Surface Layer Research Articles

Irradiation origin and stability of CO on trans-Neptunian objects. Laboratory constraints and observational evidence from JWST/DiSCo-TNOs

The James Webb Space Telescope large program DiSCo-TNOs has recently shown that CO_2 ice is ubiquitous on 54 medium-size trans-Neptunian objects (TNOs). TNO surfaces are found to define three main spectral and thus compositional groups that are likely linked to their position before planetary migration. CO ice is observed on the spectral type that is richest in CO_2 and on the type that is richer in CH_3OH and organics. Considerations on the thermal evolution of TNOs predicted the depletion of hypervolatiles such as CO from their surface layers, however. We investigate a potential irradiation origin of CO as well as its stability by studying the distribution of CO in two TNO compositional types and compared it with irradiation experiments. We studied the 4.68 μm band of CO and the 2.70 μm band of CO_2 to probe the relation between the two molecules in 33 TNOs. We performed ion irradiation experiments on CO_2 and CH_3OH ices at 45 and 60 K with 30 keV H^+. We compared the laboratory spectra to TNO observations by focusing on the band areas and positions. We find that the two types of surfaces in which CO is detected are very distinct in terms of their relative abundances and chemical environment. CO that is observed on surfaces that are rich in CO_2 are consistent with being produced by CO_2 irradiation, specifically, at 45 K. On objects that are rich in CH_3OH and complex organics, CO is more likely formed by irradiation of CH_3OH. As the CO band areas are only partly related with temperature, the chemical environment plays a major role in the CO retention. We find that the CO that is observed on TNO surfaces is compatible with being a secondary molecule that is entirely formed by late irradiation processes. Its abundance and stability is mostly controlled by the matrix from which it formed.

The Role of Internal Phosphorus Loading in the Archipelago Sea Ecological Status

In eutrophic aquatic ecosystems like the Archipelago Sea in the northern Baltic, the role of the sediment as a sink and source of nutrients is especially important. Based on previous research on the Archipelago Sea, it can be concluded that the amount of stored phosphorus that can be released with time from sediments is large, and internal phosphorus recycling processes may thus play a key role in phosphorus fluxes in the coastal zone. The release of nutrients from the sediment has been suggested as an explanation for the fact that a substantial reduction in the external nutrient load does not always result in a corresponding reduction in nutrient concentrations and phytoplankton biomass in recipient waters. However, the magnitude of the actual internal phosphorus load in the Archipelago Sea has not been successfully estimated, or the estimates have been evidently too high. In this study, calculations were performed based on the measured water quality data to estimate how much phosphorus has been transported from the bottom water layer to the surface layers during the biological production season for use in algal production. In other words, the magnitude of the effective internal phosphorus load in the Archipelago Sea was determined. The calculations resulted in a summer internal net phosphorus load in the surface layer of approximately 270 tons over 5 months. The other total phosphorus load in the Archipelago Sea, which mainly (60%) originates from the catchment area, was 575 t/a. A permanent way to mitigate internal loading has been thought to be to reduce external loading. However, a decrease in internal loading occurs with an unknown delay, making it impossible to predict the recovery rate.

Complex Study of Settlements Dating from the Paleolithic to Medieval Period in the Ural Mountains on the Border of Europe and Asia

Soil, geochemical, microbiological, and archeological studies were conducted at eight settlements dating from the Paleolithic to Late Medieval and Modern Ages near the southern Trans-Urals Mountains, Russia. The forest-steppe landscapes, rivers, and abundant mineral resources have attracted people to the region since ancient times. Cultural layers (CLs) are marked by finds of ceramics fragments, animal bones, stone, and metal tools. The properties of CLs include close-to-neutral pH, being well structured, the absence of salinity, enrichment with exchangeable calcium, and anthropogenic phosphorus (0.2–0.4%). The majority of CLs start at a depth of 3–25 cm, extend to 40–60 cm, and contain 6–10% organic carbon (Corg) in the 0–20 cm layer, reflecting carbon input from modern-day processes. At the Ishkulovo site (0.6–0.8 ka BP), Corg decreases to 1.3% because the CL is below 80 cm, and in the absence of fresh organic material input, carbon has been mineralized. The proximity of sites to deposits of copper, chromium, zinc, and manganese in the Ural Mountains creates natural high-content anomalies in the region, as indicated by their abundance in soils and parent rocks. In the past, these elements were also released into CLs from metal products, ceramic fragments, and raw materials used in their manufacture. The sites are quite far (18–60 km) from the Magnitogorsk Metallurgical plant, but industrial stockpiles of S (technogenic coefficient—Ct 30–87%), and, less often, Cr, Mn, and Sr (Ct 30–40%) accumulated in surface layers. These three factors have led to the concentration of pollutants of the first (arsenic, chromium, lead, and zinc) and second (cobalt, copper, and nickel) hazard classes at CLs, often in quantities 2–5 times higher than values for parent materials and geosphere average content (“Clarke” value), and, and less often, more than the allowable content for human health. This may have influenced their health and behavioral functions. Due to the above properties, chernozems have a high buffering capacity and a strong bond with heavy metals. Therefore, no inhibition of microbes was observed. The microbial biomass of the 0–10 cm layer is high, 520–680 µg C/g, and microbes cause the emission of 1.0 C-CO2 µg/g of soil per hour. During the ancient settlements’ development, a favorable paleoclimate was noted based on the data cited. This contributed to the spread of productive paleolandscapes, ensuring the development of domestic cattle breeding and agriculture.

Cs- O2 -Li as enhanced NEA surface layer with increased lifetime for GaAs photocathodes

GaAs-based photocathodes are the only viable source capable of providing spin-polarized electrons for accelerator applications. This type of photocathode requires a thin surface layer, in order to achieve negative electron affinity (NEA) for efficient photoemission. However, this layer is vulnerable to environmental and operational effects, leading to a decay of the quantum efficiency η characterized by a decay constant or lifetime τ. In order to increase τ, additional agents can be introduced during the activation procedure to improve the chemical robustness of the surface layer. This paper presents the results of recent research on Li as an enhancement agent for photocathode activation using Cs and O2, forming Cs-O2-Li as an enhanced NEA layer. Measurements yielded an increase in lifetime by a factor of up to 19±2 and an increase in extracted charge by a factor of up to 16.5±2.4, without significant reduction of η. This performance is equal to or better than that reported for other enhanced NEA layers so far. Published by the American Physical Society 2025

Research on the Influence of Magnetic Field Assistance on the Quality of an Electro-Spark Deposition Layer

Aimed at solving the problems of single control measures in the electro-spark deposition (ESD) process, difficulty controlling the micro-process using heterogeneous materials (for the electrode and matrix), and the unstable quality and reliability of repairs to the deposition layer, a method of magnetic-field-assistance electro-spark deposition (MFESD) was proposed. An MFESD device was built, and a Ni electrode was used for deposition on the surface of 45 steel under the conditions of deposition voltages of 30 V, 60 V, and 90 V, respectively. This study examined the impact of the magnetic field’s intensity and frequency on the microstructure and mechanical properties of electro-spark deposition layers. The results show that the sputtering and protrusion of the electrode material on the surface of the deposition layer gradually decrease with an increase in the magnetic field’s intensity and frequency, defects such as pores and cracks are obviously improved, and the structure is uninterrupted and compact. The surface roughness of the deposited layer decreases with an increase in the magnetic field’s intensity and frequency, and its surface roughness decreases by 44.3%. The cross-section effect of the deposited layer is improved. The thickness of the deposited layer increases with an increase in the magnetic field’s intensity and frequency; the thickness of the deposited layer increases by 13.39%, and its maximum thickness can reach 54.396 μm. At the same time, the microhardness of the deposited layer increases with an increase in the two aforementioned properties of the magnetic field, and its hardness increases by 5.32%. Using a magnetic field to control ESD can effectively control the microscopic process of deposition and obtain high-quality deposition coatings, which have important significance in the surface remanufacturing of key components of high-end equipment.

Characterization of PuO2 With Visible and UV Raman Spectroscopy: Discrimination Between the Bulk, Surface, and an Intermediate Disordered Layer

ABSTRACTRaman spectroscopy is an ideal tool in the characterization of materials including PuO2. The wavelength‐dependent absorptivity of the material defines the light penetration depth and the relative Raman scattering contribution from the bulk and the surface. The surface contribution to the total Raman scattering was investigated for PuO2 calcined at various temperatures and recorded with laser wavelengths of 355, 325, and 244 nm. These experiments provided the first glimpse of the wavelength‐dependent disappearance and emergence of new phonons and electronic bands from the PuO2 surface layers. The first indication of the wavelength transition in the Raman spectra was the loss of the 2LO2 (overtone, ~1155 cm−1) band and the weakening intensity of the Г1 → Γ5 electronic band (~2135 cm−1) with the 355‐nm excitation laser. The Γ5 electronic band was barely visible with the 244‐nm excitation. The electronic band located at ~1050 cm−1, corresponding to the Г1 → Γ4 electronic transition was observed to dramatically increase in intensity while the Г1 → Γ3 electronic band (2640 cm−1) sharpened as the UV wavelength was increased in energy from the near‐ to deep‐UV (355–325–244 nm). The FWHM of the T2g band was found to vary with calcination temperature (450°C and 900°C) with the 325‐nm laser and the 244‐nm laser. The T2g band attributes, the strong emergence of the Г1 → Γ4 electronic band, and the disappearance of the 2LO2 overtone acquired with the 244‐nm excitation for the different calcination temperatures suggest a shallow penetration depth.

Surface induced crystallization/amorphization of phase change materials

Surface-induced crystallization/amorphization of a Germanium-antimony-tellurium nanolayer is investigated using the phase field model. A Ginzburg-Landau (GL) equation introduces an external surface layer (ESL) within which the surface energy and elastic properties are adequately distributed. Next, the coupled GL and elasticity equations for the crystallization/ amorphization are solved. For the initial surface crystalline nucleus, unphysical crystallization along the ESL appears for the ESL widthΔξ⩾2nmwhile oval growth occurs forΔξ⩽1nm. The ESL results in a faster surface nucleus growth than the sharp surface model but does not affect the crystallization rate inside the bulk. Initial homogeneous conditions cause a simultaneous crystallization in the bulk and later in the ESL. The ESL effect on amorphization is studied to determine the ESL width more precisely. For both the initial amorphous nucleus and homogenous conditions, the amorphization temperature shows a reduction from the sharp surface model to the ESL model withΔξ=0.5nmand then remains almost constant for largerΔξ. Combining the above results gives0.5⩽Δξ⩽1nmas a proper range for the ESL width. The ratio of the effective ESL width to the interface width (Δsat/Δη) and the ratio of the difference between the surface energies of transforming phases to the surface energy of the initial phase (Δγ/γin) are considered crucial parameters in determining the ESL effect on the phase transformation and a linear relation asΔsat/Δη≅6.235Δγ/γinis found based on current and previous works, which can help estimate the effective ESL width for any surface-induced transformations.

A bond strength analysis of carboncor asphalt layer on road surfaces

Transport infrastructure is a critical component of socio-economic development, particularly in rapidly urbanizing Vietnam, where increasing traffic congestion poses significant challenges. Road surface quality and durability are essential factors in ensuring the efficiency and longevity of the transportation system. Carboncor Asphalt (CA) material, with its superior resistance to cracking, water damage, and harsh weather conditions, is a promising solution for road surface construction in Vietnam. However, there is a limitation of research on the mechanical behavior of carboncor asphalt in the specific climatic and environmental conditions of the country. To address this knowledge gap, this study investigates the shear behavior of a carboncor asphalt layer interfaced with both asphalt concrete and cement concrete surface layers. A comprehensive range of laboratory tests is conducted to assess the bond strength between the carboncor asphalt layer and the overlying road surfaces. Results indicate a negative correlation between temperature and bond strength for the overlay carboncor asphalt layer on both asphalt and cement concrete substrates. Notably, bond strength demonstrated a significant increase over time. The findings in this study are expected to have significant implications for road construction and maintenance using CA overlay in Vietnam. By providing a scientific foundation for material selection, design, and construction of road surfaces tailored to local conditions, this study aims to enhance investment efficiency and reduce maintenance costs

Size-dependent phase change in energy storage materials: Comparing the impact of solid-state wetting and of coherency stress.

Coherent phase transformations in interstitial solid solutions or intercalation compounds with a miscibility gap are of practical relevance for energy storage materials and specifically for metal hydride or lithium-ion compound nanoparticles. Different conclusions on the size-dependence of the transformation conditions are reached by modeling or theory focusing on the impact of either one (internal, solid-state-) critical-point wetting of the nanoparticle surface or coherency constraints from solute-saturated surface layers. We report a hybrid numerical approach, combining atomistic grand canonical Monte Carlo simulation with a continuum mechanics analysis of coherency stress and modeling simultaneously wetting and mechanical constraints. When the ratio between chemical and misfit-strain-related contributions to the solute-solute interaction energy takes values realistic for interstitial solutions-which are typical for energy storage materials-we find that the impact of solid-state wetting is weak and that of coherency stress is dominant. Specifically, mechanical interaction can act to reduce the phase transformation hysteresis at small system size, and it can make the solid more binding for solute, thereby reducing the "plateau" chemical potential at phase coexistence. We present equations for the impact of coherency stress on the size-dependence of upper consolute temperature, plateau chemical potential, and charging/discharging hysteresis.

Smuggling unnoticed: Towards a 2D view of water and dust delivery to the inner regions of protoplanetary discs

Abstract Infrared spectroscopy, e.g., with JWST, provides a glimpse into the chemical inventory of the innermost region of protoplanetary discs, where terrestrial planets eventually form. The chemical make-up of regions inside snowlines is connected to the material drifting from the outer regions, which can be modeled with dust evolution models. However, infrared observations are limited by the high dust extinction in the inner disc, and only probes the abundances of gaseous species in the disc surface layers. As a result, the bulk mass of delivered volatiles is not directly relatable to what is measured through infrared spectra. In this paper, we investigate how the delivery of dust and ice after prolonged pebble drift affects the observable reservoir of water vapor in the inner disc. We develop a 1+1D approach based on dust evolution models to determine the delivery and distribution of vapor compared to the height of the τ = 1 surface in the dust continuum. We find that the observable column density of water vapor at wavelengths probed by JWST spans many orders of magnitude over time, exhibiting different radial profiles depending on dust properties, drift rate, and local processing. In the presence of a traffic-jam effect inside the snowline, the observable vapor reservoir appears constant in time despite the ongoing delivery by pebble drift, such that water is effectively smuggled unnoticed. Differences in measured column densities then originate not only from variations in bulk vapor content, but also from differences in the properties and distribution of dust particles.

Sum-Frequency Generation in the Surface Layer of a Dielectric Spheroidal Particle: Analytical Solution

Sum-Frequency Generation in the Surface Layer of a Dielectric Spheroidal Particle: Analytical Solution

Research on High-Speed Railway Subgrade Design Method Based on Energy Dissipation and Dynamic Stability Characteristics

The subgrade structure of high-speed railways is an important foundation for the safe and smooth operation of high-speed trains, and the scientific design of the subgrade structure provides a fundamental guarantee of its durability and technical economy. As, in the development of high-speed railways in China, higher speeds are being pursued, more requirements have been put forward for the dynamic stability of subgrade structures. To address this issue, this article focuses on the control requirements for the long-term stability of subgrade deformation, and various design methods for high-speed railway subgrade structures are presented. Considering the energy dissipation and dynamic stability characteristics of subgrade filling materials, the dynamic performance of coarse-grained soil filling materials in the bottom layer and graded crushed stones in the surface layer are revealed. The methods for determining the values of dynamic parameters such as the dynamic modulus and damping ratio are provided. Based on the dynamic shakedown theory, the stress–strain hysteresis characteristics of fillers and the variation law of dissipated energy are revealed. The correlation between unit volume dissipated energy and shakedown state under cyclic loading conditions is identified. A criterion for determining the critical shakedown state of high-speed railway subgrade structures based on equivalent unit volume dissipated energy is proposed, and a method for determining the design threshold of dynamic stress and dynamic strain is also proposed. The results show that the shakedown design critical values of equivalent unit volume dissipated energy in the bottom and surface layers of the foundation were between 0.0103~0.0133 kJ/m3 and 0.0121~0.0149 kJ/m3, respectively. The critical dynamic strain range was 0.8 × 10−3~1.3 × 10−3. On this basis, a high-speed railway subgrade design method based on energy dissipation and dynamic shakedown characteristics was developed. The results can provide theoretical support for the design of high-speed railway subgrade structures with different filling material alternatives and control standards.

Evaluation of the Effect of Different Universal Adhesives on Remineralized Enamel by Shear Bond Strength and Fe-SEM/EDX Analysis

The aim of this study is to evaluate the shear bond strength of different universal adhesives applied to intact, demineralized, and remineralized enamel surfaces with total-etch and self-etch modes and to examine the effect of universal adhesives on the Ca/P mineral atomic and mass ratios of these enamel with FE-SEM/EDX (Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy) analysis. For this study, 264 bovine incisors were used. Samples in the demineralized and remineralized groups were kept in demineralization solution at 37 °C for 96 h to make an artificial initial carious lesion. After demineralization, half of the demineralized samples were remineralized with MI Paste Plus. For shear bond strength (n = 144) and FE-SEM/EDX analysis (n = 120), G-Premio Bond and Clearfil S3 Bond Universal were applied on enamel surfaces with total-etch and self-etch modes, and bond strength samples were restored with resin composite. All samples were tested. The results were evaluated statistically by a three-way ANOVA test. The shear bond strength of the remineralized enamel showed high bond strength values comparable to intact enamel for universal adhesive systems. The Ca/P mineral atomic and mass ratios in remineralized enamel showed higher values than demineralized enamel, similar to intact enamel for universal adhesive systems. Initial carious lesion surfaces are unsuitable enamel surfaces for restoration. The remineralization of this surface layer before adhesive procedures may positively affect bond strength.

Impact of a RbF post-deposition treatment on the chemical structure of wide-gap CuIn0.1Ga0.9Se2 thin-film solar cell absorber surfaces

A detailed characterization of the impact of a RbF post-deposition treatment (RbF-PDT) on the chemical structure of a wide-gap Cu(In, Ga)Se2 thin-film solar cell absorber surface with a high Ga/(Ga + In) (GGI) ratio of 0.9 is presented. Using synchrotron- and lab-based x-ray photoelectron spectroscopy, as well as x-ray-excited Auger electron spectroscopy, we observe distinct differences to RbF-PDT on absorber surfaces with the common GGI of ∼0.3. In particular, RbF-PDT reduces sodium and oxide content at the surface, while the copper concentration at the surface is not affected. We find no spectral evidence for the formation of a distinct Rb–In–Se surface layer. In addition, we observe that the GGI ratio at the surface is slightly decreased due to a reduction of the Ga and an increase in the In concentration, which may explain the observed improvement in the power conversion efficiency after the PDT (from 6.8% to 7.3%).

Tribo-Electrochemical Mechanism of Material Removal Examined for Chemical Mechanical Planarization of Stainless-Steel Using Citrate Buffer as a Complexing Agent

Chemical mechanical planarization (CMP) is a technique used to efficiently prepare defect-free, flat surfaces of stainless steel (SS) foils and sheets that are implemented in various modern devices. CMP uses (electro)chemical reactions to structurally weaken the surface layers of a workpiece for easy removal by low-pressure mechanical abrasion. Using a model CMP system of 316/316L stainless steel (SS) in an acidic (pH = 3.63) slurry with alumina abrasives, citrate buffer (CB), and H2O2, we examine the tribo-electrochemical mechanisms of SS CMP that dictate the designs of functionally efficient and cost-effective CMP slurries. The use of CB as a pH-controlled complexing agent prevents defect-causing dissolution of SS and eliminates the need for using separate (often toxic) corrosion inhibitors in the slurry. A material removal rate of 8.6 nm min−1 is obtained at a moderate down pressure of 0.014 MPa with a platen rotation speed of 95 RPM. Electrochemical techniques are strategically combined with mechanical abrasion of SS test samples to probe complex CMP mechanisms that are not readily accessible with electrochemical experiments alone. Corrosion-like reactions of salt-film formation at the SS surface act to enable the CMP process, where corrosion-induced wear plays a major role in material removal.

Investigating the salinity distribution using field measurements in the semi-arid region of southern Ethiopia

This study investigated the distribution of salinity and sodicity in the irrigated areas of Abaya Chamo. Representative water and soil samples were collected from different soil depths (0–30 cm and 30–60 cm). Sodium absorption ratio (SAR), electrical conductivity (Ec), pH, exchange sodium, magnesium, calcium, and potassium cations, and exchange sodium percentage (ESP) of the sampled sites were analyzed for soil salinity classification and severity analysis. The spatial analysis revealed predominant strongly saline (72%) and sodic (71.1%) conditions in the surface layer (0–30 cm), intensifying very strongly saline (78.7%) and sodic (71.9%) conditions at 30–60 cm depth. Combined saline-sodic conditions dominated both layers, increasing from 91.2% at the surface to 97.1% in the deeper layer, indicating severe agricultural limitations. The results show that soil in the catchments of Lakes Abaya and Chamo suffer from different salinity and sodium content classes. Therefore, appropriate remedial measures based on soil salinity and sodium content should be developed to achieve better reclamation, agricultural production, and land sustainability.

The Laser Processing of the Stainless-Steel Surface Layer of a Heat Exchanger Membrane in Order to Enhance Its Heat Transfer Coefficient

Research on temperature regulation is essential for ensuring thermal comfort and optimizing machine performance. Effective cooling systems are critical in industrial processes and everyday electronic devices in order to prevent overheating. Laser-modified heat exchangers can enhance heat dissipation without increasing weight, addressing the need for energy-efficient solutions in the market. The main aim of this experimental research was to establish an efficient method for altering the surface layer of AISI 316L stainless steel with laser pulses and to determine the effectiveness of the laser alterations to the surface layer in the context of intensifying the convective heat transfer. A series of laser-texturing processes was performed on the surface layer of AISI 316L steel using a Nd: YAG pulse laser. Selected samples were subjected to a series of measurements using a recuperator-type heat exchanger. Based on the measurements’ results, the heat transfer coefficients, α, obtained from the modified surfaces were determined. The results were compared with other data from the existing literature and those obtained from unmodified reference samples. The intensification of the convective heat transfer was achieved for 43% of the modifications conducted with a pulsed laser. The highest observed average increase in the heat transfer coefficient, α, was 16.53%. However, the effective intensification of the convective heat transfer, in some cases, was only observed for a certain range of temperatures or flow dynamics parameters.

How amino acids intercalate in CaFe layered double hydroxides: A combined RIXS and NEXAFS study.

Two-dimensional layered double hydroxides (LDHs) are ideal candidates for a large number of (bio)catalytic applications due to their flexible composition and easy to tailor properties. Functionality can be achieved by intercalation of amino acids (as the basic units of peptides and proteins). To gain insight on the functionality, we apply resonant inelastic soft x-ray scattering and near edge x-ray absorption fine structure spectroscopy to CaFe LDH in its pristine form as well as intercalated with the amino acids proline and cysteine to probe the electronic structure and its changes upon intercalation. We observe the activation of pristine LDH defect states by soft x-rays and their passivation by the intercalated molecules. The nitrogen at the amino amino is found to form C=NH+ bonds and thus generating positive charge at the amino group, moving it away from the positively charged LDH layers. The carboxyl group in cysteine is deprotonated and thus in zwitterionic state after intercalation. This negative charge is used to compensate the positive layer charge. For intercalated proline the spectral signature of a protonated carboxyl group is observed, however, we find orbital overlap to defects at the layer surfaces indicating strong interaction with the carboxyl groups.

Release of PAHs from reclaimed asphalt mixtures into the water environment after passivation by cold in-place recycling technology.

The paper deals with an analysis of the amount of 16 polycyclic aromatic hydrocarbons (PAHs (Polycyclic aromatic hydrocarbons-16 defined by US EPA.)) released from reclaimed asphalt mixtures used in base layers of road surfaces and in binder layers in road construction using cold in-place recycling. For the ten samples tested, the sum of 16 PAHs was determined directly for the crushed asphalt mixture and for its 24-h leachate. The crushed asphalt samples were used to make cylindrical asphalt specimens of the cold recycling mixture. The asphalt specimens were prepared to simulate as realistically as possible the use of the mixtures in road reconstructions implementing the cold in-place recycling technology, which should ensure the passivation of PAHs. The asphalt specimens were subjected to a dynamic leaching test under laboratory conditions with regular replacement of the leaching liquid. The results showed that the concentration of PAHs released into the water environment from the test specimens (passivated material) was approximately 40-50% lower than the amount of PAHs released from the asphalt mixtures in the 24-h leaching test. When compared to the input PAH concentrations in the asphalt mixtures (36-1323mg.kg-1), on average, only 0.15% of PAHs is released from the passivated material. Dynamic leaching test has shown that the wrapping of the original asphalt mixture with a new binder and its subsequent compaction leads to the preservation of PAHs in the original material at such a level that their total concentrations are reduced by two orders of magnitude.

Research on the optimal laser preparation process parameters of groove-shaped micro-texture on the mill roll surface

Laser micro-texture preparation technology significantly excels in micro-texture processing, yet there has been scant reported research on utilizing this technology for micro-texture processing and texture morphology control on the surface of wheat mill rolls. The aim was to ascertain the ideal laser preparation process parameters for the creation of groove-shaped micro-textures on the surface of the chilled alloy cast iron, serving as the surface layer material of the wheat mill roll. An experiment was conducted using a nanosecond pulsed fiber laser to explore the impact of laser power, scanning times, scanning velocity, and pulse frequency on the morphology and dimensions of the groove-shaped micro-textures. It was found that with laser power set at 7 W, 15 scanning times, a pulse frequency of 35 kHz, and a scanning speed of 500 mm/s, the desired microgroove can be successfully fabricated on the surface of the mill roll. The findings of this study offer insights for the surface modification of critical components in grain and oil machinery and equipment through the application of laser micro-texturing technology.