Characterization of surface roughness of unworn hydrogel contact lenses at a nanometric scale using methods of modern metrology

2013 ◽  
pp. n/a-n/a ◽  
Author(s):  
Ştefan Ţălu
Keyword(s):  
Surface Roughness ◽  
Contact Lenses ◽  
Modern Metrology

scholarly journals Characterization of surface roughness of new nanophotonic soft contact lenses using lacunarity and AFM method

2018 ◽  
Vol 72 (3) ◽  
pp. 157-166 ◽  
Author(s):  
Aleksandra Mitrovic ◽  
Bozica Bojovic ◽  
Dragomir Stamenkovic ◽  
Dejana Popovic
Keyword(s):  
Surface Roughness ◽  
Surface Characterization ◽  
Contact Lenses ◽  
Tear Film ◽  
Basic Material ◽  
Machining Processes ◽  
Soft Contact ◽  
Average Roughness ◽  
Soft Contact Lenses

The aim of this study was to develop new soft contact lens (SCL) materials which would, after recommended and existing machining processes, improve surface roughness. Nanomaterials (fullerene, fullerol and methformin hydroxylate fullerene) were incorporated into commercial material for SCL (SL38) based on PHEMA, which were derived by the technology in the production lab of the company Soleko (Milan, Italy). Nanophotonic SCLs (SL38-A, SL38-B, SL38-C, respectively) were produced in the company Optix (Belgrade, Serbia) from the obtained materials. For the surface characterization of SCLs, AFM analysis and lacunarity method were performed. The results showed that for the SL38-B average roughness value is lower than those of SL38-A and SL38. The topography parameters of SL38-C were between the parameters of SL38-A and SL38-B. Lacunarity analysis of AFM images confirmed that SCLs surface state should belong to either group of adequate (slanted p-diagram) or inadequate (contorted p-diagram) roughness concerning tear film stability. Nanophotonic SCL SL38-C exibits more acceptable performance considering SCL surface functional behavior as compared to other SCLs. The positive result of incorporating nanomaterials into basic material for SCL is better quality of the nanophotonic SCLs surfaces. On the bases of these experiments, the assumption that incorporation of fullerene derivate will not increase surface roughness parameters is confirmed.

scholarly journals Post-Processing and Surface Characterization of Additively Manufactured Stainless Steel 316L Lattice: Implications for BioMedical Use

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1376
Author(s):  
Alex Quok An Teo ◽  
Lina Yan ◽  
Akshay Chaudhari ◽  
Gavin Kane O’Neill
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Surface Characterization ◽  
High Surface ◽  
Surface Characteristics ◽  
Post Processing ◽  
Stainless Steel 316L ◽  
Processing Methods ◽  
Particulate Debris

Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the customisation of structure and surface characteristics; there is little guidance for the post-processing of these metals. We carried out this study to ascertain the effects of various combinations of post-processing methods on the surface of an additively manufactured stainless steel 316L lattice. We also characterized the nature of residual surface particles found after these processes via energy-dispersive X-ray spectroscopy. Finally, we measured the surface roughness of the post-processing lattices via digital microscopy. The native lattices had a predictably high surface roughness from partially molten particles. Sandblasting effectively removed this but damaged the surface, introducing a peel-off layer, as well as leaving surface residue from the glass beads used. The addition of either abrasive polishing or electropolishing removed the peel-off layer but introduced other surface deficiencies making it more susceptible to corrosion. Finally, when electropolishing was performed after the above processes, there was a significant reduction in residual surface particles. The constitution of the particulate debris as well as the lattice surface roughness following each post-processing method varied, with potential implications for clinical use. The work provides a good base for future development of post-processing methods for additively manufactured stainless steel.

scholarly journals Skewness and Kurtosis: Important Parameters in the Characterization of Dental Implant Surface Roughness—A Computer Simulation

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Karl Niklas Hansson ◽  
Stig Hansson
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Roughness Parameter ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Implant Surface ◽  
Bone Response ◽  
Dental Implant Surface ◽  
Skewness And Kurtosis

The surface roughness affects the bone response to dental implants. A primary aim of the roughness is to increase the bone-implant interface shear strength. Surface roughness is generally characterized by means of surface roughness parameters. It was demonstrated that the normally used parameters cannot discriminate between surfaces expected to give a high interface shear strength from surfaces expected to give a low interface shear strength. It was further demonstrated that the skewness parameter can do this discrimination. A problem with this parameter is that it is sensitive to isolated peaks and valleys. Another roughness parameter which on theoretical grounds can be supposed to give valuable information on the quality of a rough surface is kurtosis. This parameter is also sensitive to isolated peaks and valleys. An implant surface was assumed to have a fairly well-defined and homogenous “semiperiodic” surface roughness upon which isolated peaks were superimposed. In a computerized simulation, it was demonstrated that by using small sampling lengths during measurement, it should be possible to get accurate values of the skewness and kurtosis parameters.

Mathematical Modeling of Flattening Process on Rough Surfaces in Thermal Spray

1996 ◽  
Author(s):  
H. Fukanuma
Keyword(s):  
Mathematical Modeling ◽  
Surface Roughness ◽  
Thermal Spray ◽  
Rough Surfaces ◽  
Time Decrease ◽  
Flattening Process

Abstract Thermal spray layers are formed on rough surfaces; however, the flattening process on rough surfaces has not yet been clarified. A mathematical flattening model which takes into account the roughness of the substrate or previously coated layers is proposed in this paper. As a result of surface roughness, the flattening degree and the flattening time decrease with increasing surface roughness in this model. In addition, the characterization of surface roughness is introduced for the flattening model. Several calculated cases of the flattening model are shown.

GROWTH AND CHARACTERIZATION OF EPITAXIAL Si/CoSi2 AND Si/CoSi2/Si HETEROSTRUCTURES

1985 ◽  
Vol 56 ◽  
Author(s):  
B.D. HUNT ◽  
N. LEWIS ◽  
E.L. HALL ◽  
L.G. JTURNER ◽  
L.J. SCHOWALTER ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Growth Temperature ◽  
Molecular Beam ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Cross Sectional ◽  
Reactive Deposition ◽  
Ion Channeling ◽  
Formation Method

AbstractThin (<200Å), epitaxial CoSi2 films have been grown on (111) Siwafers in a UHV system using a variety of growth techniques including solid phase epitaxy (SPE), reactive deposition epitaxy (RDE), and molecular beam epitaxy (MBE). SEN and TEN studies reveal significant variations in the epitaxial silicide surface morphology as a function of the sillciqd formation method. Pinhole densities are generally greater than 107 cm-2, although some reduction can be achieved by utilizing proper growth techniques. Si epilayers were deposited over the CoSi2 films inthe temperature range from 550ºC to 800ºC, and the reesuulttinng structures have been characterized using SEM, cross—sectional TEN, and ion channeling measurements. These measurements show that the Si epitaxial quality increases with growth temperature, although the average Si surface roughness and the CoSi2 pinhole density also increase as the growth temperature is raised.

Analysis of CoCrMo Surface Oxide Removal by Alumina Blasting before Porcelain Firing in Dental Restorations

2012 ◽  
Vol 730-732 ◽  
pp. 9-14 ◽  
Author(s):  
Bruno Henriques ◽  
Filipe Silva ◽  
Delfim Soares
Keyword(s):  
Heat Treatment ◽  
Surface Roughness ◽  
Chemical Composition ◽  
High Alumina ◽  
X Ray ◽  
Dental Restorations ◽  
Ceramic Bond ◽  
Xrf Scanning ◽  
Oxide Removal

The purpose of this work was to perform a chemical and mechanical characterization of a preoxidized CoCrMo alumina blasted surface. This is a commonly performed surface treatment used in metal-porcelain systems for dental restorations to remove oxides formed during preoxidation heat treatment from the metal’s surface. CoCrMo dental alloy’s specimens produced by lost wax process were examined in terms of chemical composition using X-Ray fluorescence spectroscopy (XRF), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS); in terms of mechanical characteristics through the means of a microhardness test and in terms of surface roughness using a profilometer. It was investigated the chemical composition of various surface conditions: non-preoxidized, preoxidized, ground oxidized surface and sandblasted oxidized surface. After alumina blasting, the oxides level on metal’s surface remained high. Alumina blasting treatment (Ø110 µm) produced an 84% increase of CoCrMo surface hardening and an increase in surface roughness (Ra=0.58 µm). It was found alumina contaminants on the metal’s surface. Therefore, it was concluded that alumina blasting do not entirely removes the oxide layer formed during preoxidation heat treatment. It produced a chemical and mechanical surface modification that can influence the metal-ceramic bond strength.

scholarly journals Surface roughness characterization of stainless steel after laser assisted machining

Mechanik ◽  
2019 ◽  
Vol 92 (12) ◽  
pp. 827-829 ◽  
Author(s):  
Agata Felusiak ◽  
Martyna Wiciak-Pikuła ◽  
Tadeusz Chwalczuk ◽  
Piotr Kieruj ◽  
Paweł Twardowski
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Cutting Parameters ◽  
Cemented Carbide ◽  
Roughness Parameters ◽  
Laser Assisted Machining ◽  
Carbide Inserts ◽  
Cemented Carbide Inserts

The paper presents the analysis of the influence of laser assisted machining (LAM) on various parameters of surface roughness of stainless steel. The tests were carried out for cemented carbide inserts with varying cutting parameters. In most cases, a significant reduction in the roughness parameters was observed using LAM.

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