Roughness Parameters Research Articles

ANALYZING THE EFFECTS OF MANUFACTURING PARAMETERS MODIFICATION ON FINAL SURFACE ROUGHNESS IN SELECTIVE LASER MELTING PARTS

Selective Laser Melting (SLM) is an additive manufacturing technique widely used today for producing metal components. This method enables the fabrication of geometrically complex parts while reducing costs and production time compared to traditional manufacturing techniques. However, a notable drawback of SLM is its tendency to produce high surface roughness and superficial defects such as balling, porosity, debris, and waviness. This study evaluates the effects of modifying two manufacturing parameters—scanning speed and laser power—on the final surface roughness. To achieve this, cylindrical specimens were fabricated using various combinations of these parameters, and the resulting surface roughness metrics (Sa, Sq, Ssk, Sku, Sdr, among others) were measured using an optical 3D surface roughness measurement instrument. A Taguchi L8 design was applied to analyse the influence of the manufacturing parameters on the measured roughness characteristics. This study investigates the influence of laser power and scanning speed on surfaces manufactured through Selective Laser Melting (SLM) and their effects on the previously described roughness parameters. The authors observed that the manufacturing parameters have varying impacts on the final surface roughness of components produced via SLM. Due to the inherent characteristics of the process, a specific combination of parameters that reduces roughness within a specimen's layer may increase roughness at the layer boundaries. These findings underscore the complex relationship between manufacturing parameters and surface roughness in SLM-produced parts, emphasizing the need for strategies, such as surface finishing post-treatments, to achieve the desired surface quality.

A Study of the Effect of Roughness on the Three-Body Wear Mechanism from a Microscopic Point of View: Asperity Peak Removal

The presence of particles leads to varying degrees of mass loss on a metal sealing surface, which severely affects the seal’s lifespan. Understanding the complex wear mechanism and optimizing the surface roughness morphology are particularly important in engineering. By characterizing the surface of the metal (SS 304) with different roughness parameters Ra, Rp, Rpk, Rpc and Rku, the variation mode of mass loss under abrasive wear conditions was revealed. Unlike traditional two-body wear, the involvement of abrasive particles significantly impacts surface Ra and other surface morphologies (asperity peak features). A contact model for metal rough surfaces, distinct from two-body contact, was established to clarify the changes in removal mechanisms. It was found that the change in the contact between the particle and the asperity peak led to a change in the mass loss and guided the appropriate metal roughness range: Ra 0.05 μm and Ra 0.6–0.8 μm. In addition, it was found that the removal of asperity peaks is holistic under low roughness, and only parts of asperity peaks are removed under high roughness. Notably, the metrological methods used in this study supplement existing roughness measurements. By exploring the complex removal mechanism of asperity peaks, micro-scale guidance for surface (texture) design, machining, and optimization is provided.

Preliminary safety and in vivo efficacy of Acmella oleracea extract‐loaded glycolipid emulsion serum—Effects on ocular irritation, dermal absorption, and facial skin biophysical and microrelief properties

AbstractObjectiveSubstantial efforts have been progressively devoted to developing innovative, safe, and effective topical anti‐aging products that not only improve the appearance of aged skin but also prioritize environmental sustainability and the responsible use of natural resources. Thus, the current study targeted to evaluate novel, natural emulsion/serum comprising new glycolipid emulsifier (lauryl glucoside/myristyl glucoside/polyglyceryl‐6 laurate) and Acmella oleracea plant extract as a model active.MethodsThe developed serum was assessed concerning its stability (freeze–thaw test, accelerated study), safety (in vitro screening of eye irritation potential, dermal absorption study) and efficacy (randomized, active/reference‐controlled, half‐face, in vivo study). Changes in skin biophysical properties, microrelief, roughness, texture, surface, and volume parameters were assessed in the periocular and perioral areas of human volunteers after 2 weeks of product application, utilizing several bioengineering and topography techniques.ResultsThe stability study demonstrated favourable stability profile of the developed serum, with practically unaffected stability‐indicating parameters (apparent viscosity, yield, flow point, storage and loss moduli, loss factor, pH, electrical conductivity) during freeze–thaw cycling and after 3 months of storage at 45°C. The hen's egg test on the chorioallantoic membrane of fertilized chicken eggs confirmed the absence of ocular irritation potential of investigated serum; no effects of haemorrhage, lysis or coagulation were occurred. Skin permeation study using diffusion cells revealed no permeation of spilanthol from the tested A. oleracea extract‐loaded serum through the pig ear skin into the receptor medium, thus suggesting no absorption into systemic circulation. In vivo efficacy study corroborated beneficial effects of evaluated serum on the condition/appearance of facial skin, at both periocular and perioral areas—significant (p < 0.05) increase in skin hydration (10%–40%) and smoothness (~15%); significant (p < 0.05) decrease in roughness (20%–30%), scaliness (~30%), and wrinkles (~15%)—implying more hydrated, smoother, visibly milder skin.ConclusionThe present findings confirmed the stability, preliminary safety (no ocular irritation, no dermal absorption, and good skin tolerability), and efficacy (improved skin hydration and microrelief) of the A. oleracea extract‐loaded, glycolipid‐based serum, supporting its potential as a safe and effective topical anti‐aging product.

Fluorescence Behavior of Cyanine Fluorophore Cy3 Confined in Anodic Porous Alumina: Advanced Surface Analysis

In this study, an advanced analysis of the three-dimensional (3-D) surface microtexture of anodic porous alumina (APA) arrays was conducted to investigate their efficacy in confining cyanine fluorophore Cy3. The microstructural characterization of APA plays a pivotal role in enhancing the understanding of the material's surface properties, especially when applied to biological arrays and fluorescent dye confinement. To achieve this, Atomic Force Microscopy (AFM) was employed to obtain precise 3-D surface microtexture data. These measurements were complemented by stereometric analyses, adhering to ISO 25178-2: 2012 standards, ensuring a robust quantitative and qualitative evaluation of the surface micromorphology. The analysis revealed a clear correlation between surface roughness parameters and micromorphological changes as a function of varied processing conditions. Notably, the increase in certain fabrication parameters led to significant alterations in the superficial texture, with observable changes in the fractal dimension of the surface structure. The APA arrays, fabricated using a specialized anodization technique followed by a tailored annealing procedure, exhibited extraordinarily large pore sizes, ranging from 1 to 2 μm, which are well-suited for accommodating the Cy3 dye molecules. These pore dimensions offer an enhanced capacity for dye confinement, providing a stable environment for the cyanine fluorophore while promoting optimal fluorescence behavior.

Yarn‐to‐Yarn Surface Area and Roughness as Structural Engineering Tools for Optimizing the Electrical Output of Triboelectric Nanogenerators: Geometrical and Experimental Verification

AbstractThis paper investigates the performance of woven triboelectric nanogenerators (W‐TENGs) fabricated with different fabric patterns, specifically plain, twill, and hopsack weaves, using wool and polyester yarns. It is intended to enhance the electrical output and efficiency of W‐TENGs for potential applications in wearable electronics by optimizing the weaving pattern. Results indicate that W‐TENGs with twill 2/2 and hopsack 2/2 patterns exhibit superior electrical outputs, attributed to their higher contact surface area and roughness. The twill 2/2 pattern demonstrates the highest electrical output, generating an open‐circuit voltage of 4.7 V, a short‐circuit current of 4 µA, and a transferred charge of 0.35 µC. This study also highlights the critical role of surface area and dielectric material roughness in determining the output performance of triboelectric structures. A theoretical model is developed to calculate the real contact surface area of the woven fabrics with different patterns. Statistical analysis reveals significant relationships between surface roughness parameters and electrical performance. Dynamic testing under varying contact forces and frequencies demonstrates the practical applicability and robustness of the W‐TENGs. Furthermore, the devices exhibit excellent durability, maintaining stable performance over extended periods. This research provides new insights into fabric design strategies for optimizing energy harvesting in wearable devices.

Design of parameters for running-in cylinder liner piston rings based on running-in attractor

Purpose The purpose of this study aims to shorten the running-in time and improve the running-in quality of cylinder liner piston rings (CLPRs), the running-in tests were carried out and running-in parameters of CLPRs were designed based on running-in attractor theory, which can guide the choice of optimal working conditions for other friction pairs. Design/methodology/approach The running-in state and time under different working conditions are identified by the evolution law of the running-in attractor phase trajectory and fractal and chaotic characteristic quantities. The CLPRs running-in tests under different conditions were conducted and the friction signals were collected. The constructed phase trajectories and calculated chaotic parameters of the running-in attractor are obtained and the running-in state and time are identified by the evolution law of phase trajectories and chaotic characteristic quantities. The running-in quality is obtained by the surface morphology fractal dimension and characteristic roughness parameters. Findings The running-in parameters for short running-in time and good running-in quality are designed based on the fractal and chaotic theory and the optimal solution method are used to verify the results through the single objective or multi-objective optimization, and the corresponding optimal running-in parameters are obtained. Originality/value The optimal working condition parameters obtained from the design have guiding significance for the selection of CLPR running-in parameters, and this work can provide ideas for the other friction pairs. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0179/

Improving the efficiency of polymer solar cells based on chitosan@PVA@rGO composites via gamma-irradiated treatment of rGO nanoparticles

Polymer solar cells (PSCs) are growing as attractive contenders for renewable energy technologies given their low cost, adaptability, and environmental sustainability, rendering them valuable in combating climate change. Interestingly, this work investigates the augmentation of photon absorption and overall efficiency in low-cost, effective active layers (ALs) via gamma irradiation treatment, thereby raising the number of active absorption sites. For the first time, novel Chitosan@PVA@rGO (CPG) composite sheets were created as AL materials and treated to varied dosages of in-situ gamma irradiation (0, 10, 20, 30, and 40 KGy) to optimize their microstructural and physicochemical characteristics. The processed ALs were subjected to comprehensive tests, which included J–V variable evaluation as well as evaluations of microstructure, porosity, morphology, contact angle, optical characteristics, and electrochemical impedance spectroscopy (EIS). The findings reveal that the composites' surface properties got better gradually as gamma irradiation dosages grew; peak performance was reached at 30 KGy (75.9 % apparent porosity and roughness parameter Ra = 6.22 μm). Extended gamma irradiation resulted in increased DSSC efficiency, which reached 6.85 % after 10 KGy and 7.63 % after 20 KGy. High-energy gamma photons boosted mobility and decreased resistive limits by reducing carrier recombination and facilitating charge carrier movement inside CPG compounds. This increased the longevity and charge transfer efficiency of the solar cell. After 30 KGy alteration, the CPG AL's optimized efficiency of 8.78 % and Jsc of 20.23 mA/cm2 indicate a 44.3 % improvement in efficacy over the pristine material. The insertion of oxygen-enriched free radicals into the CPG structure is responsible for the improvement in photovoltaic efficiency because it creates continuous pathways for fast electron transport. This work provides an innovative perspective on the use of heteroatom-doped ALs in PSCs by highlighting the benefits of co-doping and regulated heteroatom species.

PHYSICO-MECHANICAL PROPERTIES OF METALLIC PARTS ELECTROCHEMICALLY PRINTED USING COPPER NITRATE ELECTROLYTE

The process of electrochemical 3D printing of copper parts using a concentrated copper nitrate electrolyte has been investigated. It was established that in a nitrate copper plating electrolyte with a copper nitrate concentration of 500 g/l, it is possible to obtain locally electrodeposited metal parts with a compact fine-crystalline structure and an average profile height of 150 μm. The working current densities of electrochemical printing in this case were 2.45…2.7 A/dm2. It has been shown that reducing the speed of movement of the working electrode (anode) leads to an improvement in the uniformity of metal deposition along the entire trajectory of movement and the reduction of the crystals size of the metal deposit. This is obviously a consequence of a change in the current mode of electrodeposition. It was established that on the surface with initial parameters of microroughness (Rz(1)=1.128 Ra(1)=0.2925) during electrochemical 3D printing, a metal structure with roughness parameters – Rz(1)=95.72 Ra(1)=16.32 has been formed. The formation of a compact but at the same time a highly rough metal structure makes the application of the electrochemical 3D printing method promising in the production technology of printed circuit boards and in the field of microelectronics as a whole. The micromechanical tests of samples of electrochemically printed copper deposits showed the following. The microhardness of the electrochemically printed copper deposit is approximately 30% higher, but the plasticity coefficient and Young’s modulus acquire values close to the corresponding parameters of hydrometallurgical copper. This indicates that the method of obtaining metal objects by electrochemical 3D printing does not contribute to a significant deterioration of the elasticity of the obtained material.

FRACTAL-BASED MODELING OF RAIL ROUGHNESS

This paper uses fractal modeling techniques to effectively depict the roughness characteristics of the rails examined in this study by means of both the structure function and the Weierstrass–Mandelbrot function to capture the intricate nature of the rail roughness. Experimental analysis of the roughness of the railway rails from Faurei Railway Testing Center (RTC Faurei) in Romania proves that the roughness height exhibits distinct mathematical fractal characteristics. The study evaluated and compared 41 classical statistical parameters derived from roughness measurements with simulated fractal parameters. The classical roughness parameters, including the Autocorrelation function, Amplitude Density Function, as well as Bearing Area Curves, and rail acoustic roughness, were determined from a profile obtained using the Weierstrass function and compared to the measured ones, revealing a noticeable congruence between the generated charts. The research findings indicate a strong convergence between experimental measurements and simulated profiles, with most parameters falling within a 10% relative error range. This aspect highlights the approach of fractal potent in assessing rail roughness behavior. Consequently, the simulated parameters could potentially analyze rail roughness quality to maintain and track grinding and mitigate the rolling noise.

Tool wear and surface topography shaping after TPl multi-axis milling of Ni-based superalloy of the torus milling cutter using the strategy of adaptive change of the active cutting edge segment

This paper details an investigation of the process of multi-axis high-speed milling of the surface of Ni-based superalloy Inconel 718 parts used the torus milling cutter. Presents the issues and development of the own models of the multi-axis milling in a kinematic variant of the TPl (Tool Pulling) type in terms of tool wear. Because the cutting speed in finishing high-speed milling is the parameter with the greatest influence on tool life and surface roughness, the dependence of the variation of the cutting speed at the torus part of the cutter was first determined as a function of the distance from the tip point along the axial direction and the geometrical parameters of the torus. A model for multi-axis milling of the TPl type was developed and described in a simplified manner, which forms the basis of an own ACACES strategy for segmenting the cutting edge of a torus milling cutter. The adaptation of a given segment to the active cutting edge during machining was based on tool wear and kinematic roughness criteria. Simulations and experiments of multi-axis milling were carried out, and the necessary analyses were performed. In this paper, in addition to testing an in-house strategy for multi-axis milling used the torus milling cutter, the problem of defining the cutting speed in relation to the nominal diameter and effective diameter of the tool is investigated for the first time. In addition, wear measurement was carried out using an in-house methodology, taking full advantage of the capabilities of the multi-axis machining centre, which significantly reduced measurement time and positively influenced the effectiveness of tool life assessment. Using the own ACACES strategy of the multi-axis surface milling of parts made of Ni-based superalloys, an almost fourfold increase in torus cutter life was achieved compared to the conventional strategy, while maintaining the required machined surface roughness parameters.

A Statistical Approach for Characterizing the Behaviour of Roughness Parameters Measured by a Multi-Physics Instrument on Ground Surface Topographies: Four Novel Indicators

With a view to improve measurements, this paper presents a statistical approach for characterizing the behaviour of roughness parameters based on measurements performed on ground surface topographies (grit #080/#120). A S neoxTM (Sensofar®, Terrassa, Spain), equipped with three optical instrument modes (Focus Variation (FV), Coherence Scanning Interferometry (CSI), and Confocal Microscopy (CM)), is used according to a specific measurement plan, called Morphomeca Monitoring, including topography representativeness and several time-based measurements. Previously applied to the Sa parameter, the statistical approach based here solely on the Quality Index (QI) has now been extended to a multi-parameter approach. Firstly, the study focuses on detecting and explaining parameter disturbances in raw data by identifying and quantifying outliers of the parameter’s values, as a new first indicator. This allows us to draw parallels between these outliers and the surface topography, providing reflection tracks. Secondly, the statistical approach is applied to highlight disturbed parameters concerning the instrument mode used and the concerned grit level with two other indicators computed from QI, named homogeneity and number of modes. The applied method shows that a cleaning of the data containing the parameters values is necessary to remove outlier values, and a set of roughness parameters could be determined according to the assessment of the indicators. The final aim is to provide a set of parameters which best describe the measurement conditions based on monitoring data, statistical indexes, and surface topographies. It is shown that the parameters Sal, Sz and Sci are the most reliable roughness parameters, unlike Sdq and S5p, which appear as the most unstable parameters. More globally, the volume roughness parameters appear as the most stable, differing from the form parameters. This investigated point of view offers thus a complementary framework for improving measurement processes. In addition, this method aims to provide a global and more generalizable alternative than traditional methods of uncertainty calculation, based on a thorough analysis of multi-parameter and statistical indexes.

The Influence of Roughness on the Properties of Electroactive Polypyrrole.

This study describes the properties of electroactive polypyrrole and its applications, with a focus on the roughness of the material. This parameter is crucial as it influences the applicability of coated layers, leading to highly adherent coatings or programmed wettability. The first raised aspect covers the electrodeposition procedure, which can help tailor the desired smoothness determined by roughness parameters. Features such as the deposition method, synthetic solution components, potential boundaries, substrate type, and utilized additives are evaluated. In the following section, the application aspects are discussed with a focus on modern, currently developed subjects such as medical applications, including cell-adherent coatings, antibacterial coatings, and drug delivery modules, as well as more technological fields like improved adhesion to the substrate and the improved mechanical properties of the deposited coating.

Retrieval of soil moisture in salinized farmland soil by multi-polarization SAR

ABSTRACT Synthetic Aperture Radar (SAR) is a potent instrument for estimating soil moisture across vast farmland areas. However, when soil salinity rises, existing SAR retrieval models for soil moisture become less accurate. Soluble salts in soil water alter the inherent correlation between the SAR backscattering coefficients and soil water, thus compromising the performance of retrieval models. The need to get surface roughness parameters from the field also limits the widespread application of the model. To address these issues, we developed a retrieval model for salty soil moisture assessment under small-scale roughness surfaces. First, we found a method to distinguish between slightly rough and rough surfaces using scattering entropy obtained from full-polarization decomposition. Then, we harnessed the co-polarization ratio to mitigate the effect of surface roughness in slightly rough conditions. Later, we developed a soil moisture retrieval model based on the co-polarization ratio, considering incidence angle, residual roughness, and soluble salt content. The validation of the model was verified using field surveying data, yielding an RMSE of 0.026 cm3 ·cm− 3 for the estimated soil moisture. This accuracy is comparable to or surpasses the level achieved by SAR for non-salinized soil moisture retrieval. Our findings showed that Scattering entropy is an effective parameter for distinguishing scattering mechanisms on farmland surfaces effectively. Specifically, when the scattering entropy of farmland is less than 0.5, the co-polarization ratio can mitigate some surface roughness effects. Additionally, when the soil-soluble salt content is incorporated, our model can accurately estimate the soil moisture of salty soil.

Investigation of the influence of packaging cardboard surface topography on the quality of printed products

The article investigates the impact of surface topography of various types of packaging cardboard on the quality of offset printed impressions. It analyzes the morphological structure of coated (GD2) and uncoated (UD3) cardboard, their microstructure, as well as surface roughness parameters such as Ra, peak, and valley areas. The article also provides a comparative analysis of the morphological indicators of unprinted cardboard surfaces and their printed impressions. Recommendations are proposed for selecting packaging materials to ensure optimal print quality.

Influence of material orientation, loading angle, and single-shot repetition of laser shock peening on surface roughness properties

Titanium alloy Ti6Al4V is extensively utilized in biomedical applications due to its excellent biocompatibility, corrosion resistance, and mechanical properties. The design of dental implant surface textures has changed throughout time to address issues with oral rehabilitation in both healthy and damaged bones. The longevity of an implant is significantly impacted by surface roughness. This study examines the use of laser shock peening (LSP) as a surface modification technique to improve the mechanical properties of implants. A numerical model is developed using the commercial finite elements software in ABAQUS/Explicit for simulating dynamic conditions. The aim of the study is to develop surface roughness parameters using computational methods such as studies have not yet been contemplated. The single shot angle, shot repeat, time, material orientation, and laser power are applied for the first time simultaneously to evaluate the impact of material orientation and loading angles on surface roughness parameters. The study showed that the developed computational model’s compressive residual stress was −578.45 MPa, while the experimental samples were −592.18 MPa. Consequently, the difference between the computational and experimental results was 2.32%. Without regard to material orientation or angle, the compressive residual stress of the samples under examination was found to be −578.450 MPa after three repetitions and to decreased to −1.620 MPa after four. These results demonstrate that by varying the material orientation and loading angle, the Ra value may be increased four times.

When Frictions are Fractional: Rough Noise in High-Frequency Data

The analysis of high-frequency financial data is often impeded by the presence of noise. This article is motivated by intraday return data in which market microstructure noise appears to be rough, that is, best captured by a continuous-time stochastic process that locally behaves as fractional Brownian motion. Assuming that the underlying efficient price process follows a continuous Itô semimartingale, we derive consistent estimators and asymptotic confidence intervals for the roughness parameter of the noise and the integrated price and noise volatilities, in all cases where these quantities are identifiable. In addition to desirable features such as serial dependence of increments, compatibility between different sampling frequencies and diurnal effects, the rough noise model can further explain divergence rates in volatility signature plots that vary considerably over time and between assets.

An Experimental Investigation into the Enhancement of Surface Quality of Inconel 718 Through Axial Ultrasonic Vibration-Assisted Grinding in Dry and MQL Environments

Ultrasonic vibration-assisted grinding (UVAG) has proven to be beneficial for grinding difficult-to-machine materials. This work attempts to enhance the grinding performance of Inconel 718 through a comprehensive study of UVAG characteristics. Grinding experiments were performed in both dry and Minimum Quantity Lubrication (MQL) environments, and assessment of the grinding forces, specific energy, residual stress, and surface topography was done. A substantial reduction of both surface roughness and grinding force components was observed in UVAG compared to conventional grinding (CG). Utilizing UVAG with MQL at the maximum vibration amplitude led to a 64% reduction in tangential grinding force and a 51% decrease in roughness parameter, Ra, when compared to CG conducted in a dry environment. The high-frequency indentations of the abrasives in UVAG generated compressive residual stresses on the ground surface. Surface parameters pointed to uniform texture and SEM images showed widening of abrasive grain tracks on the workpiece surface during UVAG. The utilization of UVAG under MQL produced a synergistic impact and resulted in the lowest grinding forces, specific energy, and optimal surface quality among all the grinding conditions investigated. Overall analysis of the results indicated that the axial configuration of the vibration set-up is favorable for UVAG, and the high-frequency periodic separation-cutting characteristic of the process improves lubricating efficiency and grinding performance.

Towards a new roughness parametrization through the effective distribution function

Turbulent flows over rough surfaces can be encountered in a wide range of engineering applications. Despite the progress made after several decades of studies, the prediction of drag and roughness function from the surface geometrical parameters remains an open question. Several methods have shown encouraging results. However, they lack generality and present some scatter in the data. In this paper we propose a new parameter, the effective distribution ( $ED$ ), which lays foundation on the effective slope with some changes to take into account the sheltering effect of large roughness elements and the drag induced by pinnacles higher than the average roughness elements. To develop this new correlation between geometrical features of the wall and the drag, we performed a set of simulations of the turbulent flow over a rough surface made of triangular elements varying their height and spatial distribution. The $ED$ correlates quite well both with the drag and the roughness function for a wide range of cases having different mean roughness height, skewness and kurtosis. To further validate the $ED$ , and assessing how it can be generalized to real rough wall, an irregular wall made from the superposition of random sinusoidal function was considered. Results were consistent with the correlation here presented.

Determination of Optical and Structural Parameters of Thin Films with Differently Rough Boundaries

The optical characterization of non-absorbing, homogeneous, isotropic polymer-like thin films with correlated, differently rough boundaries is essential in optimizing their performance in various applications. A central aim of this study is to derive the general formulae necessary for the characterization of such films. The applicability of this theory is illustrated through the characterization of a polymer-like thin film deposited by plasma-enhanced chemical vapor deposition onto a silicon substrate with a randomly rough surface, focusing on the analysis of its rough boundaries over a wide range of spatial frequencies. The method is based on processing experimental data obtained using variable-angle spectroscopic ellipsometry and spectroscopic reflectometry. The transition layer is considered at the lower boundary of the polymer-like thin film. The spectral dependencies of the optical constants of the polymer-like thin film and the transition layer are determined using the Campi–Coriasso dispersion model. The reflectance data are processed using a combination of Rayleigh–Rice theory and scalar diffraction theory in the near-infrared and visible spectral ranges, while scalar diffraction theory is used for the processing of reflectance data within the ultraviolet range. Rayleigh–Rice theory alone is sufficient for the processing of the ellipsometric data across the entire spectral range. We accurately determine the thicknesses of the polymer-like thin film and the transition layer, as well as the roughness parameters of both boundaries, with the root mean square (rms) values cross-validated using atomic force microscopy. Notably, the rms values derived from optical measurements and atomic force microscopy show excellent agreement. These findings confirm the reliability of the optical method for the detailed characterization of thin films with differently rough boundaries, supporting the applicability of the proposed method in high-precision film analysis.

Eccentric magnetic abrasive finishing of 316 steel

This paper presents a new method of eccentric magnetic-abrasive finishing as applied to 316 stainless steel. The proposed solution is based on solid ferromagnetic abrasive grains (Fe-Si) held by an external magnetic field. A workpiece fixed in a holder with a certain eccentricity is inserted between the grains and the holder is rotated. The use of an additional eccentricity has a significant impact on the nature of the process, in particular, it increases the speed of the sample relative to the abrasive grains, makes it possible to use more abrasive grains, induces mixing abrasive grains, which can prolong their active life time. In this study, a three-factor, five-level design of experiment was conducted. The variable parameters were: machining time, eccentric value, and rotational speed. Samples in the form of rollers with a diameter of 3 mm were mounted in a special holder that allowed to obtain the assumed eccentricity. Based on the results obtained, regression equations were developed for selected roughness parameters Ra, Rz, Rq, Rt. The value of Ra roughness decreased from the initial value of 0.575 μm to a value below 0.1 μm (an 80% decrease) in 9.1 min. The results obtained provided the basis for further research in conducting eccentricity in magnetic-abrasive machining as an intensifying element of the process.