Surface Roughness Research Articles

Assessing the impact of marine growth on the structural integrity of jacket platforms

ABSTRACT The marine organisms of the jacket platform will directly affect the surface roughness and hydrodynamic coefficient of the platform. Therefore, it is of great significance to effectively analyze the influence of the attachment of marine growth on the structural performance of the platform. Firstly, the distribution law of marine growth was established by the statistical data in Bohai Sea of China. Secondly, the hydrodynamic coefficients of the platform which were changed due to marine growth were determined, and the finite element model of the platform was established. Finally, the finite element simulation results of the platforms with attachment patterns of no marine growth, uniform marine growth, and non-uniform marine growth respectively were compared. It is shown that the calculation results of the platform with uniform marine growth were relatively conservative. Meanwhile, the attachment of marine biofouling produced a significant effect on the structural hydrodynamic load, etc. of the platform.

Analysis of Resistance in Magnetic Flux Leakage (MFL) Detectors for Natural Gas Pipelines

This study systematically explores the sources and influencing factors of resistance encountered by magnetic flux leakage (MFL) detectors in natural gas pipelines through a theoretical analysis, experimental investigation, and numerical simulation. The research methodology involves the development of a fluid–structure interaction model using ABAQUS 2023 finite element software, complemented by the design and implementation of a pull-testing platform for MFL detectors. This platform simulates detector operation under various interference conditions and quantifies the resulting frictional resistance. The findings reveal that the primary source of frictional resistance is the contact interaction between the MFL detector and the pipeline wall. Key factors influencing the magnitude of this resistance include the detector’s mass, the structural design and materials of the sealing cups and support plates, as well as the surface roughness of the pipeline. Both experimental results and numerical simulations demonstrate a pronounced increase in frictional resistance with heightened interference levels. The theoretical model exhibits strong agreement with experimental data, though deviations are observed under conditions of severe interference. This study provides a detailed understanding of frictional resistance patterns under diverse structural and operational scenarios, offering both theoretical guidance and practical recommendations for the design of low-resistance MFL detectors.

Machining Eco-Friendly Jute Fiber-Reinforced Epoxy Composites Using Specially Produced Cryo-Treated and Untreated Cutting Tools

In recent years, consumers have become increasingly interested in natural, biodegradable and eco-friendly composites. Eco-friendly composites manufactured using natural reinforcing filling materials stand out with properties such as cost effectiveness and easy accessibility. For these reasons, in this research, a composite workpiece was specially manufactured using eco-friendly jute fibers. Two cost-effective cutting tools were specially produced to ensure high-quality machining of this composite workpiece. One of these specially manufactured cutting tools was subjected to DC&T (deep cryogenic treatment and tempering) processes to improve its performance. At the end of the research, when the lowest and highest Fd (delamination factor) values obtained with DC&T-T1 and T1 cutting tools were compared, it was observed that 5.49% and 6.23% better results were obtained with the DC&T-T1 cutting tool, respectively. From the analysis of the S/N (signal-to-noise) ratios obtained using Fd values, it was found that the most appropriate machining parameters for the composite workpiece used in this investigation were the DC&T-T1 cutting tool, a 2000 rev/min spindle speed and a 100 mm/min feed rate. Through ANOVAs (analyses of variance), it was discovered that the most significant parameter having an impact on the Fd values was the spindle speed, with a rate of 53.01%. Considering the lowest and highest Ra (average surface roughness) values obtained using DC&T-T1 and T1 cutting tools, it was seen that 19.42% and 16.91% better results were obtained using the DC&T-T1 cutting tool, respectively. In the S/N ratio analysis results obtained using Ra values, it was revealed that the most appropriate machining parameters for the composite workpiece used in this investigation were the DC&T-T1 cutting tool, a 2000 rev/min spindle speed and a 100 mm/min feed rate. In the ANOVAs, it was revealed that the most significant parameter having an effect on the Ra values was the feed rate at 37.86%.

3D printing of biomimetic hierarchical surface textures using L-PBF for improving tribological performance of Ti6Al4V alloy

Energy and material losses due to friction and wear during the use of materials bring about very serious costs in every sector. In order to minimize friction and wear losses of materials, different surface engineering applications are used, especially surface coatings, thermal, mechanical and thermochemical processes. On the other hand, it has been shown in recent years that the tribological properties of materials can be controlled by creating different types of biomimetic hierarchical patterns on the surface of materials. Therefore, this study investigates both the individual and the synergetic effects of both biomimetic surface textures and thermal oxidation process on the tribological performance of Ti6Al4 V alloy. For this purpose, hierarchical models were produced using the laser powder bed fusion (L-PBF) technique, which is one of the additive manufacturing methods. Snake skin, shark skin and tree frog models were used as biomimetic hierarchical models. Additionally, flat and random snake skin models were used to examine the effect of texture orientation. Moreover, thermal oxidation was carried out at 700 ⁰C for 2 h and 4 h and the wear tests were carried out using a reciprocation-type tribo-tester under dry and simulated body fluid (SBF) conditions. As the oxidation time increased, the hardness and surface roughness of the material increased. A significant improvement in the wear rate of biomimetic models was observed compared to the non-textured sample. Lower tribological performance was observed in the tree frog model (hexagonal geometry) compared to other biomimetic models due to the presence of sharp corners. In particular, the snakeskin model provided the best wear rate because it trapped wear residue and provided additional hydrodynamic pressure. The highest tribological performances for all samples were observed in the samples oxidized at 700 ⁰C for 4h.

Effect of sodium hypochlorite and EDTA pretreatment on the resin infiltration efficacy and acid resistance of enamel white spot lesions: an in vitro study

BackgroundThis in vitro study aimed to evaluate the effect of sodium hypochlorite (NaOCl) and ethylene diamine tetraacetic acid (EDTA) as pretreatments on the resin infiltration efficacy and acid resistance of enamel white spot lesions (WSLs).MethodsEnamel blocks prepared from the buccal surfaces of sound human premolars were placed in a demineralisation solution for 3 days to establish artificial enamel WSLs. All the blocks with WSLs were randomly divided into four groups (n = 40 per group): RI (Control): resin infiltration only. N/RI: 5.25% NaOCl pretreatment + resin infiltration; E/RI: 17% EDTA pretreatment + resin infiltration; NE/RI: combined pretreatment of 5.25% NaOCl with 17% EDTA + resin infiltration; Enamel pore exposure was measured by using SEM observation and Image J software in each group after pretreatment prior to resin infiltration (n = 8 per group). Resin penetration depth and enamel surface microhardness were assessed after resin infiltration (n = 8 per group for each test) by a confocal laser scanning microscope and a Vickers’ microhardness test respectively. The remaining specimens were subjected 7 days of pH cycling after which surface enamel roughness and microhardness were assessed by an atomic force microscope and a microhardness test respectively.ResultsCompared to the control group, the enamel surface pore exposure (p = 0.007), resin penetration depth (p = 0.011) and enamel surface microhardness (p < 0.001) were all significantly increased after the pretreatment of 5.25% NaOCl alone or combined with 17% EDTA by one-way ANOVA. After pH cycling, no significant differences were found in enamel surface roughness or microhardness among the four groups (p = 0.55) by two-way ANOVA.ConclusionsEnamel surface pretreatment of 5.25% NaOCl or combined with 17% EDTA improved the efficacy of the resin infiltration of WSLs, but might be useless in enhancing the acid resistance of resin-infiltrated WSLs.

Effect of feed rate during induction hardening on the hardening depth, microstructure, and wear properties of tool-grade steel work roll

Rolls are the most critical yet vulnerable parts of cold rolling mills. It is crucial for them to withstand long rolling campaigns without losing surface roughness or incurring damage. Newly developed rolls are made from tool-grade steel with high roughness, lower wear, and high damage resistance. One of the most important advantages is the elimination of the need for chrome plating, which is currently widely used on standard steel rolls but is ecologically harmful. We investigated a type of steel with 8% chromium for use in cold rolling using light optical microscopy (LOM), X-ray crystallography (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), hardness measurements, and tribological tests. In this study, a roll with a diameter of 325 mm was electro-slag remelted and forged, machined to a diameter of 305 mm, and quenched and tempered to simulate industrial roll production. A forged roll was induction heated and hardened at four different feed rates (i.e., 24 mm/min, 30 mm/min, 36 mm/min, and 42 mm/min), tempered at 515℃ for 24h and again at 480℃ for 24h, and dissected for in-depth analysis. We identified a clear relationship between the feed rate of the roll during induction hardening and the depth of hardness, the sizes of carbides, and the wear properties of the roll. By reducing the feed rate of the roll through the inductor, we increased the depth of the hardened layer from 16 mm (at a feed rate of 36 mm/min) to 25 mm (at a feed rate of 24 mm/min), which is a 56.25% increase. Such an increase is expected to extend the lifespan of the working roll without having negative effects on the wear resistance and other important parameters. XRD analysis showed that the sample had a 0.4% residual austenite, which means it had a significantly lower risk of roll damage during operation than standard steel grades

Advances in constructing Carbon Fiber‐MXene multilevel structures to reinforce interfacial properties of carbon fiber reinforced polymer composites

AbstractCarbon fiber reinforced polymers (CFRPs) have received widespread attention due to their excellent mechanical properties. However, the poor interfacial properties between CF and resin matrix urgently need feasible and efficient surface modification strategies of CF to regulate the interface. Due to its unique layered structure and abundant surface groups, MXene has been increasingly used in the field of CFRP interfacial modification in recent years. It possesses the advantages of good stability, large specific surface area, abundant adsorption sites and rich functional groups, which could effectively improve surface polarity, roughness and wettability of carbon fibers, thus enhancing effective interfacial bonding and enabling hierarchical regulation of interface in CFRPs. This paper reviews feasible strategies for constructing CF‐MXene multilevel structures, including electrophoretic deposition, chemical grafting, electrostatic self‐assembly, and sizing coating. Then, the strengthening mechanism involving surface morphology, mechanical properties, and interfacial strength of CFRPs are systematically evaluated centered on interfacial activity, interfacial adhesion, surface roughness and surface energy. Meanwhile, the problems in introducing MXene to CF surfaces and future research directions are systematically prospected. This paper could provide valuable guidance to construct CF‐MXene multilevel structures to reinforce interfacial properties of CFRPs composites, thus realizing hierarchical modulation of CFRPs interfaces.Highlights A feasible strategy for constructing CF‐MXene multilevel structures is built. The main methods for constructing CF‐MXene multilevel structures are provided. Treatment processes and reinforcing mechanisms of CFRPs are evaluated.

Thermo-responsive microparticle swimmer as a remote tool for cell delivery in tissue engineering

Developing biocompatible and flexible cell manipulation tools is crucial for effective cell delivery in tissue engineering. Herein, thermo-responsive microparticle swimmers, composed of an alginate core and a rough gelatin surface, are developed as a tool for remote cell manipulation and the construction of patterned cell models. The microparticles are fabricated using a novel bio-friendly surface assembly strategy, which leverages morphology-induced gelatin adsorption combined with temperature-cycling crosslinking to deposit multiple gelatin layers onto microfluidic-derived rough microparticles. Gelatin molecules can adsorb onto the rough surface at 25 °C and become cross-linked at 4 °C to form a stable coating layer while preserving the coarse morphology for additional assembly cycles. The gelatin layers remain intact at room temperature for cell loading and transport, but rapidly dissipate at 37 °C, enabling cell release. Moreover, complex manipulations of living cell populations, such as remote tweezing, can be achieved by the introduction of magneto-responsive moieties. These versatile microparticles provide an efficient tool for the in vitro construction of flexible and dynamic patterned cell models, with promising applications in tissue engineering, drug screening, and organoid development.

Optimizing dental composites with nano limestone and tricalcium particulate fillers: A study on physical and mechanical properties

This study investigates the enhancement of dental composites using nano limestone and tricalcium phosphate fillers. Five composite formulations (TLC0-TLC4) were developed using organic polymers (Bis-GMA, TEGDMA, DMAEMA, CQ) and inorganic fillers. The methodology involved fabricating these composites and evaluating their physical and mechanical properties, including density, water absorption, solubility, polymerization shrinkage, hardness, compressive strength, and surface roughness. Results showed that density and voids increased with filler content, with TLC4 achieving the highest density at 1.39 ± 0.16 g/cm³. Water absorption and solubility increased, while polymerization shrinkage decreased to 0.66 ± 0.05% in TLC4. TLC4 demonstrated the highest hardness (72.8 ± 2.4 H.R.V.), compressive strength (248.41 ± 3.11 MPa), and surface roughness (0.62 ± 0.25 µm). Thermal analysis revealed significant weight loss and decomposition, while Fourier-transform infrared spectroscopy analysis provided detailed chemical composition insights. Wear resistance was evaluated through pin-on-disc tests and signal-to-noise ratio analysis, with FE-SEM confirming TLC4's superior performance. VIKOR analysis using the ENTROPY method ranked TLC4 as the most effective composite. This study offers valuable data for selecting and optimizing restorative dental materials.

Bio-colonisation, durability, and microstructural analysis of concrete incorporating magnetite and oyster shell waste aggregates in marine environment

This study evaluates the impact of bio-colonisation and seawater attack on the durability, microstructure and mineralogy of two distinct concrete formulations. These formulations are designed to meet the specifications of marine infrastructure applications, particularly those intended as biomimetic solutions for infrastructures typically used for boat anchoring, which are commonly responsible for the displacement and destruction of marine habitats. The first formulation incorporates magnetite aggregates, resulting in a heavy concrete capable of stabilising the base structure of the biomimetic concrete mooring. In the second formulation, natural gravel is partially substituted by oyster shell waste, to reduce the carbon footprint of these marine infrastructures. Experimental tests were conducted to evaluate the bio-colonisation and durability of the two concrete formulations under marine exposure. After 24 months of immersion, the surface biomass on both formulations exhibited similar kinetic bio-receptivity, primarily attributed to the binder and surface roughness rather than the type of aggregates used. The porosity accessible to water decreases in marine conditions, suggesting that the biofilm contributes to this decrease. Durability results indicate that while both concrete types deteriorate under seawater exposure, the oyster shell aggregates demonstrated better resilience to natural seawater aggressiveness compared to magnetite aggregates over long-term exposure. Elemental mapping showed no obvious zonation of elements. However, a slight increase in surface roughness was observed, with no macroscopic damage detected. This research enhances our understanding of how magnetite and oyster shell waste aggregates respond to bio-colonisation and seawater attack, which are critical factors in the development of biomimetic marine infrastructure.

Multi-Mechanism Collaborative Bionic Fixation Technique Between a Wide Range of Solid Interfaces.

For rough surfaces, stable, fast, and repeatable fixation has wide applicability in transportation, fire protection, and other fields. Different rough surfaces present technical challenges for achieving convenient and reliable fixation. Based on the highly adhesive attachment structures of typical organisms, a multi-mechanism (negative pressure adsorption, mechanical locking, and chemical bonding) cooperative bionic fixation device is proposed. The device is equipped with a suction disc with gradient guide channels, a microneedles friction-enhancing unit, and fast-curable UV glue. These components work together to complete the fixation. The detachment work (max. 5.7 and 5.5 J) and pull-off force (max. 377 and 175 N) are evaluated on sandpaper of different roughness under vertical and horizontal pulling respectively. By analyzing the detachment process and experimental curves, the cooperative principle of the multi-mechanism is identified. In addition, the microneedles with soft backing at the bionic fixation device bottom improve its adaptability to rough surfaces. The gradient guide channels of the suction disc create Laplace pressure to speed up the UV glue flow and shorten fixation time. Furthermore, its applicability is demonstrated by combining it with monitoring equipment and an adult to attach to rough surfaces.

Dominant Role of Surface Peak-Valley Features in Droplet Infiltration Dynamics.

In this study, droplet infiltration dynamics on microtextured surfaces is explored to demonstrate the dominant role of surface peak-valley features in the capillary-driven wetting process. Even though two rough surfaces have nearly the same roughness, the microtopography and distribution of surface peaks and valleys may be completely different, leading to variations in liquid infiltration characteristics. Experimental results show that under the same surface roughness (Sa = 12.0 μm), the positively skewed surface dominated by micropillars (Ssk > 0) is more conducive to liquid infiltration compared with the negatively skewed surface dominated by micropits (Ssk < 0). The physical mechanism is fully analyzed in terms of the equilibrium of the air-liquid interface by constructing a hydrodynamic model. This study also demonstrates that the dominant influence of surface peak-valley features on droplet infiltrating dynamics is independent of the materials. Moreover, the cooling efficiency of the prepared surfaces is compared, and the results indicate that the micropillar surfaces with positive skewness exhibit superior heat dissipation performance under similar conditions because of their excellent infiltration features and large spreading area, proving that positively skewed surfaces have high utilization potential in high-density heat dissipation technology.

Influence of wood modification on parameter settings and treatment results in CO2 laser structuring of beech veneers

In this study, the possible influences of thermal modification of wood on the quality of laser texturing of beech veneers are investigated by comparing native and thermally modified samples. By varying the process parameters of a CO2 laser, the surfaces of both types of veneer were textured and the resulting surface roughness and aspect ratios were analyzed in order to evaluate the efficiency of the laser texturing and the quality of the textures produced. The main results show that the thermal modification of the wood influences the cutting widths, the removal depths, and the surface roughness, with thermally modified veneers generally having larger cutting widths and different removal depths compared to native veneers, indicating the influence of the wood modifications on the material physical and chemical properties and their interaction with the laser processing. Furthermore, the study shows how the laser processing parameters—feed rate and laser power—influence the surface quality and structural dimensions of the engraved lines, and establishes that the moisture content of the wood has a significant influence on its thermal conductivity and thus on the laser cutting process. The research work highlights the complexity of laser texturing of wood and emphasizes the need to take into account the change in the intrinsic properties of the material as a result of thermal modification.

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.

Shear Behavior and Acoustic Emission Characteristics of Propped Rough Fractures

AbstractShearing stimulation with proppant is widely used in geothermal and hydrocarbon reservoirs. However, the shear behavior associated with proppant-proppant and proppant-fracture interactions has not been clearly elaborated. This paper investigates surface damage and the interactions between proppant and surface roughness through direct shear tests with acoustic emission (AE) monitoring. The AE events show distinct spatial and temporal distribution patterns under the influence of proppant. The small magnitude AE events, representing proppant slipping and crushing, start to occur in large areas from the beginning of the shear deformation, and the large magnitude AE events occur mostly at the peak and during the residual phase and are concentrated on asperities. Crushed proppant grains and asperities form a gouge layer that prevents further damage to the fracture surface, reduces shear dilation and promotes aseismic creep. Fine proppant grains tend to remain intact, while the coarse proppant grains tend to be crushed. Our results suggest that acoustic emission characteristics can be used to infer different stages of shear behavior of propped fractures. These findings enhance our understanding of the shear behavior of propped fractures and provide evidence for monitoring their conditions using seismic signals.

Surface characteristics evolution of 316L stainless steel induced by tension loading

316L stainless steel has been employed as a medical implant material owing to its advantageous biocompatibility and durability. The microstructure and surface characteristics of 316L play a crucial role in implant application. Diverse processing methods were utilized to modify the surface properties of 316L to customize the characteristics of medical devices. Mechanical deformation induces changes in the microstructure and causes changes in surface topography. In this study, we introduced deformation to 316L by applying uniaxial tension at strain values ranging from 2% to 25%. During sample preparation, electrochemical polishing was employed to eliminate the deformed layers generated by mechanical grinding. After the tensile test, a contact angle test was conducted. The surface relief of 316L was examined using three-dimensional (3D) laser scanning microscopy and atomic force microscopy. X-ray diffraction with CuK radiation in the Bragg–Brentano (θ–θ) mode was also employed to identify the phase transformation. It can be concluded that higher strain levels increased surface roughness and the number of slip lines. At higher strain levels, samples exhibited a martensitic transformation, affecting topography changes and the surface free energy. The contact angle measurement results and surface free energy determination showed improved wettability following plastic deformation. Determining the factors that affect surface wettability requires an understanding of the relationship between surface free energy, topography, and surface roughness. Deformation-induced martensite can significantly increase the surface free energy and wettability of 316L stainless steel (SS) by altering strain levels. It is important to consider surface characteristics to understand slip mechanisms at grain boundaries, particularly in cases where surfaces have been electropolished. Nevertheless, the surface also manifested deformation-induced martensitic (DIM) transformation, potentially posing a risk to the passive film and contributing to corrosion, consequently reducing the implant’s lifespan.

Labyrinth seal design for space applications

Labyrinth seals, extensively used in space applications, serve to prevent the loss of liquid lubricants and shield satellite subsystems from contamination. These seals are essential for the reliable functioning of bearings and for protecting satellite subsystems from contamination. This study compares analytical predictions of lubricant loss against experimental measurements and computer simulations to optimize labyrinth seal configurations. Analytical models tend to overestimate mass loss by 5–8 times compared to experimental data, indicating limited reliability for complex seal geometries. Simulations using MolFlow+ and COMSOL Multiphysics align closely with experimental results, providing accurate mass loss predictions. Key findings highlight that labyrinth length, width, and surface roughness are critical factors in minimizing evaporative mass loss. Notably, stepped labyrinth seals with relief grooves and optimized step positioning effectively reduce molecular beaming effects and improve sealing performance compared to straight geometries. Effective sealing not only reduces mission failures but also helps to minimize space debris, thereby promoting safer satellite missions.

Use of BODIPY and BORANIL Dyes to Improve Solar Conversion in the Fabrication of Organic Photovoltaic Cells Through the Co-Sensitization Method

This work addresses the implementation of the co-sensitization technique to increase the energy efficiency of organic dye-sensitized solar cells (DSSCs). Fluorescent dyes derived from boron complexes— (BORANIL) and (BODIPY)— were successfully synthesized and used as co-sensitizers in different volume percentage ratios to verify the most effective concentration for photon capture through these sensitizers. The dyes were optically characterized using ultraviolet–visible spectroscopy (UV-VIS) and Fourier transform infrared (FTIR), analyzing them through the optical performance of each hybrid combination of dyes, an optimization of the photon collection capacity in the tests performed in a volume percentage ratio of 25:75 or 1:3. The morphology and surface roughness of the electrodes were analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Through electrochemical characterizations, it was found that the highest photovoltaic conversion efficiency was obtained with the ATH1005 (D) dye mixed with ATH032 (G) in the proportion of 25%:75% or DG 1:3, with efficiency (η) of 3.45%, against 2.43% and 1.90% for DG 1:1 and DG 3:1 cells, respectively. Cells with BODIPY dyes also present higher conversion efficiencies compared to BORANIL cells. The results corroborate the presentation of organic solar cells as a viable option for electricity generation.

Enhancing power density in D-mode GaN HEMT direct-current triboelectric nanogenerators through ICP-etched surface engineering

In the evolving landscape of energy harvesting, the refinement of friction properties in metal-semiconductor direct current triboelectric nanogenerators (MSDC TENGs) has garnered significant attention. While prior research predominantly concentrated on achieving superior performance in MSDC TENGs through material manipulation, structural adjustments, and friction mode optimization, there has been a noticeable dearth of investigations into surface engineering or modification of semiconductor materials. In this paper, the surface patterning of depletion mode GaN-based high electron mobility transistor (D-GaN HEMT) as friction materials is done by inductively coupled plasma etching method, involving both mechanism analysis and experimental exploration. Through modulation of etching depth and pattern density, a systematically arranged diamond pattern is created on the surface, augmenting surface roughness and charge density. Consequently, the surface-patterned D-GaN HEMT TENG achieves a maximum short-circuit current of 60 µA and a peak power density of 4.05 W/m², which is about 2.8 times greater than the pristine D-GaN HEMT TENG. Furthermore, the power supply capabilities of the surface-patterned D-GaN HEMT TENG are scrutinized, revealing its proficiency in capacitive charging and discharging. The successful activation of a deep ultraviolet LED underscores its potential applications in ultraviolet disinfection. This research holds substantial significance in optimizing the power generation efficiency and performance of MSDC TENGs employing D-GaN HEMT.

Investigation of photocatalysis/vibration-assisted finishing of reaction sintered silicon carbide

Reaction-sintered silicon carbide (RS-SiC) is an ideal material for spacecraft reflectors due to its excellent mechanical properties. However, its high hardness, brittleness, and multiphase nature pose significant challenges to conventional polishing techniques. To address this, photocatalytic modification and vibration assistance have been employed to enhance both precision and efficiency in the polishing process of RS-SiC. In this work, the oxidative properties of RS-SiC surface during photocatalytic reaction are elucidated using molecular dynamics simulation coupled with X-ray photoelectron spectroscopy analysis. Parameters including concentration of TiO2 and H2O2, frequency, and amplitude of vibration table are optimized, indicating that the TiO2 concentration serves as the primary influence on the oxidation rate. Further investigation into the effects of spindle rotation speed and polishing pressure during the material removal process shows that roughness is minimized when material removal rate equals oxidation rate. Ultimately, on the basis of optimized parameters, a material removal rate reaching 2.1 μm/h and surface roughness of 0.26 nm in Ra are achieved. This study provides significant guidance for the further application of photocatalysis/vibration-assisted finishing technology.