Original Surface Research Articles

ACCURACY OF REPLICATION OF SURFACE TEXTURE WITH A CONTACT PROFILE METHOD

Surface texture is of great importance in specifying the function of a surface. The surface finish of products influences the friction performance, wear resistance, bearing, sliding, lubricating properties, functionality, etc. Replicas of surface textures are widely used in many industries for evaluating the condition of textures when no measurable surfaces are available for measurements or in the case of non-dismantled objects of immense dimensions. The replication’s reliability and accuracy are significant concerns in actual applications. Although there are several parameters, Ra and Rz are still most often defined in technical product documentation as the indicators of whether a surface texture is within certain tolerance limits. In real production conditions, tactile stylus profilometers are still the most common instruments for measuring surface texture. For all the reasons mentioned above, the accuracy of the Technovit® 3040 replica was analysed. The quality of the Technovit® 3040 replica was researched on 15 samples processed with six conventional machining methods. Average roughness parameters Ra and Rz were measured on original surfaces and then compared to replica surfaces. A qualitative comparison of the profile geometries of original surfaces and their replicas was discussed.

Experimental study on femtosecond laser ablation of 4H–SiC substrate

Silicon carbide (SiC) is an ideal substrate for manufacturing high-power electronic devices and microwave devices and has broad application prospects. The surface treatment of SiC wafers plays a critical role and faces challenges in the semiconductor industry. Among the multiple treatment methods, the laser-based method has gradually attracted the attention of scholars. Therefore, this research uses a femtosecond laser to ablate 4H–SiC sliced wafers and analyzes the influence of key parameters, such as laser pulse energy, defocus amount, repetition frequency, and scanning intervals, on the laser ablation depth, width, and surface morphology. Scanning electron microscopy and laser coherence-focused microscopy were used to characterize the laser ablation surface. When the defocus amount was 6 mm, the microgroove profile formed by the laser was U-shaped. The scanning interval parameters had to be optimized to obtain the optimized surface roughness. The results show that the optimized surface roughness (Sa ) was 0.267 μm, and brittle fracture areas such as microcracks and pits on the original surface were removed. Effective removal facilitates further material surface processing, which provides valuable insights for similar researchers and benefits for the semiconductor industry.

Phosphate and nitrogen‐rich polyelectrolyte complex flame retardant treatment for cotton fleece

AbstractThe soft nap and deep pile that impart comfort and warmth to cotton fleece also amplify its flammability. Using ambient aqueous processing, an environmentally benign polyelectrolyte complex (PEC), consisting of poly(allylamine hydrochloride) and sodium hexametaphosphate, was deposited on cotton fleece. This treatment adds only 12.5% weight, reduces peak heat release by 68% and total heat release by 74%, and protects from fire via intumescence. Without treatment, fleece burns aggressively with long afterburn and afterglow times, leaving no residue. With the applied PEC, the fabric self‐extinguishes within a few seconds and exhibits no afterglow. In addition, it withstands at least five simulated laundering cycles in alkaline detergent, maintaining a 57% reduction in fire growth capacity afterward. The original soft surface can be restored to the fleece by manual brushing. This simple and environmentally benign treatment provides an opportunity to effectively protect highly flammable textured cellulosic textiles in a safe way.

Investigation on triboelectrification behavior of surface nanocrystallization of medium carbon steel

The triboelectrification behavior of metal friction pairs is a crucial area of research for understanding the friction and wear. In this study, the triboelectrification behavior of surface nanocrystallization of medium carbon steel was investigated. Friction and wear tests were performed using a spherical-on-disc tribometer under oil-free lubrication while measuring triboelectric current signals. The results demonstrated that microstructural differences in chemically identical materials give rise to distinct charging behavior. In particular, nanocrystalline medium carbon steel surfaces exhibited significantly lower triboelectrification properties compared to their original surfaces. The main reason for the different triboelectrification behavior of the nanocrystalline medium carbon steel surfaces was attributed to the lattice distortion of nanospheres, which was explained using the theory of work function. And the underlying mechanism was experimentally verified using a D/max-Ultima+ X-ray diffractometer to measure the lattice distortion of nanospheres in medium carbon steel. Moreover, the study found a correlation between triboelectric current, friction coefficient, and loads. The findings of this study provide valuable insights into the role of surface microstructure in the friction and wear of materials.

X-ray computed microtomography: A non-invasive and time-efficient method for identifying and screening Roman copper-based coins

This study utilises X-ray Computed Micro-Tomography (μXCT) as a non-destructive and non-invasive method to recover the original surface features and reveal the characteristics of encrusted, illegible Roman copper-based coins before any physical cleaning process is performed. The coins were retrieved from the topsoil during an archaeological survey in the countryside of the ancient city of Aquileia, Italy, and were severely degraded, covered with accumulated matter and pronounced encrustations developed over centuries of aging buried in soil. Despite their condition, most of the coins were identified from a numismatic standpoint using tomographic data alone, with the aid of reference images. They were subsequently cleaned using traditional manual methods and the results compared with μXCT. X-ray Fluorescence (XRF) analysis of the coins after the physical cleaning confirmed their numismatic attribution and revealed information regarding the influence of different alloy compositions on the applicability of the μXCT method, as well as on the corrosion process of the coins.This study showcases how the application of μXCT on fragile corroded metal artifacts prior to any intrusive manual procedures can expedite the identification process, mitigating the risk of information loss caused by physical handling and cleaning. This approach proves particularly valuable when dealing with large numbers of coins that would typically require restoration for identification purposes. It also emphasises the numerous advantages of using μXCT for coin identification, provenance determination, dating, virtual restoration, digitisation, and long-term preservation.

The Implementation of Neural Networks for Polymer Mold Surface Evaluation.

This paper presents the measurement and evaluation of the surfaces of molds produced using additive technologies. This is an emerging trend in mold production. The surfaces of such molds must be treated, usually using laser-based alternative machining methods. Regular evaluation is necessary because of the gradually deteriorating quality of the mold surface. However, owing to the difficulty in scanning the original surface of the injection mold, it is necessary to perform surface replication. Therefore, this study aims to describe the production of surface replicas for in-house developed polymer molds together with the determination of suitable descriptive parameters, the method of comparing variances, and the mean values for the surface evaluation. Overall, this study presents a new summary of the evaluation process of replicas of the surfaces of polymer molds. The nonlinear regression methodology provides the corresponding functional dependencies between the relevant parameters. The statistical significance of a neural network with two hidden layers based on the principle of Rosenblatt's perceptron has been proposed and verified. Additionally, machine learning was utilized to better compare the original surface and its replica.

Variability and relationships between the size, composition and optical properties of suspended particulate matter in the coastal waters of western Spitsbergen, assessed through measurements of size-fractionated seawater samples

Measurements of inherent optical properties (IOPs) and characteristics of concentration and composition of suspended particles were made on original and size-fractionated surface water samples from Arctic fjords and coastal waters of western Spitsbergen in the Svalbard archipelago, in the summer months of 2021 and 2022. Optical measurements included the spectral scattering coefficient of particles, and spectral absorption coefficients of particles as well as depigmented (non-algal) particles and phytoplankton. Assemblages of suspended particles were characterised by measuring the mass concentrations of suspended particulate matter (SPM), particulate organic matter (POM), particulate inorganic matter (PIM), and phytoplankton pigments including chlorophyll a (Chla). All measurements were performed on original (unfiltered) seawater and on size-fractionated samples obtained by filtration using a combination of nylon meshes and membrane filters. This allowed us to determine the contribution of the fractions of very small (VS), small (S) and combined medium and large particles (ML) to the total SPM and Chla, as well as to the total scattering and absorption coefficients. The obtained results: (i) indirectly indicate a clear variability in particle size distributions occurring in the studied marine environment (e.g., the contribution of ML size fraction to SPM (the ratio SPMML/SPM) varied between 0.10 and 0.52); (ii) indicate noticeable differences in composition between size fractions (e.g., the POM/SPM ratio was on average 0.21 for the S fraction, and 0.34 and 0.32 for the VS and ML fractions, respectively); (iii) in most cases indicate that the fraction S had the largest contribution to all analysed spectral optical coefficients, followed by the VS and ML fractions (the average contributions of the S fraction to scattering coefficient of particles and absorption coefficient of particles or depigmented (non-algal) particles were above 0.6 in the entire analysed spectral ranges); (iv) allowed for the identification of statistical relationships between selected characteristics describing changes in particle size and variability of particle IOPs (e.g., we observed statistical relations between SPMML/SPM and the spectral slope of scattering coefficient by particles, as well as SPM-specific coefficients of scattering by particles).

КОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИЕ В ИЗУЧЕНИИ ГЕОМЕТРО-ГРАФИЧЕСКИХ ДИСЦИПЛИН

The training of engineering personnel includes mastering all the necessary competencies that allow solving modern engineering problems at a high professional level. Geometric and graphic disciplines are the basis of a welltrained specialist. Studying descriptive geometry, engineering and computer graphics is necessary in the modern world of digital technology. Therefore, to use classical tools (a ruler, a pencil, a compass) it is necessary to master and automate designing, which provides the ability to design, calculate and model objects of various complexity. The paper aims to develop a new methodology for performing computational and graphic work (CGW) in the training course “Engineering and Computer Graphics”, which allows you to move from a flat representation of the original and design surface to a visual form for the purpose of analyzing and determining optimization paths. The application of the resulting methodology will improve the efficiency of training engineering and construction personnel.

ViboPneumo: A Vibratory-Pneumatic Finger-Worn Haptic Device for Altering Perceived Texture Roughness in Mixed Reality.

Extensive research has been done in haptic feedback for texture simulation in virtual reality (VR). However, it is challenging to modify the perceived tactile texture of existing physical objects which usually serve as anchors for virtual objects in mixed reality (MR). In this paper, we present ViboPneumo, a finger-worn haptic device that uses vibratory-pneumatic feedback to modulate (i.e., increase and decrease) the perceived roughness of the material surface contacted by the user's fingerpad while supporting the perceived sensation of other haptic properties (e.g., temperature or stickiness) in MR. Our device includes a silicone-based pneumatic actuator that can lift the user's fingerpad on the physical surface to reduce the contact area for roughness decreasing, and an on-finger vibrator for roughness increasing. The results of our perceptual study showed that the participants could perceive changes in roughness, both increasing and decreasing, compared to the original material surface. We also observed the overlapping roughness ratings among certain haptic stimuli (i.e., vibrotactile and pneumatic) and the originally perceived roughness of some materials without any haptic feedback. This suggests the potential to alter the perceived texture of one type of material to another in terms of roughness (e.g., modifying the perceived texture of ceramics as glass). Lastly, a user study of MR experience showed that ViboPneumo could significantly improve the MR user experience, particularly for visual-haptic matching, compared to the condition of a bare finger. We also demonstrated a few application scenarios for ViboPneumo.

Analytical and numerical study of properties surfaces with high impedance

Original high-impedance surface (HIS) is studied in this paper. Analytical and numerical (using Ansoft HFSS package) research was done for this structure. It is demonstrated that this structure illuminated by plane wave operates as HIS with wide resonant band. Moreover effective magnetic permeability of the structure under study is calculated.

The Original Appearance of the Kazan Church in the City of Ustyuzhna

Comprehensive scientific research has been carried out, including laser scanning of the attic space of the Kazan Church in Ustyuzhna (Vologda region), which has much in common with the Smolensk Church in the village of Gordeevka in Nizhny Novgorod, where, among other things, traces of the original decoration of the facades of the church before the rebuilding of the XIX century were found. In the course of field studies in 2023, it was possible to confirm the presence of an internal brick staircase embedded in the ground floor level to an unfinished (but originally intended for construction) bell tower. Illustrations of decorative elements of the facades, now hidden from view and located in the attic space, are presented. Comparison with domestic and foreign trends of the late 17th century and particular features of the construction of the «Stroganov» churches makes it possible to attribute the architectural monument in question to the galaxy of churches built by Grigory Dmitrievich Stroganov in the context of the experience of using the order system in Russian church architecture. Based on the given set of features, a conclusion is made about the initial finishing of the facades. Similar to the Smolensk Church, the original surface of the walls of the Kazan Church was, in all likelihood, unplastered chain brickwork with lime-sand grouting.

Application of 3D printing for fabrication of superhydrophobic surfaces with reversible wettability.

Control of surface wettability is needed in many applications. The potential use of 3D printing technology to gain control over wettability remains largely unexplored. In this paper, Fused Deposition Molding (FDM) 3D printing technology was utilized to print polylactic acid (PLA) microplate array structures to generate superhydrophobic surfaces with reversable wetting properties. This was achieved by spraying polydimethylsiloxane (PDMS) and silica (SiO2) solutions, over microplate surfaces. Anisotropic wetting properties were also achieved based on the surface structure design. Due to the shape memory properties of PLA, the morphology of the microplate arrays could be switched between the original upright shape and deformed shape. Through alternating pressing and heating treatments, the microplate arrays showed anisotropic wettability switching. The difference between the contact angle (CA) and sliding angle (SA) of water droplets on the original surface parallel to and perpendicular to the microplate array direction were ΔCA = 7° and ΔSA = 3° respectively, and those on the surface of the deformed microplate array were ΔCA = 7° and ΔSA = 21°, respectively. This process enabled reversible alteration in the wetting behavior of water droplets on the original and deformed surfaces between sliding and sticking states. PLA-based shape memory anisotropic superhydrophobic surfaces with tunable adhesion were successfully applied to rewritable platforms, micro droplet reaction platforms, and gas sensing.

Improving the corrosion protection of plasma electrolysis-treated light metal by polymeric functionalization

Suppressing the rate of corrosive degradation has been the primary challenge in the widespread use of lightweight metals across a variety of potential applications because their native passive layer is still susceptible to chemical attacks in aqueous or humid environments. This work explores the roles of polyaniline in tandem with a TiO2 layer in improving the corrosion properties of pure Ti. The anodic TiO2 surface is a result of a plasma electrolysis treatment in a non-acidic, phosphate-based electrolyte. The emeraldine base form of the polymer is subsequently applied to modify the surface properties of the plasma-electrolyzed Ti samples to further protect the surface against polar species that might interact with TiO2. The deposition of the thin layer of polyaniline retains the original surface microstructure of the plasma electrolysis layer. Nevertheless, the presence of polyaniline successfully reduces the corrosion current density and passive current density of plasma-electrolyzed Ti by ~50%. The corrosion protection mechanism is explained in the context of equivalent circuit models based on impedance measurements.

THE INTERACTION BETWEEN A WHITE MATERIAL INSIDE AND OUTSIDE A POTTERY VESSEL FROM EASTERN EIN-SHAMS, EGYPT

This work aims to investigate a pottery vessel from eastern EIN-Shams, Egypt, lying in sandy soil from citizen lands, returning to the New Kingdom-Egypt. This pottery vessel was covered with white material from inside and outside. In terms of origin, this vessel is made of buff-colored clay; it has big pores, many cracks, and large missing areas filled with that material, with an uneven surface texture, that strongly bonds with the body pores, and shrinks away from the edges in some areas, in this way obscuring the original surface. In this respect, several physicochemical investigations in terms of chemical composition, physical properties, and nature of this white material were performed, to analyze the influence of it on the ancient pottery vessel. The analytical methods used in this research were USB digital microscopy, X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), and differential thermal analysis (DTA). The results of the USB digital microscopy showed the presence of gypsum crystals, large, flaked pottery surfaces, and quartz. SEM-EDX revealed the presence of organic fibers, chloride salts in a significant percentage, iron, and aluminum oxides. XRD investigation emphasizes the presence of gypsum and sodium chloride salts. DTA results revealed that the firing temperatures of the pottery vessel range between around 750-800°C.

Adsorption properties of the surface of Silochrome S-80 modified with aluminium alizarinate

Silica-based materials are widely used in the processes of concentration and separation of various organic substances. Successful use of SiO2 is due to its chemical resistance, thermal stability, the nature and distribution of functional groups on the surface, as well as the possibility of creating materials based on it with certain textural characteristics, which are regulated by synthesis conditions and surface modification. For the solution of specific problems of chromatography, it is necessary to obtain new adsorbents with fixed functional groups, layers or elements, by varying which the number and types of adsorption centres of the original surface change. Chelate complexes of transition metals, including those deposited in the form of adsorption layers, are used as promising modifying additives of particular interest. In this work, SiO2 based on Silochrome S-80, modified with aluminium alizarinate was studied by physicochemical method. Using thermogravimetry it was established that aluminium alizarinate is stable up to 270 °C. Using adsorption porosimetry, it was shown that modification of silica leads to a decrease in the average diameters and total volumes of pores, and specific surface areas from 84 to 79 m²/g. Using IR and Raman spectroscopy, the fixation of chelates on the surface of Silochrome was proven. The gas chromatographic method was used to study the adsorption processes of organic compounds (n-alkanes, nitromethane, heptene-1, aromatic hydrocarbons, ketones and alcohols) capable of various types of intermolecular interactions. The modification of silica with an alizarin-containing complex contributes to a change in the Henry adsorption constants and the contributions of specific interactions to the heat of adsorption. In this case, the highest values of ∆ q̅dif,1(special) are characteristic of organic compounds prone to donor-acceptor and π-complex formation. According to the analysis of compensation thermodynamic dependencies q̅dif,1 - ∆S̅S1,c it was shown that entropy is the determining thermodynamic parameter during the adsorption of test compounds on the surface of the studied chromatographic materials.

Study on subsurface damage behavior in ductile ultra-precision grinding of sapphire based on acoustic emission signal processing

Chemical corrosion, photothermal absorption and acoustic emission were used to multidimensionally evaluate and monitor subsurface damage behavior in ductile ultra-precision grinding of sapphire. The optimum ductile grinding surface can be obtained at different grinding depths when grinding with constant-depth. The density of corrosion dislocation craters and the value of photothermal absorption increased with grinding depth, and the subsurface damage scales under the ductile grinding surface were distinct. Subsurface damage was dominated by cracks and spalling. Severe brittle fractures occurred at greater grinding depths in varied-depth grinding. The corroded grinding surface consisted of the original polishing surface, the ductile grinding surface, and the brittle fracture characteristic. The amplitude and fluctuation of grinding force increased with grinding depth. The original signal and Fourier transform cannot monitor the damage behavior. A signal processing model based on wavelet transform, signal reconstruction and fast Fourier transform was developed. The processed signal characteristics can correspond to the damage behavior under the ductile grinding surface.

Retrieval of Desert Microwave Land Surface Emissivity Based on Machine Learning Algorithms

Based on the community radiative transfer model, ensemble tree-based random forest algorithm, and extreme gradient boosting tree algorithm, this study established a random forest retrieval model (RF) and an extreme gradient boosting tree retrieval model (XGBoost) for the microwave land surface emissivity by using ERA5 reanalysis data and the observed brightness temperature of 10.65 GHz vertical polarization from FY3C Microwave Radiation Imager-I. In addition, an optimized Bayesian regularized neural network retrieval model (M2_30NN) has also been established on the basis of the original neural network land surface emissivity retrieval model (M1_20NN). The results show that compared with the simulated brightness temperature of the original land surface emissivity, the simulated brightness temperature of the land surface emissivity from each retrieval model is not only significantly improved in the correlation coefficient with the observed brightness temperature (5.92% (M1_20NN), 4.23% (M2_30NN), 14.21% (RF), 13.07% (XGBoost)), but also in the evaluation indexes of root mean square error, mean absolute error and explained variance regression score in the training datasets. Furthermore, in terms of testing datasets and spatiotemporal independence test datasets, the retrieval results of RF and XGBoost models can capture the spatial distribution patterns that are consistent with observations well, and also show great numerical improvement compared with the original model. In general, the XGBoost retrieval model is the best, followed by the RF retrieval model.

Effect of laser shock peening on the dissolution of precipitates and pitting corrosion of AA6061-T6 with different original surface roughness

The effect of laser shock peening (LSP) on the electrochemical corrosion behavior of AA6061-T6 with different original surface roughness in the 3.5 wt% NaCl solution was investigated by surface morphology measurement, microstructural characterization, and electrochemical corrosion testing. The results show that LSP improves passivation current density by 76.6%− 78.2% and polarization resistance by 287.2%− 288.9%, but does not change the influence law of the surface roughness on the corrosion behavior of aluminum alloy. LSP promoted the complete dissolution of nano-sized Al8Fe2Si particles, generation of ultrafine grains, and local dissolution of micron-sized Al8Fe2Si particles, contributing to the improved corrosion resistance.

Ni-Rich Cathode Active Materials Surface Degradation in Ambient Air with Stabilisation Treatment Proposal

Ni-rich cathode active materials, such as NMC811 (Li[Ni0.8Mn0.1Co0.1]O2), are promising cathode materials due to their higher theoretical capacity of 200mAh/g, lower cobalt ratio, and overall decreased material expenses. However, the material undergoes a phase transition from layered ( ) through spinel ( ) to rock salt ( ) at high state of charge with oxygen release, and formation of rock salt structures on the surface with lithium carbonates and lithium hydroxides (Residual Lithium Compound (RLC)) while material is exposed to ambient air, all of which is followed by an increase in surface impedance and a decrease in final battery performance.Here, we explore the chemical and electrochemical evaluation of the Ni-rich cathode active material surfaces when exposed to ambient air for fourteen days (RH~40%). The combination of Fourier-transform infrared spectroscopy (FT-IR) and electrochemical impedance spectroscopy (EIS) will be investigated. These complementary non-destructive approaches will be utilised to characterise the decomposition of the original layered surface and formation of RLC. In addition, the research will be evaluated using STA, XRD, formation, diffusion coefficient, and cycle life in a half-cell using lithium-ion discs as counter electrodes. Furthermore, we show a technique for stabilising the material in air using Experimental ElectroRite®1 Additive provided by Lubrizol Ltd. which reduces the formation of the RLC and the corresponding surface phase changes, often attributed to the presence of Ni2+ ions. This work contributes to a greater understanding of the surface stabilisation through chemical treatment required and suggests routes to create stable water-based Ni-rich cathode inks.

Crocodile tail traces and dinosaur footprints. Bathonian?- Callovian. Imilchil. High Central Atlas. Morocco

Three types of ichnites from a new site discovered in Imilchil were studied and described. The structures of pes and manus prints and tail traces of tetrapods provide data to separate: real ichnites (theropod footprints and crocodile tail drag marks); and sauropod’ subtraces. Most of the theropod footprints are deformed by collapse of their walls, the sauropod subtraces show the strong deformation of about ten well-stratified sedimentary levels. The surface on which we can see theropod and crocodile ichnites is the tracking surface, i. e. the original surface on which they were printed.