Surface Roughness Characteristics Research Articles

Chromatic confocal precision measurement accuracy analysis with surface roughness based on a scalar diffraction and raytracing hybrid model

Chromatic confocal sensors are widely used in surface inspection steps in precision machining. However, it is still a challenge to achieve optimum accuracy when measuring rough surfaces. Rough surfaces can lead to a deviation of several hundred nanometers in the measurement results, which is approximately twice the nominal measurement accuracy of the sensor. The wave optical model is commonly used to analyze the impact of surface roughness characteristics on the accuracy of chromatic confocal sensors. The model is computationally complex and highly dependent on the surface profile. In this paper, an improved model is proposed by combining the scalar diffraction and raytracing. Based on the generalized Harvey-shack (GHS) scattering theory and the masking effect function, the model reveals the relationship between the statistical parameters of rough surface and the error of spectral confocal signal. Based on this model, we find that the rough surface with the root mean square (RMS) roughness 0.01–0.3 μm introduces about 0.05–1 μm deviation in profile measurement. We further experimentally verified the effect of surface roughness on the spectral signals and proved the reliability of the analytical model. The model can be used as a theoretical basis for analyzing scattering phenomena caused by surface roughness and as a reference for sensor selection, design and data compensation for measuring rough surfaces using chromatic confocal sensors.

Exploring the Potential Application of an Innovative Post-Weld Finishing Method in Butt-Welded Joints of Stainless Steels and Aluminum Alloys.

The prerequisite of the weld bead finishing is intricately linked to the quality of the welded joint. It constitutes the final, yet pivotal, stage in its formation, significantly influencing the reliability of structural components and machines. This article delineates an innovative post-weld surface finishing method, distinguished by the movement of a specialized cutting tool along a butt weld. This method stands out due to its singular approach to machining allowance, wherein the weld bead height is considered and eradicated in a single pass of the cutting tool. Test samples were made of AISI 304L, AISI 316L stainless steels and EN AW-5058 H321, EN AW-7075 T651 aluminum alloys butt-welded with TIG methods. Following the welding process, the weld bead was finished in accordance with the innovative method to flush the bead and the base metal's surface. For the quality control of welded joints before and after the weld finishing, two non-destructive testing methods were chosen: Penetrant Testing (PT) and Radiographic Testing (RT). This article provides results from the examination of 2D profile parameters and 3D stereometric characteristics of surface roughness using the optical method. Additionally, metallographic results are presented to assess changes in the microstructure, the microhardness, and the degree of hardening within the surface layer induced by the application of the innovative post-weld finishing method.

Tool wear and surface roughness characteristics in sustainable machining of additively manufactured titanium alloys

Titanium is widely acknowledged as a challenging metal due to its inherent characteristics. Manufacturers often encounter challenges such as tool wear, reduced tool lifecycle, and increased cutting heat when working with Ti64. This research investigates the cutting characteristics of additively manufactured (AMed) Ti64 under dry cutting, Minimum Quantity Lubrication (MQL), Cryogenic Carbon dioxide (CO2), and a hybrid approach combining MQL and CO2 conditions. Surface roughness, flank wear, temperature, chip morphology, and microhardness were analyzed to assess the impact of cooling strategies. Results indicate that the hybrid approach outperforms individual methods, showing superior surface finish and reduced tool wear. Machined Surface roughness (Ra) measurements reveal a substantial improvement in the hybrid condition, reducing Ra values by 62.44–67.02%, 35.65–41.38%, and 18.68–27.59% compared to dry, MQL, and CO2. Tool wear assessments exhibit significantly lower flank wear values in the hybrid condition, emphasizing the synergistic benefits of lubrication and cryogenic cooling. This research provides valuable insights into tailoring cooling strategies for optimal precision in machining AMed-Ti64 material, which is crucial for achieving high-quality manufacturing outcomes.

Investigation of the Influence of Machining Parameters and Surface Roughness on the Wettability of the Al6082 Surfaces Produced with WEDM.

Electrical Discharge Machining (EDM) is a non-conventional machining technique, capable of processing any kind of conductive material. Recently, it has been successfully utilized for producing hydrophobic characteristics in inherently hydrophilic metallic materials. In this work, Wire Electrical Discharge Machining (WEDM) was utilized for producing hydrophobic characteristics on the surface of the aluminum alloy 6082, and various parameters that can affect wettability were investigated. Adopting an orthogonal Taguchi approach, the effects of the process parameter values of peak current, pulse-on time, and gap voltage on the contact angles of the machined surfaces were investigated. After machining, all samples were observed to have obtained hydrophobic properties, reaching contact angles up to 132°. The peak current was identified as the most influential parameter regarding the contact angle, while the gap voltage was the less influential parameter. A contact angle variation of 30° was observed throughout different combinations of machining parameters. Each combination of the machining parameters resulted in a distinct surface morphology. The samples with moderate roughness values (3.4 μm > Sa > 5.7 μm) were found to be more hydrophobic than the samples with high or low values, where the contact angle was measured under 115°. In addition, the finite element modeling of the experimental setup, with parametric surfaces of uniform random and Perlin noise types of roughness, was implemented. Time dependent simulations coupling phase field and laminar flow for the modelingof the wetting of surfaces with different surface roughness characteristics showed that an increase in the Sa roughness and total wetted area can lead to an increase in the contact angle. The combination of experimental and computational results suggests that the complexity of the wettability outcomes of aluminum alloy surfaces processed with WEDM lies in the interplay between variations of the surface chemical composition, roughness, micro/nano morphology, and the surface capability of forming a composite air/water interface.

Extraction and characterization of a new natural cellulosic fiber from the Habara Plant Stem (HF) as potential reinforcement for polymer composites

In this present work, characterize the chemical, physical, thermal and Morphological behaviour of raw and alkali-treated (NaOH 5 %,10 % & 15 %) new natural cellulose Habara plant stem fiber (HF). From the chemical analysis, the 10 % alkali-treated HF obtained cellulose (67.9 %), hemicellulose (12.7 %), lignin (11.8 %) wax (0.18 %), moisture (2.44 %) and Ash (1.21 %). Fourier Transform Infrared Spectroscopy Analysis, alkali treatment effectively eliminates hemicellulose and lignin from the surfaces of natural fiber, as seen changes in the FTIR peaks at 1730, 1480, and 1140 cm−1.The X-ray analysis results indicate that, there is crystalline cellulose present, with a crystallinity level of 43.87 %, and that the other components are amorphous. In addition, the thermal stability of lignocellulosic fiber up to 230 °C was observed, and the degradation steps of each major component could be identified. The 10 % alkali-treated HF provides tensile strength of 790.9 MPa, with an elongation at break of about 3.41 %. The Scanning Electron Microscope analysis showcased the morphological changes on the fiber fractured surface, diameter variation, and impurities, etc. The Atomic Force Microscopy was used to determine the surface roughness characteristics of the HF, which confirmed the possible reinforcement in the structure of the polymer matrix composite structure.

Tailoring the structural, morphological, surface wettability and hardness features of Makrofol HS for surface applications: effect of DBD treatment

ABSTRACT In current research, Makrofol HS polymeric films have been utilized to evaluate the alterations in the surface properties under an atmospheric-pressure dielectric barrier discharge (DBD) plasma source. Upon DBD plasma exposure with various exposure durations ranging from 10 min to 120 min, the structural, surface wettability, surface free energy, surface roughness, and hardness features of Makrofol HS films have been studied and analyzed using different techniques. The FTIR spectra demonstrated that small changes in the band intensities correspond to the C-O-C as well as C=O bonds. Further, the changes in the absorption bands are correlated to the treatment time, leading to two critical processes, degradation, and crosslinking. The results of surface wettability displayed that the liquids' contact angle decreased from 84 ± 3o, 77 ± 3o and 62 ± 2o for water, glycerol, and dimethyl to 45 ± 1o, 42 ± 1o, and 36 ± 1o for untreated and treated samples at the highest treatment time, respectively. Also, the surface free energy significantly amended with increasing plasma exposure time. This modification in the treated surface indicates the increase in the polar groups on the treated surfaces, which then become hydrophilic surfaces. The samples' surface roughness parameters Ra, Rq, and Rz increased from 0.057 ± 0.003, 0.084 ± 0.004 and 0.366 ± 0.02 mm for untreated samples to 1.463 ± 0.073, 1.707 ± 0.085, and 6.839 ± 0.34 mm for treated samples at the highest treatment time, respectively. The Vickers hardness measurements showed an increase in the Vickers hardness from 12.31 ± 0.61 kgf/mm2 for the untreated sample to 44.89 ± 2.24 kgf/mm2 for the treated sample at the highest duration.

Mg incorporation induced microstructural evolution of reactively sputtered GaN epitaxial films to Mg-doped GaN nanorods

Mg-doped GaN films/nanorods were grown epitaxially on c-sapphire by reactive co-sputtering of GaAs and Mg at different N2 percentages in Ar–N2 sputtering atmosphere. Energy dispersive x-ray spectroscopy revealed that the Mg incorporation increases with increase of Mg area coverage of GaAs target, but does not depend on N2 percentage. In comparison to undoped GaN films, Mg-doped GaN displayed substantial decrease of lateral conductivity and electron concentration with the initial incorporation of Mg, indicating p-type doping, but revealed insulating behaviour at larger Mg content. Morphological investigations by scanning electron microscopy have shown that the films grown with 2%–4% Mg area coverages displayed substantially improved columnar structure, compared to undoped GaN films, along with rough and voided surface features at lower N2 percentages. With increase of Mg area coverage to 6%, the growth of vertically aligned and well-separated nanorods, terminating with smooth hexagonal faces was observed in the range of 50%–75% N2 in sputtering atmosphere. High-resolution x-ray diffraction studies confirmed the epitaxial character of Mg-doped GaN films and nanorods, which displayed complete c-axis orientation of crystallites and a mosaic structure, aligned laterally with the c-sapphire lattice. The catalyst-free growth of self-assembled Mg-doped GaN nanorods is attributed to increase of surface energy anisotropy due to the incorporation of Mg. However, with further increase of Mg area coverage to 8%, the nanorods revealed lateral merger, suggesting enhanced radial growth at larger Mg content.

Analysis of flux footprints in fragmented, heterogeneous croplands

An accurate quantification of fluxes from heterogeneous sites and further bifurcation into contributing homogeneous fluxes is an active field of research. Among such sites, fragmented croplands with varying surface roughness characteristics pose formidable challenges for footprint analysis. We conducted two flux monitoring experiments in fragmented croplands characterized by two dissimilar surfaces with objectives to: (i) evaluate the performance of two analytical footprint models in heterogeneous canopy considering aggregated roughness parameters and (ii) analyze the contribution of fluxes from individual surfaces under changing wind speed. A set of three eddy covariance (EC) towers (one each capturing the homogenous fluxes from individual surfaces and a third, high tower capturing the heterogeneous mixed fluxes) was used for method validation. High-quality EC fluxes that fulfill stationarity and internal turbulence tests were analyzed considering daytime, unstable conditions. In the first experiment, source area contribution from a surface is gradually reduced by progressive cut, and its effect on high-tower flux measurements is analyzed. Two footprint models (Kormann and Meixner ‘KM’; analytical solution to Lagrangian model ‘FFP’) with modified surface roughness parameters were applied under changing source area contributions. FFP model has consistently over predicted the footprints (RMSEFFP = 0.31 m−1, PBIASFFP = 19.00), whereas KM model prediction was gradually changed from over prediction to under prediction towards higher upwind distances (RMSEKM = 0.02 m−1, PBIASKM = 8.50). Sensitivity analysis revealed that the models are more sensitive to turbulent conditions than surface characteristics. This motivated to conduct the second experiment, where the fractional contribution of individual surfaces (α and β) to the heterogeneous fluxes measured by the high tower (T3) was estimated using the principle of superposition (FT3 = α FT1 + β FT2). Results showed that α and β are dynamic during daylight hours and strongly depend on mean wind speed (U) and friction velocity (u*). The contribution of fluxes from adjoining fields [1 − (α + β)] is significant beyond 80% isopleth. Our findings provide guidelines for future analysis of fluxes in heterogeneous, fragmented croplands.

Characterization of the micrometer scale surface roughness of meteoritic samples

This study investigates the key role of boulders, particularly their surface texture, which are primary surface features on small airless planetary bodies, that serve as indicators to better understand the geological history and evolutionary processes undergone by the small bodies and their respective parent bodies. In particular, this study focuses on characterizing the unpolished surface of meteorite samples, which can be likened to the surfaces of boulders on small bodies. We use surface roughness metrics such as the mean (bidirectional) slope and a Hapke mean slope angle in order to characterize the surface texture of the samples. Furthermore, considering a fractal roughness of the surface we estimate the Hurst exponent and the associated scaling factor at an arbitrary scale of ∼60 μm. We find that on the ∼4 μm scale, the mean bidirectional slope and the mean Hapke slope are in the range of 20–40° and 15–35° respectively, with carbonaceous chondrites collectively exhibiting the lowest average value for both. Furthermore, we provide surface roughness measurements for a subsample of the Ryugu sample A0008, which is broadly in agreement with the measurements derived from MASCam data. This study also investigated intra-sample heterogeneities, specifically surface roughness variations between matrix and non-matrix components such as impact melt, shock veins, and chondrules. The results suggest that surface roughness variations exist between these components and the matrix, however, the amplitude of the variation is strongly influenced by the petrological homogeneity of the chosen region of interest.

Impact of Pressure on Surface Roughness and Kerf Characteristics Using Low Pressure Abrasive Water Jet Cutting

Impact of Pressure on Surface Roughness and Kerf Characteristics Using Low Pressure Abrasive Water Jet Cutting

A Review of Emerging Technologies in Ultra-Smooth Surface Processing for Optical Components.

Advancements in astronomical telescopes and cutting-edge technologies, including deep ultraviolet (DUV) and extreme ultraviolet (EUV) lithography, have escalated demands and imposed stringent surface quality requirements on optical system components. Achieving near-ideal optical components requires ultra-smooth surfaces with sub-nanometer roughness, no sub-surface damage, minimal surface defects, low residual stresses, and intact lattice integrity. This necessity has driven the rapid development and diversification of ultra-smooth surface fabrication technologies. This paper summarizes recent advances in ultra-smooth surface processing technologies, categorized by their material removal mechanisms. A subsequent comparative analysis evaluates the roughness and polishing characteristics of ultra-smooth surfaces processed on various materials, including fused silica, monocrystalline silicon, silicon carbide, and sapphire. To maximize each process's advantages and achieve higher-quality surfaces, the paper discusses tailored processing methods and iterations for different materials. Finally, the paper anticipates future development trends in response to current challenges in ultra-smooth surface processing technology, providing a systematic reference for the study of the production of large-sized freeform surfaces.

A permeability model for the fractal tree-like fracture network with self-affine surface roughness in shale gas reservoirs

The complex natural fracture network with self-affine rough surface and branching characteristics significantly impacts the gas transport in shale gas reservoirs. However, its effects on the permeability have not been studied so far. This study proposes an analytical permeability model for the fractal tree-like fracture network with self-affine surface roughness and branching characteristics. Firstly, the self-affine rough profiles of fracture surface are generated at different fractal dimensions by the Weierstrass–Mandelbrot function and a rough fractal tree-like fracture network is constructed with these surface profiles and branching characteristics. Then, an analytical permeability model is proposed to consider the effects of fracture surface roughness and tree-like branching characteristics on gas flow. This analytical model is verified by numerical simulations. Finally, the velocity distribution of the fracture network and the sensitivity of its structure parameters are analyzed. It is found that eddy flow is more easily formed on rougher fracture surfaces with larger fractal dimension when their fracture aperture is at millimeter scale. The eddy flow disappears when the fracture aperture is at micron scale. Bigger gas flow resistance and more energy loss are observed for smaller fracture aperture and rougher fracture surface. The gas velocity in rough fractures decreases by 60% at micron scale, but decreases by 50% at millimeter scale. Gas flow resistance also increases with the increase of branch angle, branch level and length ratio, but decreases with aperture ratio. As a result, permeability decreases with fractal dimension, branch angle, branch level and length ratio, but increases with aperture ratio.

Tissue-mimicking composite barrier membranes to prevent abdominal adhesion formation after surgery

Postoperative abdominal adhesions often occur after abdominal surgery; barrier membranes which mimic peritoneal tissue can be constructed to prevent abdominal adhesions. To this end, silk fibroin (SF) sheets were coated with polyvinyl alcohol (PVA) and agarose (AGA) at PVA:AGA ratios of 100:0, 70:30, 50:50, 30:70, and 0:100 to create a composite anti-adhesive barrier and allow us to identify a suitable coating ratio. The membranes were characterized in terms of their molecular organization, structure, and morphology using Fourier transform Infrared spectrometer (FT-IR), differential scanning calorimeter (DSC), and scanning electron microscope (SEM), respectively. The physical and mechanical properties of the membranes and their biological performance (i.e., fibroblast proliferation and invasion) were tested in vitro. Each membrane showed both smooth and rough surface characteristics. Membranes coated with PVA:AGA at ratios of 100:0, 70:30, 50:50, and 30:70 exhibited more –OH and amide III moieties than those coated with 0:100 PVA:AGA, which consequently affected structural organization, degradation, and fibroblast viability. The 0:100 PVA:AGA-coated degraded the fastest. Barrier membranes coated with 100:0 and 70:30 PVA: AGA demonstrated reduced fibroblast proliferation and attachment. The membrane coated with 70:30 PVA:AGA exhibited a stable appearance, and did not curl under wet conditions. Therefore, SF sheets coated with 70:30 PVA:AGA show promise as anti-adhesive barrier membranes for further development.

Surface roughness characterization using representative elementary area (REA) analysis

We proposed the Representative Elementary Area (REA) analysis method and illustrated how it is needed to evaluate representative roughness parameters of surfaces. We used mean height (Sa) roughness to study how its variations converge to a steady state as we expanded the area of investigation (AOI) using combined scan tiles obtained through Confocal Laser Scanning Microscopy. We tested quartz and glass surfaces, subjecting them to various levels of polishing with grit sizes ranging between # 60 and #1200. The scan tiles revealed a multiscale roughness texture characterized by the dominance of valleys over peaks, lacking a fractal nature. REA analysis revealed Sa variations converged to a steady state as AOI increased, highlighting the necessity of the proposed method. The steady-state Sa, denoted as SaREA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Sa}}}_{{\ ext{REA}}}$$\\end{document}, followed an inverse power law with polishing grit size, with its exponent dependent on the material hardness. The REA length representing SaREA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Sa}}}_{{\ ext{REA}}}$$\\end{document} of glass surfaces, followed another inverse power law with polishing grit size and an indeterminate relationship for quartz surfaces. The multiscale characteristics and convergence to steady state were also evident in skewness, kurtosis, and autocorrelation length (Sal) parameters. Sal increased to a maximum value before decreasing linearly as AOI was linearly increased. The maximum Sal, termed as Salmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Sal}}}_{{\ ext{max}}}$$\\end{document}, exhibited a linear relationship with REA. In the absence of REA analysis, the magnitude of uncertainty depended on the polishing grit size. Finely polished surfaces exhibited a 10–20% variability, which increased to up to 70% relative to the steady-state Sa with coarser polishing.

Digital light processing technique aided 3D printing hierarchical super-wetting mesh coated with hydrophobic SiO2 for highly efficient oil-water separation

Gravity-driven filtration using super-wetting mesh surfaces holds significant promise in addressing oil pollution resulting from human activities. However, conventional techniques need help fabricating efficient separation mesh structures due to their limited stability in oily-water solutions. To overcome this, we employed a Digital Light Processing (DLP) 3D printing technique to fabricate a mesh with a micro-patterned surface using a UV light-curable polyurethane (PU). A post-UV curing step was implemented to transform the soft segments of PU into a solid state. To enhance the super-wetting properties, hydrophobic modified silica (m-SiO2)/UV curable polydimethylsiloxane (PDMS) solution was applied through dip coating, resulting in a hierarchical structure with high surface roughness and superhydrophobic characteristics. In oil–water separation tests, the hierarchical superhydrophobic mesh, featuring a pore size of 300 µm, demonstrated exceptional performance, achieving a remarkable flow flux of 37,410 L/m2 h with a separation efficiency of 97.46 %. Furthermore, the separation efficiency remained consistently above 97.0 % under varying pH conditions and oil mixtures, highlighting the excellent water-repellence capacity of the hierarchical mesh developed in this study.

Multifunctional aerogel with antibiofouling properties for efficient solar steam generation and seawater desalination

Water purification through solar steam generation is an emerging renewable technology with a massive capacity for freshwater generation. However, designing a multifunctional evaporating system with efficient solar-driven steam conversion along with seawater desalination is still a challenge for large scale freshwater generation. Herein, we propose a design for multifunctional photothermal aerogel containing Ag3VO4 nanoparticles incorporated in reduced graphene oxide with prominent characteristics of large surface area, higher porosity, and surface roughness. The proposed aerogel is fabricated via a facile method and can be used as an all-in-one system for water decontamination via solar steam generation, photocatalytic degradation/disinfection of organic pollutants and desalination of seawater simultaneously. The photothermal aerogel simply floats on air-water interface, with a higher flux of localized heat at the surface that efficiently promotes water evaporation at a rate of 2.1 kg/(m2 h). Moreover, the aerogel can denaturalize microorganism and desalinate seawater even under saline conditions. We anticipate that such an efficient and stable photothermal aerogel will offer a sustainable strategy for water purification via desalination, decomposition, and solar steam generation allowing us to address the current clean water crisis on a large scale.

Industrial application of diamond-electrochemical honing method

The method of diamond-electrochemical honing (DEH) is a finishing method that provides the required characteristics of surface roughness, the distribution of residual surface stress diagrams, which ultimately ensures the formation of a high-strength electroplated coating. This article presents studies of changes in surface roughness, residual stresses and other parameters depending on the selected DEH modes for parts made of steels 30KhGSA, 30KhN2MFA, 35KhN2MFASH, 50A. The article presents the design of the instrument-khon; with the solution of the issue of the geometric characteristics of the cathode part, the insulating coating and the material of the hone tool guides. The regime support of the DEH was formed on the basis of studies, the results of which are given in the article. The selected kinematic-geometric indicators of the hone-tool — workpiece system make it possible to form the drives of the DEH equipment. The optimal composition of the DEH electrolyte was chosen with the creation of an electrolyte storage and supply system. The article contains the results of studies demonstrating the effect of DEH on the reliability and durability of parts subject to the use of this method. Data on the technical and economic efficiency of the created industrial site of the DEH are presented.

An assessment of the impact of L.Salvadora persica and G.Tea on the surface roughness and hardness of heat-cured acrylic-based denture soft liners.

Background: Soft denture liners are a type of dental prosthesis that functions as a cushioning material, alleviating the stress induced by the act of chewing. They offer relief to persons who encounter discomfort when wearing complete or partial dentures, particularly when these dentures are situated on rigid surfaces that support the denture. The objective of this study: is to assess the effects of including L.Salvadora persica. and green tea (G.Tea) extract powders on the surface roughness and hardness characteristics of acrylic-based soft liners.  Materials & Procedures: 30 specimens were constructed using wax molds and acrylic-based heat-cured denture soft lining material. The standard curing procedure was used. The samples were separated into three equal groups: group A, the control group, with no additives in the soft-liner material; group B, with 5.12% weight percept L.salvadora persica extract powder; and group C, with 5.12% weight present green tea (G.Tea) extract powder. The samples were then prepared for surface hardness and roughness testing. Results: The results revealed that there was a non-significant rise in the mean values of surface roughness for both group B and group C, group B having the highest mean values followed by group C. When compared to the control group, the results showed a considerable rise in the mean values of surface hardness in group (B), which had the highest mean value for surface hardness, followed by group (C). Conclusion: The results of this study indicate that the incorporation of L.salvadora persica  at a concentration of 1.024g and green tea (G.Tea) extract powders at a concentration of 1.024g shown a positive impact on the surface hardness of denture soft lining materials

(Invited) In Situ Characterization during Electrode Processing: The Role of Hidden Parameters

Micron and nano-sized functional materials play a key role for future technologies that are currently developed in the field of energy conversion (electrolysers, fuel cells) and electrocatalysis (N2 fixation, CO2 reduction reaction). While new materials with outstanding properties are continuously developed, they rarely find their way into – urgently needed – large scale production and industrial applications.1 One reason for this are hidden parameters that occur during ink formulation, coating (and decal transfer), cell assembly, and operation. We propose the development of coherent workflows that help us to identify reliable correlations. These should be developed for each electrocatalyst, bridging synthesis, electrode and gas diffusion electrode (GDE) / membrane electrode assembly (MEA) fabrication, and testing. All information, including “negative” results like crack formation, delamination, structural ageing and dissolution, must be reported until the relevant hidden parameters are deciphered, and the design chain is understood. Then, materials and electrodes derived from complementary processes and exhibiting subtle variations in composition and structure, can be evaluated against each other.However, this implies to fill the “blackbox” between technical catalysts and electrochemical testing in flow cells, GDEs or MEAs, with quantitative data on powders, ink formulations and coating properties. In the past years, we developed a toolbox of methods that starts from key control characteristics for technical catalysts, i.e., Pt/C for polymer electrolyte membrane fuel cells, that thereon enable the in situ analysis of ink formulations and pastes during the dispersion process and at application concentration.2,3 This is followed by the assessment of the resulting coatings from large-area crack analysis down to the level of surface roughness and pore size characteristics.4 Finally, this input is connected with performance and stability testing results to enable the comparison of different materials, the assessment of structure property relations, and ultimately to establish inline process control during electrode manufacturing. In this contribution, the developed methods will be summarized and related to their current limitations and prospects, in particular for unraveling hidden parameters during electrode fabrication and MEA assembly as well as in line process control. Literature [1] Siegmund, Daniel; Metz, Sebastian; Peinecke, Volker; Warner, Terence E.; Cremers, Carsten; Grevé, Anna; Smolinka, Tom; Segets, Doris; Apfel, Ulf-Peter; Crossing the Valley of Death : From Fundamental to Applied Research in Electrolysis, JACS Au 1 (2021), 527 – 535.[2] Bapat, Shalmali; Segets, Doris; Sedimentation Dynamics of Colloidal Formulations through Direct Visualization : Implications for Fuel Cell Catalyst Inks, ACS Applied Nano Materials 3 (2020), 7384 – 739.[3] Bapat, Shalmali; Giehl, Christopher; Kohsakowski, Sebastian; Peinecke, Volker; Schäffler, Michael; Segets, Doris; On the state and stability of fuel cell catalyst inks, Advanced Powder Technology 32 (2021), 3845 – 3859.[4] Jaster, Theresa; Albers, Simon; Leonhard, Armin; Kräenbring, Mena-Alexander; Lohmann, Heiko; Zeidler-Fandrich, Barbara; Özcan, Fatih; Segets, Doris; Apfel, Ulf-Peter; Enhancement of CO₂RR product formation on Cu-ZnO-based electrodes by varying ink formulation and post-treatment methods, JPhys Energy 5 (2023), 024001.

Imaging systems and techniques for fusion-based metal additive manufacturing: a review

This study presents an overview and a few case studies to explicate the transformative power of diverse imaging techniques for smart manufacturing, focusing largely on various in-situ and ex-situ imaging methods for monitoring fusion-based metal additive manufacturing (AM) processes such as directed energy deposition (DED), selective laser melting (SLM), electron beam melting (EBM). In-situ imaging techniques, encompassing high-speed cameras, thermal cameras, and digital cameras, are becoming increasingly affordable, complementary, and are emerging as vital for real-time monitoring, enabling continuous assessment of build quality. For example, high-speed cameras capture dynamic laser-material interaction, swiftly detecting defects, while thermal cameras identify thermal distribution of the melt pool and potential anomalies. The data gathered from in-situ imaging are then utilized to extract pertinent features that facilitate effective control of process parameters, thereby optimizing the AM processes and minimizing defects. On the other hand, ex-situ imaging techniques play a critical role in comprehensive component analysis. Scanning electron microscopy (SEM), optical microscopy, and 3D-profilometry enable detailed characterization of microstructural features, surface roughness, porosity, and dimensional accuracy. Employing a battery of Artificial Intelligence (AI) algorithms, information from diverse imaging and other multi-modal data sources can be fused, and thereby achieve a more comprehensive understanding of a manufacturing process. This integration enables informed decision-making for process optimization and quality assurance, as AI algorithms analyze the combined data to extract relevant insights and patterns. Ultimately, the power of imaging in additive manufacturing lies in its ability to deliver real-time monitoring, precise control, and comprehensive analysis, empowering manufacturers to achieve supreme levels of precision, reliability, and productivity in the production of components.