Roughness Formation Research Articles

Harvesting of flow current through implanted hydrophobic PTFE surface within silicone-pipe as liquid nanogenerator

Harvesting of flow current through implanted hydrophobic surface within silicone pipe as liquid nanogenerators where Tap water (TW), and DI water (DIw) as liquid reservoirs to successfully convert induced mechanical energy into electrical energy. Here, we used a commercial PTFE film for the generation of a hydrophobic surface as a source of mechanical energy. The surface roughness of the hydrophobic surface is confirmed using atomic force microscopy, and contact angle analyses. The generation of power through the interaction of TW and DI with inbuilt PTFE in silicone tube is described. The higher output voltage (Voc), and short circuit currents (Isc) were attained through an interaction of TW and DIw with N-PTFE. The lower Voc, and Isc’s were produced when DI water interacts with N-PTFE electrode, whereas TW produced higher Voc and Isc’s, respectively, due to a lack of free mobile ions in DIw than TW. The TW-Sh-TENG and DIw-Sh-TENG are produced the maximum peak-to-peak Voc, and Isc of 29.5 V and 17.4 V and 3.7 μA, and 2.9 μA, respectively. Significant power output enhancement of ~ 300% from TW-Sh-TENG from DIw-N-TENG due to the formation of higher surface roughness and lead to the slipping of water droplets by super-hydrophobicity.

Investigation of the performance of cermet tools in the turning of Haynes 25 superalloy under gaseous N2 and hybrid nanofluid cutting environments

Co-based superalloys such as Ni-based, Fe-based, and other such superalloys are classified as difficult-to-machine materials. Due to the poor machinability of superalloys, their machining is a big challenge for metal cutting industries. However, the machining of superalloys under ecological cutting environments (e.g., MQL, nanofluids, cryogenic cooling, etc.) has shown promising results. The present study investigated the effects of ecological cutting environments on the performance of cermet cutting tools. To this purpose, Co-based Haynes 25 superalloy was turned under MQL, graphene nanoplatelet (GnP) doped mono nanofluids, multiwalled carbon nanotube (MWCNT) doped mono nanofluids, GnP/MWCNT doped hybrid nanofluids, gaseous N2 based cutting environments, and mono/hybrid nanofluids combined with N2. Viscosity, pH, thermal conductivity, and wettability properties were investigated to determine the characteristics of the nanofluid mixtures. Cutting temperature, tool wear, wear mechanisms, surface roughness, surface topography, and chip formation morphology were chosen as the machining performance criteria. The experimental results showed that the cermet cutting tool and the GnP/MWCNT+N2 hybrid cutting environment contributed significantly to the Haynes 25 machining performance. Compared to the dry cutting environment, the N2 cutting environment showed the best performance improvement (63.57%) for cutting temperature, whereas the GnP/MWCNT+N2 hybrid cutting environment yielded the best performance and the best the improvement in tool flank wear (45.13%) and surface roughness (36.36%).

Experimental Study of Quarry Dust and Aluminium Oxide Suspension as Cutting Fluid for Drilling of Titanium Alloy

In the aerospace field, titanium alloys are extensively used for the airframe and engine parts to improve aircraft fuel consumption. Drilling through these parts in a single-shot process to produce high quality holes is challenging. During drilling, high temperatures are generated owing to the friction between the cutting tool and workpiece, causing the process becomes inefficient in terms of tool life and surface quality. To reduce the temperature produced in the cutting zone, different types of cooling techniques during drilling have been used by researchers. In this study, the feasibility of quarry dust suspension as coolant in drilling of titanium alloy was performed. The effects of different concentrations of quarry dust on surface roughness, thrust force, and burr formation were evaluated, and their machining performances were compared with those obtained using aluminium oxide suspension. Before the experiments, both suspensions were prepared by dispersing quarry dust and aluminium oxide particles into deionised water at various concentrations ranging from 0 wt% to 0.10 wt%. Results indicated that by using 0.06 wt% of quarry dust suspension, thrust force and surface roughness showed an improvement by 8.31% and 18.29%, respectively, compared with those of aluminium oxide suspension at the same concentration. The burr height formed at the drilled holes using 0.06 wt% of quarry dust was also lower than that formed with aluminium oxide suspension at the same concentration.

Influence of the carrier wafer during GaN etching in Cl2 plasma

In this study, we have performed a thorough characterization of the GaN surface after etching up to 100 nm in Cl2 plasma under various bias voltages and according to the carrier wafer used (Si, SiO2, Si3N4, and photoresist). The objective of this article is to evaluate the etch damage and contamination of the GaN surface when materials with other chemical nature are present during etching. The effects of etching conditions on surface morphology and chemical compositions of etched GaN films are studied in detail using XPS and AFM measurements. To this aim, a universal methodology is proposed to estimate accurately by XPS the stoichiometry of the GaN surface exposed to reactive plasmas when only an Al Kα x-ray source is available. The results indicate that the GaN etching mechanisms are very sensitive to the chlorine radical density present in the plasma, the latter being strongly influenced by the carrier wafer. Substrates that are more chemically reactive with Cl2 plasma such as silicon or photoresist compared to SiO2 or Si3N4 will lead to a greater loading of atomic chlorine, which in turn will lead to lower GaN etch rates. Moreover, the GaN surface contamination will depend on the etch by-products ejected by the carrier wafer. The GaN surface exposed to Cl2 plasma shows a Ga-depleted surface because of the more important reactivity of Cl with Ga rather than N, except in the SiO2 carrier wafer case. In this latter case, the formation of Ga–O bond limits the Ga removal. Regarding the surface roughness, it seems that the contaminants play a little role in the roughness formation except for the oxygen released by the SiO2 carrier wafer. On the other hand, the surface roughness evolution is clearly driven by the chlorine radical flux reaching the GaN surface. At low bias voltage, a preferential crystalline orientation etching driven by the Cl radicals leads to the formation of hexagonal shaped defects that are associated to screw-type threading dislocations already present in the pristine GaN material. At higher bias, the enlargement of the defects is limited, leading to a very low surface roughness value but to amorphized surfaces.

Surface roughness of Ti6Al4V samples produced by laser powder bed fusion for bone implants

This study describes the surface roughness of heat-treated Ti6Al4V ELI samples without surface finishing (as-built condition) depending on the position of the build plate. Surface roughness was studied at the top and side surfaces of horizontal and vertical samples using a profilometer and Scanning Electron Microscopy. Morphology of tested samples is shown. It was shown that the top and side surfaces of vertical and horizontal samples had different morphologies, but they had fairly close roughness values, since the formation of roughness was mainly associated with sticking of the powder material both on the upper surface of the samples and on the side surfaces. It was found that samples that were far away from the argon inlet and recoater start line had higher surface roughness.

Superfície de implantes dentários tratados com dióxido de titânio e melhorias na osseointegração

Objective: To analyze the studies that used titanium dioxide in the anatase phase in dental implants, focusing on the properties of wettand photocatalysis and its improvements in osseointegration. Method: The search strategy used combinations of keywords: titaniumdioxide and dental implant and osseointegration and anatase and hydrophilicity, in the Pubmed, Medline, Cochrane, Scielo, Scopus and Lilacs databases. Results: The best results were confirmed by 14 studies and are directly related to titanium dioxide in the anatase phase by the electrochemical anodization method, acid attack and irradiated by violet light (UV) and photocatalysis that promotes wetability. Final Considerations: Improvements and benefits were confirmed by surface treatment in dental implants using titanium dioxide. Contact angle, roughness and bone formation (BIC or BMC) were analyzed to verify the factors for acceleration and improvements in osseointegration.

Vibratory finishing application in “smart manufacturing” for manufacturing precision sleeve type products

Vibration processing of parts and the possibilities of its application in the conditions of "smart production" are described. The main technologies used in "smart production" are considered. The processes of roughness formation during the processing of a part in the medium of abrasive granules are investigated. It is revealed that the thickness of the removed layer and the steady-state roughness are different for the outer and inner surfaces, and also depend on the mass and length of the part. Technological recommendations are given for the design of technological processes of vibration treatment, which ensure the readiness of the part for the subsequent coating.

Effect of Cutting Environment and Swept Angle Selection in Milling Operation

Cutting fluids are frequently aim to enhance machinability through cooling, lubricating and flushing actions. However, their use in machining creates major concerns in terms of health footprint and environmental effect. and human health throughout their lifecycle. To diminish these problems, alternative methods were used, namely; dry cutting and minimum quantity lubrication. This research also will investigate the effect of swept angle selection, 30% and 60% of tool diameter stepover under different cutting conditions during milling of aluminum alloy material. Their impact on tool wear, surface roughness, burr and chip formation were compared. Results pointed that the application of lower swept angle in conjunction with minimum quantity lubricant system, has significantly reduced tool wear, decreased burr and chip formation, as well as improved surface quality as compared to dry machining. The work clearly shows how the importance of swept angle selection and cutting condition in refining machining performance could improve the machinability of the material.

Providing of roughness during finishing with an edge tool having a small end cutting-edge angle

The mechanism of roughness formation during processing with an edge tool is investigated. It was found that when machining with a tool having a small end cutting-edge angle, scratches are formed as a result of jamming of small chips between the workpiece and the blade in the area of its minor flank. Keywords: finishing, cutting tool, cutting edge angle, built-up, chips, jamming, scratch, roughness, minor flank, sharpening to a point, high-speed cutting. zgs1931@mail.ru

Deposition, Morphological, and Mechanical Evaluation of W and Be-Al2O3 and Er2O3 Co-Sputtered Films in Comparison with Pure Oxides

Compact and defect-free high melting point oxide strengthened metallic matrix configurations are promising to resolve the hydrogen permeation and brittleness issues relevant to the fusion research community. Previous studies on oxide addition to metallic matrix demonstrated a mitigation in brittleness behavior, while deposition techniques and material configurations are still to be investigated. Thus, here, we report the structural, morphological, and mechanical characterization of metal-oxides thin layers co-deposited by radio frequency (RF)and direct current (DC) magnetron sputtering. A total of six configurations were deposited such as single thin layers of oxides (Al2O3, Er2O3) and co-deposition configurations as metal-oxides (W, Be)—(Al2O3, Er2O3). The study of films roughness by atomic force microscopy (AFM) method show that for Al2O3 metallic-oxides is increased to an extent that could favor gaseous trapping, while co-depositions with Be seem to promote an increased roughness and defects formation probability compared to W co-depositions. Lower elastic modulus on metal-oxide co-depositions was observed, while the indentation hardness increased for Be and decreased for W matrix configurations. These outputs are highly relevant for choosing the proper compact and trap-free configuration that could be categorized as a permeation barrier for hydrogen and furtherly studied in laborious permeation yield campaigns.

Surface Morphology Signature of Critical Separated Length and Glass Transition Temperature during Seeded Dispersion Polymerization.

The properties of colloids are considerably affected by particles' surface morphology. In this work, for understanding the mechanism of roughness formation in polymeric core-shell (CS) particles, the surface morphology of synthesized CS particles through seeded dispersion polymerization (SDP) in the presence of poly(methyl methacrylate) seeds was investigated. The results revealed that shell polymers with higher solubility parameters (δ) and glass transition temperatures (Tg) had a rougher surface. These parameters directly affect the time needed for chain deformation, which is a critical parameter in controlling the final morphology. We suggested a relation based on these parameters to predict the surface morphology (smoothness or roughness) of CS particles synthesized through SDP in water.

Multi-physics modeling of side roughness generation mechanisms in powder bed fusion

Surface roughness is a serious concern in powder bed fusion (PBF) additive manufacturing, especially for aerospace and biomedical applications. An adequate surface quality of as-built components is desired due to difficulty in post-processing of interior sides and intricate geometries of printings. The side surface draws more attention than the top surface and a comprehensive understanding of side roughness mechanisms is required to interpret effectively. However, observation of side roughness formation in experiments is yet difficult. In this paper, the formation process of the side surfaces in electron beam PBF is analyzed by a 3-D mesoscale multi-physics simulation, so as to provide an insight view into side roughness mechanisms from the viewpoint of heat and mass transfer. The melting process and the resulting side surface morphologies of thin-walled parts are exclusively analyzed. It turns out that the melted traces in cases with a relatively low heat input generally have greater fluctuations than in cases with a high heat input, which leads to a higher side roughness. The proposed investigation reveals that the melt pool flow driven by surface tension is the main cause of track shape fluctuation. This fluctuation is driven by the random distribution of powder particles and the Plateau–Rayleigh instability, which describes the disintegration into a chain of drops. An analytical estimation of minimum limit of side roughness in as-built parts and the mechanisms for the generation of the side roughness are depicted systematically, based on which some improvement measures are proposed finally. This will help improve surface quality in metal additive manufacturing.

Modelling and analysis of initial icing roughness with fixed-grid enthalpy method based on DPM-VOF algorithm

Ice particles could form under the continuous impingement of incoming supercooled droplets in icing conditions, which will change the surface roughness to enhance the further heat and mass transfer during icing process. A fixed-grid porous enthalpy method based on the improved Discrete Phase Model (DPM) and Volume of Fluid (VOF) integrated algorithm is developed to solve the multiphase heat transfer problem to give more detailed demonstration of the formation of initial ice roughness. The algorithms to determine the criterion of transformation from DPM to VOF and the allocation of source items during transformation are improved to the general DPM-VOF algorithm. Two verification cases, namely two glycerine-solution droplets impact and single droplet freeze, are conducted to verify the accuracy and reliability of the enthalpy-DPM-VOF method, where the simulation results match well with experiment phenomena. Ice roughness on a NACA0012 airfoil is precisely captured and the effects on convective heat transfer characteristics are preliminarily revealed. The results illustrate that the enthalpy-DPM-VOF method could successfully capture the characteristics of motion and the phase change process of droplet, as well as balance the calculation accuracy and efficiency.

Development of Bio-Cutting Fluid (Cirtullus lanatus) and its Performance Assessment on the Machining of AISI 1525 Steel Using Taguchi Technique and Grey Relational Analysis

Due to traditional mineral oils' adverse environmental and health effects, vegetable oil-based cutting fluids have become widely attractive in machining. The majority of the vegetable oils used in literature are edible and may compete with human consumption if promoted, thereby making it more expensive as cutting fluids. However, few studies have been carried out on the applicability of lesser-known vegetable oils as cutting fluids. This study, therefore, aims at investigating the efficiency of lesser-known vegetable oil (watermelon oil) as a machining cutting fluid. The developed watermelon oil was mechanically compared to the traditional mineral oil in turning AISI 1525 steel based on cutting temperature, surface roughness, and chip formation mode. The experiment depended on Taguchi plan with L9 orthogonal arrangement utilizing feed rate, depth of cut, and cutting speed as critical input parameters. Moreover, the grey relational analysis optimization approach was employed to analyze the parameter impacts and achieve the best possible cutting parameters. The optimization showed that the best combinations of cutting parameters for cutting speed, feed rate, and depth of cut were (355 rev/min, 0.1 mm/rev and 1 mm), and (355 rev/min, 0.1 mm/rev, and 1.25 mm) for watermelon and mineral oils, respectively.

The effect of surface properties on bond strength of birch, black alder, grey alder and aspen veneers

In this study, the effect of veneer preparation process on surface roughness, wettability and adhesive bond formation between birch ( Betula pendula Roth), black alder ( Alnus glutinosa L.), grey alder ( Alnus incana L.) and aspen ( Populus tremula L.) were evaluated. It is commonly known that adhesive bond is as strong as its weakest link. However, the results of present study show, that bond strength is not always directly related to properties of weakest wood material used in bonding. The roughness (Ra) for the birch was (11.13 μm) followed by black alder (13.32 μm), grey alder (17.25 μm) and aspen (23.28 μm). The best wettability was achieved on aspen (0.3°), which was followed by grey alder (5.0°), black alder (10.7°) and birch (43.6°). The results show that bonding lower quality and density wood species with birch does not significantly decrease the bond quality as it could be expected. This study shows that the bonds between birch and low quality and density wood species were significantly stronger than bonds formed solely between these low quality and density wood species. These results also imply that in utilization of low quality wood species by veneer-based industry does not immediately require adapting and changing the current processing parameters according to lower quality wood properties, if they are used in combination with higher density and quality wood.

Self-organization and evolution in dynamic friction systems

The dynamic features of the friction process of the contacting pairs affect their durability and functional suitability. There-fore, the problems of their dynamics and vibrational activity always attract the attention of researchers in the field of tribology. It is known that self-organization processes take place during friction, such as the formation of selective transfer phenom-ena during friction, formation of equilibrium roughness. But known studies do not take into account changes in the dynamic properties of the system in the process of its functioning. The primary sources of self-organization are energetic in nature, but the relationship of these phenomena with the dynamic properties of the system has not been explained, and their modeling has not yet been performed. The paper presents the results of experimental and mathematical modeling of evolutionary changes of friction system due to the power of irreversible transformations of energy input to friction zone, which characterizes the goal of research. In order to achieve the goal, the paper deals with the mathematical modeling of the processes of self-organization in a dynamic friction system in combination with the analysis of the equilibrium of the system, its stability, and the manifolds formed in the vicinity of the equilibrium. It is shown that the proposed mathematical models are integro-differential functionally coupled equations that describe self-organization. Examples are given of dynamic restructuring of the friction system, including bifurcations of the attracting sets of its deformation displacements along the trajectory of the friction forces work. The paper briefly presents the results of the experimental study of the vibration characteristics of the contacting pairs during the development of their wear by the example of two systems: steel-brass and steel-glycerin-brass. It is shown that in the system of friction, new properties always establish naturally due to the work of forces. These properties are determined by the evolutionary change of the parameters of the dynamic coupling and the attractive sets of deformation displacements. The study and experiments show that measurement of parameters available for estimation of some coordinates in the dynamic friction system allows one to solve the problem of non-decoupled dynamic monitoring of the state of friction units and also opens new ways of improvement of friction units.

Effect of brushing on surface roughness, fluoride release, and biofilm formation with different tooth-colored materials

Background/purposeTooth brushing, material mechanical ageing procedure, is the most effective way in removing biofilm. The purpose of this study was to investigate the surface roughness, fluoride-release, and S. mutans biofilm formation on various tooth-colored restorative materials before and after brushing. Materials and methodsDiscs of materials, a nanocomposite (Filtek Z350XT; CO), a giomer (Beautifil II; GIOMER), a resin-modified glass-ionomer material (Fuji II LC; RMGI), and a conventional glass-ionomer material (Fuji IX GP Extra; GI), were prepared, polished with abrasive discs (SofLex), and divided into brushed and not brushed groups. The surface roughness of specimens was observed using a contact profilometer, fluoride-release was measured using a fluoride-specific ion electrode, and S. mutans biofilm formation, biovolume and live/dead cells, was observed under a confocal laser scanning microscope. ResultsHigher roughness was observed on GI and RMGI than on CO and GIOMER. Brushing had no effect on the roughness. The fluoride-release of GI and RMGI was higher than that of GIOMER. The fluoride-release decreased after brushing in all materials. The biovolume of S. mutans was not significantly different between GIOMER, RMGI and GI, while CO showed the highest. Brushing resulted in a higher biovolume for all materials, except CO, which showed no change. After brushing, all the tested materials demonstrated identical biovolumes. There were no significant differences in live/dead cells among all groups. ConclusionBrushing demonstrated a negative effect on the fluoride-release and biovolume of S. mutans biofilms for all tested materials except nanocomposites.

Relationship between the roughness of the friction surface of wear-resistant composites and their composition

The wear resistance of galvanic composites based on iron alloys under conditions of abrasive wear has been investigated. The relationship between wear resistance and surface roughness of composites during wear has been established. A model of the formation of the surface roughness of composites during abrasive wear is proposed. The optimal content of the dispersed phase in the composite was determined from the point of view of the ratio of the strength of the dispersed phase and matrix.

Post-processing of 3D printed thermoplastic CFRP composites using cryogenic machining

Additive manufacturing (AM) or three-dimensional (3D) printing allows manufacturing of parts of complex shapes using carbon fiber reinforced polymer (CFRP) composites. However, in many cases, the parts fabricated by 3D printing suffer from poor surface quality and dimensional accuracy, requiring extensive post-processing. This research aims at improving the dimensional accuracy and surface finish of 3D printed CFRP composites by analyzing the effectiveness of three sustainable machining practices: dry, minimum quantity lubrication (MQL), and cryogenic machining, as post-processing techniques for 3D printed CFRP composites. This study specifically investigates effects of printing and machining parameters and cooling/lubricating conditions on the machining performance, i.e., burr formation, surface finish, cutting forces, and tool wear during edge and slot milling of 3D printed thermoplastic CFRP composites. Among three sustainable machining processes, cryogenic machining significantly reduced burr formation and tool wear, and improved surface finish irrespective of the fiber orientation and machining conditions. The application of MQL at the tool-workpiece interface was found to be effective in reducing tool wear, surface roughness, and burr formation to some extent compared to dry machining. However, MQL process was not able to completely eliminate burr formation for most of the machining conditions. Cryogenic machining caused the highest cutting forces due to the increased surface and sub-surface hardness of the workpiece caused by application of liquid nitrogen; however, no adverse effect of increased cutting forces was observed. This study finds that cryogenic machining is able to completely eliminate or reduce burrs by 90% and bring down the surface roughness (Rq) from >10 μm to about 1 μm, thus making it a suitable post-process technique for 3D printed CFRP composites.

Investigations on tool wear, surface roughness, cutting temperature, and chip formation in machining of Cu-B-CrC composites

Investigations on tool wear, surface roughness, cutting temperature, and chip formation in machining of Cu-B-CrC composites