Improved Surface Roughness Research Articles

Growth of ultrathin Bi2Se3 films by molecular beam epitaxy

Bi 2 Se 3 is a widely studied 3D topological insulator having potential applications in optics, electronics, and spintronics. When the thickness of these films decreases to less than approximately 6 nm, the top and bottom surface states couple, resulting in the opening of a small gap at the Dirac point. In the 2D limit, Bi2Se3 may exhibit quantum spin Hall states. However, growing coalesced ultrathin Bi2Se3 films with a controllable thickness and typical triangular domain morphology in the few nanometer range is challenging. Here, we explore the growth of Bi2Se3 films having thicknesses down to 4 nm on sapphire substrates using molecular beam epitaxy that were then characterized with Hall measurements, atomic force microscopy, and Raman imaging. We find that substrate pretreatment—growing and decomposing a few layers of Bi2Se3 before the actual deposition—is critical to obtaining a completely coalesced film. In addition, higher growth rates and lower substrate temperatures led to improvement in surface roughness, in contrast to what is observed for conventional epitaxy. Overall, coalesced ultrathin Bi2Se3 films with lower surface roughness enable thickness-dependent studies across the transition from a 3D-topological insulator to one with gapped surface states in the 2D regime.

INFLUENCE OF CHEMICAL TREATMENT ON THEMECHANICAL PROPERTIES AND MORPHOLOGY OF MUSA PARASIDICA FIBER (PLANTAIN)

By substituting various kinds of cellulosic fibers with synthetic ones, it is possible to create composites that are better for the environment. Pinewood, coir, sisal, plantains, abaca, and banana fibers are all suitable sources of material. The strength of adhesion between the matrix polymer and fiber is the most crucial element in finding appropriate fiber reinforcement in composites. Plantain (Musa parasidica) fibers were treated with an alkaline solution at various concentrations for varying soaking times. An Instron testing machine and a scanning electron microscope (SEM) were utilized to determine the effect of this chemical alteration on the mechanical characteristics and surface morphology of the fiber. Following treatment, fibers had an improved surface roughness and reached an optimal tensile strength of 651MPa, according to micrographs taken with a scanning electron microscope.

Surface Topography and Biocompatibility of cp–Ti Grade2 Fabricated by Laser‐Based Powder Bed Fusion: Influence of Printing Orientation and Surface Treatments

The selective laser melting process, commonly known as laser‐based powder bed fusion (LB‐PBF), enables the production of structures with unprecedented degrees of freedom that represents an excellent condition for development of metallic implants for biomedical applications. Herein, the effects of laser energy density on relative density and microstructure (presence of internal defects) of cp‐TiGd2 fabricated by LB‐PBF are studied. Additionally, the influence of printing orientation and different surface treatments on surface topography and biocompatibility are investigated. The aim of the research is to develop additive manufacturing process parameters that can achieve full density of cp‐TiGd2 with satisfactory biocompatibility, as a low‐cost alternative to biomedical materials such as Ti–6Al–4 V and Ti–6Al–7Nb. A wide range variation of process parameters leads to an optimized process with high density up to 99.97 ± 0.008%, improved surface roughness, and noncytotoxicity in horizontal and inclined as‐built condition, as well as in Al2O3 (blasting angle 0°) condition.

Investigation of electropolishing performance on surface residual stress and morphology of electrical discharge machined maraging steel

Electrical Discharge Machining (EDM)-machined maraging steel components are promising in the application field of aerospace and production tools. However, the unavoidable adverse effects of recast/white layer formation, high tensile residual stress, and micro-crack on the machined surface necessitate post-treatment techniques. The current study proposed Electropolishing (EP) as a post-treatment process to eliminate EDM’s adverse effects. The performance of EP on surface residual stress and morphology of ED machined surface was evaluated for an optimum combination of parameters, including applied voltage, polishing time, agitation, and temperature. Residual stress has been analyzed using the “sin2 ψ method” of X-ray Diffraction (XRD). After EDM, the generated surface residual stress was 407.17 MPa which had been relaxed to 35.27 MPa after EP. The surface morphology of maraging steel surfaces after EDM and EP were compared using an Atomic Force Microscope (AFM) and Field Emission Scanning Electron Microscope (FESEM). It is observed that micro-cracks, globules, voids, and thermal pitting marks were entirely eradicated following EP. It can also be seen that the EP has successfully removed the formed recast layer during EDM after 6 mins of polishing time. An average of 7.94 µm layer has been removed from the surface, removing all the surface defects. The optical profilometer analyzed the surface roughness profiles, and a 78% improvement in surface roughness was observed after EP.

Improvement of the frictional behavior of Al 7075-T6 by ultrasonic-assisted ball burnishing process

Nowadays, 7000 series aluminum alloys, especially, Al 7075 have found extensive applications especially in aerospace industries. Compared to high-strength steel alloys, Al 7075 has exhibited desirable mechanical properties such as high specific strength. However, their corrosion susceptibility and poor abrasion properties have limited the application of these alloys. Complementary operations such as ultrasonic-assisted ball burnishing have been suggested to overcome these limitations. Therefore, in this study, a newly developed 28 kHz ultrasonic-assisted ball burnishing device was designed and fabricated. Then, the effect of burnishing process was experimentally assessed on surface roughness, surface hardness, grain size, friction coefficient, and wear rate of the workpieces made of Al 7075. The results reveal the greater effectiveness of the ultrasonic-assisted ball burnishing process compared to conventional burnishing processes, in terms of improvements in surface roughness, surface hardness, grain size, frictional behavior, and wear rate. The friction coefficient was declined by 36.09% in the case of ultrasonic-assisted ball burnishing which was remarkably higher than conventional burnishing process with 7.39% reduction.

Development of Novel Low-Cost Sustainable Abrasive Flow Finishing Media From Ground Tire Rubber and Its Performance Evaluation

Abstract The present experimental endeavor aims to develop and study the characteristics of a novel ground tire rubber media (GTRM) through rheological, thermal, and mechanical characterizations. Thermogravimetric analysis reveals the presence of natural and styrene butadiene rubber in ground tire rubber (GTR) and confirms the thermal stability of developed GTRM under the working temperature of the abrasive flow finishing (AFF) process. Investigation reveals that incorporating GTR into media improves AFF performance up to 50 phr, after which it degrades due to poor self-deforming characteristics and abrasive holding capacity at higher GTR fractions. It has also been observed that the percentage of oil and the size of the GTR particles are significant media parameters that govern the GTRM property and thus influence its performance. GTRM with bigger GTR produces deep abrasive cut marks and nonuniform shearing. A comprehensive study reveals that GTRM containing 50 phr GTR (80 mesh), 10% oil, and 60% SiC (220 mesh) results in the highest percentage improvement in surface roughness (% ΔRa) of 44% on flat geometry. The same media, but with coarser SiC (80 mesh), was also used to polish a micro-grooved workpiece. Results show 64% improvement in Ra for the top surface and 58% for the bottom, respectively. Both surfaces still contain a few pits and unevenness; however, the surfaces and top edge of the groove became smooth after AFF.

Effect of electrochemical oxidation degree of carbon fiber on the interfacial properties of carbon fiber–reinforced polyaryletherketone composites

Electrochemical oxidation of carbon fiber (CF) is used to enhance the interfacial adhesion of CF-reinforced polyaryletherketone (CF/PAEK) composites. The effect of current intensity parameter on surface structure of CF and interfacial properties of the corresponding thermoplastic composites are deeply investigated. The results show that the current intensity in the range of 80 A–300 A does not lead to a decrease in the mechanical property of CFs. When the current intensity is 200 A, CF/PAEK composites have the highest interfacial performance, which is mainly due to the improvement of CF surface roughness, wettability, and oxygen content. In addition, the degree of graphitization of CF surface is also a crucial factor affecting the interfacial properties of CF/PAEK. The higher the content of carboxyl groups, the more disordered the structures exist on the CF surface, which are not conducive to the strong adhesion of CF to PAEK resin. Therefore, balancing the wettability and graphitization degree of the CF surface is the key to enhancing the CF/PAEK interfacial properties by electrochemical treatment techniques.

Electrochromic and optical studies on Nb2O5–NiO mixed oxide films for smart window applications

Coatings of Nickel oxide (NiO), Niobium oxide (Nb2O5) and their mixed oxide (Nb2O5–NiO) were deposited on glass and conducting glass substrates by simple spin coating technique. Structural, morphological, optical and electrochemical properties of the mixed oxide (Nb2O5–NiO) films were analyzed and the data was compared with individual oxide coatings. As-prepared Nb2O5–NiO coatings showed transparent in nature, while Li + intercalated Nb2O5–NiO (termed as Li–Nb2O5–NiO) coatings were black in color. In addition, Nb2O5–NiO coatings showed better electrochromic reversibility and fast switching. All the as-prepared and Li+ intercalated coatings were subjected to IR absorption studies. Interestingly, Li–Nb2O5–NiO coatings showed better Infra-red (IR) absorption whereas bleached Nb2O5–NiO coatings did not show any remarkable IR absorption. The Li–Nb2O5–NiO coating absorbed about 65% of IR radiation falling on it and allowed the remaining 35% radiation to pass through the coating. In order to prevent the remaining 35% of IR radiation from passing through the coating, laser treatment was carried out on the coating using Pulsed Laser Deposition (PLD) unit. This laser treated Li–Nb2O5–NiO coatings showed better IR reflectance compared to normal Li–Nb2O5–NiO due to its improved surface roughness. It is concluded that the collective effect of IR absorption (by modifying the electronic structure of materials by ion intercalation) and IR reflectance (by increasing the surface roughness) played on a laser treated Li– Nb2O5–NiO coating resulted in a better IR blocking window.

Tuning of electrocatalytic activity of mixed metal dichalcogenides supported NiMoP coatings for alkaline hydrogen evolution reaction

The mixed metal dichalcogenides combination of WS2–MoS2 was coated onto Cu substrate by electroless NiMoP plating technique and the electrocatalytic hydrogen evolution reaction (HER) performance was investigated. The enhanced structural, morphological parameters and boosted electrocatalytic performance of the various metal-metal molar ratio of WS2–MoS2 onto NiMoP plate were identified under variable operating conditions and it was successfully evaluated by various characterization techniques. The well-defined crystalline nature, phase, particle size, structure, elemental analysis and surface morphology of prepared coatings were analyzed by FESEM, XRD, AFM and EDS mapping. The electrochemical analysis was performed using open circuit potential (OCP) analysis, chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), Tafel curves, linear sweep voltammetry (LSV), cyclic voltammetry (CV) and polarization studies to find the activity of prepared electrocatalyst towards electrochemical hydrogen evolution reactions. The performance of bare NiMoP and WS2–MoS2/NiMoP plates were compared and found that the HER activity of NiMoP can be reinforced by composite incorporation through the synergic effect arises with in the catalytic system, which improves surface roughness and enhances the magnitude of electrocatalyst toward HER. The achievement of enhanced catalytic performance of coatings was authenticate by the kinetic parameters such as decreases in Tafel slope (98 mV dec−1), enhanced exchange current densities (9.32 × 10−4 A cm−2), and a lower overpotential. The consistent performance and durability of the catalyst were also investigated. The enhanced electrocatalytic activity of WS2–MoS2/NiMoP coatings increased with respect to the surface-active sites associated with combination of mixed dichalcogenides and the synergic effect arises in between different components present in the coating system. This work envisages the progressive strategies for the economical exploration of a novel WS2–MoS2/NiMoP water splitting catalyst used for large scale H2 generation. The prepared WS2–MoS2/NiMoP embedded Cu substrate possess high catalytic activity due to its least overpotential of 101 mV at a benchmark current density of 10 mA cm−2, which demonstrated the sustainable, efficient and promising electrocatalytic property of prepared catalyst towards HER under alkaline conditions.

Effect of Aluminium Oxide with Boron Nitride Grinding Wheel on Surface Roughness with Finishing of EN-8 Steel

This paper focuses on the effect of internal grinding process using a grinding wheel on the surface roughness aspect of ductile material. The surface roughness depends on various machining parameters which are feed rate, cutting speed, material removal rate and depth of cut. As varying the different machining parameters in internal grinding process, small internal grinding wheel made out of aluminium oxide-Al2O3 with boron nitride and adhesive type i.e., vitrified bond has been used for this study. Additionally, coolant also constitutes a major role to improve surface roughness, material removal rate and the wheel life. The roughness value was measured by using Mitutoyo portable roughness tester code: 178-561-02E surf test-SJ-210. Comparatively, it could be deduced that the wheel using Al2O3 with boron nitride has a better surface roughness in comparison with Al2O3 grinding wheel intern increases the wheel life.

Influence of Internal Grinding Wheel using Aluminium Oxide with Boron Nitride and its Relation to Dressing and Surface Roughness

Performance of grinding wheel depends on different factors from dressing operations to wheel topography. This will directly show effect on grinding force, surface quality and wheel durability. During grinding, an improved wheel should reduce the number of passes as well as the dressing time (wheel gets loading) to increase the production rate and minimize the total cycle time to complete the parts. This paper presents several process parameters to obtain the improved surface roughness and round tolerance such as coarse dress depth of cut 30 microns for the first pass, fine dressing depth of cut 20 microns for the second pass and a dressing speed and feed rate of 0.5m/min respectively. The experiments with the optimal dressing parameters have been considered to check the wheel durability and its performance. The parameters investigated were wheel life, surface roughness and round tolerance from the experiments with different cutting variables like depth of cut, speed, feed rate and percentage of wheel depletion. For this purpose, a single point diamond dresser with four different test samples using Aluminium Oxide (Al2O3) with Boron Nitride (BN) for internal grinding wheels were chosen for the experiment.

Welding Defect and Mechanical Properties of Nanosecond Laser Cleaning 6005A Aluminum Alloy.

Nanosecond laser cleaning effectively removes oxide film and dirt from the surface of aluminum body parts for rail transit, as well as improving surface properties. The effect of laser cleaning on the quality of weld was studied in detail for different scanning frequencies and cleaning speeds. The effect of post-weld laser cleaning on weld quality was investigated. After laser cleaning at different parameters, the surface oxygen content was decreased and the surface roughness and surface hardness were increased. Variation of surface oxygen content was related to energy density and spot density. The lowest oxygen content was obtained at 150 W, 100 Hz and 0.8 m/min. Laser-generated craters changed surface morphology and improved surface roughness. The mechanical properties of the welded joints were slightly improved, which relates to a decrease in porosity. The minimum porosity of the laser-cleaned weld was 0.021%. This work provides new ideas for the nanosecond laser cleaning of aluminum alloy and its welding properties.

EXPERIMENTAL INVESTIGATION AND OPTIMIZATION OF WIRE EDM PARAMETERS FOR SURFACE ROUGHNESS, MATERIAL REMOVAL RATE AND SURFACE TOPOGRAPHY IN MACHINING OF AISI D3

Wire electric discharge Machining is a crucial alternative machining technique. As a consequence of its superior precision, finish, machinability of any hard material, and ability to form complex shapes, demand for it continues to rise. In this research, we apply the Taguchi Method in conjunction with the Grey relational analysis approach to determine the optimal parameters in WEDM for the machining of AISI D3. WEDM machines allow for cutting by adjusting process parameters such as pulse on time, pulse off time, servo voltage, wire feed rate, current, and more to get the desired results in terms of response variables like surface roughness and material removal rate. Grey Relational Analysis is used for optimization of all these parameters with multi-response features. Best WEDM parameters are determined by studying grey relational grade. Specifically, the findings demonstrate its improved surface roughness and material removal rate prediction skills and application to such industrial WEDM cutting, which leads to the effective selection of machining settings for improved Machining quality

Green silver nanoparticles functionalised gelatin nanocomposite film for wound healing: Construction and characterization

Wound dressings have progressed from simple to advance by the interdisciplinary approaches of chemical, materials and biological fields to engineer the functional materials that can improve wound healing by reducing bacterial infections on wound site. In the present study, Praecitrullus fistulosus extract was used for the preparation of silver nanoparticles (Ag NPs) via a green synthesis method for wound healing. The synthesized Ag NPs were characterized via Ultraviolet–Visible (UV–Vis) spectroscopy, High-Resolution X-ray Diffractometer (HRXRD), and High-Resolution Transmission Electron Microscopy (HRTEM). The gelatin-Neem extract-nanocomposite films were prepared by incorporating green Ag NPs via solvent casting method. The physico-chemical, morphological, structural, thermal, and biological properties of the nanocomposite (NCP) films were determined in order to check their efficacy for wound healing applications. The NCP films were showing significantly higher water absorption capacity, folding endurance, and porosity as compared to the control gelatin (GLT) film. The observed pH of the NCP film was found to be 5.9, which is suitable for human skin. Antibacterial activity of the NCP films against gram-negative bacteria (Escherichia coli) was higher compared to GLT film. The surface roughness was found to be 22.7 nm for the NCP film containing Ag NPs. The thermal stability of the GLT film was improved after the incorporation of Ag NPs. The high antimicrobial activity, porosity and improved surface roughness of NCP films would favour the adherence, growth and proliferation of seeded cells that is pre-requisite for ideal dressing materials.

Performance Improvement of Micro-Abrasive Jet Blasting Process for Al 6061

Aluminum 6061 is a precipitation-hardened alloy, containing magnesium and silicon as its major alloying element, and it is widely used in industries due to its remarkable mechanical properties and weld ability. Several types of machining manners are researched for aluminum 6061 alloys, and micro-abrasive jet blasting (μ-AJM) is one of the most developed processes for improving surface roughness. When operating μ-AJM on aluminum alloys, sufficient consideration of environmental variables such as particle types, nozzle diameter, pressure, standoff distance, and injection time is a prerequisite for the appropriate degree of roughness. To find the optimal conditions, a statistical method of analysis of variables was used to investigate the maximum value for depth, diameter, width, etc., of the blasting surface. According to experimental results, multiple factors have a great influence on the condition of surface roughness. The blasting processes were conducted as square and cylindrical experiments, and the parameters for optimal conditions have been derived from a surface roughness measurement system.

Electrical Conductivity of Additively Manufactured Copper and Silver for Electrical Winding Applications.

Efficient and power-dense electrical machines are critical in driving the next generation of green energy technologies for many industries including automotive, aerospace and energy. However, one of the primary requirements to enable this is the fabrication of compact custom windings with optimised materials and geometries. Electrical machine windings rely on highly electrically conductive materials, and therefore, the Additive Manufacturing (AM) of custom copper (Cu) and silver (Ag) windings offers opportunities to simultaneously improve efficiency through optimised materials, custom geometries and topology and thermal management through integrated cooling strategies. Laser Powder Bed Fusion (L-PBF) is the most mature AM technology for metals, however, laser processing highly reflective and conductive metals such as Cu and Ag is highly challenging due to insufficient energy absorption. In this regard, this study details the 400 W L-PBF processing of high-purity Cu, Ag and Cu-Ag alloys and the resultant electrical conductivity performance. Six Cu and Ag material variants are investigated in four comparative studies characterising the influence of material composition, powder recoating, laser exposure and electropolishing. The highest density and electrical conductivity achieved was 88% and 73% IACS, respectively. To aid in the application of electrical insulation coatings, electropolishing parameters are established to improve surface roughness. Finally, proof-of-concept electrical machine coils are fabricated, highlighting the potential for 400 W L-PBF processing of Cu and Ag, extending the current state of the art.

Influence mechanism of RF bias on microstructure and superconducting properties of sputtered niobium thin films

In this study, radio frequency (RF) biased direct current (DC) magnetron sputtering was used to simultaneously improve the surface roughness and superconducting properties of Nb thin films for Josephson circuits application. The surface roughness of the Nb films decreased with an increase in RF powers, whereas the transition temperature, transition width, and residual resistance ratio of the Nb film were optimum at an RF power of 20 W but will deteriorate at higher RF powers. The film resistivities at 10 K obviously increased when the RF power was increased to 40 W and 60 W, which indicates that electron-impurity scattering and scattering on lattice defects are severer in these Nb films. The microstructures, impurities (mainly Ar) and dislocation states were correlated with the electrical and superconducting properties of Nb films. In summary, an optimal process for depositing Nb films with simultaneously improved surface roughness and superconducting properties was found, the Nb film deposited at a DC power of 500 W and an RF bias power of 20 W with a substrate bias voltage of approximately −100 V had the best overall quality. The method is prospective to be applicated in multilayer superconducting electronic devices fabrication based on Nb and other superconductors.

Effect of nano-minimum quantity lubrication on cutting temperature and surface roughness of milling AISI D3 tool steel

Machining is the manufacturing process used to create components that are the right size and shape. For machining processes, numerous cooling methods are employed. Surface finish of workpiece is affected by heat generated at tool workpiece interface because of friction. The machining technologies include conventional cooling, minimum quantity lubrication, cryogenic cooling, and nanofluid cooling. Because of its excellent qualities, AISI D3 is appropriate for creating blanking and shaping tools. It has high strength, good hardenability, and resistance to wear. The major aim of this study is to see how a tiny amount of lubricant combined with TiO2 nanofluids affects the cutting temperature and surface roughness when milling AISI D3 material. The results suggest that using nanoparticles in combination with lubricant reduces cutting temperature and improves surface roughness. Because the cutting fluid's thermal conductivity has increased, adding TiO2 to MQL results in cutting temperatures of 215.6 °C, 207.1 °C, 199.2 °C, and 195.1 °C for 0.3 %, 0.5 %, 0.7 %, and 0.9 % TiO2, respectively. Surface roughness (Ra) values for 0.3 %, 0.5 %, 0.7 %, and 0.9 % TiO2 in MQL are 0.501, 0.498, 0.481, and 0.455, respectively. A 0.9 % TiO2 nanoparticle concentration is believed to be superior for lower cutting temperatures and better surface quality.

Mathematical Modeling and Experimental Validation of Surface Roughness in Ball Burnishing Process

Burnishing is a cold working technique used as a surface enrichment to meet the desired surface properties of the workpiece. It improves the visual properties, dimensional tolerances, fatigue strength, surface roughness, and hardness of the work material by applying appropriate pressure through a complex ball burnishing tool to cause plastic deformation. In the current work, the mathematical modeling of the burnishing process was carried out to predict surface roughness by considering the process parameters such as contact radius, penetration depth, and elastic rebound. Further, a customized tungsten carbide (W.C.) insert having a hardness of 80 HRC was developed for the burnishing operation. The micro-hardness of the resulting burnished surface improved from 44 to 48 HRC. The surface quality of the tungsten carbide insert improved by up to 17.1 nm through polishing. Several experiments were performed by selecting appropriate process parameters using developed model feedback. The surface quality of the workpiece improved by up to 45 nm, which resulted in automatic improvements in fatigue strength up to seven times that of the virgin material. The results predicted from the mathematical model were in good agreement (less than 5% deviation) with the experimental results. This study helps to understand the surface formation mechanism in the burnishing process in more detail. Additionally, the achieved results show a significant improvement in the surface finish (~95%), indicating the potential of the burnishing process and how fast and cost-effective it is. The novelty of this paper lies in the improvement in surface roughness and the validation of our mathematical model results with the experimental results.

Highly Stable and End‐group Tuneable Metal–Organic Framework/Polymer Composite for Superior Triboelectric Nanogenerator Application

AbstractTriboelectric nanogenerators (TENGs) are receiving significant attention lately as efficient mechanical energy harvesting devices. They are finding multiple uses in numerous low‐power applications. Current TENG designs, although innovative, fall short on practical demands like performance tunability, modulatory, and stability. This invites further research in the use of new materials for TENGs. Metal‐organic frameworks (MOFs) offer a unique feature of molecular tunability to optimize energy conversion which has been exploited in this study. Prototypal hybridization strategy is deployed on underexplored isoreticular subfamily UiO‐66(Zr) MOFs through UiO‐66‐X/PVDF (X = H or Br) composites for TENG output tuning and amplification. UiO‐66‐X/PVDF exhibits good aquatic and thermal stability accompanying substantial boost in TENG power. Functionalized H2BDC linker improved surface roughness and potential. UiO‐66‐Br encased in PVDF matrix boosted charge and TENG performance by enhancing electrification. Computational details support observations. Device captures waste energy in a vertical contact‐separation mode and functions consistently amidst diverse environmental settings. Functionalized TENG‐2 delivers a Vp–p of 110.41 V, which is 2.92 times and 14.12 times higher than unfunctionalized TENG‐1 and PVDF film, respectively. Findings reveal maiden example of ligand‐mediated functional group‐driven performance tuning of TENG and mechanistic insight using isoreticular MOFs/PVDF composites.