Evaluation Of Surface Topography Research Articles

Generation of Residual Stresses and Improvement of Surface Integrity Characteristics by Laser Shock Processing

The influence of different parameters of laser shock processing applied to a precipitation-hardened aluminium alloy 6082-T651, on residual stress, surface tophraphy and microhardness was investigated. Processing was performed with an innovative Nd:YLF laser with the power densities of 2 and 4 GW/cm2, with a uniform pulse duration of 18 ns. Laser shock processing experiments were performed with the closed ablation method to ensure a higher shock-wave pressure. In the first phase, the study was focused on an evaluation of surface topography, with the record of the surface roughness profile and with the surface evaluation at a scanning electron microscope JEOL JXA-8600M. Then followed measurement of microhardness HV0.2in the cross section region. In the second phase comparison of residual stresses which were measured using the X-ray diffraction, was performed. Laser shock processing turned out to be a very efficient technique to improve surface properties. On the basis of the micro plastic deformation induced by shock waves, an increased dislocation density in the specimen surface was obtained. The gradient of dislocation piling through the specimen depth improved the variation of microhardness and residual stresses, which, in turn, improves fatigue strength of the material under dynamic loading.

An improved method for measurement of change in skin roughness caused by cleansing products under mild application conditions

The aim of this study was to develop a method for the evaluation of subtle change in skin roughness caused by cleansing products under mild application conditions using a non-invasive three-dimensional (3D) analysis system. A double-blind comparative study of the modified soap chamber test was performed using two soap bars and a syndet bar. Skin changes were evaluated by visual scoring [mean cumulative irritation index (MCII)] and by bioengineering measurements [transepidermal water loss (TEWL), skin capacitance, and skin surface roughness]. MCII of the syndet bar was statistically higher than that of one soap bar, and TEWL increase after application of the syndet bar was statistically higher than that of both soap bars. Skin capacitance decreased significantly only after application of the syndet bar. The change in the average roughness of the skin surface was significantly greater after the application of the syndet bar than with classic soap bars. A simple, fast, and objective evaluation of skin surface topography was performed using a modified soap chamber test and a non-invasive 3D analysis system. The results suggest that measurement of skin roughness using a non-invasive 3D analysis system might be a good method for the evaluation of a subtle change caused by cleansing products under mild application conditions.

Functional Evaluation Software Design of Surface Topography Based on MATLAB

In order to build the software evaluation and testing platform for surface topography measuring device and related enterprise, it is urgent to exploit the surface topography measurement and evaluation standard software application system. This paper proposes a novel method of surface topography design software base on exiting international standards. The method is introduced to obtain the reference line of surface profile. According to the reference line of surface roughness defined by the related standards, the functional evaluation parameters of surface characteristics were calculated. The procedure in designing the graphical user interface (GUI) is given based on the MATLAB software platform. This method realizes the software system that can evaluate the parameters of surface topography. The experimental analysis results show that the surface topography functional evaluation software using MATLAB has simple structure and reliable performance.

Complex microtopography analysis in sliding friction of steel-ferodo material pair

The tribological behaviour—friction, wear and lubrication—of machine elements highly depends on the operating state and also on the original topography of the working pair. Wear tests and 3D surface roughness measurements were carried out to analyse the effect of surface topography in friction and wear between ground steel specimens of various machining directions and different surface quality levels and a ferodo sliding pair. Three different techniques were used for surface topography evaluation: a parameter-based technique, a slicing method, and power spectral density analysis. Several parameters were found to be sensitive to surface wear phenomena; their changes indicate, among other things, surface platoing or the appearance of dominant scratches. The peak angle and height of asperities convey important information on numerous tribological changes. Power spectral density (PSD) analysis shows that the result of changes in the topography is an ‘equilibrium’ surface.

Comparison of Porosity Measurement Techniques for Porous Titanium Scaffolds Evaluation

Porous titanium has been used for grafts and implant coatings as it allows the mechanical interlocking of the pores and bone. Evaluation of porous scaffolds for bone regeneration is essential for their manufacture. Porosity, pore size, pore shape and pore homogeneity are parameters that influence strongly the mechanical strength and biological functionality. In this study, porous titanium samples were manufactured by powder metallurgy by using pure titanium powders mixed with a pore former. The quantification of the porosity parameters was assessed in this work by geometric method and gamma-ray transmission, the non-destructive techniques and metallographic images processing, a destructive technique. Qualitative evaluation of pore morphology and surface topography were performed by scanning electron microscopy and optical microscopy. The results obtained and the effectiveness of the techniques used were compared in order to select those most suitable for characterization of porous titanium scaffolds.

Comparative Evaluation of Surface Topography and Fracture Resistance of Teeth Restored with Condensable Glass Ionomer and Posterior Composite Resin : - An Invitro SEM study.

Comparative Evaluation of Surface Topography and Fracture Resistance of Teeth Restored with Condensable Glass Ionomer and Posterior Composite Resin : - An Invitro SEM study.

Effect of Bleaching on Color Change and Surface Topography of Composite Restorations

This study was conducted to determine the effect of 15% carbamide peroxide bleaching agent on color change and surface topography of different composite veneering materials (Filtek Z350 (3M ESPE), Esthet X (Dentsply India), and Admira (Voco, Germany). Methods. 30 samples were fabricated for evaluation of color change using CIELAB color system and Gonioreflectometer (GK 311/M, ZEISS). 45 disc-shaped specimens were made for evaluation of surface topography after bleaching (Nupro White Gold; Dentsply) using SEM. Statistical analysis. One way ANOVA and Multiple comparison tests were used to analyze the data. Statistical significance was declared if the P value was .05 or less. Results and conclusion. All the specimens showed significant discoloration (ΔE > 3.3) after their immersion in solutions representing food and beverages. The total color change after bleaching as compared to baseline color was significant in Filtek Z350 (P = .000) and Esthet X (P = .002), while it was insignificant for Admira (P = .18). Esthet X showed maximum surface roughness followed by Admira and Filtek Z350. Bleaching was effective in reducing the discoloration to a clinically acceptable value in all the three groups (ΔE < 3.3).

Geometrical modelling of scanning probe microscopes and characterization of errors

Scanning probe microscopes (SPMs) allow quantitative evaluation of surface topography with ultra-high resolution, as a result of accurate actuation combined with the sharpness of tips. SPMs measure sequentially, by scanning surfaces in a raster fashion: topography maps commonly consist of data sets ideally reported in an orthonormal rectilinear Cartesian coordinate system. However, due to scanning errors and measurement distortions, the measurement process is far from the ideal Cartesian condition. The paper addresses geometrical modelling of the scanning system dynamics, presenting a mathematical model which describes the surface metric x-, y- and z- coordinates as a function of the measured x′-, y′- and z′-coordinates respectively. The complete mathematical model provides a relevant contribution to characterization and calibration, and ultimately to traceability, of SPMs, when applied for quantitative characterization.

Effect of nanoscale surface topography on low temperature direct wafer bonding process with UV activation

Low temperature direct wafer bonding is a promising technology for microelectromechanical systems (MEMS), sensors as well as silicon-on-insulator (SOI) materials. The bond quality is closely related to the wafer-bow, surface adhere energy and nanoscale surface topography. Effective surface activation and nanoscale surface topography evaluation is critical for the bonding process. For the low temperature silicon wafer direct bonding process with ultra violet (UV) light activation, surface nanoscale topography is modified and characterized before and after UV irradiation by the control of irradiation duration. The measured data of nanoscale topography by atomic force microscope (AFM) is evaluated by both bearing ratio and root-mean-square (RMS) approaches, from which the results are then correlated with the bond strength to understand the bonding process. It is shown that the bear ratio approach is more suitable for characterizing the surface roughness and optimizing the bonding process through the control of UV irradiation duration. The approach is also applicable to a wide variety of low temperature wafer bonding process where surface roughness is modified.

Design, fabrication and evaluation of nanoscale surface topography as a tool in directing differentiation and organisation of embryonic stem-cell-derived neural precursors

A major limitation in the translation of stem cells technology to clinical applications is the lack of efficient control over their proliferation and differentiation. Recent in vitro research findings suggest that biomaterials with nanoscale surface topography can influence cell behaviour like adhesion, proliferation and differentiation. Therefore, the identification of biomaterials that support appropriate ES cell attachment, proliferation and differentiation into cells of interest is an attractive strategy worth investigation. In this study we present the design and fabrication of thin films of gold with surface topography of varying roughness using a combination of microfabrication techniques. We then explored their biomimetic potential to direct differentiation of ES cell-derived neural precursors. Standard glass coverslips and tissue culture plastic were used as reference materials. Our preliminary results show that ES-derived neural precursors best adhered on gold and underwent the highest differentiation on gold films with root mean square surface roughness ( R q) of 21 nm (72 ± 6%) after five days of culture in the absence of traditional soluble neurotrophic factors. Moreover, when cells were seeded on a combination of micro-scale grooves with nanoscale surface roughness, axonal outgrowth orientation was observed to be influenced by the grating axis. This data identifies gold as a potential biomaterial candidate with suitable cytocompatibility for ES cell research. It further lends support to the hypothesis that biomaterial design may optimize ES cell-derived neural differentiation and organisation. This may find utility as a tool to synergically complement soluble chemical factors currently used in in vitro protocols for the stimulation and modelling of ES differentiation. Ultimately, substrate patterning may hold special utility in the design of neural prostheses because repair of neurological injuries requires directional guidance.

Laser Shock Processing of ENAW 6082 Aluminium Alloy Surface

The present paper treats results of laser shock processing applied to a precipitationhardened ENAW 6082-T651 aluminium alloy. Processing was performed with a Nd:YLF-yttrium lithium fluoride crystal laser with power densities of 2 and 4 GW/cm2, producing a pulse of 18 ns. Laser shock processing experiments were performed with the closed ablation method, the application of an ablative coating and a transparent tamping medium to obtain a higher shock-wave pressure. In the first phase, the surface study focused on the record of surface profile with a roughness gauge and on an evaluation of surface topography at a scanning electron microscope. In the second phase, residual stresses were measured using the relaxation hole-drilling method at a processed specimen surface. Then followed measurement of microhardness in the cross section. The hardening results obtained were evaluated on the basis of variations of residual stresses and of microhardness, and of macro and microstructural changes of the surface, i.e. the surface layer. The purpose of processing was to improve fatigue strenght and, consequently, extend the life of a machine component in operation.

The Application of Motif Characterizing Method in the Surface Topography Evaluation of MEMS Device

The surface topography characterization of MEMS device is very important to bonding technology of MEMS device. Motif characterizing method is a characterizing method of surface topography by graph. Aiming at the diversity and regionality of surface topography of MEMS device, in this study we have sampled the surface of MEMS device by 3-dimentinal grids using the surface profiler developed by us and characterizes the surface topography of MEMS device by the extended Motif characterizing method. The surface of MEMS device is divided into several Motif regions; the surface topography of every divided region can be evaluated respectively; the details of every region can be zoomed and these regions as a whole or every region can be revolved and projected; one of these regions can be as the reference of other regions. So the height, gradient and other characteristics of others regions of the whole MEMS device surface can be analyzed relative to the reference region; the whole and local surface topography of whole MEMS device can be analyzed.

Synovial Membrane Microarthroscopy of the Equine Midcarpal Joint

To evaluate the value of microarthroscopy in the equine midcarpal joint using the vital stains methylene blue, trypan blue, neutral red, and Janus green B to observe components of the synovial lamina propria, vascular architecture, and synoviocytes. Experimental. Ten horses. Microarthroscopy of left and right midcarpal joints was performed with and without vital staining of the synovium. Four vital stains (methylene blue, trypan blue, neutral red, and Janus green B) were evaluated, with each stain used in 5 joints. Synovial biopsy specimens were collected from the dorsomedial and dorsolateral aspects of the joint. All dyes were biocompatible. At x 60 without vital staining, synovial surface topography, vascular network, and translucency were observed. Intra-articular vital dyes improved evaluation of synovial surface topography. At x 150 with vital staining, individual synoviocytes were clearly identified with all dyes, except neutral red. Although methylene blue provided the best in vivo microscopic differentiation of the structure of the intima, trypan blue had superior retention in conventionally processed synovial biopsies. Methylene blue, trypan blue, neutral red, and Janus green B stains can be used safely for microarthroscopy. Good visualization of cells and vascular network can be obtained by microarthroscopy, and microarthroscopic evaluation of the synovium compares favorably with conventional histologic evaluation of biopsy specimens. Microarthroscopy may be beneficial in both research and clinical diagnosis of equine articular diseases.

Biologic effects of surface roughness and fluorhydroxyapatite coating on osteointegration in external fixation systems: an in vivo experimental study.

The concomitant influence of surface roughness and fluorhydroxyapatite (FHA) coating of titanium (Ti) implants on bone response was investigated. For this purpose, titanium screw-shaped implants with a lower degree (Y371) and a higher degree (TiPore300) of surface roughness, coated with FHA and uncoated, were transversally inserted into the diaphyses of sheep tibiae for 12 weeks. Four sheep received Y371 (group A) and Y371 + FHA (group B) screws and four sheep received TiPore300 (group C) and TiPore300 + FHA (group D) screws. For each type of material, the morphology and microstructure of implant-facing bone were evaluated. The host bone of each tibia was used as a control. In all groups the bone tissue did not reach a complete maturation. The higher degree of roughness, perhaps due to an excessive irregularity of the surface, induced the worst osteointegration: a fibrous tissue layer between screw and new bone tissue was often present. Nevertheless, as viewed by XRD, no crystallographic change of the apatite lattice was observed in any of the implants. In contrast, the microhardness value, an index of bone mineralization, was higher in the uncoated screws and decreased progressively in the following order: group C > group A > group B > group D. The association of plasma spraying with roughness treatment constitutes a complex system that seems to interfere with bone mineralization. A chemical change of the surface, perhaps with more Ti release or more coating degradation, could be responsible for such impairment. The authors emphasize the necessity for simultaneous evaluation of surface topography and chemistry as well as an improvement in plasma-spraying and post-processing techniques and in standard procedures for materials characterization.

The accuracy of fast 3D topography measurements

One important factor in surface engineering is the evaluation of the surface topography, i.e. measurement and analysis. These measurements of the surface roughness are normally done by stylus instruments and 2D profiles due to available standards. 3D surface topography evaluation is, however, in some cases necessary and frequently used, a standard is under development, and newly developed measurement instruments are used. Specially interferometric instruments are of interest here since measuring time is critical and their accuracy and comparability to stylus instruments must be evaluated. Therefore, in this study a number of engineering surfaces have been measured and evaluated: plateau-hones cylinder liners for engines, polished steel roller for bearings, grounded and honed gear surfaces from gear boxes, and steel sheet surfaces used in car bodies. By the use of a precise relocation technique, an exact comparison was possible between an interferometric instrument (Wyko RST Plus) and a 3D stylus instrument (Somicronic 3D). To be able to judge and analyze differences between the instruments an Atomic Force Microscope (AFM) was used. The AFM is extremely accurate for this type of surfaces, but limited in its measuring range. The result shows a very good agreement between the instruments with deviations of approximately 5–20% depending on the parameter evaluated. The stylus in general gives lower values. The results from the AFM are generally found between the parameters of these instruments, and for soft surfaces, such as sheets or smooth surfaces, the interference instrument has a slightly better agreement to the AFM. This is due to the stylus tip geometry and the relatively high contact pressure having difficulties measuring small features and also damaging softer surfaces. The result from an interferometric measurement occasionally shows optically introduced artifacts caused by local surface slopes which exaggerate the topography. By knowing the degree of influence from these peculiarities it is still possible to use fast interferometric instruments and to estimate its deviation from what would have been the result with a stylus instrument.

Introduction of fractal dimension to adhesive strength evaluation of plasma-sprayed coatings

The adhesive strength of ceramic coatings depends on the surface roughness of substrates. Taking account of the bonding mechanisms, however, surface roughness may not be a proper measure to evaluate the surface topography of substrates. Here, fractal dimension is proposed for the evaluation of surface topography. Physically the fractal dimension can include hook-shaped indentations which generate a mechanical interlocking force. By applying fractal dimension to the evaluation of the surface topography of substrates and relating it to the adhesive strength of alumina coatings, it was concluded that fractal dimension properly evaluates the adhesive strength as compared with surface roughness.

Evaluation of surface topography of metal-bonded diamond wheel utilizing three-dimensional profilometry

A three-dimensional profilometry has been developed for the purpose of evaluating grinding wheel surface topography. By applying this method to the measurement of topography of a metal-bonded diamond wheel dressed by an abrasive stick method, the effect of dressing conditions on the generation mechanism of diamond cutting points has been investigated. The results obtained are as follows. (1) The tips of the diamond grains located in the wheel outermost surface layer are flattened. (2) The distribution pattern of cutting points in the radial direction changes from exponential to uniform as the dressing condition becomes rough. (3) The rough dressing condition causes a higher grain protrusion, but the degree is restricted in the case where dislodgment of diamond grain is dominant.

Grinding surface characterization by CEST

A newly developed Computer Evaluation of Surface Topography (CEST)_tecnique is used to characterize grinding surface. This CEST technique calculates the profile spectrial moments and finds variances of heights, slopes and curvatures of asperities for any anisotropic homogeneous surface in the form of pictorial conic sections. Ten different soft steel ground surfaces were evaluated using CEST techniques to study the effects of five different operating variables on surface finish. Results showed strong anistropic properties for all the ground surfaces. Also, the cross-feed and depth of cut were shown to be the two strongest factors influencing the surface characteristics. Finally, suitable operating conditions for grinding soft steel are suggested to produce desired surface quality.

Automatic evaluation of surface topography by cross-correlation of SEM stereo pair images

Automatic evaluation of surface topography by cross-correlation of SEM stereo pair images

Comparison Of Two Common Methods Of Surface Topography Evaluation

This paper compares some of the advantages and limitations of two methods used for surface topography evaluation, the dual-beam interference microscope and the stylus-type profiling instrument. Consideration is primarily limited to diamond-machined or other high quality surfaces, such as those commonly encountered on optical elements. Parameters discussed include horizontal and vertical resolution, horizontal and vertical range, and surface damage.