal lines of different types in Li2NaN

The search for new topological states has been shifted from electronic fermionic states to phononic bosonic ones, and topological elements with conventional linear band crossing have also been extended into the high order dispersion field. In this Letter, based on theoretical calculations and effective model analysis, we predicted the quadratic phonon states in the hexagonal compound Li2NaN. Particularly, two quadratic nodal lines are found, which are distributed along the same straight Γ–A path, protected by the C6v point group symmetry. The detailed band surface distribution and effective Hamiltonian construction are elucidated, demonstrating the quadratic order dispersion. These two quadratic nodal lines were further categorized into type-I and type-III, and their surface spectral properties were calculated, in which clear drumhead surface states are observed for both quadratic nodal lines, and they stretched throughout the entire Brillouin zone. Furthermore, the surface states were well separated from the bulk band projection, which is extremely beneficial for experimental detection. Notably, phononic quadratic nodal line states have been rarely studied and, more importantly, a type-III line has even not been reported thus far. Therefore, our work can pave the way for related studies for both quadratic nodal lines and type-III states, and the presented material can serve as an ideal candidate to promote further experimental investigation.

Targeting REE deposits associated with carbonatite and alkaline complexes in northeast India

Rare earth elements (REEs) are considered critical metals globally. About 62% of the global resources of REEs occur associated with carbonatites and alkaline complexes. However, the entire production of REEs in India currently comes from monazite-bearing beach sands, although a variety of REE enriched source rocks, particularly carbonatites and alkaline complexes occur in different parts of the country. There is, therefore, a significant potential in the county for new REE deposit discoveries associated with carbonatites and alkaline complexes. This paper describes a generalised carbonatite-alkaline complex related REE mineral systems model and applies a knowledge-driven model to demarcate REE exploration targets in the Karbi-Meghalaya plateau, NE India. The main components of the mineral systems are (1) pockets of metasomatised subcontinental lithospheric mantle (SCLM) which form fertile source regions for REE-bearing fluids; (2) extensional geodynamics; (3) permeable lithosphere architecture for tapping REE-enriched fluids from SCLM and focusing them to near-surface levels, and (4) a post-emplacement tectonic regime that preserves the deposits. Spatial proxies representing each of these components are mapped and integrated using fuzzy inference system (FIS) to identify prospective targets. Systemic and stochastic uncertainties associated with the model were quantified to aid target selection and further work.Main recommendations of this exercise are the following: (1) project-scale ground exploration for the Sung valley and Jasra complexes; (2) further regional-scale data collection for the Mikir Hills in the areas surrounding Samchampi and Barpung Complexes and around the swarms of dykes in the Garo Hills around Swangkre; (3) follow-up exploration in the areas north of Silchar and south of Nongstoin and (4) detailed geochemical sampling and surface or air-borne radiometric surveys for the Mawpyut Ultramafic Complex.The REE-mineral-systems model and the workflow demonstrated in this article could be used for targeting REE deposits in geologically similar terrains worldwide.

Interfacial slip verification and slip defect identification in shrink-fitted bimetallic sleeve roll used in hot rolling mill

Shrink-fitted sleeve rolls have several advantages including the ability to reuse shafts by replacing worn sleeves and the ability to apply to next-generation rolls. However, the authors’ previous simulation showed a “non-uniform slip” may appear between the shaft and the shrink-fitted sleeve even under free rolling and when no overall uniform slip condition is satisfied. In this paper, the rolling experiment is conducted by using a miniature rolling mill to verify the slip phenomenon realized by the numerical simulation. To understand the phenomenon, the slip defect formation and the slip growth are investigated by observing the slipped surfaces in detail. It is found that the slip defect starts from the contact of the surface roughness where the width of the defect coincides with the pitch of the machining feed. Eventually, the slip defect is developed by erosion wear and cohesive wear during the rolling and finally forming a large oval-shaped erosion groove at the end of the scratch. Finally, the fatigue strength of the sleeve roll is evaluated by considering the slip defect geometry observed from the experiment.

The influence of zinc ions concentration on β-lactoglobulin structure – physicochemical properties of Zn–β-lactoglobulin complexes

The study of metal-ions binding to whey proteins is the first step for their application in nutraceuticals. This study is focused on the investigation of the zinc ions concentration (6, 60 and 600 mg/L) effect on the metallocomplexes formation (ZnβLG3, ZnβLG30, ZnβLG300) with the β-lactoglobulin and their characterization by a series of instrumental and computational techniques. Detailed surface morphology of the metallocomplexes was investigated by transmission and scanning electron microscopy combined with energy dispersive X-ray analysis, and X-ray diffraction. Moreover, metallocomplex formation was monitored by attenuated total reflectance infrared spectroscopy and Raman spectroscopy. Experimental results were complemented by molecular dynamics (MD) studies indicating the precise binding sites of βLG to Zn2+(aq) ions and quantum mechanics (QM) simulation combined with density functional theory (DFT). Electron microscopy studies indicated that with increasing concentrations of Zn2+(aq) ions, the surface morphology of βLG changes, and the formed metallocomplexes exhibit higher porosity. Meanwhile, spectroscopic studies indicated the formation of metallocomplexes through the binding of Zn2+(aq) ions to amino acids (AAs) such as glutamic acid (Glu), aspartic acid (Asp), tryptophan (Trp), tyrosine (Tyr), and phenylalanine (Phe). Strong positive correlations between the increasing concentration of Zn2+(aq) ions and the number of binding sites were determined based on the MD results. DFT calculations confirm the strong binding affinity of Asp− and Glu− to Zn2+(aq) ions.

Core-level binding energy shifts between interior, terrace and edge atoms in MnO(001) thin films

Understanding the physical origin of core-level photoemission line shapes can offer valuable information about the chemical and physical properties of surfaces. For instance, in a large number of transition metals oxides, changes in the line shape allow the accurate determination of their oxidation states and cation site symmetry. Yet, despite this importance, experimental investigations on core-level shifts have been much neglected in recent years. In order to provide further evidence of the physical relevance, we have, in this contribution, introduced a new aspect of interior-, terrace- and edge- atom core-level binding energy shifts to describe monolayers of MnO(001) films grown on an Au(111) substrate. By this means we were able to distinguish the line shape contributions related to different types of atomic sites. We show that their relative intensities and energy shifts are able to provide information about the relative amount of under coordinated atoms on the surface and, thus give insights into their catalytic properties. Our findings reveal the importance of a detailed surface science characterization to provide the correct interpretation of distinct photoemission line shapes when considering thin film samples as well as nanostructures in general.

Fermi surface tomography

Fermi surfaces are essential for predicting, characterizing and controlling the properties of crystalline metals and semiconductors. Angle-resolved photoemission spectroscopy (ARPES) is the only technique directly probing the Fermi surface by measuring the Fermi momenta (kF) from energy- and angular distribution of photoelectrons dislodged by monochromatic light. Existing apparatus is able to determine a number of kF -vectors simultaneously, but direct high-resolution 3D Fermi surface mapping remains problematic. As a result, no such datasets exist, strongly limiting our knowledge about the Fermi surfaces. Here we show that using a simpler instrumentation it is possible to perform 3D-mapping within a very short time interval and with very high resolution. We present the first detailed experimental 3D Fermi surface as well as other experimental results featuring advantages of our technique. In combination with various light sources our methodology and instrumentation offer new opportunities for high-resolution ARPES in the physical and life sciences.

The Effects of Selected Measurement Errors on Surface Texture Parameters.

Surface texture measurement, characterized by areal parameters, is very susceptible to measurement errors. Various types of errors differently affect surface texture parameters. In this paper, two types of measurement errors were investigated. To analyze the impact of the presence of scratches, circular valleys of various diameters were added to surface textures measured by a white light interferometer. Measurement errors were larger for higher scratches. Skewness and kurtosis were mostly affected by the presence in valleys, and changes of spatial parameters were also comparatively high. The difference between the results of measurement of the same surface details two times after a break of three months was also studied. This difference was caused by errors of relocation, spikes and non-measured point presences, high-frequency noise, and surface ageing. Spatial parameters were found to be the most stable.

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) for Analysis of Surface and Interface Chemistry of Porous Transport Layers

As the United States energy infrastructure moves towards the integration of hydrogen energy, the reliable production of hydrogen through water electrolyzers is imperative. In proton exchange membrane water electrolyzes (PEMWE’s), the porous transport layer (PTL) plays an important role. When choosing PTL material, one should consider corrosion resistance, electrical conductivity, and ability to support the structure of the electrochemical cell. Due to these requirements, titanium is the current state-of-the-art anode PTL material. However, titanium quickly forms a layer of titanium oxide which significantly decreases conductivity of the PTL and respectively decreases the overall efficiency of the PEMWE system. Coatings are commonly applied to the PTL to combat this complication, but the use of noble metals leads to cost concerns. Additionally, the degradation of coated PTLs is not yet well known.Advanced physicochemical characterization of PTLs at various stages of fabrication and testing is vital to understand their properties and the impact on electrochemical performance in order to improve durability and meet cost targets. Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) is currently used to cross section areas of the PTL for subsequent analysis with Scanning Transmission Electron MicroscopyEnergy-dispersive X-ray Spectroscopy (STEM-EDS) analysis to visualize the elemental information of the PTL materials and PTL coatings, specifically looking at detrimental oxide layer formation. Unfortunately, this approach is time-consuming and difficult, motivating the development of alternative approaches that allow the characterization of wide sample sets more efficiently. Additionally, STEM-EDS analysis only provides elemental information, so if several oxide layers preside, it can be difficult to differentiate them. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) depth profiling is a very powerful technique that has been commonly used to characterize thin films and buried interfaces. Unlike the FIB-SEM and STEM-EDS combination, ToF-SIMS can be performed relatively quickly in several areas of the PTL, provides chemical information, and is sensitive to trace elements. An added advantage of ToF-SIMS is ability to do 2D and 3D chemical analysis on different scales. This enables visualization of elemental and chemical distribution on both larger scale (70x70 um) areas, and smaller areas (20x10 um) which provides more detailed surface and interface information. This allows for detailed tracking of all major constituents of the PTL and coating. It also allows to follow changes in oxide layers upon fabrication and after electrochemical testing, as well as track homogeneity of the surface and oxide layer interfaces throughout different parts of the PTL. This presentation will demonstrate capabilities of this technique for characterization of PTLs, along with progress and potential challenges. ToF-SIMs results will be compared to TEM analysis of cross-sections obtained with FIB-SEM. This study will highlight similarities and differences between the techniques, technique optimization for these morphologically challenging samples, and paths for future investigation moving forward.

Innovations in Post-Mortem Battery Material Characterization for Diagnosing Failure Mechanisms

An increasing demand for clean and renewable energy provides motivation for additional innovations to be sought in energy storage. Lithium-ion batteries (LIBs) have seen many advancements in terms of their cathode chemistries, including electrode coatings that are used to increase durability and capacity of cathode materials. These coatings are effective, but create additional interfaces in the battery system, that adds to complexity in characterization. To address many key issues of LIB failures, further insights are necessary that provide details on currently unknown and partially known intermediate states, side reactions, and/or mechanisms of degradation at electrode interfaces. In this work, a method is developed to enable a detailed surface analysis and additional characterization of coated cathode particles harvested from post-mortem LIBs. Procedures are outlined for the safe handling and preparation of post-mortem materials for high-quality single particle electron microscopy analyses, paired with ultramicrotome techniques for high-throughput cross-sectional imaging with elemental and structural analyses of the coatings themselves.Commonly seen in post-mortem results, the materials are kept intact as whole electrodes or large collections of particles while still held within binders and other cathode slurry components from cell fabrication. These samples are often briefly rinsed with electrolyte solvents [e.g., most commonly dimethyl carbonate (DMC)] to rinse away residual lithium salts.1 While important insights have been gained from such studies, details of surface defects are difficult to discern amidst the debris of additives and binders. To address this, we developed a non-destructive procedure for the separation of cathodes particles from their supports, followed by washing to remove binders, additives, and residual electrolyte with relatively safe and accessible solvents. This method enables high-quality single particle imaging by scanning and transmission electron microscopy (SEM and TEM) techniques. Nano-scale features on the particle surfaces can be observed with high-resolution on the post-mortem cathode particles. With this procedure, insights can be gained about the retention of coatings after battery cycling, in addition to observing visible surface defects that result from charge cycling.Typical cross-sectional analyses of interfacial systems involve expensive, time-consuming methods like focused ion beam (FIB) milling that require extensive training, and are low-throughput when FIB lift-out samples are prepared for TEM. An alternative high-throughput technique for the cross-sectional analysis of coated cathode particles by ultramicrotome was previously developed in our group.2 This technique involves embedding coated cathode particles in epoxy, from which ultra-thin slices (<100 nm) that can contain many [approx. 50-200] particles at a time are cut with a diamond knife. The resultant sheets of epoxy are deposited onto TEM grids so the cross-sections can be imaged by TEM. These sections also enable the particle coatings to be characterized separately from the bulk cathode by electron dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED). This technique was demonstrated on as-synthesized (pre-electrochemistry) samples but was adapted here for the prepared post-mortem samples to assess degradation of the particles and their coatings.Combining the newly developed techniques for obtaining high-quality images of single whole-particles and particle cross-sections this work provides a safe, relatively inexpensive, and high-throughput methodology for the post-mortem characterization of LIB materials. This data can be correlated to as-synthesized materials and electrochemical cycling data to create a detailed profile of cathode aging and degradation as it relates to LIB failures. We are expanding this method to a variety of standard and coated cathode systems to provide detailed information needed for the next steps towards developing new innovations in electrode designs aimed at achieving more durable LIBs.

Applicability of the landscape evolution model in the absence of rills

Despite numerous applications of physically-based models for incised landscapes, their applicability for overland flow on unchanneled surfaces is not known. This work challenges a widely used landscape evolution model for the case of non-uniform rainfall and absence of rills using laboratory flume experiment. Rainfall with an average intensity of 85 mm h−1 was applied for 16 h during which high resolution laser scans of the morphology were captured. The overland flow was modeled as a network that preserves the water flux for each cell in the discretized domain. This network represented the gravity-driven surface flow and determined the evolution direction. The model was calibrated using the first 8 h of the experiment and was then used to predict the second 8 h. The calibrated model predicted, as expected, a smoother surface morphology (and less detailed overland flow network) than that measured. This difference resulted from quenched randomness (e.g., small pebbles) within the experimental soil that emerged during erosion and that were captured by the laser scans. To investigate the quality of the prediction, a low-pass filter was applied to remove the small-scale variability of the surface morphology. This step confirmed that the model simulations captured the main characteristics of the measured morphology. The experimental results were found to satisfy a scaling relation for the exceedance probability of discharge even in absence of rills. However, the model did not reproduce the experimental scaling relation as the detailed surface micro-roughness was not accounted for by the model. A lower cutoff on the scale of applicability of the general landscape evolution equation is thus suggested, complementing other work on the upper cutoff underpinned by runoff-producing areas.

Insights into the substitutional chemistry of La1−xSrxCo1−yMyO3 (M = Pd, Ru, Rh, and Pt) probed by in situ DRIFTS and DFT analysis of CO oxidation

We report the detailed surface chemistry of platinum, palladium, rhodium, and ruthenium substituted into lanthanum strontium cobaltate perovskite catalysts toward CO oxidation. The catalysts were synthesized by the solution combustion method and characterized in detailed using a series of techniques. To explore the effect of noble metal ion substitution on CO oxidation, surface intermediates were probed by operando diffuse reflectance infrared Fourier transform spectroscopy. It was recognized that La1−xSrxCo1−yRhyO3 and La1−xSrxCo1−yPdyO3 show the best activities for the reaction. DFT calculations were set up to unravel the details of the surface phenomena responsible for altering the CO oxidation activity upon noble metal ion substitution. The computational analysis conclusively demonstrated the experimentally hypothesized role of surface carbonate formation and revealed the altered mechanism for CO oxidation over the synthesized perovskites upon noble metal ion substitution.

Novel nitrogen based heterocyclic compound as Q235 steel corrosion inhibitor in 15% HCl under dynamic condition: A detailed experimental and surface analysis

The present research explores the synthesis of three heterocyclic rings of pyrazol, pyran, and pyrimidine (Py-OH) in one single compound using a multicomponent synthesis approach and its application for the protection of tubular steel (Q235 steel) in acidizing solution (15% HCl) under the dynamic condition at 1500 rpm using weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP). Py-OH's maximum inhibition performance result is 94.46% (200 mg/L). The results of EIS and PDP reveal the corrosion process is charge transfer controlled, and Py-OH acts as a mixed type inhibitor. The maximum increase in Rct value is 393.7 Ω cm2, and the decrease in icorr value is 23 μA/cm2. The adsorption of Py-OH obeyed the Freundlich isotherm. The value of Ea is 80.17 kJ/mol. The protection ability of Py-OH falls as the temperature rises from 308 K to 338 K. The results of SEM, EDX and AFM confirmed the inhibitor layer formation that corresponds to the decrease in surface roughness of Q235 steel, supporting its corrosion protection excellency. Furthermore, the results of XPS further enriched the Py-OH adsorption using the lone pair electrons residing over the N and S.

A hybrid 3D object auto-completion approach with self-supervised data augmentation for fragments of archaeological objects

It is a common case that archaeological finds are frequently found in fragments and cannot always be reassembled in their entirety. Additionally, the completion of their shape and volume is sometimes costly and occasionally requires a lot of manual work, in particular for exhibition purposes. As a first step, improving the geometry of the fragments could potentially help the archaeological conservators in the assembling process. In this direction, in this paper we propose an end-to-end hybrid approach (i.e. point clouds to benefit from the limited complexity and creating results in mesh benefiting from their visualization capabilities) for the digital auto-completion of fragmented archaeological artifacts with missing parts in combination with a novel self-supervised data augmentation scheme in order to address a significant limitation in the archaeological domain (i.e. limited available observations and absence of the complete object). Our approach uses only 5 fragments of a partly preserved archaeological object for training. As a first step, an object (i.e artifact fragment) in mesh representation is converted to point cloud, from which more fragments of the incomplete original object are artificially generated, with the help of 3D surfaces, to augment the dataset. This dataset is then passed in a GAN-based Cascaded refinement network for generating a complete output, which is, finally, converted back to a mesh. Our experiments showed that the proposed hybrid approach, can be successfully used to complete and restore the geometry of a partly preserved archaeological object without having ever seen the complete form of it. However, due to the complexity of the fragments, such methods in most cases cannot generate their fine decorative and surface details.

A moving eulerian-lagrangian particle method for thin film and foam simulation

We present the Moving Eulerian-Lagrangian Particles (MELP), a novel mesh-free method for simulating incompressible fluid on thin films and foams. Employing a bi-layer particle structure, MELP jointly simulates detailed, vigorous flow and large surface deformation at high stability and efficiency. In addition, we design multi-MELP: a mechanism that facilitates the physically-based interaction between multiple MELP systems, to simulate bubble clusters and foams with non-manifold topological evolution. We showcase the efficacy of our method with a broad range of challenging thin film phenomena, including the Rayleigh-Taylor instability across double-bubbles, foam fragmentation with rim surface tension, recovery of the Plateau borders, Newton black films, as well as cyclones on bubble clusters.

Character articulation through profile curves

Computer animation relies heavily on rigging setups that articulate character surfaces through a broad range of poses. Although many deformation strategies have been proposed over the years, constructing character rigs is still a cumbersome process that involves repetitive authoring of point weights and corrective sculpts with limited and indirect shaping controls. This paper presents a new approach for character articulation that produces detail-preserving deformations fully controlled by 3D curves that profile the deforming surface. Our method starts with a spline-based rigging system in which artists can draw and articulate sparse curvenets that describe surface profiles. By analyzing the layout of the rigged curvenets, we quantify the deformation along each curve side independent of the mesh connectivity, thus separating the articulation controllers from the underlying surface representation. To propagate the curvenet articulation over the character surface, we formulate a deformation optimization that reconstructs surface details while conforming to the rigged curvenets. In this process, we introduce a cut-cell algorithm that binds the curvenet to the surface mesh by cutting mesh elements into smaller polygons possibly with cracks, and then derive a cut-aware numerical discretization that provides harmonic interpolations with curve discontinuities. We demonstrate the expressiveness and flexibility of our method using a series of animation clips.

Experimental study on failure mechanism of CFRP-to-aluminium single-lap adhesive joints under tension after out-of-plane pre-impact

ABSTRACT This paper presents the influence of impact energy and impact surface on the impact damage characteristics and residual tensile performances of carbon fibre reinforced plastics (CFRP)-to-aluminium single-lap adhesive joints. Experimentally, the internal damage morphologies of joints after pre-impact were inspected with X-ray micro-computed tomography (X-CT). The failure processes and detailed fracture surfaces were obtained by the digital image correlation (DIC) system and scanning electron microscopy (SEM). The results show that the joints impacted on aluminium surfaces exhibit superior impact resistance to the CFRP pre-impact surface under the out-of-plane impact load. The joints pre-impacted on different surfaces have similar failure processes during the tensile process. Firstly, the delamination damage propagates from the impact location to the edge of overlap region. Subsequently, the delamination damage reaches the CFRP end, where the local stiffness of CFRP adherend is significantly reduced, and cracks appear in the adhesive layer. Finally, the cracks propagate from the CFRP end to the overlap area centre with further increased tensile load, and the joint rapid fracture occurs after the tensile load reaching its peak. The delamination damage of CFRP adherends caused by out-of-plane impact load is the dominant factor to affect the bearing capacity of CFRP-to-aluminium single-lap adhesive joints.

Modeling a screw extruder for FFF 3D printing

The article presents the development and modeling of a screw extruder for 3D printers operating on the FFF technology, namely, the Fused Filament Fabrication (“production by fusing threads”). Extruders, usually installed on FFF 3D printers, use a thermoplastic polymer filament as a material. There are two filament standards: 1.75mm and 2.85mm. The minimum cost of such a filament starts from $ 11 per kilogram (ABS plastic 1.75 mm). The cost of more expensive filaments can reach several thousand or even tens of thousands per kilogram (depending on the material, filler, the presence of inhibitors, dyes, etc.). The cost of the material is much higher than granulated primary plastics and even more so recycled materials. In addition, the extruder nozzle diameter is typically limited to 1.2mm for 1.75mm filament. Thus, when printing large products, for which the detail and roughness of vertical surfaces are not so important, increase in the diameter of the extruder nozzle will increase significantly the printing speed due to the increase in the thickness of the print layer and the width of the print line.&#x0D; To produce filament, screw filament extruders are used, which work on the principle of injection molding machines. The authors propose a calculation of the parameters of a screw extruder for an FFF 3D printer, which will directly use granulated primary plastics or crushed plastic recyclables as a material. The use of a screw extruder will reduce the cost of the printed product and increase significantly the diameter of the extruder nozzle, which will significantly reduce the production time for large-sized products.&#x0D; When designing a screw extruder, it is necessary to adhere to two main strategies: minimizing the weight and size parameters of the extruder and ensuring the required linear productivity. On the one hand, the extruder must be as light as possible to be able to increase the printing speed, on the other hand, it must provide the necessary linear performance to be able to extrude plastic at printing speeds. Modeling is made for nozzles with a diameter of 1mm and 5mm. According to the calculation results, the screw extruder has a 3-fold and 37-fold margin of linear productivity, respectively.