Showing papers on "Surface roughness published in 2008"
TL;DR: A superhydrophobic surface is a surface with a water contact angle close to or higher than 150° as discussed by the authors, and it is the combination of surface roughness and low-surface-energy modification that leads to super-hydrophobicity.
Abstract: A superhydrophobic surface is a surface with a water contact angle close to or higher than 150°. In this feature article, we review the historical and present research on superhydrophobic surfaces, including the characterization of superhydrophobicity, different ways to fabricate rough surfaces, and low-surface-energy modifications on inorganic and organic rough surfaces. It is the combination of surface roughness and low-surface-energy modification that leads to superhydrophobicity. Notably, research on superhydrophobic surfaces has not only fundamental interest but various possible functional applications in micro- and nano-materials and devices.
1,588 citations
TL;DR: It is shown that low-density vertically aligned carbon nanotube arrays can be engineered to have an extremely low index of refraction, as predicted recently by theory and, combined with the nanoscale surface roughness of the arrays, can produce a near-perfect optical absorption material.
Abstract: An ideal black material absorbs light perfectly at all angles and over all wavelengths. Here, we show that low-density vertically aligned carbon nanotube arrays can be engineered to have an extremely low index of refraction, as predicted recently by theory [Garcia-Vidal, F. J.; Pitarke, J. M.; Pendry, J. B. Phys. Rev. Lett. 1997, 78, 4289-4292] and, combined with the nanoscale surface roughness of the arrays, can produce a near-perfect optical absorption material. An ultralow diffused reflectance of 1 x 10(-7) measured from such arrays is an order-of-magnitude lower compared to commercial low-reflectance standard carbon. The corresponding integrated total reflectance of 0.045% from the nanotube arrays is three times lower than the lowest-ever reported values of optical reflectance from any material, making it the darkest man-made material ever.
659 citations
TL;DR: In this article, liquid nitrogen as a cryogenic coolant was investigated in detail in terms of application methods in material removal operations and its effects on cutting tool and workpiece material properties, cutting temperature, tool wear/life, surface roughness and dimensional deviation, friction and cutting forces.
Abstract: The cooling applications in machining operations play a very important role and many operations cannot be carried out efficiently without cooling. Application of a coolant in a cutting process can increase tool life and dimensional accuracy, decrease cutting temperatures, surface roughness and the amount of power consumed in a metal cutting process and thus improve the productivity. In this review, liquid nitrogen, as a cryogenic coolant, was investigated in detail in terms of application methods in material removal operations and its effects on cutting tool and workpiece material properties, cutting temperature, tool wear/life, surface roughness and dimensional deviation, friction and cutting forces. As a result, cryogenic cooling has been determined as one of the most favourable method for material cutting operations due to being capable of considerable improvement in tool life and surface finish through reduction in tool wear through control of machining temperature desirably at the cutting zone.
420 citations
TL;DR: The in vivo test suggested that, in similar conditions, the surface treatment had a beneficial effect on the implant biocompatibility measured through removal torque, and the anodized dental implant presented the highest removal torque.
Abstract: The biological properties of titanium depend on its surface oxide film. Several mechanical and chemical treatments have been used to modify the surface morphology and properties of titanium dental implants. One possible method of improving dental implant biocompatibility is to increase surface roughness and decrease the contact angle. In the present work, the biological properties of dental implants were investigated through in vivo and in vitro tests. The effects of surface roughness, contact angle and surface morphology on titanium dental implant removal torque were investigated. Machined dental implants and discs made with commercially pure titanium ASTM grade 4 were submitted to sandblasting treatments, acid etching and anodizing. The sample surface morphologies were characterized by SEM, the surface roughness parameters were quantified using a laser non-contact profilometer, and a contact angle measurement was taken. Dental implants were placed in the tibia of rabbits and removed 12 weeks after the surgery. It was found that: (i) acid etching homogenized the surface roughness parameters; (ii) the anodized surface presented the smallest contact angle; (iii) the in vivo test suggested that, in similar conditions, the surface treatment had a beneficial effect on the implant biocompatibility measured through removal torque; and (iv) the anodized dental implant presented the highest removal torque.
398 citations
TL;DR: The quantified contribution of pure nanometer and sub-micron surface structures on the adhesion of vascular (endothelial) and bone (osteoblasts) cells were demonstrated and it was clearly identified that both endothelial and bone cells selectively adhered onto sub- micron and nanometer surface features by 400% and 50% more than onto flat regions, respectively.
392 citations
TL;DR: Laser metal sintering proved to be an efficient means of construction of dental implants with a functionally graded material which is better adapted to the elastic properties of the bone and should minimize stress shielding effects and improve long-term performance.
387 citations
TL;DR: In this paper, the effect of cutting parameters (cutting speed, feed rate and depth of cut) on cutting forces and surface roughness in finish hard turning of MDN250 steel (equivalent to 18Ni(250) maraging steel) using coated ceramic tool.
377 citations
TL;DR: In this paper, the effect of machining parameters, e.g., cutting speed, feed rate and depth of cut on tool wear and surface roughness was studied, and it was observed that increase of reinforcement element addition produced better mechanical properties such as impact toughness and hardness, but tensile strength showed different trend.
362 citations
TL;DR: In this paper, the root-mean-squared (RMS) roughness of the sample, taken over a square area with edge dimensions of 200 times the average indentation depth of the dominating phase of the material, should be less than five times.
361 citations
TL;DR: The effect of roughness on hypersonic boundary layer transition has been studied for three primary purposes: to trip a laminar layer to turbulence, to determine whether naturally occurring roughness is expected to cause early transition, and to determine the largest allowable roughness that will not affect the location of transition as mentioned in this paper.
Abstract: The effect of roughness on hypersonic boundarylayer transition has been studied for three primary purposes: to trip a laminar layer to turbulence, to determine whether naturally occurring roughness is expected to cause early transition, and to determine the largest allowable roughness that will not affect the location of transition. Roughness is often divided into two classes: isolated roughness in which each protuberance can be considered separately, and distributed roughness similar to sandpaper, in which the roughness elements are many and are not considered separately. The effects of roughness on hypersonic transition are reviewed, considering the physics of the process, known parametric effects, some of the common correlations, and a few case studies. The three or more modes by which roughness can affect transition are outlined. At hypersonic edge Mach nunbers, it requires very large roughness heights to affect transition. Various correlations are often used to estimate the effect of roughness; several of these are described, although none provide good agreement with all the data.
321 citations
TL;DR: A literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture.
Abstract: Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale.
TL;DR: In this paper, an experimental investigation of small deep hole drilling of Inconel 718 using the EDM process was conducted, and the output responses measured were material removal rate (MRR) and depth averaged surface roughness (DASR).
Abstract: This paper reports on an experimental investigation of small deep hole drilling of Inconel 718 using the EDM process. The parameters such as peak current, pulse on-time, duty factor and electrode speed were chosen to study the machining characteristics. An electrolytic copper tube of 3 mm diameter was selected as a tool electrode. The experiments were planned using central composite design (CCD) procedure. The output responses measured were material removal rate (MRR) and depth averaged surface roughness (DASR). Mathematical models were derived for the above responses using response surface methodology (RSM). The results revealed that MRR is more influenced by peak current, duty factor and electrode rotation, whereas DASR is strongly influenced by peak current and pulse on-time. Finally, the parameters were optimized for maximum MRR with the desired surface roughness value using desirability function approach.
TL;DR: The size effect in the imaginary part of the dielectric function is significant for both polarizations of light, parallel and perpendicular to the strips with relatively large A-parameter.
Abstract: Ag permittivity (dielectric function) in coupled strips is different from bulk and has been studied for strips of various dimensions and surface roughness. Arrays of such paired strips exhibit the properties of metamagnetics. The surface roughness does not affect the Ag dielectric function, although it does increase the loss at the plasmon resonances of the coupled strips. The size effect in the imaginary part of the dielectric function is significant for both polarizations of light, parallel and perpendicular to the strips with relatively large A-parameter.
TL;DR: In this paper, the surface and subsurface damages have been studied with scanning electron microscope (SEM) and the effects of grinding conditions on surface/subsurface damage have been discussed.
Abstract: The difficulty and cost involved in the abrasive machining of hard and brittle ceramics are among the major impediments to the widespread use of advanced ceramics in industries these days. It is often desired to increase the machining rate while maintaining the desired surface integrity. The success of this approach, however, relies in the understanding of mechanism of material removal on the microstructural scale and the relationship between the grinding characteristics and formation of surface/subsurface machining-induced damage. In this paper, grinding characteristics, surface integrity and material removal mechanisms of SiC ground with diamond wheel on surface grinding machine have been investigated. The surface and subsurface damages have been studied with scanning electron microscope (SEM). The effects of grinding conditions on surface/subsurface damage have been discussed. This research links the surface roughness, surface and subsurface damages to grinding parameters and provides valuable insights into the material removal mechanism and the dependence of grinding-induced damage on grinding conditions.
TL;DR: In this paper, the authors presented the prediction and evaluation of thrust force and surface roughness in drilling of composite material using candle stick drill, which was based on Taguchi method and the artificial neural network.
TL;DR: In this article, the authors identify a relationship between surface quality, turning process parameters and fatigue behavior of 34CrNiMo6 and show that residual stress on fatigue life is more pronounced than the effect of surface roughness.
TL;DR: The surface damage produced by the CAD/CAM milling procedure significantly reduced the strength of zirconia which could be further weakened by different surface treatment methods resulting in unexpected failures at stresses much lower than the ideal strength of the material.
TL;DR: In this paper, an ANN model of surface roughness parameters (Ra and Rt) is developed with the cutting conditions such as feed rate, cutting speed and depth of cut as the affecting process parameters.
TL;DR: In this article, a second-order model has been established between the cutting parameters and surface roughness using response surface methodology, and the predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface rouness in the machining of GFRP composites.
Abstract: This paper discusses the use of Taguchi and response surface methodologies for minimizing the surface roughness in machining glass fiber reinforced (GFRP) plastics with a polycrystalline diamond (PCD) tool. The experiments have been conducted using Taguchi’s experimental design technique. The cutting parameters used are cutting speed, feed and depth of cut. The effect of cutting parameters on surface roughness is evaluated and the optimum cutting condition for minimizing the surface roughness is determined. A second-order model has been established between the cutting parameters and surface roughness using response surface methodology. The experimental results reveal that the most significant machining parameter for surface roughness is feed followed by cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in the machining of GFRP composites. The predicted values are confirmed by using validation experiments.
TL;DR: In this article, the effect of roughness on wetting mechanisms and relevant roughness parameters are discussed. But the focus of this paper is not on surface roughness, but on surface mechanics, physics, chemistry, and biology.
Abstract: Superhydrophobicity can be used for many applications that require non-adhesive and water-repellent surfaces. A successful design of superhydrophobic surfaces requires a correct assessment of the surface roughness effect on wetting. Roughness is an important property in surface mechanics, physics, chemistry, and biology, and it is critical for many tribological applications. Roughness can be defined in different ways, and the definition should be adequate to the problem under investigation. Our recent studies of biological and biomimetic superhydrophobic surfaces show that traditional roughness parameters, such as the root-mean-square, correlation length, or fractal dimension, are not always appropriate for the analysis of wetting. This is, in particular, due to the hierarchical nature of wetting mechanisms and interfaces. We discuss the effect of roughness on wetting mechanisms and relevant roughness parameters and ways to broaden the concept and scope of surface roughness.
TL;DR: In this paper, the structure and dynamic properties of interfacial water at the graphite and silica solid surfaces were investigated using molecular dynamics simulations, and the effect of surface properties on the characteristics of inter-surface water was quantified by computing density profiles, radial distribution functions, surface density distributions, orientation order parameters, and residence and reorientation correlation functions.
Abstract: The structure and dynamic properties of interfacial water at the graphite and silica solid surfaces were investigated using molecular dynamics simulations. The effect of surface properties on the characteristics of interfacial water was quantified by computing density profiles, radial distribution functions, surface density distributions, orientation order parameters, and residence and reorientation correlation functions. In brief, our results show that the surface roughness, chemical heterogeneity, and surface heterogeneous charge distribution affect the structural and dynamic properties of the interfacial water molecules, as well as their rate of exchange with bulk water. Most importantly, our results indicate the formation of two distinct water layers at the SiO2 surface covered by a large density of hydroxyl groups. Further analysis of the data suggests a highly confined first layer where the water molecules assume preferential hydrogen-down orientation and a second layer whose behavior and characteri...
TL;DR: In this article, an artificial neural network (ANN) and regression model were developed to predict surface roughness in abrasive waterjet machining (AWJ) process, where machining parameters of traverse speed, waterjet pressure, standoff distance, abrasive grit size and abrasive flow rate were considered as model variables.
TL;DR: In this paper, the influence of machined surface roughness on the fatigue life of 7010 aluminium alloy has been investigated and a model of fatigue life prediction was developed, using this definition of local Kt.
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01 Mar 2008
TL;DR: In this article, the relationship between surface energy and surface forces is investigated and Lubrication is measured in tight spots and friction is found to be present in the early stages of friction.
Abstract: 1. Introduction 2. Characterizing Surface Roughness 3. Mechanical Properties of Solids and Real Area of Contact 4. Friction 5. Surface Energy and Capillary Pressure 6. Relationship Between Surface Energy and Surface Forces 7. Physical Origins of Surface Forces 8. Measuring Surface Forces 9. Lubrication 10. Lubrication in Tight Spots 11. Atomistic Origins of Friction 12. Wear
TL;DR: In this paper, a rippled poly(dimethylsiloxane) (PDMS) elastomer bilayer film is used to regulate surface roughness and adhesion by applying mechanical strain.
Abstract: We report a new dry adhesive structure using a rippled poly(dimethylsiloxane) (PDMS) elastomer bilayer film, whose surface roughness and adhesion can be reversibly regulated by applying mechanical strain. It has a set of advantages not offered by other techniques for regulation of adhesion, including real-time tunability, no requirement of specific surface chemistry, operability under ambient conditions, and relative ease of control. To understand the mechanism for adhesion regulation quantitatively, we have modeled the mechanics of adhesion in the limits of small- and large-amplitude ripples, and show good agreement with indentation experiments. We demonstrate the real-time tunability of the new adhesive structure by repeatedly picking and releasing a glass ball simply by modulating the mechanical stretch of the rippled PDMS film.
TL;DR: The feasibility of creating Ti6Al4V surfaces having both a microtexture and a nanotexture is demonstrated, and it is shown that their properties can be tailored by controlling the length of exposure to a mixture of H2SO4 and H2O2.
TL;DR: The theory of roughness-induced superhydrophobicity is presented in this paper, where the effect of surface roughness upon wetting and capillary adhesion force is discussed.
Abstract: Non-adhesive and water-repellent surfaces are required for many tribological applications. Roughness-induced superhydrophobicity has been suggested as a way to reduce adhesion and stiction. In this paper, the theory of roughness-induced superhydrophobicity is presented. Wetting is studied as a multiscale process involving the macroscale (water droplet size), microscale (surface texture size), and nanoscale (molecular size). We study fundamental physical mechanisms of wetting, including the transition between various wetting regimes, contact angle and contact angle hysteresis. The effect of surface roughness upon wetting and capillary adhesion force is discussed. Practical recommendations for the design of superhydrophobic surfaces are formulated.
TL;DR: A series of pillar-like patterned silicon wafers with different pillar sizes and spacing are fabricated by photolithography and further modified by a self-assembled fluorosilanated monolayer, finding the dynamic contact angles of water on these surfaces to be consistent with the theoretical predictions of the Cassie model and the Wenzel model.
Abstract: A series of pillar-like patterned silicon wafers with different pillar sizes and spacing are fabricated by photolithography and further modified by a self-assembled fluorosilanated monolayer. The dynamic contact angles of water on these surfaces are carefully measured and found to be consistent with the theoretical predictions of the Cassie model and the Wenzel model. When a water drop is at the Wenzel state, its contact angle hysteresis increases along with an increase in the surface roughness. While the surface roughness is further raised beyond its transition roughness (from the Wenzel state to the Cassie state), the contact angle hysteresis (or receding contact angle) discontinuously drops (or jumps) to a lower (or higher) value. When a water drop is at the Cassie state, its contact angle hysteresis strongly depends on the solid fraction and has nothing to do with the surface roughness. Even for a superhydrophobic surface, the contact angle hysteresis may still exhibit a value as high as 41 degrees for the solid fraction of 0.563.
TL;DR: In this article, the performance of commercial scanning white light interferometers in a range of measurement tasks was examined, and it was found that most instruments report errors when used in regions close to a discontinuity or those with a surface gradient that is large compared to the acceptance angle of the objective lens.
Abstract: This paper examines the performance of commercial scanning white light interferometers in a range of measurement tasks. A step height artefact is used to investigate the response of the instruments at a discontinuity, while gratings with sinusoidal and rectangular profiles are used to investigate the effects of surface gradient and spatial frequency. Results are compared with measurements made with tapping mode atomic force microscopy and discrepancies are discussed with reference to error mechanisms put forward in the published literature. As expected, it is found that most instruments report errors when used in regions close to a discontinuity or those with a surface gradient that is large compared to the acceptance angle of the objective lens. Amongst other findings, however, we report systematic errors that are observed when the surface gradient is considerably smaller. Although these errors are typically less than the mean wavelength, they are significant compared to the vertical resolution of the instrument and indicate that current scanning white light interferometers should be used with some caution if sub-wavelength accuracy is required.
TL;DR: In this article, the effects of reinforcement particles on the machinability of metal matrix composites were investigated experimentally and it was shown that the surface residual stresses on a machined MMC are compressive, the surface roughness is controlled by feed and particle pull-out influences the roughness when feed is low.
Abstract: Machining forces, chip formation, surface integrity and shear and friction angles are important factors to understand the machinability of metal matrix composites (MMCs). However, because of the complexity of the reinforcement mechanisms of the ceramic particles, a fair assessment of the machinability of MMCs is still a difficult issue. This paper investigates experimentally the effects of reinforcement particles on the machining of MMCs. The major findings are: (1) the surface residual stresses on the machined MMC are compressive; (2) the surface roughness is controlled by feed; (3) particle pull-out influences the roughness when feed is low; (4) particles facilitate chip breaking and affect the generation of residual stresses; and (5) the shear and friction angles depend significantly on feed but are almost independent of speed. These results reveal the roles of the reinforcement particles on the machinability of MMCs and provide a useful guide for a better control of their machining processes.