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1
Yun, Yong Il, Il Young Park et Seung Jin Song. « Performance Degradation due to Blade Surface Roughness in a Single-Stage Axial Turbine ». Journal of Turbomachinery 127, no 1 (1 janvier 2005) : 137–43. http://dx.doi.org/10.1115/1.1811097.
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Turbine blades experience significant surface degradation with service. Previous studies indicate that an order-of-magnitude or greater increase in roughness height is typical, and these elevated levels of surface roughness significantly influence turbine efficiency and heat transfer. This paper presents measurement and a mean-line analysis of turbine efficiency reduction due to blade surface roughness. Performance tests have been conducted in a low-speed, single-stage, axial flow turbine with roughened blades. Sheets of sandpaper with equivalent sandgrain roughnesses of 106 and 400 μm have been used to roughen the blades. The roughness heights correspond to foreign deposits on real turbine blades measured by Bons et al. [1]. In the transitionally rough regime (106 μm), normalized efficiency decreases by approximately 4% with either roughened stator or roughened rotor and by 8% with roughness on both the stator and rotor blades. In the fully rough regime (400 μm), normalized efficiency decreases by 2% with roughness on the pressure side and by 6% with roughness on the suction side. Also, the normalized efficiency decreases by 11% with roughness only on stator vanes, 8% with roughness only on rotor blades, and 19% with roughness on both the stator and rotor blades.
2
Craig, Michael, Jay Raval, Bruce Tai, Albert Patterson et Wayne Hung. « Effect of Channel Roughness on Micro-Droplet Distribution in Internal Minimum Quantity Lubrication ». Dynamics 2, no 4 (14 octobre 2022) : 336–55. http://dx.doi.org/10.3390/dynamics2040019.
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This research studied the effect of channel roughness on micro-droplet distributions in internal minimum quantity lubrication for effective machining. Mixtures of different oils and air were flown though internal channels with simulated different roughness: as fabricated, partially threaded, and fully threaded. The airborne droplets were collected, analyzed, and compared with simulated results by computational fluid dynamics. For low-viscous lubricant, the rough channel surface helped to break large droplets in the boundary layer into smaller droplets and reintroduce them into the main downstream flow. The opposite trend was found for the higher viscous lubricant. The study also performed chemical etching to roughen selected surfaces of carbide cutting tools. The synergy of hand and ultrasonic agitation successfully roughened a carbide surface within twelve minutes. Scanning electron microscopy examination showed deep etching that removed all grinding marks on a WC–Co cutting tool surface.
3
Kheur, Mohit, Tabrez Lakha, Saleha Shaikh, Supriya Kheur, Batul Qamri, Lee Wan Zhen, Nadin Al-Haj Husain et Mutlu Özcan. « A Comparative Study on Simulated Chairside Grinding and Polishing of Monolithic Zirconia ». Materials 15, no 6 (16 mars 2022) : 2202. http://dx.doi.org/10.3390/ma15062202.
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This study evaluated the effects of different simulated chairside grinding and polishing protocols on the physical and mechanical properties of surface roughness, hardness, and flexural strength of monolithic zirconia. Sintered monolithic zirconia specimens (15 mm × 3 mm × 3 mm) were abraded using three different burs: diamond bur, modified diamond bur (zirconia specified), and tungsten carbide bur, along with a group of unprepared specimens that served as a control group. The study was divided into two phases, Phase 1 and Phase 2. Surface roughness, surface hardness, and flexural strength were assessed before and after the grinding procedure to determine the ‘best test group’ in Phase 1. The best abrasive agent was selected for Phase 2 of the study. The specimens in Phase 2 underwent grinding with the best abrasive agent selected. Following the grinding, the specimens were then polished using commercially available diamond polishing paste, a porcelain polishing kit, and an indigenously developed low-temperature sintered zirconia slurry. The physical and mechanical properties were again assessed. Results were analyzed using one-way ANOVA test. Specimens were observed under scanning electron microscopy (SEM) and X-ray diffraction (XRD) for their microstructure and crystalline phases, respectively. Grinding with diamond burs did not weaken zirconia (p > 0.05) but produced rougher surfaces than the control group (p < 0.05). Tungsten carbide burs did not significantly roughen the zirconia surface. However, specimens ground by tungsten carbide burs had a significantly reduced mean flexural strength (p < 0.05) and SEM revealed fine surface cracks. Phase transformation was not detected by XRD. Polishing with commercially available polishing agents, however, restored the surface roughness levels to the control group. Dental monolithic zirconia ground with tungsten carbide burs had a significantly reduced flexural strength and a smooth but defective surface. However, grinding with diamond burs roughened the zirconia surface. These defects may be reduced by polishing with commercially available polishing agents. The use of tungsten carbide burs for grinding dental zirconia should not be advocated. Grinding with diamond abrasives does not weaken zirconia but requires further polishing with commercially available polishing agents.
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Wang, Jun, Jose Antonio Sánchez, Borja Izquierdo et Izaro Ayesta. « Influence of AISI D2 Workpiece Roughness on Heat Partition and Plasma Channel Radius in the WEDM Process ». Metals 10, no 10 (12 octobre 2020) : 1360. http://dx.doi.org/10.3390/met10101360.
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As an important advanced machining process, in Wire Electrical Discharge Machining (WEDM) certain fundamental issues remain need to be studied in-depth, such as the effect of part surface roughness on heat transfer mechanisms. In the WEDM process, roughing cut wire goes into the workpiece to do the first shaping and in trim cut the wire sweeps on the outer surface to improve the surface roughness. In both of these two cases, the generation of sparks depends on the passing surface roughness. Therefore, with AISI D2 material and brass wire, this paper presents a study of the influence of part surface roughness on heat partition and the radius of the plasma channel in the WEDM process. Through extensive single discharge experiments, it is shown that the removal capacity per discharge can increase if the discharge occurs on a smoother surface. A Finite Element thermal model was then used for inverse fitting of the values of heat partition and radius of the plasma channel. These parameters completely define the characteristics of the heat conduction problem. The results indicate a strong correlation between an increase in heat partition ratio and a decrease in part surface roughness. The values of plasma channel radius show an increase in this value when discharging on rougher surfaces. It means that with the increasing of plasma channel radius, the heat source goes into the workpiece more dispersed. In the case of rougher surface, although the there is more area that affected by the heat source, finally the temperature of most area cannot reach to the melting point and it causes the smaller crater radius and volume, while the metal removal rate decreases. These results contribute towards a more complete understanding of the influence of surface roughness to the spark occurring.
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Mulleners, K., P. Gilge et S. Hohenstein. « Impact of Surface Roughness on the Turbulent Wake Flow of a Turbine Blade ». Journal of Aerodynamics 2014 (30 décembre 2014) : 1–9. http://dx.doi.org/10.1155/2014/458757.
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Roughened aeroengine blade surfaces lead to increased friction losses and reduced efficiency of the individual blades. The surface roughness also affects the wake flow of the blade and thus the inflow conditions for the subsequent compressor or turbine stage. To investigate the impact of surface roughness on a turbulent blade wake, we conducted velocity field measurements by means of stereo particle image velocimetry in the wake of a roughened turbine blade in a linear cascade wind tunnel. The turbine blade was roughened at different chordwise locations. The influence of the chordwise location of the added surface roughness was examined by comparing their impact on the width and depth of the wake and, the positions and distribution of vortical structures in the wake. Additionally, the friction loss coefficients for different surface roughness positions were estimated directly from the velocity field.
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XIAO, BOQI, YIDAN ZHANG, YAN WANG, GUOPING JIANG, MINGCHAO LIANG, XUBING CHEN et GONGBO LONG. « A FRACTAL MODEL FOR KOZENY–CARMAN CONSTANT AND DIMENSIONLESS PERMEABILITY OF FIBROUS POROUS MEDIA WITH ROUGHENED SURFACES ». Fractals 27, no 07 (novembre 2019) : 1950116. http://dx.doi.org/10.1142/s0218348x19501160.
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In this paper, fluid transport through fibrous porous media is studied by the fractal theory with a focus on the effect of surface roughness of capillaries. A fractal model for Kozeny–Carman (KC) constant and dimensionless permeability of fibrous porous media with roughened surfaces is derived. The determined KC constant and dimensionless permeability of fibrous porous media with roughened surfaces are in good agreement with available experimental data and existing models reported in the literature. It is found that the KC constant of fibrous porous media with roughened surfaces increases with the increase of relative roughness, porosity, area fractal dimension of pore and tortuosity fractal dimension, respectively. Besides, it is seen that the dimensionless permeability of fibrous porous media with roughened surfaces decreases with increasing relative roughness and tortuosity fractal dimension. However, it is observed that the dimensionless permeability of fibrous porous media with roughened surfaces increases with porosity. With the proposed fractal model, the physical mechanisms of fluids transport through fibrous porous media are better elucidated.
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Jemat, Afida, Mariyam Jameelah Ghazali, Masfueh Razali et Yuichi Otsuka. « Effects of Surface Treatment on Titanium Alloys Substrate by Acid Etching for Dental Implant ». Materials Science Forum 819 (juin 2015) : 347–52. http://dx.doi.org/10.4028/www.scientific.net/msf.819.347.
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Many studies were carried out to investigate the ability of titanium alloys for dental implant. Surface treatment is one of the famous methods to increase the titanium surface properties. The purpose of this paper is to investigate the effects of acid etching on the surface topography and roughness of titanium alloys (Ti6Al4V ASTM 1472-99). Acid etchings were carried out by using different type of acids with same time exposures. All etched surface were characterized by using an X-ray diffraction (XRD), a scanning electron microscope (SEM) and a roughness tester. Acid etched and pure surface were comparatively analysed. Results obtained show that the type of acids influenced the surface topography as well as roughness properties. The microstructure of the surface is highly modified after acid etching. Further we can confirm that, the experimental etched titanium alloys had features of a roughened surface with micro-roughness. In general, the experimental surface (0.137 μm – 3.986 μm) was significantly rougher than control surface (0.124 μm).
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Bennett, Jean M. « Surface Roughness and Scattering ». Proceedings of The Manufacturing & ; Machine Tool Conference 2004.5 (2004) : 15–16. http://dx.doi.org/10.1299/jsmemmt.2004.5.15.
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Alaskari, Ayman M., Abdulaziz I. Albannai, Meshal Y. Alawadhi, Abdulkareem S. Aloraier, Tatiana Liptakova et Abdullah A. Alazemi. « Surface Evaluation of a Multi-Pass Flexible Magnetic Burnishing Brush for Rough and Soft Ground 60/40 Brass ». Materials 13, no 19 (8 octobre 2020) : 4465. http://dx.doi.org/10.3390/ma13194465.
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Burnishing is an advanced finishing process that produces higher-quality surfaces with better hardness and roughness than conventional finishing processes. Herein, a flexible magnetic burnishing brush comprising stainless steel pins under permanent magnet poles was used to investigate the influence of multiple passes and directions on the produced surface of soft and rough ground prepared brass. In total, five different samples were burnished on each of the two brass samples prepared. Four samples were processed in the same direction for up to four passes and the fifth sample was processed with two passes in the opposite direction. Results indicate that there was approximately a 30% increase in hardness and an 83% increase in microroughness for rougher-surface brass samples. For smoothly prepared surfaces, there was approximately a 14% increase in hardness and a 35% increase in microroughness. In the same direction of multi-pass burnishing, increasing the number of passes negatively affected surface roughness; for rougher surfaces, the surface hardness reduced and process uniformity increased owing to surface over-hardening and flaking mechanisms, and for smoother surfaces, the hardness, roughness, and process non-uniformity increased with the number of passes owing to repeated surface deformation at some locations and high flaking at other locations. Compared to single-pass burnishing, wherein the surface roughness and microhardness showed almost no change with high process uniformity, in burnishing with two opposite-direction passes, the produced surface exhibited better surface roughness, process uniformity, and microhardness improvements owing to a reverse strain mechanism. Hence, opposite burnishing passes are recommended.
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Taslim, M. E., L. Setayeshgar et S. D. Spring. « An Experimental Evaluation of Advanced Leading Edge Impingement Cooling Concepts ». Journal of Turbomachinery 123, no 1 (1 février 2000) : 147–53. http://dx.doi.org/10.1115/1.1331537.
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The main objective of this experimental investigation was to measure the convective heat transfer coefficient of impingement for different target wall roughness geometries of an airfoil leading edge, for jet to wall spacings and exit flow schemes. Available data in the open literature apply mostly to impingement on flat or curved smooth surfaces. This investigation covered two relatively new features in blade leading-edge cooling concepts: curved and roughened target surfaces. Experimental results are presented for four test sections representing the leading-edge cooling cavity with cross-over jets impinging on: (1) a smooth wall, (2) a wall with high surface roughness, (3) a wall roughened with conical bumps, and (4) a wall roughened with tapered radial ribs. The tests were run for two supply and three exit flow arrangements and a range of jet Reynolds numbers. The major conclusions of this study were: (a) There is a heat transfer enhancement benefit in roughening the target surface; (b) while the surface roughness increases the impingement heat transfer coefficient, the driving factor in heat transfer enhancement is the increase in surface area; (c) among the four tested surface geometries, the conical bumps produced the highest heat transfer enhancement.
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Bhushan, Bharat, et Kristian To̸nder. « Roughness-Induced Shear- and Squeeze-Film Effects in Magnetic Recording—Part II : Applications ». Journal of Tribology 111, no 2 (1 avril 1989) : 228–37. http://dx.doi.org/10.1115/1.3261893.
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Surface roughness-induced hydrodynamic gas lubrication theory including rarefaction effects is used to explain the effects of surface roughness on the magnetic head-medium spacing. Since video-recording operates at h/σ (film thickness/standard deviations of composite roughness) ≤ 3, the spacing increases with the roughness because the head surface remains at the distance on the order of 3σ from the mean of the tape surface. Data processing tapes operate at h/σ ≥ 4, and the increase in spacing with the roughness is found to be due to roughness-induced squeeze films. Squeeze motion can be generated by the isolated high asperities on the tape surface and bearing load variations due to a moving roughness (in shear flow) which are expected to increase with an increase in the surface roughness, and modulations of surfaces from other instabilities. Increase in signal-to-noise ratio and in amplitude variation for a rougher tape is also explained by the surface roughness variations. Influence of surface roughness on the head-disk spacing is also analyzed. Recommendations are made for an optimum roughness orientation and magnitude and whether the roughness should lie on the stationary or moving surfaces.
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Li, Biying, Tairan Fu et Congling Shi. « Correlations between High-Temperature Oxidation Kinetics and Thermal Radiation Characteristics of Micro-Structured Nickel Surfaces Oxidized at 1173 K ». Metals 9, no 1 (23 décembre 2018) : 17. http://dx.doi.org/10.3390/met9010017.
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Micro-structured surface functional materials were widely used in electronics, batteries, solar cells, and many other products. However, oxidation at high temperatures greatly affects the material service life and performance. This study focuses on the oxide layer characteristics after high-temperature oxidation and the thermal emissivity of metal materials with micro-structured surfaces. Micro-structured surfaces with various groove morphologies were prepared on 99.9% purity nickel samples. The high-temperature oxidation characteristics of the nickel samples with the microstructure surfaces and the total hemispherical emissivities were measured after various oxidation times in high-temperature (1173 K) air to characterize the correlations between the micro-structure surface oxidization and the emissivity at elevated temperatures. The initial surface roughness greatly affects the surface roughness after oxidation with the oxidation increasing the surface roughness on smooth or less rough surfaces but making the surface smoother for very rough surfaces. The oxidation results show that rougher initial surfaces have larger oxide grain sizes with longer oxidation times leading to smaller grain sizes. The measured total hemispherical emissivity increased with the temperature (500–1400 K) and the oxide layer thickness. The experiments further illustrates that, for the same oxide layer thickness, the measured emissivities become larger for oxides with larger grain sizes caused by the rougher original surfaces. This analysis provides an understanding of the oxidation kinetics of microstructured surfaces and how the oxidized microstructure surfaces affect the thermal radiation properties.
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Salami, Daniele, et Maria Aparecida Alves de Cerqueira Luz. « Effect of prophylactic treatments on the superficial roughness of dental tissues and of two esthetic restorative materials ». Pesquisa Odontológica Brasileira 17, no 1 (mars 2003) : 63–68. http://dx.doi.org/10.1590/s1517-74912003000100012.
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Dental prophylaxis is a common way to remove dental plaque and stain, both undesirable factors in most dentistry procedures. However, besides cleaning the tooth surface, prophylactic techniques may increase the surface roughness of restorations and dental tissues, which, in turn, may result in plaque accumulation, superficial staining and superficial degradation. This study evaluated the effect of three prophylactic techniques - sodium bicarbonate jet, pumice paste and whiting paste - on the superficial roughness of two restorative materials - a composite resin and a compomer - and on the superficial roughness of two dental surfaces - enamel and cementum/dentin - through rugosimetric and scanning electron microscopy (SEM) analysis. Statistical analysis of the rugosimetric data showed that the use of pumice paste on enamel produced a significantly smoother surface than the natural surface. However, comparing the effect of the three techniques, prophylaxis with the pumice paste produced a rougher surface than did the other techniques as regards enamel and cementum/dentin probably due to its abrasiveness. On composite resin, the pumice paste only produced a rougher surface than did the whiting paste. On compomer, all of the applied treatments produced similar results. Based on rugosimetric and SEM analysis, we could conclude that the prophylactic treatments employed did not improve roughness of the studied surfaces. As to the effects of the techniques, they were different depending on the surfaces on which the prophylactic treatments were applied.
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Zhong, Zhao-Wei. « Surface roughness of machined wood and advanced engineering materials and its prediction : A review ». Advances in Mechanical Engineering 13, no 5 (mai 2021) : 168781402110176. http://dx.doi.org/10.1177/16878140211017632.
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This article discusses the surface roughness of wood and advanced engineering materials after machining and its prediction. The topics are surface roughness of precision-machined advanced engineering materials, machining of WC and Inconel, rapidly solidified Al alloys, surface roughness of wood materials, and prediction of surface roughness. Findings include that ductile streaks on silicon and glass surfaces ground or lapped with inexpensive machines largely reduced the polishing time to obtain the required surface roughness. Abrasive jet machining could remove the patterns from recycled wafers and improve the surface roughness. The roughness of WC-Co coatings was significantly improved by using the method of fast regime fluidized bed machining. As beryllium is a toxic element, the rapidly solidified Al alloy may be a good insert material to replace BeCu. Higher bonding strengths resulted from rougher surfaces of wood samples. Wood samples had reduced bonding strengths after soaking in water. Optimum artificial neural networks (ANNs) with necessary inputs could accurately predict the roughness values. ANNs trained using particle swarm optimization and genetic algorithms could predict surface roughness better than typical ANNs. Minimum quantity lubrication is a hot research topic to minimize the amount of the fluid for cost and environmental considerations.
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Teng, Fu-Yuan, Chia-Ling Ko, Hsien-Nan Kuo, Jin-Jia Hu, Jia-Horng Lin, Ching-Wen Lou, Chun-Cheng Hung, Yin-Lai Wang, Cheng-Yi Cheng et Wen-Cheng Chen. « A Comparison of Epithelial Cells, Fibroblasts, and Osteoblasts in Dental Implant Titanium Topographies ». Bioinorganic Chemistry and Applications 2012 (2012) : 1–9. http://dx.doi.org/10.1155/2012/687291.
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The major challenge for dental implants is achieving optimal esthetic appearance and a concept to fulfill this criterion is evaluated. The key to an esthetically pleasing appearance lies in the properly manage the soft tissue profile around dental implants. A novel implant restoration technique on the surface was proposed as a way to augment both soft- and hard-tissue profiles at potential implant sites. Different levels of roughness can be attained by sandblasting and acid etching, and a tetracalcium phosphate was used to supply the ions. In particular, the early stage attaching and repopulating abilities of bone cell osteoblasts (MC3T3-E1), fibroblasts (NIH 3T3), and epithelial cells (XB-2) were evaluated. The results showed that XB-2 cell adhesive qualities of a smooth surface were better than those of the roughened surfaces, the proliferative properties were reversed. The effects of roughness on the characteristics of 3T3 cells were opposite to the result for XB-2 cells. E1 proliferative ability did not differ with any statistical significance. These results suggest that a rougher surface which provided calcium and phosphate ions have the ability to enhance the proliferation of osteoblast and the inhibition of fibroblast growth that enhance implant success ratios.
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Tang, Yiwei, Nianwei Dai, Jun Wu, Yiming Jiang et Jin Li. « Effect of Surface Roughness on Pitting Corrosion of 2205 Duplex Stainless Steel Investigated by Electrochemical Noise Measurements ». Materials 12, no 5 (4 mars 2019) : 738. http://dx.doi.org/10.3390/ma12050738.
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The influence of surface roughness on the pitting corrosion behaviour of 2205 duplex stainless steel (DSS) in a chloride-containing environment was investigated using electrochemical noise (EN) techniques and morphology observation. A rougher surface condition increased the frequency of pit initiation because of the increase in more occluded pit sites. Rough surface finish also accelerated pit growth by increasing the actual dissolution rate in the pit. Metastable pits on rougher surfaces had longer lifetimes and grew to larger sizes, as their inner chemical environment was more easily maintained. However back-scatter images showed that pitting initiates on DSS 2205 regardless of the roughness condition.
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Soler, Daniel, Martín Telleria, M. Belén García-Blanco, Elixabete Espinosa, Mikel Cuesta et Pedro José Arrazola. « Prediction of Surface Roughness of SLM Built Parts after Finishing Processes Using an Artificial Neural Network ». Journal of Manufacturing and Materials Processing 6, no 4 (3 août 2022) : 82. http://dx.doi.org/10.3390/jmmp6040082.
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A known problem of additive manufactured parts is their poor surface quality, which influences product performance. There are different surface treatments to improve surface quality: blasting is commonly employed to improve mechanical properties and reduce surface roughness, and electropolishing to clean shot peened surfaces and improve the surface roughness. However, the final surface roughness is conditioned by multiple parameters related to these techniques. This paper presents a prediction model of surface roughness (Ra) using an Artificial Neural Network considering two parameters of the SLM manufacturing process and seven blasting and electropolishing processes. This model is proven to be in agreement with 429 experimental results. Moreover, this model is then used to find the optimal conditions to be applied during the blasting and the electropolishing in order to improve the surface roughness by roughly 60%.
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Grosfils, Patrick, et James F. Lutsko. « Impact of Surface Roughness on Crystal Nucleation ». Crystals 11, no 1 (23 décembre 2020) : 4. http://dx.doi.org/10.3390/cryst11010004.
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We examine the effect of rough surfaces on crystal nucleation by means of kinetic Monte Carlo simulations. Our work makes use of three-dimensional kMC models, explicit representation of transport in solution and rough surfaces modeled as randomly varying height fluctuations (roughness) with exponentially decaying correlation length (topology). We use Forward-Flux Sampling to determine the nucleation rate for crystallization for surfaces of different roughness and topology and show that the effect on crystallization is a complex interplay between the two. For surfaces with low roughness, small clusters form on the surface but as clusters become larger they are increasingly likely to be found in the bulk solution while rougher surfaces eventually favor heterogeneous nucleation on the surface. In both cases, the rough surface raises the local supersaturation in the solution thus leading to another mechanism of enhanced nucleation rate.
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Schwartz, Z., C. H. Lohmann, J. Oefinger, L. F. Bonewald, D. D. Dean et B. D. Boyan. « Implant Surface Characteristics Modulate Differentiation Behavior of Cells in the Osteoblastic Lineage ». Advances in Dental Research 13, no 1 (juin 1999) : 38–48. http://dx.doi.org/10.1177/08959374990130011301.
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This paper reviews the role of surface roughness in the osteogenic response to implant materials. Cells in the osteoblast lineage respond to roughness in cell-maturation-specific ways, exhibiting surface-dependent morphologies and growth characteristics. MG63 cells, a human osteoblast-like osteosarcoma cell line, respond to increasing surface roughness with decreased proliferation and increased osteoblastic differentiation. Alkaline phosphatase activity and osteocalcin production are increased. Local factor production is also affected; production of both TGF-β1 and PGE2 is increased. On rougher surfaces, MG63 cells exhibit enhanced responsiveness to 1,25-(OH)2D3. Prostaglandins mediate the effects of surface roughness, since indomethacin prevents the increased expression of differentiation markers in these cells.
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Nowak, Wojciech J. « Effect of Surface Roughness on Oxidation Resistance of Stainless Steel AISI 316Ti During Exposure at High Temperature ». Journal of Materials Engineering and Performance 29, no 12 (11 novembre 2020) : 8060–69. http://dx.doi.org/10.1007/s11665-020-05267-x.
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AbstractIn the present work, the influence of surface roughness on oxidation kinetics of AISI 316Ti stainless steel and its consequences in term of oxidation resistance were investigated. Namely, the effect of surface roughness on oxidation resistance was evaluated during different types of cyclic oxidation tests at 900 and 1000 °C. The obtained results revealed that alloy possessing higher surface roughness showed longer lifetime compared to that with lower surface roughness. It was also found that more severe cyclic conditions suppressed the positive effect of surface roughness on sample’s lifetime. The better oxidation resistance of rougher alloy was correlated with suppressed formation of Fe-rich nodules on ground surfaces and explained by the combined effect of introduced defects in the near-surface region and possible increase in residual stresses caused by mechanical surface preparation.
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Petersen, Philip G., Lloyd V. Smith et Derek Nevins. « The effect of surface roughness on oblique bicycle helmet impact tests ». Proceedings of the Institution of Mechanical Engineers, Part P : Journal of Sports Engineering and Technology 234, no 4 (15 juin 2020) : 320–27. http://dx.doi.org/10.1177/1754337120917809.
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The friction between a helmet and impact surface affects the accelerations imparted to the head. The roughness of the impact surface is, therefore, a consideration when developing oblique impact standards. An 80-grit abrasive paper is commonly used in oblique impact tests to simulate a road surface, but has not been validated for bicycle impacts and may not accurately represent real road surfaces. In the following study, a helmeted NOCSAE headform with a Hybrid III neck was dropped onto a 45° anvil at 6.5 m/s using a twin wire guided drop tower. Helmeted drops were performed in two orientations (frontal and side) on road surfaces, roughened steel surfaces, 80-grit abrasive paper and a low friction surface. For each impact, measures of linear and rotational acceleration were obtained. These metrics were compared across impact orientations and surfaces to assess the influence of surface roughness on headform impact response. Frontal impacts were less sensitive to the impact surface roughness than side impacts across metrics. Among metrics, rotational acceleration showed the largest effect due to surface roughness. Compared to the road surface, peak rotational acceleration from impacts on the 80-grit surface were 6.5% less and 48% greater for frontal and side impacts, respectively. Based on consideration of the peak and cumulative impact measures, steel impact surfaces appear to better simulate road impact than the commonly used 80-grit abrasive paper.
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Yu, Ning, et Andreas A. Polycarpou. « Combining and Contacting of Two Rough Surfaces with Asymmetric Distribution of Asperity Heights ». Journal of Tribology 126, no 2 (1 avril 2004) : 225–32. http://dx.doi.org/10.1115/1.1614822.
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The statistical approach of describing rough surfaces is extended to include the contact of two rough surfaces in which their distribution of asperity heights can either be symmetric or asymmetric, and the asymmetry is modeled using the normalized Weibull distribution. In considering the contact between two rough surfaces, as in most practical applications, the contact can be approximated by an equivalent rough surface in contact with a smooth plane. The roughness parameters of the equivalent surface are obtained using the spectral moment method, and its validity is verified using realistic surface roughness measurements. This paper presents a method to obtain the equivalent rough surface with a Weibull distribution of asperity heights, in which the standard deviation and skewness parameters of asperity heights of the actual contacting surfaces are preserved. The advantages of this method are demonstrated via direct comparisons with a previously proposed method as well as with exact numerical simulation of the contact parameters of several different actual surfaces from magnetic storage and MEMS applications. For practical engineering applications, where the roughness parameters of each individual surface are known, contour plots for the skewness value of the equivalent rough surface are provided for practical ranges of combinations of standard deviation ratios and skewness values. As expected when the roughness of one of the contacting surfaces dominates, the skewness is solely determined by the rougher surface.
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Pavliček, Pavel, et Ondřej Hýbl. « White-light interferometry on rough surfaces--measurement uncertainty caused by surface roughness ». Applied Optics 47, no 16 (21 mai 2008) : 2941. http://dx.doi.org/10.1364/ao.47.002941.
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Lungevics, Janis, Ernests Jansons et Karlis Agris Gross. « Skeleton Runner Roughness and Surface Contact Area Influence on Sliding Ability : Field Experiments ». Key Engineering Materials 800 (avril 2019) : 303–7. http://dx.doi.org/10.4028/www.scientific.net/kem.800.303.
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Scientists and sport athletes are constantly seeking for the methods which could improve surface sliding ability on ice. Modifications of contact area and surface roughness are relatively easy but not yet fully understood methods for sliding ability improvements. This research contains information of how one can perform on-field experiments with skeleton sleigh to determine the influence of surface contact area and roughness on sliding ability. Two types of surface roughness i.e. polished (3000 grain sandpaper) and scratched (600 grain sandpaper) are compared using three different contact areas. Obtained data showed that rougher surfaces tend to slide faster if contact area is larger but the effect reverses if contact area is reduced.
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Song, Kwanwoo, Jinwook Lee, Seong-O. Choi et Jooyoun Kim. « Interaction of Surface Energy Components between Solid and Liquid on Wettability, and Its Application to Textile Anti-Wetting Finish ». Polymers 11, no 3 (14 mars 2019) : 498. http://dx.doi.org/10.3390/polym11030498.
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With various options of anti-wetting finish methods, this study intends to provide basic information that can be applied in selecting a relevant anti-wetting chemical to grant protection from spreading of liquids with different surface energy profiles. With such an aim, the anti-wetting effectiveness of fluorinated coating and silane coating was investigated for liquids having different surface energy components, water (WA), methylene iodide (MI) and formamide (FA). The wetting thermodynamics was experimentally investigated by analyzing dispersive and polar component surface energies of solids and liquids. The role of surface roughness in wettability was examined for fibrous nonwoven substrates that have varied surface roughness. The presence of roughness enhanced the anti-wetting performance of the anti-wetting treated surfaces. While the effectiveness of different anti-wetting treatments was varied depending on the liquid polarities, the distinction of different treatments was less apparent for the roughened fibrous surfaces than the film surfaces. This study provides experimental validation of wetting thermodynamics and the practical interpretation of anti-wetting finishing.
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Norafifah, H., M. Y. Noordin, S. Izman et D. Kurniawan. « Acid Pretreatment of WC-Co for Surface Roughening and Cobalt Removal Prior to CVD Diamond Coating ». Applied Mechanics and Materials 315 (avril 2013) : 592–96. http://dx.doi.org/10.4028/www.scientific.net/amm.315.592.
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Chemical vapor deposition (CVD) diamond coatings are being developed to be applied on carbide cutting tools to enhance wear resistance and increase tool life. As a prerequisite, for ensuring adhesion of CVD diamond on tungsten carbide substrate, it is necessary to prepare high surface roughness and to remove the cobalt on tungsten carbide surface during the pretreatment. In this study, a two step acid pretreatment was examined for those purposes. Etching using modified Murakamis reagent was initially performed to roughen the surface. Subsequently, the carbide was immersed in nitric acid to remove cobalt. Concentration of the acid solutions and reaction time were varied. Results showed that the initial step by modified Murakamis reagent etching resulted in a surface roughness of Ry = 6.95 µm, which is a 15% increase from the average initial surface roughness. The second step by nitric acid immersion on modified Murakamis reagent etched carbide samples resulted in carbide surfaces with zero cobalt content, confirming the effectiveness of the pretreatment.
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Fenelon, Thomas, Mahmoud M. Bakr, Laurence J. Walsh et Roy George. « Effects of Lasers and Their Delivery Characteristics on Machined and Micro-Roughened Titanium Dental Implant Surfaces ». Bioengineering 7, no 3 (11 août 2020) : 93. http://dx.doi.org/10.3390/bioengineering7030093.
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The aim of the study was to investigate the effects of neodymium: yttrium aluminium garnet (Nd:YAG) (1064 nm) and erbium: yttrium aluminium garnet (Er:YAG) (2940 nm) laser energy on titanium when delivered with conventional optics (focusing handpieces or plain ended optical fibres) or with a conical tip. Machined and micro-roughened implant discs were subjected to laser irradiation under a variety of energy settings either dry (without water) or wet (with water). Samples were scanned using a 3D non-contact laser profilometer and analysed for surface roughness, volume of peaks and the maximum diameter of the ablated area. Conical tip designs when used with both lasers showed no surface effect at any power setting on both machined and micro-roughened implant surfaces, regardless of the irrigation condition. When used with conventional delivery systems, laser effects on titanium were dose related, and were more profound with the Nd:YAG than with the Er:YAG laser. High laser pulse energies caused surface fusion which reduced the roughness of micro-roughened titanium surfaces. Likewise, repeated pulses and higher power densities also caused greater surface modifications. The presence of water reduced the influence of laser irradiation on titanium. It may be concluded that conical fibres can reduce unwanted surface modification, and this may be relevant to clinical protocols for debridement or disinfection of titanium dental implants.
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Brandt, Bjoern, et Torsten Rabe. « Surface Characteristics of LTCC Substrates Fabricated by Pressure-Assisted Sintering ». Journal of Microelectronics and Electronic Packaging 10, no 4 (1 octobre 2013) : 144–49. http://dx.doi.org/10.4071/imaps.385.
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Plane LTCC substrates can be produced in zero-shrinkage technology by pressure-assisted sintering. The application of axial pressure during sintering supports densification, enhances cofiring of different materials, and restrains deformation. However, the sintered surfaces are affected by the release tapes and by the setters used in the pressure-assisted sintering process. In this study, the effect of release tape particle size on the surface properties of sintered substrates was investigated. Moreover, the substitution of release tape by the use of a vitreous carbon setter was tested. Surface roughness and sheet resistances of metallic thin films on the respective samples were determined. It was found that the roughness of the substrates is not directly correlated with the adequacy of the surface for thin-film deposition. Compared with a freely sintered sample with an average roughness (Ra) of 0.31 μm, pressure-assisted sintering created smoother surfaces using fine-grained release tapes (Ra = 0.18 μm) and rougher surfaces using coarse release tapes (Ra = 0.46 mm). Still, sheet resistances were higher on all sinter-pressed samples. The vitreous carbon setter created unusual trenched surface structures, characterized by varying roughness values and intermediate sheet resistances on the LTCCs tested.
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Brandt, Bjoern, et Torsten Rabe. « Surface Characteristics of LTCC Substrates Fabricated by Pressure-assisted Sintering ». Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, CICMT (1 septembre 2013) : 000261–67. http://dx.doi.org/10.4071/cicmt-tha42.
Texte intégralRésumé :
Plane LTCC substrates can be produced in zero-shrinkage technology by pressure-assisted sintering. The application of axial pressure during sintering supports densification, enhances co-firing of different materials and restrains deformation. However, the sintered surfaces are affected from the release tapes and setters used in the pressure-assisted sintering process. In this study, the effect of release tape particle size on the surface properties of sintered substrates was investigated. Moreover, the substitution of release tape by the use of a vitreous carbon setter was tested. Surface roughness and sheet resistances of metallic thin-films on the respective samples were determined. It was found, that roughness of the substrates is not directly correlated with the adequacy of the surface for thin-film deposition. Compared to a freely sintered sample with an average roughness (Ra) of 0.31 μm, pressure-assisted sintering created smoother surfaces using fine-grained tapes (Ra = 0.18 μm) and rougher surfaces using coarse release tapes (Ra = 0.46 mm). Still, sheet resistances were higher on all sinter-pressed samples. The vitreous carbon setter created unusual, trenched surfaces structures, characterized by varying roughness values and intermediate sheet resistances on the LTCCs tested.
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Kheraif, Abdulaziz Abdullah Al. « Surface Roughness of Polyvinyl Siloxane Impression Materials Following Chemical Disinfection, Autoclave and Microwave Sterilization ». Journal of Contemporary Dental Practice 14, no 3 (2013) : 483–87. http://dx.doi.org/10.5005/jp-journals-10024-1349.
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ABSTRACT Background Autoclave sterilization and microwave sterilization has been suggested as the effective methods for the disinfection of elastomeric impressions, but subjecting elastomeric impressions to extreme temperature may have adverse effects on critical properties of the elastomers. Aim To evaluate the effect of chemical disinfection as well as autoclave and microwave sterilization on the surface roughness of elastomeric impression materials. Materials and methods The surface roughness of five commercially available polyvinyl siloxane impression materials (Coltene President, Affinis Perfect impression, Aquasil, 3M ESPE Express and GC Exafast) were evaluated after subjecting them to chemical disinfection, autoclaving and microwave sterilization using a Talysurf Intra 50 instrument. Twenty specimens from each material were fabricated and divided into four equal groups, three experimental and one control (n = 25). The differences in the mean surface roughness between the treatment groups were recorded and statistically analyzed. Results No statistically significant increase in the surface roughness was observed when the specimens were subjected to chemical disinfection and autoclave sterilization, increase in roughness and discoloration was observed in all the materials when specimens were subjected to microwave sterilization. Conclusion Chemical disinfection did not have a significant effect but, since it is less effective, autoclave sterilization can be considered effective and autoclaving did not show any specimen discoloration as in microwave sterilization. Microwave sterilization may be considered when impressions are used to make diagnostic casts. A significant increase in surface roughness may produce rougher casts, resulting in rougher tissue surfaces for denture and cast restorations. Clinical significance Autoclave sterilization of vinyl polysiloxane elastomeric impressions for 5 minutes at 134°C at 20 psi may be considered an effective method over chemical disinfection and microwave sterilization, because chemical disinfection does not eliminate all disease-causing microorganisms and microwave sterilization leads to a rougher impression surface. How to cite this article Al Kheraif AA. Surface Roughness of Polyvinyl Siloxane Impression Materials Following Chemical Disinfection, Autoclave and Microwave Sterilization. J Contemp Dent Pract 2013;14(3):483-487.
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Tilger, Meik, Dirk Biermann, Mohamed Abdulgader et Wolfgang Tillmann. « The Effect of Machined Surface Conditioning on the Coating Interface of High Velocity Oxygen Fuel (HVOF) Sprayed Coating ». Journal of Manufacturing and Materials Processing 3, no 3 (3 septembre 2019) : 79. http://dx.doi.org/10.3390/jmmp3030079.
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Roughening the substrate surface is essential for thermal sprayed coatings. In this regard, sandblasting has established itself as an easy to use surface conditioning procedure. The quality of the obtained roughness depends on the conditions of the sandblasting material, adjusted parameters, and the kind of the process execution (manual or mechanical). These preconditions limit the reproducibility of the roughness obtained. Sandblasting causes residual compressive stress and may also lead to the inclusion of sand particles and notches in the roughened surface, which affects the interfacial properties of the coating, as well as the flexural strength of the coated parts. The hardness of the roughened surface plays, thereby, an important role. However, in order to reliably avoid these effects, microfinishing can be used as an alternative to generate a homogenous roughened substrate surface, control the induced residual stresses, and increase the reproducibility. In addition, the roughened surface pattern can be produced during the chip forming process of the to-be-coated parts. The utilization of the appropriate combination of machining processes and parameters should lead to the required surface pattern and thus to an enhanced coating adhesion and flexural strength of the coated part. The induced residual stresses and the quality of the obtained surface roughness have a significant influence on the coating adhesion and the lifespan of the coated parts. This paper aims to analyze, as a first step, the effect of the turning and microfinishing on the surface conditioning of the bearing steel 100Cr6 (AISI 52100). The investigation concludes by comparing the microfinished with the sandblasted surfaces with regard to the interface to and the adhesion of the WC–Co high velocity oxygen fuel (HVOF) sprayed coatings on them. Surface conditioning plays a decisive role by the induced residual stresses and the elimination of adhesion defects.
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Xu, Zhijia, Qinghui Wang et Jingrong Li. « Modeling porous structures with fractal rough topography based on triply periodic minimal surface for additive manufacturing ». Rapid Prototyping Journal 23, no 2 (20 mars 2017) : 257–72. http://dx.doi.org/10.1108/rpj-09-2015-0121.
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Purpose The purpose of this paper is to develop a general mathematic approach to model the microstructures of porous structures produced by additive manufacturing (AM), which will result in fractal surface topography and higher roughness that have greater influence on the performance of porous structures. Design/methodology/approach The overall shapes of pores were modeled by triply periodic minimal surface (TPMS), and the micro-roughness details attached to the overall pore shapes were represented by Weierstrass–Mandelbrot (W-M) fractal representation, which was integrated with TPMS along its normal vectors. An index roughly reflecting the irregularity of fractal TPMS was proposed, based on which the influence of the fractal parameters on the fractal TPMS was qualitatively analyzed. Two complex samples of real porous structures were given to demonstrate the feasibility of the model. Findings The fractal surface topography should not be neglected at a micro-scale level. In addition, a decrease in the fractal dimension Ds may exponentially make the topography rougher; an increase in the height-scaling parameter G may linearly increase the roughness; and the number of the superposed ridges has no distinct influence on the topography. Furthermore, the synthesis method is general for all implicit surfaces. Practical implications The method provides an alternative way to shift the posteriori design paradigm of porous media to priori design mode through numeric simulation. Therefore, the optimization of AM process parameters, as well as the porous structure, can be potentially realized according to specific functional requirement. Originality/value The synthesis of TPMS and W-M fractal geometry was accomplished efficiently and was general for all implicit freeform surfaces, and the influence of the fractal parameters on the fractal TPMS was analyzed more systematically.
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Otto, K. A., K.-D. Matz, S. E. Schröder, R. Parekh, K. Krohn, R. Honda, S. Kameda et al. « Surface roughness of asteroid (162173) Ryugu and comet 67P/Churyumov–Gerasimenko inferred from in situ observations ». Monthly Notices of the Royal Astronomical Society 500, no 3 (27 octobre 2020) : 3178–93. http://dx.doi.org/10.1093/mnras/staa3314.
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ABSTRACT Alteration processes on asteroid and comet surfaces, such as thermal fracturing, (micrometeorite) impacts or volatile outgassing, are complex mechanisms that form diverse surface morphologies and roughness on various scales. These mechanisms and their interaction may differ on the surfaces of different bodies. Asteroid Ryugu and comet 67P/Churyumov–Gerasimenko, both, have been visited by landers that imaged the surfaces in high spatial resolution. We investigate the surface morphology and roughness of Ryugu and 67P/Churyumov–Gerasimenko based on high-resolution in situ images of 0.2 and 0.8 mm pixel resolution over an approximately 25 and 80 cm wide scene, respectively. To maintain comparability and reproducibility, we introduce a method to extract surface roughness descriptors (fractal dimension, Hurst exponent, joint roughness coefficient, root-mean-square slope, hemispherical crater density, small-scale roughness parameter, and Hapke mean slope angle) from in situ planetary images illuminated by LEDs. We validate our method and choose adequate parameters for an analysis of the roughness of the surfaces. We also derive the roughness descriptors from 3D shape models of Ryugu and orbiter camera images and show that the higher spatially resolved images result in a higher roughness. We find that 67P/Churyumov–Gerasimenko is up to 6 per cent rougher than Ryugu depending on the descriptor used and attribute this difference to the different intrinsic properties of the materials imaged and the erosive processes altering them. On 67P/Churyumov–Gerasimenko sublimation appears to be the main cause for roughness, while on Ryugu micrometeoroid bombardment as well as thermal fatigue and solar weathering may play a significant role in shaping the surface.
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Zhao, Da Peng, Yuan Zhang, He Min Nie et Ming Yan. « Mesenchymal Stem Cells Adhesion on Micro-to-Nano-Scaled Hierarchical Ti Implants Fabricated by Powder Metallurgy and Anodization ». Key Engineering Materials 770 (mai 2018) : 70–79. http://dx.doi.org/10.4028/www.scientific.net/kem.770.70.
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The osseointegration of titanium (Ti) implants highly depends on their surface properties, including roughness, wettability and composition. Ti surfaces with micron-scale roughness have demonstrated more rapid bone apposition compared with polished ones. Besides, Ti implants with nanostructured surface also exhibit better cell adhesion and proliferation behavior. However, the optimal surface for bone regeneration is still unknown, partly due to the difficulty in fabricating surfaces with highly reproducible micron-and nanotopography. In this study, Ti implants with two hierarchies of roughness were fabricated by powder metallurgy, followed by anodization treatment to obtain self-assembled TiO2nanotubes on the micro-roughened surface. X-ray diffraction (XRD), scanning electron microscopy (SEM), 3D Laser Scanning Microscope (3D LSM), and fluorescence microscope were used to investigate the properties of the samples.Raof the powder metallurgy surface was about 5 μm, while, nanotubes of around 100 nm in diameter were observed after the anodization process. Compared with the reference samples, i.e., the ones with either smooth or single-level-structure surfaces, the ones with micro-to-nanoscaled hierarchical topography exhibited lower contact angle, higher protein adsorption and significantly improved mesenchymal stem cells (MSCs) early adhesion.
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Rifat, Mustafa, Saurabh Basu, Edward C. De Meter et Guha Manogharan. « Effect of Prior Surface Textures on the Resulting Roughness and Residual Stress during Bead-Blasting of Electron Beam Melted Ti-6Al-4V ». Crystals 12, no 3 (10 mars 2022) : 374. http://dx.doi.org/10.3390/cryst12030374.
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The finishing of additive manufactured (AM) components is crucial for endowing them with fatigue resistance. Unfortunately, current AM processes naturally promote anisotropic surface characteristics that make it challenging to optimize finishing processes. In this study, bead-blasting is explored as a process for finishing Electron Beam Melted (EBM) Ti-6Al-4V. The effects of anisotropic roughness characteristics on the mechanics of bead-blasting are delineated using surface texture measurements via optical profilometry and residual stress measurements via X-ray diffraction. As-received surfaces resulting from AM, as well as those that have been Electrical Discharge Machined (EDM), are studied. It is seen that pre-processed roughness textures heavily influence the final textures and residual stresses. These linkages are quantified using a plasticity index as the governing metric—a rougher surface features a larger plastic index, which results in comparatively greater evolution of its texture characteristics than a smoother surface after equivalent bead-blasting treatments. The mechanics of this evolution are delineated using energy-controlled indentation as a model representing a single impact in bead-blasting. It is seen that rougher surfaces featuring complex textures in as-received states also produce complex stress states featuring a greater level of locally tensile stresses during indentation compared with smoother surfaces. Approaches to address these complications are proposed that can potentially transform a printed, non-functional surface into one that is optimized for fatigue resistance.
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Seo, Beomdeok, Hideyuki Kanematsu, Masashi Nakamoto, Yoshitsugu Miyabayashi et Toshihiro Tanaka. « Copper Surface Treatment Method with Antibacterial Performance Using “Super-Spread Wetting” Properties ». Materials 15, no 1 (5 janvier 2022) : 392. http://dx.doi.org/10.3390/ma15010392.
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In this work, a copper coating is developed on a carbon steel substrate by exploiting the superwetting properties of liquid copper. We characterize the surface morphology, chemical composition, roughness, wettability, ability to release a copper ion from surfaces, and antibacterial efficacy (against Escherichia coli and Staphylococcus aureus). The coating shows a dense microstructure and good adhesion, with thicknesses of approximately 20–40 µm. X-ray diffraction (XRD) analysis reveals that the coated surface structure is composed of Cu, Cu2O, and CuO. The surface roughness and contact angle measurements suggest that the copper coating is rougher and more hydrophobic than the substrate. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements reveal a dissolution of copper ions in chloride-containing environments. The antibacterial test shows that the copper coating achieves a 99.99% reduction of E. coli and S. aureus. This study suggests that the characteristics of the copper-coated surface, including the chemical composition, high surface roughness, good wettability, and ability for copper ion release, may result in surfaces with antibacterial properties.
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Zhou, Zilong, Jing Zhang, Xin Cai, Shanyong Wang, Xueming Du et Haizhi Zang. « Permeability Experiment of Fractured Rock with Rough Surfaces under Different Stress Conditions ». Geofluids 2020 (1 juin 2020) : 1–15. http://dx.doi.org/10.1155/2020/9030484.
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To investigate the permeability changes and the mechanisms of fractured rock under dynamic and static stresses produced by earthquakes, permeability experiments on fractured rock with rough surfaces under axial dynamic and static stresses were conducted on the MTS815 Rock Mechanics Testing System. Surface asperity was investigated by scanning the specimen surfaces before and after testing. The results show that the roughness of fracture surface has a great influence on the permeability when the axial displacement is not enough to cause the fracture rock to slip. Moreover, the rougher fracture surface leads to severer surface damage as indicated by the more gouge productions. The accumulation of gouge materials on larger roughness fracture surfaces causes a slow drop in permeability. The fracture surfaces experience larger degradations, but it has small weights of gouge materials on fracture surface after testing under axial dynamic stress. The reason is that the gouge material transport and mobilization tend to occur in process of dynamic loading. Therefore, the permeability drops of axial dynamic stress are larger than those of axial static stress.
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Goyenvalle, Eric, Eric Aguado, Ronan Cognet, Xavier Bourges et G. Daculsi. « Calcium Phosphate Ceramic Blasting on Titanium Surface Improve Bone Ingrowth ». Key Engineering Materials 361-363 (novembre 2007) : 1351–54. http://dx.doi.org/10.4028/www.scientific.net/kem.361-363.1351.
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Surface roughness modulates the osseointegration of orthopaedic and dental titanium implants. High surface roughness is currently obtained by blasting of titanium implants with silica or aluminium abrasive particles. This process includes into the surface abrasive particles and may cause the release of cytotoxic silica or aluminium ions in the peri implant tissue. To overcome this drawback, we currently develop an innovative gridblasting process using Biphasic Calcium Phosphate (BCP) particles (RBBM Resorbable and Biocompatible Blast Media) to generate biocompatible roughened titanium surface. This work present the technique of blasting using RBBM particles to provide a roughened surface which does not release cytotoxic elements and (ii) to assess the effects of such a roughened surface for bone osteointegration in critical size rabbit defect. Our results demonstrate that resorbable biphasic calcium phosphate abrasive particles can be used to create titanium surface roughness. This grid blasting process increases surface roughness of titanium implants and offers a non cytotoxic surface for rapid and efficient osteointegration.
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Honda, Takashi, Katsuyuki Kida, Edson Costa Santos et Yuji Kashima. « The Influence of Surface Texture on Rolling-Contact Fatigue of PEEK Bearings in Water ». Advanced Materials Research 154-155 (octobre 2010) : 1713–16. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1713.
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The effect of machining conditions on the rolling contact fatigue (RCF) strength of PEEK polymer bearings was investigated. RCF tests were carried out by using bearings machined by different conditions. The surface profile and roughness were observed before and after testing by laser confocal microscope. Pitting and cracking were associated with the different initial surface conditions. From the obtained results, we found that the RCF strength of machined surfaces decreases when the surface becomes rougher.
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El-Gabry, Lamyaa A., et Deborah A. Kaminski. « Experimental Investigation of Local Heat Transfer Distribution on Smooth and Roughened Surfaces Under an Array of Angled Impinging Jets ». Journal of Turbomachinery 127, no 3 (31 août 2004) : 532–44. http://dx.doi.org/10.1115/1.1861918.
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Measurements of the local heat transfer distribution on smooth and roughened surfaces under an array of angled impinging jets are presented. The test rig is designed to simulate impingement with crossflow in one direction. Jet angle is varied between 30, 60, and 90deg as measured from the target surface, which is either smooth or randomly roughened. Liquid crystal video thermography is used to capture surface temperature data at five different jet Reynolds numbers ranging between 15,000 and 35,000. The effect of jet angle, Reynolds number, gap, and surface roughness on heat transfer and pressure loss is determined along with the various interactions among these parameters.
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J. Nowak, Wojciech, Krzysztof Siemek, Kamil Ochał, Barbara Kościelniak et Bartek Wierzba. « Consequences of Different Mechanical Surface Preparation of Ni-Base Alloys during High Temperature Oxidation ». Materials 13, no 16 (10 août 2020) : 3529. http://dx.doi.org/10.3390/ma13163529.
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The influence of surface roughness on its high temperature oxidation for an Ni-base superalloy was studied using laser profilometry, atomic force microscopy, mass change measurements, glow-discharge optical emission spectrometry, scanning electron microscopy, X-ray diffraction, and positron annihilation methods. The isothermal and cyclic air oxidation tests were performed at 1000 °C and showed dependence of oxidation behavior on surface roughness. Smoother surfaces oxidation resulted in the formation of a multilayered oxide scale consisting of NiO, Cr2O3, and internally oxidized Al2O3 while a rougher surface formed protective Al2O3 scale. The factors responsible for different oxidation behaviors were determined as higher concentration of vacancies and increased residual stresses in the near-surface region of studied alloys.
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Zhitao Yang, Zhitao Yang, Changjian Liu Changjian Liu, Yachen Gao Yachen Gao, Jiyu Wang Jiyu Wang et and Wenlong Yang and Wenlong Yang. « Influence of surface roughness on surface plasmon resonance phenomenon of gold film ». Chinese Optics Letters 14, no 4 (2016) : 042401–42403. http://dx.doi.org/10.3788/col201614.042401.
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Wang, Le Feng, Bin Guo, Gui Ming Huang, Wei Bin Rong et Li Ning Sun. « Effects of Asperity Shape on the Adhesion Hysteresis Originated from Surface Roughness ». Advanced Materials Research 213 (février 2011) : 201–5. http://dx.doi.org/10.4028/www.scientific.net/amr.213.201.
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Adhesion of solid surfaces plays a significant role in many technical fields especially at micro and nano scale. The effect of asperity shape on the adhesion hysteresis originated from surface roughness has been investigated theoretically in this paper. Based on the adhesive contact model of single asperities with axisymmetric power-law shapes, the roughness-induced adhesion hysteresis is modeled by assuming the asperity heights follow a Gaussian distribution on the rough surface. The analysis results show that the dissipation energy decreases dramatically when the surface becomes rougher for all the shape indices, and the shape index affects the adhesion hysteresis at different levels with the variance of surface roughness. A general parameter consisting of the shape index of asperities is proposed to characterize the adhesion hysteresis. These will be helpful to understand and control the adhesion hysteresis for solid-solid contact.
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Yi, Bingqi, Ping Yang, Bryan A. Baum, Tristan L'Ecuyer, Lazaros Oreopoulos, Eli J. Mlawer, Andrew J. Heymsfield et Kuo-Nan Liou. « Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect ». Journal of the Atmospheric Sciences 70, no 9 (1 septembre 2013) : 2794–807. http://dx.doi.org/10.1175/jas-d-13-020.1.
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Abstract Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu–Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m−2 over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1–2 W m−2. The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.
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Tsao, Chung Chen. « Cutting Performance and Predictive Models for End Milling Aluminum Alloy ». Advanced Materials Research 83-86 (décembre 2009) : 646–53. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.646.
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End milling is considered to be one of the most commonly applied for both roughing and finishing operations to make flat surfaces, slots and pockets in precision molds and dies. Predictive models were developed for cutting force, flank wear and surface roughness in end milling aluminum alloy by regression analysis. The correlation coefficients for cutting force, flank wear and surface roughness equations were 91.6 %, 89.8 % and 79.6 %, respectively. The goal of these predictive equations is to become a good assistant to the researcher in understanding the machining process. Through the analysis of variance (ANOVA), however, it can be found that the cutter diameter, the helix angle and the feed rate are the important milling process parameters to obtain the machined quality on cutting force, flank wear and surface roughness. The investigations show that cutting force, flank wear and surface roughness can be improved in end milling aluminum alloy by using the lower cutter diameter, medium helix angle and lower feed rate.
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Gokhale, A., et W. J. Drury. « Surface roughness of anisotropic fracture surfaces ». Materials Characterization 30, no 4 (juin 1993) : 279–86. http://dx.doi.org/10.1016/1044-5803(93)90075-7.
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Yonemoto, Yukihiro, Kanta Tashiro, Minori Yamashita et Tomoaki Kunugi. « Experimental Correlation for Splashing Condition of Droplets on Solid Substrates ». Fluids 7, no 1 (16 janvier 2022) : 38. http://dx.doi.org/10.3390/fluids7010038.
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Droplet splashing behaviors of water-ethanol binary mixture liquids on roughened solid surfaces were experimentally observed in order to investigate the effects of surface tension, viscosity, and wettability/surface roughness on the splashing occurrence. The range of the droplet volumes was from 1.7 μL to 32.6 μL. The ranges of the surface tension and the viscosity were from 21.1 mN/m to 71.9 mN/m, and from 1 mPas to 2.91 mPas, respectively. The surface roughness range was from 0.03 μm to 1.25 μm for Ra. The present experimental data were evaluated on the basis of the existing models. Resulting from these experiments, a simple model using the Ohnesorge number evaluated by the capillary length was proposed and the accuracy of the predicted critical values such as the critical Weber and Reynolds numbers were discussed. The result indicated that the liquid properties and the quantification of the surface condition such as surface roughness are important factors for the prediction of the splashing behavior.
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Cathles, L. Maclagan, Dorian S. Abbot, Jeremy N. Bassis et Douglas R. MacAyeal. « Modeling surface-roughness/solar-ablation feedback : application to small-scale surface channels and crevasses of the Greenland ice sheet ». Annals of Glaciology 52, no 59 (2011) : 99–108. http://dx.doi.org/10.3189/172756411799096268.
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AbstractSurface roughness enhances the net ablation rate associated with direct solar radiation relative to smooth surfaces, because roughness allows solar energy reflected from one part of the surface to be absorbed by another part. In this study we examine the feedback between solar-radiation-driven ablation and growth of surface roughness on the Greenland ice sheet, using a numerical model of radiative transfer. Our experiments extend previous work by examining: (1) the effects of diurnal and seasonal variation of solar zenith angle and azimuth relative to incipient roughness features, (2) the evolution of roughness geometry in response to radiatively driven ablation and (3) the relative solar energy collection efficiencies of various roughness geometries and geographic locations and orientations. A notable result of this examination is that the time evolution of the aspect ratio of surface features under solar-driven ablation collapses onto a roughly universal curve that depends only on latitude, not the detailed shape of the feature. The total enhancement of surface melt relative to a smooth surface over a full ablation season varies with this ratio, and this dependence suggests a way to parameterize roughness effects in large-scale models that cannot treat individual roughness features. Overall, our model results suggest that surface roughness at the latitudes spanned by the Greenland ice sheet tends to dissipate as the ablation season progresses.
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Grigoruk, V. I., V. I. Kanevskii, S. A. Kolenov et V. S. Sidorenko. « Scattering of light by quartz rough surface described as sequence of surface three-cornered form irregularities ». Surface 9(24) (30 décembre 2017) : 69–80. http://dx.doi.org/10.15407/surface.2017.09.069.
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Kim, Jeong Jun, et Jong Kook Lee. « Influence of Processing Factors on the Surface Properties of Zirconia Coatings Fabricated by Room Temperature Spray Process ». Journal of Nanoscience and Nanotechnology 20, no 7 (1 juillet 2020) : 4152–57. http://dx.doi.org/10.1166/jnn.2020.17609.
Texte intégralRésumé :
Highly roughened surfaces on dental implants enhance the bone-bonding ability and in vivo cell adhesion on the implant surface. In this study, zirconia substrates were coated by powder coating using room temperature spray processing to improve their surface properties. Processing factors (particle size of the starting powder, number of repetitions of the deposition cycle, and spraying distance) were controlled to form a dense coating layer with high surface roughness on the zirconia substrate. Starting zirconia powders for coating were heat-treated at high temperature to control the particle size and kinetic energy. The coating layer fabricated from starting powder with a particle size of about 1.52 μm shows a homogeneous and dense microstructure, and it has a maximum surface roughness about 0.37 μm. The surface roughness of the film coatings increased with the number of times that the deposition cycle was repeated. No phase changes between the starting powder and the coating layer were observed, and all of the materials show identical tetragonal phases.