Surface Geometric Structure Research Articles

Three-Dimensional Multilayer Vertical Filament Meshes for Enhancing Efficiency in Fog Water Harvesting.

Novel types of vertical filament mesh (VFM) fog harvesters, 3D VFM fog harvesters, and multilayer 3D VFM fog harvesters were developed by mimicking the water-harvesting nature of desert beetles and the spider silks from fog. Four different types of polymer filaments with different hydrophilic–hydrophobic properties were used. The polymer filaments were modified with the polyurethane–sodium alginate (PU–SA) mixture solution, and a simple spraying method was used to form alternating 3D PU–SA microbumps. Polymer VFMs exhibited a higher fog-harvesting efficiency than the vertical metal meshes. Moreover, the hydrophobic VFM was more efficient in fog harvesting than the hydrophilic VFM. Notably, the fog-harvesting efficiency of all VFMs increased by 30–80% after spraying with the mixed PU–SA solution to form a 3D geometric surface structure (3D PU–SA microbumps), which mimicked the desert beetle back surface. This modification caused the fog-harvesting efficiency of PTFE 3D VFM to be thrice higher than that of Fe VFM. This increase was attributed to the improved synergistic effects of fog capturing, droplet growing, and droplet shedding. The multilayer VFMs were more efficient in fog harvesting than the single-layer VFMs because of a larger droplet capture area. The fog-harvesting efficiency of two-layer and four-layer polymer VFMs was approximately 35% and about 45% higher than that of the single-layer polymer VFMs, respectively. The four-layer PTFE 3D VFM with the type B PU–SA bump surface (bump/PU–SA) had the highest efficiency of 287.6 mL/m2/h. Besides the high fog-harvesting efficiency, the proposed polymer VFMs are highly stable, cost-effective, rust-free, and easy to install in practical applications. These advantages are ascribed to the elasticity of the polymer filaments. This work provides new ideas and methods for developing high-performance fog harvesters such as the 3D VFM.

The Effect of Laser Beam Processing on the Properties of WC-Co Coatings Deposited on Steel.

The main objective of the present work is to determine the effects of laser processing on properties of WC-Co electro-spark deposited (ESD) coatings on steel substrates. Tungsten carbide coatings have been applied to steel substrates using a manual electrode feeder, model EIL-8A. The laser beam processing (LBP) of electro-spark coatings was performed using an Nd:YAG fiber laser. The microstructure and properties of laser treated/melted coatings were evaluated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), surface geometric structure (SGS) and roughness measurements and adhesion, microhardness, residual stresses, corrosion resistance and application tests. The obtained experimental data were subjected to statistical analysis and multidimensional numerical and visual exploratory techniques. It has been shown conclusively that the laser-treated ESD WC-Co coatings are characterized by lower microhardness, higher resistance to corrosion, increased roughness and better adhesion to the substrate. LBP homogenizes the chemical composition, refines the microstructure and heals microcracks and pores of ESD coatings. The laser treated ESD WC-Co coatings can be used in frictional sliding nodes (e.g., on the front seal rings used in pumps) and as protective layers.

Soft Gripper Design Based on the Integration of Flat Dry Adhesive, Soft Actuator, and Microspine

Soft grippers can be used to grasp objects with various geometric surface structures or stiffness but typically encounter difficulty in providing high grasping force. Although the combination of soft grippers with adhesive technology can increase their load capacity, this approach has disadvantages of compatibility and limited application range. This article has reported a bioinspired design of a soft gripper that integrates flat dry adhesive, soft actuator, and microspine to improve the comprehensive grasping ability of the soft gripper on smooth or rough surfaces. The adhesive strength of flat dry adhesives with different thickness or cross-linking ratios was investigated to ensure that a large grasping force can be provided. Soft actuators with uniform and nonuniform cross-sectional heights were compared, and results indicated that the soft actuator with a nonuniform cross-sectional height exhibited remarkable advantages for designing the integrated gripper. A microspine-spring-shape memory alloy coil structure was designed to control the retraction and protrusion of microspine and distribute the load on rough surfaces evenly. The proposed integrated gripper with the aforementioned design can lift regularly or irregularly shaped objects with smooth or rough surfaces and provide a higher adhesive force than the nonadhesive gripper. After inserting a flexible pressure film sensor into the soft gripper, the surface property of the grasped object can be measured, which is beneficial for the selection of a suitable grasping strategy in unknown environments. The designed gripper can be used in many applications, such as in unmanned aerial vehicles, industrial manipulators, and climbing robots.

Mass wear application of cooperated elements for evaluation of friction pair components condition

In this study, the influence of the geometrical surface structure shape on wear process of friction pairs elements with conformal contact was analyzed. Characteristics of the machine elements surface layer were described with special distinction of importance of the surface structure directivity and isotropy in terms of the surface layer transformation. This work presents the results of experimental tests in which the following input factors were used: specimen and counter-specimen ridge angle of intersection (0°; 30°; 45°; 60°; 90°) and specimen and counter-specimen clamp (1.0; 1.5; 2.0 MPa). The changes of the surface layer were recorded as a function of a specimen mass changes. Based on the conducted research, it was found that the ridge angle of intersection on the specimen and counter-specimen has a significant impact on the wear process intensity. The changes were uttermost for 0° angle and slightest for 9°. It was also found that the observed changes have a larger gradient for higher specimen load values. Thus, the significance of the geometrical surface structure directivity influence on the friction pair elements wear process intensity was confirmed.

Low temperature scanning tunneling microscopy and spectroscopy on laterally grown InxGa1−xAs nanowire devices

Laterally grown InxGa1−xAs nanowires (NWs) are promising candidates for radio frequency and quantum computing applications, which, however, can require atomic scale surface and interface control. This is challenging to obtain, not least due to ambient air exposure between fabrication steps, which induces surface oxidation. The geometric and electronic surface structures of InxGa1−xAs NWs and contacts, which were grown directly in a planar configuration, exposed to air, and then subsequently cleaned using atomic hydrogen, are studied using low-temperature scanning tunneling microscopy and spectroscopy (STM/S). Atomically flat facets with a root mean square roughness of 0.12 nm and the InGaAs (001) 4 × 2 surface reconstruction are observed on the top facet of the NWs and the contacts. STS shows a surface bandgap variation of 30 meV from the middle to the end of the NWs, which is attributed to a compositional variation of the In/Ga element concentration. The well-defined facets and small bandgap variations found after area selective growth and atomic hydrogen cleaning are a good starting point for achieving high-quality interfaces during further processing.

Evaluation of conifer and broad-leaved barriers in intercepting particulate matters in a wind tunnel

ABSTRACT Fugitive dust is an important source of particulate matters (PM) emission in the air. Vegetation barriers (VBs) can be an effective way to mitigate PM from fugitive dust sources. It is meaningful to choose appropriate plants to establish VBs that can efficiently capture PM from various sources. This study was conducted to establish comparable and repeatable conditions to evaluate the capability of different VB species in mitigating PM emission from certain fugitive dust source. The airflow around two VBs and their PM interception mechanism was studied in a wind tunnel with simulated PM emission source of animal feeding operations. The species used for the two VBs were conifers represented by Pinus Sylvestris var. mongolica Litv. (PS) and the broad-leaved species represented by Syringa Oblate Lindl. (SOL). The results showed that the interception efficiency of the PS vegetation barrier was only slightly lower than that of SOL vegetation, while the PS had a lower effect on the wind speed at the similar leaf surface area. On the other hand, there were a large number of disordered “ridged” stripes on the microscopic structure of the hydrophilic leaves of SOL and PS, and a large amount of fine particles deposited on the leaves were observed, indicating that the microscopic geometric surface structure increased the deposition efficiency of the particles. These findings help to better understand the potential of tree species to reduce PM in environments. Implications: To evaluate the capability of different VB species in mitigating PM emission from certain fugitive dust source, airflow around the two VBs and their PM interception mechanisms were studied in wind tunnels with comparable and repeatable conditions. The results showed that the interception efficiency of the Pinus Sylvestris var. mongolica Litv. (PS) was only slightly lower than that of the Syringa Oblate Lindl. (SOL) vegetation, while the PS had a lowering effect on the wind speed at the same low leaf surface area. Microscopic analysis of leaves surface indicated that the microscopic characteristics increased the deposition efficiency of the particles.

A New Concept in Minimally Invasive Embryo Transfer

Abstract Considerable variation in embryo transfer (ET) catheter types, diverging opinions on their quality and functionality, complications following the insertion of catheters, low efficiency of the application of ET methods in humans, and their widely varying efficiency in animals demonstrate the need to improve ET methods and to look for new types of catheters. Such an opportunity is offered by the introduction of catheters made of new-generation biomaterials. This study was aimed to introduce a new generation of biomaterials into reproductive biotechnology. New-generation materials were compared with materials that have been used for many years, and the functionality of newly produced catheters was compared in vivo. Five types of biomaterials were tested: polycaprolactone (PCL), dibutyryl chitin (DBC), polypropylene (PP), polyethylene (PE) and polylactide (PLA). The study was carried out in two stages. Firstly, the basic utility parameters such as geometric stability, surface structure and catheter resistance were evaluated. Subsequently, the biocompatibility of selected biomaterials in embryo cultures was examined, and the development potential of the obtained blastocysts was evaluated. In the second stage, in vivo with live animals, the biomaterials were tested for biocompatibility and the obtained catheters were examined for their ET functionality. Efficiency with the use of the newly produced catheters was determined, the quality of the blastocysts obtained after embryo culture in the uterus was assessed, and oviducts were subjected to histopathological examination after embryo transfer. Of the tested biomaterials, only polyethylene (PE) showed adequate biological and material properties and proved suitable for production of ET catheters.

Experimental Determination of the Surface Geometrical Structure Parameters and Tool Wear During Turning the Polymer Concrete

Abstract The paper presents the results of experimental determination of the Surface Geometrical Structure (SGS) parameters and tool wear during turning the polymer concrete. Until now, all literature reports have shown that the smoothness and roughness of the mineral cast surface was obtained directly from the mold. However, new applications of polymer concrete, even for some parts of the machine tools, forced the producers to carry out machining, which would improve the parameters of the surface layer. The topic of machining ceramic-based composite materials is a new chapter in the field of machining, which has not been sufficiently researched so far. The article describes the process of experimental determination of dependence of surface layer and tools wear parameters from cutting parameters during longitudinal turning of polymer concrete. The turning was carried out using plates made of a cubic boron nitride (CBN). After machining, the surface roughness and the maximum width of the flank wear were measured. On this basis, the mathematical model of the surface layer and tools wear parameters versus cutting parameters were defined. The authors also attempted to explain the phenomena occurring in the machining zone using variable cutting parameters. Microscopic pictures of CBN plates after machining were also performed. After the study, the final conclusions about the machining of mineral cast material were formulated.

Structural and spin state transition in the polar NiO(1 1 1) surface

Geometric and electronic structure of surfaces is of fundamental importance for the understanding of the physical and chemical phenomena of transition metal oxides. Here we report a structural and spin state transition in the NiO(111) surface. Combining aberration-corrected transmission electron microscopy and first-principles calculations, we show that the surface can be stabilized in a bulk-truncated structure and a subsurface tetrahedral reconstructed one, both with a (1×1) periodicity and the hydroxylation ruled out. The transition from the bulk-truncation to the tetrahedral reconstruction is accomplished by the shift of the subsurface Ni atoms from octahedral to tetrahedral position, accompanied by a spin transition from a low-spin state to a high-spin state.

The role of the additive manufacturing process parameters in the shaping of the surface geometric structure during micro-milling

1. AYKUT S., BAGCI E., KENTLI A., YAZICIOĞLU O., 2007, Experimental observation of tool wear, cutting forces and chip morphology in face milling of cobalt based super-alloy with physical vapour deposition coated and uncoated tool, Mater Design, 28, 1880–1888. Google Scholar

The Influence of Selected Selective Laser Sintering Technology Process Parameters on Stress Relaxation, Mass of Models, and Their Surface Texture Quality.

The article presents the results of research on the impact of basic process parameters of selective laser sintering technology on the mass of the produced models (density of the sintered material-polyamide PA 2200), stress relaxation during compression determined in accordance with the ISO 3384 standard, and geometric surface structure parameters (SGPs). During the tests, the influence of process parameters such as the location of the models on the virtual construction platform (printing direction), the density of the energy supplied to the sintered layer of powder, and the layer thickness of the manufactured material layer was taken into account. The test results confirmed that the process parameters have a significant impact on the density of the model material (in the sintered state), the mechanical properties (stress relaxation during compression), and the quality of the surface texture (SGPs). The most favorable positioning variants of the models on the construction platform were determined. The most favorable thickness variants of the combined layers and the density value of the energy supplied to the sintered powder layer were selected, depending on the expected mass, strength, and SGP quality. In addition, it has been shown that it is possible to build models with reduced mass (>20%), while maintaining satisfactory mechanical and qualitative properties of the surface texture.

Surface Treatment for Improving Selected Physical and Functional Properties of Tools and Machine Parts—A Review

Wear resistance, which is one of the main technological quality features of machine parts and tools, is determined by the properties of their surface layer. The demand for high-quality products forces manufacturers to use modern structural and tooling materials as well as efficient and cost-effective methods of their treatment. The paper presents the results of research on selected properties of tools made of tool steels and sintered carbides, as well as parts made of aluminum alloy subjected to selected surface treatment processes, such as mechanical (grinding, turning, milling, burnishing) and thermo-chemical (nitriding, sulfonitriding) processes, and physical vapor deposition (PVD) of coatings. The presented results, including analyses of the surface geometric structure, microstructure, and microhardness, as well as tribological and machining properties of selected materials, indicate the possibility of improving the functional quality of tools and machine parts.

Strain‐Enhanced Metallic Intermixing in Shape‐Controlled Multilayered Core–Shell Nanostructures: Toward Shaped Intermetallics

AbstractControlling the surface composition of shaped bimetallic nanoparticles could offer precise tunability of geometric and electronic surface structure for new nanocatalysts. To achieve this goal, a platform for studying the intermixing process in a shaped nanoparticle was designed, using multilayered Pd‐Ni‐Pt core–shell nanocubes as precursors. Under mild conditions, the intermixing between Ni and Pt could be tuned by changing layer thickness and number, triggering intermixing while preserving nanoparticle shape. Intermixing of the two metals is monitored using transmission electron microscopy. The surface structure evolution is characterized using electrochemical methanol oxidation. DFT calculations suggest that the low‐temperature mixing is enhanced by shorter diffusion lengths and strain introduced by the layered structure. The platform and insights presented are an advance toward the realization of shape‐controlled multimetallic nanoparticles tailored to each potential application.

Strain-Enhanced Metallic Intermixing in Shape-Controlled Multilayered Core-Shell Nanostructures: Toward Shaped Intermetallics.

Controlling the surface composition of shaped bimetallic nanoparticles could offer precise tunability of geometric and electronic surface structure for new nanocatalysts. To achieve this goal, a platform for studying the intermixing process in a shaped nanoparticle was designed, using multilayered Pd-Ni-Pt core-shell nanocubes as precursors. Under mild conditions, the intermixing between Ni and Pt could be tuned by changing layer thickness and number, triggering intermixing while preserving nanoparticle shape. Intermixing of the two metals is monitored using transmission electron microscopy. The surface structure evolution is characterized using electrochemical methanol oxidation. DFT calculations suggest that the low-temperature mixing is enhanced by shorter diffusion lengths and strain introduced by the layered structure. The platform and insights presented are an advance toward the realization of shape-controlled multimetallic nanoparticles tailored to each potential application.

The Influence of Anodic Alumina Coating Nanostructure Produced on EN AW-5251 Alloy on Type of Tribological Wear Process

The article presents the influence of the anodic alumina coating nanostructure produced on aluminum alloy EN AW-5251 on the type of tribological wear process of the coating. Oxide coatings were produced electrochemically in a ternary electrolyte by the DC method. Analysis of the nanostructure of the coating was performed using ImageJ 1.50i software on micrographs taken with a scanning electron microscope (SEM). Scratch tests of the coatings were carried out using a Micron-Gamma microhardness tester. The scratch marks were subjected to surface geometric structure studies with a Form TalySurf 2 50i contact profiler. Based on the studies, it was found that changes in the manufacturing process conditions (current density, electrolyte temperature) affect changes in the coating thickness and changes in the anodic alumina coating nanostructure (quantity and diameter of nanofibers), which in turn has a significant impact on the type of tribological wear. An increase in the density of the anodizing current from 1 to 4 A/dm2 causes an increase in the diameter of the nanofibers from 75.99 ± 7.7 to 124.59 ± 6.53 nm while reducing amount of fibers from 6.6 ± 0.61 to 3.8 ± 0.48 on length 1 × 103 nm. This affects on a change in the type of tribological wear from grooving to micro-cutting.

Geometric structure modification in cellulose acetate nanofibers and its impact on liquid resistance/repellency

Surface modification—altering geometric structures or surface energy—is a key factor in improving liquid resistance/repellency on a solid surface. In particular, roughness from geometric structures provides void spaces that enhance energy barriers in nanofibers that a liquid droplet should overcome to penetrate, thus preventing the transition of a liquid drop from the Cassie–Baxter state to Wenzel state. In this work, the design of a geometric structure that performs highly in liquid resistance/repellency was proposed by extending the Cassie–Baxter model into cellulose acetate (CA) nanofibers, entrapping SiO2 nanoparticles, and examining the impact of void spaces created by the entrapped SiO2 into nanofibers in prediction and experiment. The extended Cassie–Baxter equation was simplified using H*, which is characterized by Tnp. The prediction and measurement of the apparent contact angle $$ \theta_{nf} $$ in CA-SiO2 nanofabrics showed good agreement, and the results emphasized the role of void space in improving liquid resistance/repellency while minimizing chemical treatments for altering surface energy and geometric structure.

НЕКОТОРЫЕ АСПЕКТЫ НАЗНАЧЕНИЯ ПАРАМЕТРОВ СТРУКТУРЫ ПОВЕРХНОСТИ ДЕТАЛЕЙ МАШИН

The paper considers international experience of assigning requirements of profile assessment of geometrical surface structure to machine parts in technical documentation. The authors have carried out analysis of literature, standards ISO 4288:1996, ISO 1302:2002 and GOST R ISO 4287-2014 that was introduced in January 2016. They have also conducted a comparison of parameters of geometrical surface structure according to GOST 2789-73 and GOST R ISO 4287-2014. The paper shows the peculiarities of designating geometrical structure of machine parts surface according to ISO 1302:2002 and examples of assigning the established requirements. These examples will allow using ISO 1302:2002 for assigning parameters of geometrical surface structure according to GOST R ISO 4287-2014.

Wpływ parametrów skrawania przy toczeniu czołowym na strukturę geometryczną powierzchni stopu CoCr otrzymanego metodą SLM

Research on effect of machining parameters on geometrical surface structure of SLM manufactured CoCr alloy shafts after face turning is presented in the paper. Machining parameters were selected in order to obtain continuous variation of cutting speed at fixed feed ratio for given cutting depth. In consequent steps feed ratio was changed at fixed, unchanged cutting depth. As a criteria of optimal machining parameters, selected surface geometry parameters were measured. Experimental research was carried out by turning with typical tool and commercial cutting inserts

Ocena chropowatości powierzchni oraz dokładności wymiarowo-kształtowej ceramiki Al₂O₃ w stanie utwardzonym po frezowaniu

The effect of technological parameters of machining on surface roughness, dimensional and shape accuracy in the process of milling Al2O3 ceramics in hardened state was evaluated. The unique properties of ceramic materials cause more and more interest in them in various branches of industry. Ceramics in the hardened state can be processed using unconventional methods and conventional methods while maintaining the appropriate technological parameters. Ceramics cutting tests were carried out in a hardened state (face and shape milling) on a CNC milling machine using PCD tools. Geometric surface structure study and measurements of geometric dimensions were made.

Wpływ sposobu cyfrowego przetwarzania danych pomiarowych powierzchni frezowanej na wyznaczenie parametru Sq

Digital processing of recorded measurement data on the milled surface can offer operators many possibilities in the planning metrological procedures processes and give more leeway in the final configuration of the surface geometrical structure condition. Review of the current state of knowledge revolving around surface characteristics, measurement uncertainty and their quality, and primarily reproducibility of measurements not only in the laboratory but also in the industrial environment poses a major challenge. The article presents research works related to the identification of the influence of the measurement data processing method using digital data processing of milled surface on the Sq parameter. The analysis of individual stages of measurement data processing showed the direct influence of data filtration methods on the values of the Sq parameter.