Showing papers on "Surface roughness published in 2009"
TL;DR: This work combined template stripping with precisely patterned silicon substrates to obtain ultrasmooth pure metal films with grooves, bumps, pyramids, ridges, and holes, and measured surface-plasmon–propagation lengths on the resulting surfaces approach theoretical values for perfectly flat films.
Abstract: Surface plasmons are electromagnetic waves that can exist at metal interfaces because of coupling between light and free electrons. Restricted to travel along the interface, these waves can be channeled, concentrated, or otherwise manipulated by surface patterning. However, because surface roughness and other inhomogeneities have so far limited surface-plasmon propagation in real plasmonic devices, simple high-throughput methods are needed to fabricate high-quality patterned metals. We combined template stripping with precisely patterned silicon substrates to obtain ultrasmooth pure metal films with grooves, bumps, pyramids, ridges, and holes. Measured surface-plasmon-propagation lengths on the resulting surfaces approach theoretical values for perfectly flat films. With the use of our method, we demonstrated structures that exhibit Raman scattering enhancements above 10(7) for sensing applications and multilayer films for optical metamaterials.
852 citations
TL;DR: The dynamics and structure of water at hydrophobic and hydrophilic diamond surfaces is examined via non-equilibrium Molecular Dynamics simulations and the effect of the Lennard-Jones cutoff length on the interfacial properties is discussed.
Abstract: The dynamics and structure of water at hydrophobic and hydrophilic diamond surfaces is examined via non-equilibrium Molecular Dynamics simulations. For hydrophobic surfaces under shearing conditions, the general hydrodynamic boundary condition involves a finite surface slip. The value of the slip length depends sensitively on the surface water interaction strength and the surface roughness; heuristic scaling relations between slip length, contact angle, and depletion layer thickness are proposed. Inert gas in the aqueous phase exhibits pronounced surface activity but only mildly increases the slip length. On polar hydrophilic surfaces, in contrast, slip is absent, but the water viscosity is found to be increased within a thin surface layer. The viscosity and the thickness of this surface layer depend on the density of polar surface groups. The dynamics of single water molecules in the surface layer exhibits a similar distinction: on hydrophobic surfaces the dynamics is purely diffusive, while close to a h...
448 citations
TL;DR: There is a lack of a rigid quantitative correlation between factors affecting wetting, wetting behaviour and contact angle on minerals; and hence their implication for flotation process; and universal correlation of contact angle to flotation recovery is still difficult to predict from first principles.
427 citations
TL;DR: Underwater applications, the oleophobicity/philicity of an oil droplet in water was studied on the surfaces with different surface energies of various interfaces and contact angles of water and oil droplets in air and a model for predicting the contact angles was proposed.
Abstract: Biomimetics, mimicking nature for engineering solutions, provides a model for the development of superhydrophobic/superoleophobic and self-cleaning surfaces. A number of biomimetic superhydrophobic surfaces have been developed by using a hydrophobic coating, surface roughness, and the ability to form air pockets between solid and water. Oleophobic surfaces that have the potential for self-cleaning and antifouling from biological and organic contaminants in both air and water need to be studied. The surface tension of oil and organic liquids is lower than that of water, so to create a superoleophobic surface, the surface energy of the solid surface in air should be lower than that of oil. The wetting behavior of water and oil droplets for hydrophobic/philic and oleophobic/philic surfaces in three-phase interfaces was studied. In order to make the surface oleophobic at a solid-air-oil interface, a material with a surface energy lower than that of oil was used. In underwater applications, the oleophobicity/philicity of an oil droplet in water was studied on the surfaces with different surface energies of various interfaces and contact angles of water and oil droplets in air. A model for predicting the contact angles of water and oil droplets was proposed. To validate the model, the wetting behavior of flat and micropatterned surfaces with varying pitch values were studied. Furthermore, the wetting behavior of the nano- and hierarchical structures found in Lotus plant surfaces and the shark skin replica as an example of aquatic animal were also studied. On the basis of the experimental data and the model, the trends were explained.
398 citations
TL;DR: Temperature-dependent I-V and C-V spectroscopy of single InAs nanowire field-effect transistors were utilized to directly shed light on the intrinsic electron transport properties as a function of nanowires radius, serving as a versatile and powerful platform for in-depth characterization of nanoscale, electronic materials.
Abstract: Temperature-dependent I−V and C−V spectroscopy of single InAs nanowire field-effect transistors were utilized to directly shed light on the intrinsic electron transport properties as a function of nanowire radius. From C−V characterizations, the densities of thermally activated fixed charges and trap states on the surface of untreated (i.e., without any surface functionalization) nanowires are investigated while enabling the accurate measurement of the gate oxide capacitance, therefore leading to the direct assessment of the field-effect mobility for electrons. The field-effect mobility is found to monotonically decrease as the radius is reduced to <10 nm, with the low temperature transport data clearly highlighting the drastic impact of the surface roughness scattering on the mobility degradation for miniaturized nanowires. More generally, the approach presented here may serve as a versatile and powerful platform for in-depth characterization of nanoscale, electronic materials.
391 citations
TL;DR: In this paper, the influence of cutting fluids on tool wear and surface roughness during turning of AISI 304 with carbide tool has been investigated and the results indicated that in general, coconut oil performed better than the other two cutting fluids in reducing the tool wear.
388 citations
TL;DR: In this article, a new approach to model surface roughness in fused deposition modeling (FDM) is proposed, which is based on real-world FDM parts and a theoretical model is presented by considering the main factors that crucially affect surface quality.
357 citations
TL;DR: A frequency-dependent phonon scattering rate is computed from perturbation theory and related to a description of the surface through the root-mean-square roughness height Delta and autocovariance length L, and a quadratic dependence of thermal conductivity on diameter and roughness is found.
Abstract: We present a novel approach for computing the surface roughness-limited thermal conductivity of silicon nanowires with diameter D<100 nm. A frequency-dependent phonon scattering rate is computed from perturbation theory and related to a description of the surface through the root-mean-square roughness height Delta and autocovariance length L. Using a full phonon dispersion relation, we find a quadratic dependence of thermal conductivity on diameter and roughness as (D/Delta)(2). Computed results show excellent agreement with experimental data for a wide diameter and temperature range (25-350 K), and successfully predict the extraordinarily low thermal conductivity of 2 W m(-1) K-1 at room temperature in rough-etched 50 nm silicon nanowires.
348 citations
TL;DR: In this article, the authors investigated the selective laser melting of Inconel 625 using an Nd:YAG pulsed laser to produce thin wall parts with an emphasis on attaining parts with minimum top surface and side surface roughness.
Abstract: Purpose – Obtaining the required part top surface roughness and side roughness is critical in some applications. Each of these part properties can often be improved to the detriment of the other during selective laser melting (SLM). The purpose of this paper is to investigate the selective laser melting of Inconel 625 using an Nd:YAG pulsed laser to produce thin wall parts with an emphasis on attaining parts with minimum top surface and side surface roughness.Design/methodology/approach – A full factorial approach was used to vary process parameters and identify a usable Inconel 625 processing region. The effects laser process parameters had on the formation of part surface roughness for multi‐layer parts were examined. Processing parameters that specifically affected top surface and side roughness were identified.Findings – Higher peak powers tended to reduce top surface roughness and reduce side roughness as recoil pressures flatten out the melt pool and reduce balling formation by increasing wettabilit...
341 citations
TL;DR: The presence of the thin layer of Ge changes the growth kinetics of the electron-beam-evaporated Ag, leading to Ag films with smooth surface morphology and high electrical conductivity, which are very promising for large-scale applications as molecular anchors, optical metamaterials, plasmonic devices, and several areas of nanophotonics.
Abstract: We demonstrate an effective method for depositing smooth silver (Ag) films on SiO2/Si(100) substrates using a thin seed layer of evaporated germanium (Ge). The deposited Ag films exhibit smaller root-mean-square surface roughness, narrower peak-to-valley surface topological height distribution, smaller grain-size distribution, and smaller sheet resistance in comparison to those of Ag films directly deposited on SiO2/Si(100) substrates. Optically thin (∼10−20 nm) Ag films deposited with ∼1−2 nm Ge nucleation layers show more than an order of magnitude improvement in the surface roughness. The presence of the thin layer of Ge changes the growth kinetics (nucleation and evolution) of the electron-beam-evaporated Ag, leading to Ag films with smooth surface morphology and high electrical conductivity. The demonstrated Ag thin films are very promising for large-scale applications as molecular anchors, optical metamaterials, plasmonic devices, and several areas of nanophotonics.
309 citations
TL;DR: The method involves the in-situ polymerization of common monomers in the presence of a porogenic solvent to afford superhydrophobic surfaces with the desired combination of micro- and nano-scale roughness.
Abstract: Here, a facile and inexpensive approach to superhydrophobic polymer coatings is presented. The method involves the in situ polymerization of common monomers in the presence of a porogenic solvent to afford superhydrophobic surfaces with the desired combination of micro- and nanoscale roughness. The method is applicable to a variety of substrates and is not limited to small areas or flat surfaces. The polymerized material can be ground into a superhydrophobic powder, which, once applied to a surface, renders it superhydrophobic. The morphology of the porous polymer structure can be efficiently controlled by composition of the polymerization mixture, while surface chemistry can be adjusted by photografting. Morphology control is used to reduce the globule size of the porous architecture from micro down to nanoscale thereby affording a transparent material. The influence of both surface chemistry as well as the length scale of surface roughness on the superhydrophobicity is discussed.
TL;DR: In this paper, the influence of surface preparation on roughness parameters and correlation between roughness parameter and friction and wear was investigated, where dry and lubricated pin-on-disc tests, using different contact conditions, were carried out, where Al2O3 ball was used as counter-body.
TL;DR: In this article, a series of end milling experiments were conducted to comprehensively characterize surface integrity at various milling conditions, and the experimental results have shown that the milled surface shows the anisotropic nature with the range of surface roughness values from 0.6 to 1.0μm.
TL;DR: In this article, the authors investigate drop impact dynamics on different superhydrophobic surfaces, consisting of regular polymeric micropatterns and rough carbon nanofibers, with similar static contact angles.
Abstract: We experimentally investigate drop impact dynamics onto different superhydrophobic surfaces, consisting of regular polymeric micropatterns and rough carbon nanofibers, with similar static contact angles. The main control parameters are the Weber number We and the roughness of the surface. At small We, i.e., small impact velocity, the impact evolutions are similar for both types of substrates, exhibiting Fakir state, complete bouncing, partial rebouncing, trapping of an air bubble, jetting, and sticky vibrating water balls. At large We, splashing impacts emerge forming several satellite droplets, which are more pronounced for the multiscale rough carbon nanofiber jungles. The results imply that the multiscale surface roughness at nanoscale plays a minor role in the impact events for small We 120 but an important one for large We 120. Finally, we find the effect of ambient air pressure to be negligible in the explored parameter regime We 150.
TL;DR: In this article, the machined surface integrity of titanium alloy under the dry milling process was investigated and it was concluded that dry machining can be carried out with uncoated carbide tools as far as cutting condition is limited to finish and/or semi-finish operations.
Abstract: The study is focused on the machined surface integrity of titanium alloy under the dry milling process. Roughness, lay, defects, microhardness and microstructure alterations are investigated. The result of surface roughness shows that the CVD-coated carbide tool fails to produce better Ra value compared to the uncoated tool. Lay is found to be dependent on cutting speed and feed speed directions. Microhardness is altered down to 350 μm beneath the machined surface. The first 50 μm is the soft sub-surface caused by thermal softening in the ageing process. Down to 200 μm is the hard sub-surface caused by the cyclic internal work hardening and then it gradually decreased to the bulk material hardness. It was concluded that for titanium alloys, dry machining can be carried out with uncoated carbide tools as far as cutting condition is limited to finish and/or semi-finish operations.
TL;DR: In this paper, the effect of surface roughness on pool boiling heat transfer is experimentally explored over a wide range of roughness values in water and Fluorinert ™ FC-77, two fluids with different thermal properties and wetting characteristics.
Abstract: The effect of surface roughness on pool boiling heat transfer is experimentally explored over a wide range of roughness values in water and Fluorinert ™ FC-77, two fluids with different thermal properties and wetting characteristics. The test surfaces ranged from a polished surface (Ra between 0.027 m and 0.038 m) to electrical discharge machined (EDM) surfaces with a roughness Ra ranging from 1.08 m to 10.0 m. Different trends were observed in the heat transfer coefficient with respect to the surface roughness between the two fluids on the same set of surfaces. For FC-77, the heat transfer coefficient was found to continually increase with increasing roughness. For water, on the other hand, EDM surfaces of intermediate roughness displayed similar heat transfer coefficients that were higher than for the polished surface, while the roughest surface showed the highest heat transfer coefficients. The heat transfer coefficients were more strongly influenced by surface roughness with FC-77 than with water. For FC-77, the roughest surface produced 210% higher heat transfer coefficients than the polished surface while for water, a more modest 100% enhancement was measured between the same set of surfaces. Although the results highlight the inadequacy of characterizing nucleate pool boiling data using Ra, the observed effect of roughness was correlated using h Ra as has been done in several prior studies. The experimental results were compared with predictions from several widely used correlations in the literature. DOI: 10.1115/1.3220144
TL;DR: This paper develops a model function that expresses copolarized backscattering cross sections (sigmahh and sigmavv) in terms of volumetric soil moisture using L-band experimental data for both bare and vegetated surfaces and proposes a viable approach to determine these two unknowns using combined radiometer and radar data.
Abstract: Electromagnetic scattering from a rough surface is a function of both surface roughness and dielectric constant of the scattering surface. Therefore, in order to estimate soil moisture of a bare surface accurately from radar measurements, the effects of surface roughness must be compensated for properly. Several algorithms have been developed to estimate soil moisture from a polarimetric radar image, all with limited ranges of applicability. No theoretical algorithm has been reported to retrieve volumetric soil moisture of a vegetated surface. In this paper, we examine a different approach to estimate soil moisture that exploits the fact that the backscattering cross section from a natural object changes over short timescales mainly due to variations in soil moisture. We develop a model function that expresses copolarized backscattering cross sections (sigmahh and sigmavv) in terms of volumetric soil moisture using L-band experimental data for both bare and vegetated surfaces. In order to estimate soil moisture, two unknowns in the model function must be determined. We propose a viable approach to determine these two unknowns using combined radiometer and radar data. This time-series approach also provides a framework to utilize a priori knowledge on soil moisture to improve the retrieval accuracy of volumetric soil moisture. We demonstrate that this time-series algorithm is a simple and robust way to estimate soil moisture for both bare and vegetated surfaces.
TL;DR: In this paper, the surface roughness of Al-SiC (20 p) has been studied by turning the composite bars using coarse grade polycrystalline diamond (PCD) insert under different cutting conditions.
Journal Article•
TL;DR: In this article, the T aguchi method is applied to find optimum process parameters for end milling while hard machining of hardened steel, and the results match closely with ANOV A and cutting speed is most influencing parameter.
Abstract: In this paper , T aguchi method is applied to find optimum process parameters for end milling while hard machining of hardened steel. A L 18 array , signal-to-noise ratio and analysis of variance (ANOV A) are applied to study performance characteristics of machining parameters (cutting speed, feed, depth of cut and width of cut) with consideration of surface finish and tool life. Chipping and adhesion are observed to be main causes of wear . Results obtained by T aguchi method match closely with ANOV A and cutting speed is most influencing parameter . Multiple regression equations are formulated for estimating predicted values of surface roughness and tool wear
TL;DR: In this article, the wear mechanisms of tungsten carbide (WC) drills during dry high speed drilling of quasi-isotropic woven graphite fiber epoxy composites were investigated.
TL;DR: An adaptive neuro-fuzzy inference system (ANFIS) model has been developed for the prediction of the white layer thickness (WLT) and the average surface roughness achieved as a function of the process parameters.
Abstract: A wire electrical discharge machined (WEDM) surface is characterized by its roughness and metallographic properties. Surface roughness and white layer thickness (WLT) are the main indicators of quality of a component for WEDM. In this paper an adaptive neuro-fuzzy inference system (ANFIS) model has been developed for the prediction of the white layer thickness (WLT) and the average surface roughness achieved as a function of the process parameters. Pulse duration, open circuit voltage, dielectric flushing pressure and wire feed rate were taken as model's input features. The model combined modeling function of fuzzy inference with the learning ability of artificial neural network; and a set of rules has been generated directly from the experimental data. The model's predictions were compared with experimental results for verifying the approach.
TL;DR: In this paper, a neural network approach is presented for the prediction and control of surface roughness in a computer numerically controlled (CNC) lathe, which is a type of back-propagation.
TL;DR: In this article, the performance of a CBN tool during hard turning of 100Cr6-tempered steel was investigated using a series of long-duration wear tests to elucidate the cutting speed effects on the various tool wear forms.
Patent•
23 Dec 2009TL;DR: In this article, a SiConi etch with a greater or lesser flow ratio of hydrogen compared to fluorine was proposed to reduce roughness of the post-etch surface and to reduce the difference in etch rate between densely and sparsely patterned areas.
Abstract: A method of etching silicon-containing material is described and includes a SiConi™ etch having a greater or lesser flow ratio of hydrogen compared to fluorine than that found in the prior art. Modifying the flow rate ratios in this way has been found to reduce roughness of the post-etch surface and to reduce the difference in etch-rate between densely and sparsely patterned areas. Alternative means of reducing post-etch surface roughness include pulsing the flows of the precursors and/or the plasma power, maintaining a relatively high substrate temperature and performing the SiConi™ in multiple steps. Each of these approaches, either alone or in combination, serve to reduce the roughness of the etched surface by limiting solid residue grain size.
TL;DR: In this paper, the repellent characteristics of current existing super-hydrophobic surfaces to hot water (50-80 °C) were investigated and the results showed that the surface energy is more prevailing than the surface roughness in making the surface repel hot liquids.
Abstract: Superhydrophobic surfaces that can repel hot liquids stand for a new generation of self-cleaning surfaces with broad applications. However, can current existing superhydrophobic surfaces repel hot water? In this paper, the repellent characteristics of current existing superhydrophobic surfaces to hot water (50–80 °C) were investigated. Representative superhydrophobic surfaces from lotus leaves, Teflon, silica–fluoropolymer composites and sol–gel processes were fabricated on silicon wafers and their repellency to hot water was evaluated based on water-contact angle (WCA) measurements and water uptake. These so-called superhydrophobic surfaces, which usually exhibit high repellency to cool water (around 25 °C), however, show remarkably decreased repellency to hot water. This may be attributed to a decrease of surface tension when the temperature of water increases and the lower surface tension of hot water makes it a better “wetting agent” to get into the pores and fissures of rough surfaces rather than bridging them with surface tension. According to the theories of surface wettability, the wetting state of water droplets on superhydrophobic surfaces can be described as Cassie–Baxter and Wenzel states, respectively. Superhydrophobic surfaces lose their high repellency to hot water due to the transition of the wetting state from Cassie–Baxter state to Wenzel state. Surface roughness, which is usually used for improving surface hydrophobicity, however, is found to improve the wettability of a solid surface to hot water. The results in this paper also show that the wettability of a solid surface is governed by both the surface roughness and surface free energy, but the surface energy is more prevailing than the surface roughness in making the surface repel hot liquids. To fabricate hot water repellent fabrics, a nanocomposite of CNTs and Teflon was prepared and applied to commercial fabrics to produce scalding protection clothes. The repellency of the CNTs–Teflon treated fabrics to hot beverages (water, milk, coffee and tea, 50–80 °C) was studied. The spray test shows that although some superhydrophobic surfaces exhibit high repellency to static water they show reduced repellency to dynamic water.
TL;DR: In this paper, three current densities, i.e. 15m, 75m, and 150m, were applied to the AM50 magnesium alloy and the results showed that the 15m treated coatings produced at higher current density levels were thicker but showed poor corrosion resistance when compared to that of the coatings obtained at 15m.
TL;DR: In this paper, the performance of the electrodes for the finishing micro-EDM was evaluated based on the achieved surface roughness and surface characteristics with respect to material removal rate (MRR) and electrode wear ratio (EWR).
TL;DR: In this paper, the effects of depth of cut and machining time on machinability aspects such as machining force, power, specific cutting force, surface roughness and tool wear using second order mathematical models during turning of high chromium AISI D2 cold work tool steel with CC650, CC650WG and GC6050WH ceramic inserts.
Abstract: Hard turning with ceramic cutting tool has several benefits over grinding process such as elimination of coolant, reduced processing costs, improved material properties, reduced power consumption and increased productivity. Despite its significant advantages, hard turning can not replace all grinding due to lack of data concerning surface quality and tool wear and hence there is a need to study the machinability characteristics in high precision and high-hardened components. An attempt has been made in this paper to analyze the effects of depth of cut and machining time on machinability aspects such as machining force, power, specific cutting force, surface roughness and tool wear using second order mathematical models during turning of high chromium AISI D2 cold work tool steel with CC650, CC650WG and GC6050WH ceramic inserts. The experiments were planned as per full factorial design (FFD). From the parametric analysis, it is revealed that, the CC650WG wiper insert performs better with reference to surface roughness and tool wear, while the CC650 conventional insert is useful in reducing the machining force, power and specific cutting force.
TL;DR: The roughness and crystalline phase of Y-TZP materials were influenced by surface treatments, and biaxial flexural strength of materials decreased after grinding and increased after sandblasting.
Abstract: The aim of this study was to evaluate the influence of surface grinding and sandblasting on surface roughness, phase chances, and biaxial flexural strength of yttria-stabilized tetragonal zirconia (Y-TZP) materials. Thirty disk specimens of Cercon (C), DentaCAD (DC), Zirkonzahn (ZZ) were fabricated. The specimens were divided into three groups according to surface treatment (control, ground, and sandblasted). Surface roughness was measured, and X-ray diffraction analysis was performed. Finally, biaxial flexural strength was determined. The data was analyzed by two-way ANOVA. Weibull statistics was used to analyze the variability of strength. The effects of surface treatments on surface roughness values were different for each material. X-ray diffraction analysis revealed that control groups of C and ZZ were composed of tetragonal zirconia. Relative amount of monoclinic zirconia (SD) was 7.366 (0.716)% in the DC control group. In all materials, transformation occurred after treatments. Grinding decreased and sandblasting increased the strength of control groups in all materials. Ground C and DC specimens had higher Weibull modulus than control groups while lower m was found for ground ZZ. Sandblasting, resulted in lower m compared with grinding for all materials although increased strength. The roughness and crystalline phase of Y-TZP materials were influenced by surface treatments. Biaxial flexural strength of materials decreased after grinding and increased after sandblasting. The low m of sandblasted groups may indicate further weakening of the materials, resulting in unexpected failures.
TL;DR: In this article, a simple thermal based model has been developed for the determination of the material removal rate and the average surface roughness achieved as a function of the process parameters, which predicts that the increase of the discharge current, the arc voltage or the spark duration results in higher material removal rates and coarser workpiece surfaces.
Abstract: The die-sinking electrical discharge machining (EDM) process is characterized by slow processing speeds. Research effort has been focused on optimizing the process parameters so as for the productivity of the process to be increased. In this paper a simple, thermal based model has been developed for the determination of the material removal rate and the average surface roughness achieved as a function of the process parameters. The model predicts that the increase of the discharge current, the arc voltage or the spark duration results in higher material removal rates and coarser workpiece surfaces. On the other hand the decrease of the idling time increases the material removal rate with the additional advantage of achieving slightly better surface roughness values. The model’s predictions are compared with experimental results for verifying the approach and present good agreement with them.