Roughness Profile Research Articles

Profilometer Comparison of the Surface Roughness of Four Denture Base Resins: An In Vitro Study

Background: The roughness of denture base materials is mainly affected by inherent material features, the polishing technique, and the operator’s manual skills. The surface irregularities of the denture base resin’s roughness profile is one of the components characterizing the superficial topography of dental prostheses, and it is a critical parameter for describing surface morphology. Generally, the increment of the surface roughness minimizes cleanability and promotes the rate of bacterial adherence, affecting the expression of bacterial adhesins. The purpose of this in vitro study was to investigate the roughness of four commercially available denture base resins employed for removable prosthodontics. Methods: Twenty-five specimens were realized and submitted to observation for three dimensions (vertically, horizontally, 45°). Average surface roughness (Ra), Rv, Rp, and Rq were measured with a calibrated mechanical roughness tester (Taylor Hobson Surtronic 25; Taylor Hobson, Leicester, UK). Data were analyzed through a Kruskal–Wallis test. Results: Significant differences in Ra between the groups were assessed. Baltic Denture System™ (Merz Dental GmbH; Lütjenburg, Germania) showed a lower surface roughness coefficient and a more homogeneous surface. Conclusions: The functional importance of surface roughness parameters for denture base materials must be explored, not only considering recognized surface features.

Investigation of anodised surface complexity and its correlation with surface hydrophilicity using fractal analysis

Anodising is a process of developing oxide coating on surface of metal electrolytically to improve its corrosion resistance. However, there has been inadequate research on the impact of the anodised surface characteristics on hydrophobicity or hydrophilicity. Surface roughness and porosity are often used to quantify surface characteristics, while each alone could not be enough to reflect all complexity of the surface. Hence, the fractal theory utilised to quantify the complexity of the anodised surface and decode its relation with the hydrophobicity or hydrophilicity of the surface. In this study, experiments of anodising for aluminium 6061 were carried out with three concentrations of electrolyte (3.5, 2.5 and 1.5 mol) and three current densities (1.0, 1.5 and 2.0 A/dm2). In addition, the surface characteristics after anodising was studied by using Scanning Electron Microscopy (SEM) analysis. Furthermore, surface roughness measurement was performed to obtain the surface roughness profile for fractal analysis. Moreover, a hydrophobicity test was implemented on anodised samples to obtain the contact angle between the water droplet and the surface. The outcomes showed that higher fractal dimension of anodised surface resulted in a smaller contact angle presenting a more hydrophilic surface. Furthermore, anodised samples with higher current density and concentration of electrolyte will result in higher fractal dimension and hence lower contact angle indicating the anodised surface will become more hydrophilic. Therefore, it is shown that measurement of fractal dimension is a reliable indicator for predication of surface wettability after anodising in order to improve the paint adhesion.

Facile Preparation of Hydrophobic PET Surfaces by Solvent Induced Crystallization

In this work, Polyethylene terephthalate (PET), one of the most widely consumed polymers, has been used as starting material for the development of non-stick surfaces through a fast, simple and scalable method based on solvent-induced crystallization to generate roughness, followed by a fluorination step. Several solvents were tested, among which dichloromethane was chosen because it gives rise to the formation of a particulate layer with rough topography. This particulate layer was covered by a polymer thin and smooth skin that must be removed to leave the rough layer as surface. The skin has been successfully removed by two strategies based on mechanical and chemical removal, each strategy producing different surface properties. A final treatment with a diluted solution of a fluorinated silane showed that it is possible to obtain PET surfaces with a water contact angle higher than 150° and low water adhesion. The reason behind this behavior is the development of a hierarchical rough profile during the induced polymer crystallization process. These surfaces were characterized by XRD, FTIR and DSC to monitor solvent induced crystallization. Topography was studied by SEM and optical profilometry. Wetting behavior was studied by measuring the contact angles and hysteresis.

Generalized Analysis Approach of the Profile Roughness by Electron Microscopy with the Example of Hierarchically Grown Polystyrene–Iron Oxide–Silica Core–Shell–Shell Particles

The roughness as a property of core–shell (CS) microparticles plays a key role in their functionality. Quantitative evaluation of the roughness of CS microparticles is, however, a challenging task with approaches using electron microscopy images being scarce and showing pronounced differences in terms of methodology and results. This work presents a generalized method for the reliable roughness determination of nonplanar specimens such as CS particles from electron microscopic images, the method being robust and reproducible with a high accuracy. It involves a self‐written software package (Python) that analyzes the recorded images, extracts corresponding data, and calculates the roughness based on the deviation of the identified contour. Images of single particles are taken by a dual mode scanning electron microscopy (SEM) setup which permits imaging of the same field‐of‐view of the sample with high resolution and surface sensitive in SE InLens mode as well as in transmission mode (TSEM). Herein, a new type of polystyrene core–iron oxide shell–silica shell particles is developed to serve as a set of lower micrometer‐sized study objects with different surface roughness; the analysis of their images by the semiautomatic workflow is demonstrating that the particles’ profile roughness can be quantitatively obtained.

Verifying the suitability of uncoupled numerical methods for solving vehicle-bridge interaction problems

The response of a structure subjected to a moving load can be obtained using coupled or uncoupled methods. The uncoupled method is often preferred since modal superposition is applicable, which implies computational efficiency and ease of implementation. However, the uncoupled method ignores the changes in the dynamic features of the combined structural system due to the time-varying location of the load. This paper analyses the extent to which the accuracy of the uncoupled method is affected by these changes. First, a parametric study is conducted on two discretized beam models traversed by a sprung mass at a constant speed. The error associated with the uncoupled method is calculated using the coupled solution as a reference. The influence of the load to structure mass and frequency ratios and the speed of the vehicle on the error is quantified. Heavier loads travelling at higher speeds are found to increase the inaccuracy of the uncoupled method. Then, the analysis is extended to a half-car travelling on a rough profile. Although errors from the uncoupled simulation remain low for the range of parameters under investigation, they may not be acceptable in some applications, i.e., the training of an algorithm for early damage detection.

New Methodology for Evaluating Surface Quality of Experimental Aerodynamic Models Manufactured by Polymer Jetting Additive Manufacturing.

The additive manufacturing (AM) applications have attracted a great deal of interest with regard to experimental aerodynamic studies. There is a need for a universal roughness scale that characterizes different materials used in aerodynamic research. The main purpose of this paper is identification of the potential of a material jetting AM process to produce accurate aerodynamic surfaces. A new methodology to evaluate the roughness of aerodynamic profiles (airfoils) was proposed. A very short-span wing artifact for preliminary tests and a long-span wing model were proposed for design of experiments. Different artifacts orientations were analyzed, maintaining the same surface quality on the upper and lower surface of the wing. A translucent polymeric resin was used for samples manufacturing by polymer jetting (PolyJet) technology. The effects of main factors on the surface roughness of the wing were investigated using the statistical design of experiments. Three interest locations, meaning the leading-edge, central, and trailing-edge zones, on the upper and lower surfaces of the airfoil were considered. The best results were obtained for a sample oriented at XY on the build platform, in matte finish type, with a mean Ra roughness in the range of 2 to 3.5 μm. Microscopy studies were performed to analyze and characterize the surfaces of the wing samples on their different zones.

Spraying pressure-tuning for the fabrication of the tunable adhesion superhydrophobic coatings between Lotus effect and Petal effect and their anti-icing performance

The tunable adhesion behavior of superhydrophobic surfaces has received much attention due to its unique properties to control the wetting state of water droplets. Herein, we report a facile and scalable spraying pressure-tuning method to control surface morphology by adjusting the spraying pressure to fabricate the tunable adhesion superhydrophobic coating (TASC). The superhydrophobic suspension prepared by fluorinated epoxy resin and polytetrafluoroethylene particles is sprayed on the glass substrate by altering the spraying pressure between 0.25 bar and 2.0 bar to control surface morphology, line profile, and surface roughness of TASCs. The water contact angles of TASCs are greater than 150°, while the water sliding angles of these surfaces are found from 2.6° (Lotus effect) to 180° (Petal effect) with the decrease of spraying pressure, which are attributed to the transformation of the wetting state on their surface from Cassie-Baxter state to Cassie impregnating state caused by the change of line profile and the decrease of surface roughness. We have proved that TASCs with different spraying pressure can be used in the droplet transportation, selection, and microreaction platform. Furthermore, the anti-icing performance of TASCs with different surface morphology and roughness was investigated by the freezing time and the ice adhesion strength. TASC-2.0 exhibited excellent anti-icing performance with freezing time at 392 s and the ice adhesion strength at 51 kPa than TASC-0.25 exhibited relatively flat surface, which is attributed to the air pocket captured by rough structure to reduce the solid/liquid contact area and has great potential for anti-icing applications.

Nutrient quality characteristics of fresh tomatoes subjected to various transportation and disinfection treatments under commercial conditions in South African supply chains

ABSTRACT This study investigated effects of disinfection treatments and storage conditions on the nutrient quality characteristics of tomatoes harvested and transported under typical commercial conditions in South Africa. The experimental treatments included harvest of tomatoes in two seasons, three maturity stages, three transportation conditions (varying distances and road surface profiles), four disinfection treatments (control, hot water, chlorinated or anolyte water in combination with biocontrol) and two storage conditions (cold (11°C) and ambient). For fruit harvested in winter, treatment with hot water (also for summer harvest) or with anolyte water + biocontrol and storage in cold conditions resulted in the highest concentrations of ascorbic acid (AA) compared with the other treatments. Fruit transported along the shorter and relatively smoother roads maintained higher AA (summer harvest) and lycopene concentrations compared with fruit transported the longest distance with moderately rough surface profile. The harvesting season and the disinfection treatments had significant effects on the concentrations of sugars. The nutrient characteristics of the tomatoes in the supply chain were shown to be affected not only by environmental and postharvest practices, but also by the road quality, demonstrated for the first time in this study. Cold storage of tomatoes, disinfection with hot water or anolyte water + biocontrol, and transportation planning to minimise the use of rough road surfaces and to use the shortest distances to markets, were recommended as best practices for the industry. Options for improvement of fruit packaging to provide adequate cushioning against physical damage during transportation should be investigated.

INFLUENCE OF WIRE-EDM PARAMETERS ON SURFACE CHARACTERISTICS OF SUPERALLOY MONEL 400

Progressive development in the industrial field leads to the increasing demand for superalloys with enhanced mechanical properties, such as toughness, hardness, ductility, damping strength, tensile strength and improved surface finish. Monel 400, one of such superalloys, with the majority of its application in aerospace and marine fields demands a good super finish. There arises the need for some nonconventional processes like WEDM. This process is more effective to obtain complex shapes to close tolerance. This research focuses on clear understanding of the machining strategies with proper parametric combinations to achieve an improved surface finish, subsequently reducing the time and expense involved in the superfinishing procedure. The surface qualities of the selected samples are validated with the help of roughness profile and topography images. This study has proven that the increasing input current and wire feed rate (WFR) consistently decreases the surface roughness (SR; [Formula: see text] of the specimen. This paper also explains the effect of topographic parameters and microstructure over the resulting SR. In addition, the consistent contribution of WFR and input current toward the lower SR is established. The relationship between morphological behavior and parametric deviations is evaluated. A significant correlation found to exist between the rate of wire feed and the height parameters of SR such as [Formula: see text], [Formula: see text], etc.

Locally Perturbed Inaccessible Rough Surface Profile Reconstruction via Phaseless Scattered Field Data

This work addresses an iteration scheme to observe the image of an inaccessible rough surface profile from the intensity of scattered field data. The solution of the problem is based on the integral equations written on the rough surface profile. By virtue of the surface integral equations, the phaseless scattered field is represented by a nonlinear ill-posed integral operator, which is linearized by Newton’s method and regularized via Tikhonov. The surface image is reconstructed iteratively in the least-squares sense by utilizing spline-type basis functions. A detailed numerical assessment is provided, showing that the algorithm is very effective and promising.

Surface integrity of tribo-adaptive layer prepared on Ti6Al4V through μEDC process

The work presents the surface integrity of TiN/TiAlN coated surfaces produced using hexagonal boron nitride suspension in the dielectric fluid through the micro-electrical discharge coating (μ-EDC) process. The performance of the coated surfaces is evaluated on the grounds of surface topography, wettability, indentation depth, layer height, crack density, roughness profiles, residual stress, and composition analysis. The recast layer height varies between 1.53 μm and 13.38 μm, while the water contact angle lies in the range of 91.28° to 118.23° (hydrophobicity is induced). The residual stress generated due to the presence of micro-cracks on the coated surfaces prepared at a maximum voltage (60 V) and powder concentration (12 g/L) varies between 225.87 MPa and 300.93 MPa. The occurrence of Ti, Al, Cu, Zn, V, B, N, and O in EDX plots affirmed the transfer of tool and dielectric material to the work surface. The indentation depths obtained in the study lies within the range of coating thickness. The surface roughness parameters, i.e., Ra, Rq, Rz, Rsk, and Rku are also evaluated in this work. Such micro-deposited surfaces find application in lab-on-chip devices where selective surface modification is needed.

Influence of Copper Substrate Roughness on the Growth of Intermetallic Compounds Layer in SAC305 Solder Joints

This study aimed to evaluate the effect of surface morphology of copper (Cu) substrate on the intermetallic compound (IMC) growth and interfacial reactions when soldered with SAC305 lead-free solder during a thermal aging process. The surface morphology conditions of the Cu substrate influence the growth activity of the IMC layer. This study used different grits of silicon carbide (SiC) abrasive paper (400, 800 and 1200) to grind the Cu substrate to produce different surface roughness. The resulting Cu surface morphologies were examined using an infinite focus microscope (IFM), and the parameters used in this stereometric analysis were profile roughness. Hand soldering was used to melt the SAC305 solder on the Cu substrates with different surface roughness. Subsequently, the samples were subjected to an aging temperature of 150 °C for 800 hours to grow the IMC layers. Thermal aging increased the IMC thickness at the Cu-SAC305 interfaces. After thermal aging, the IMC layer thickness and related parameters were measured and analyzed with the IFM. The growth of the IMC layer thickness depended on the different surface morphology of the substrate when the aging temperatures and Cu materials were maintained in this study. In general, the IMC morphology for the rougher Cu substrate had a scallop-shaped and uniformed layer compared to those IMC from the smooth Cu substrate. The Cu substrate ground surface roughness with 400 grit SiC abrasive paper produced an average roughness, Ra of 505.02 nm; this roughness produced the thinnest IMC layers compared to the different Cu substrates ground by SiC abrasive paper of different grits.

Image Recovery of Inaccessible Rough Surfaces Profiles Having Impedance Boundary Condition

This letter addresses a reconstruction algorithm of locally rough inaccessible surface profiles via the knowledge of the scattered field data under the consideration of the impedance boundary condition (IBC). To this aim, first, the synthetic scattered field data are obtained through the solution of the conventional surface integral equation (SIE) written on the rough surface. Then, the same SIE together with the data equation is solved iteratively via Newton’s method to obtain the image of the rough surface profile. In the numerical implementation, the nonlinear ill-posed inverse problem is linearized in an iterative fashion via the Newton method and regularized by Tikhonov in the least-squares sense. The feasibility of the algorithm is provided via numerical examples, which shows that the method is effective and promising.

Inverse Scattering by Perfectly Electric Conducting (PEC) Rough Surfaces: An Equivalent Model With Line Sources

This paper presents a new method for the reconstruction of the perfectly electric conducting (PEC) rough surface profiles by utilizing electromagnetic waves. The inaccessible rough surface is illuminated by a tapered plane electromagnetic wave and the scattered field data are measured on a certain number of points above the surface under test. The method for the inverse electromagnetic imaging problem is based on a special representation of the scattered field in terms of a finite number of fictitious discrete line sources located along a plane below the rough surface. The current densities of these fictitious sources are obtained through the regularized solution of an ill-posed problem. Then, it is shown that the image of the rough surface can be directly retrieved by seeking the points in the space where the tangential component of the total electric field vanishes. Alternatively, a much more rigorous iterative method based on a regularized Newton algorithm is also presented. A comprehensive numerical analysis is provided to demonstrate the feasibility of the presented approach. In this context, the quantitative successes of both approaches are interpreted by considering a very sensitive ℓ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -norm based error function between the actual and the reconstructed surface profiles. Regarding different scattering scenarios taken into account, the error values obtained for satisfactory reconstructions are generally in the range of 10% - 30% for both methods. It is also shown that the presented algorithms are capable of reconstructing the rough surfaces which oscillate for every λ horizontally and have a peak to peak variation 0.5λ at most.

Experimental investigation on surface integrity in a face milling operation

This paper discusses the influence of surface milling on the surface integrity of a 15-5PH martensitic stainless steel. Among the surface integrity features, surface roughness and residual stress profiles are particularly studied. This experimental work aims at characterizing the sensitivity of three technological parameters, namely the number of teeth, the axial runout of the milling cutters and the tilt angle. On these features, it is shown that the surface roughness is determined by the axial runout of the milling cutter when milling with multiple cutters without tilt angle. In contrast, the residual stress state is not significantly affected by any of these parameters.

Improving the performance of a combined horizontal and vertical axis wind turbine for a specific terrain using CFD

Flow of air in a mountainous terrain is highly influenced due to the profile and surface roughness. A fluid flow study prior to the placement of the turbine will greatly enhance the performance by suitably locating the horizontal axis wind turbine (HAWT) for maximum throughput. In addition, the placement of vertical axis wind turbine (VAWT) at a strategic location not only helps increase the overall output for a given space, but also helps in enhancing the output from the HAWT to an extent. In order to find the optimized configuration, an Analysis of Variance (2k design) using Computational Fluid Dynamics (CFD) is performed to identify the parameters of interest namely, separation between VAWT and HAWT, gap between the blade tips and the hill inclination angle. Further, the parameters were optimized using Taguchi method to enhance the signal to noise ratio, irrespective of the hill inclination by considering the inclination as noise and power as signal. The optimized configuration was implemented in a terrain and the output evaluated and performance improvement presented.

Experimental and numerical investigations on the process quality and microstructure during induction heating assisted incremental forming of Ti-6Al-4V sheet

• Development of induction heating SPIF system to provide localized heating to deform Ti-6AI-4V alloy sheet. • A Nickel ball-roller forming tool has been integrated into the SPIF system to improve the surface quality. • The relation between mechanical and microstructural behaviours was investigated by analysing forming force, geometric accuracy, thickness profile and surface roughness with recrystallisation, grain refinement and micro-hardness throughout the process. • A Finite Element (FE) model was established to verify the experimental results. The FE obtained strain and strain rate history was used as input to form a constitutive model to investigate the microstructural evolution. • Arrhenius model has been established by calculating of Zener-Hollomon parameter (Z-parameter) to correlate the grain size and micro-hardness at specific regions. The conventional single point incremental forming (SPIF) process is unable to perform high geometrical accuracy and formability for the Ti-6AI-4V alloy sheet. In response, this article has proposed a reliable high-frequency induction heating-assisted SPIF system. Rapid localised heating (600 ℃ and 700 ℃ ) was integrated with a synchronized Inconel 625 Nickel alloy ball-roller forming tool to achieve high geometric accuracy and surface quality. This article also produced new insights into correlating mechanical and microstructural properties in SPIF at 600 ℃ and 700 ℃ . By investigating the mechanical properties (forming force, geometric accuracy, thickness profile), an explicit finite element (FE) simulation was established to predict the results. The output strain history from the FE simulations was used as input and integrated with electron backscatter diffraction (EBSD) and micro-hardness characterisations, to form a constitutive model (Arrhenius model) to calculate the Zener-Hollomon parameter (Z-parameter). The grain size and micro-hardness experimental results were correlated with Z-parameter calculation to predict the microstructural development at the initial, middle, and final stages of the deformation process. The mechanical results revealed that the 700 ℃ experiment performed enhanced geometric accuracy and thickness profile, with a reduced forming force. However, the surface quality is reduced as the lubricant dissipated rapidly, while the ball-roller tool effectively compensated for this behaviour by reducing the friction. At the microstructural level, 600 ℃ revealed strong strain hardening and grain deformation, and 700 ℃ revealed better grain refinement by dynamic recovery (DRV) and dynamic recrystallisation (DRX). A proportional relationship between Z parameters and grain size and a low-high-low micro-hardness profile was proposed.

Comparison of the flexural and surface properties of milled, 3D-printed, and heat polymerized PMMA resins for denture bases: An in vitro study.

To compare the flexural properties and the adhesion of Lactobacillus salivarius (LS), Streptococcus mutans (SM), and Candida albicans (CA) on heat-polymerized (CV), CAD-CAM milled (CAD), or 3D-printed (3D) Poly (methylmethacrylate) (PMMA). Ultimate Flexural Strength (UFS), Flexural Strain (FS) (%) at Flexural Strength, and Flexural Modulus (FM) of specimens (65.0×10.0×3.3 mm) from each PMMA group (n=6) were calculated by using the 3-point bending test. The surface roughness profiles (R) were measured before and after polishing with a contact profilometer. LS, SM, and CA adhesion on PMMA specimens (n=18) (10 mm in diameter, 3 mm in height) was assessed after 90 minutes and 16 hours by using scanning electron microscopy. The Kruskal-Wallis test with post hoc analysis was performed to compare the groups (alpha=0.05). Mean UFS values were 80.79±7.64 MPa for CV, 110.23±5.03 MPa for CAD, and 87.34±6.39 MPa for 3D. Mean FS values were 4.37±1.04% for CV, 4.71±0.62% for CAD, and 6.19±0.13 % for 3D. Mean FM values were 2542±301 MPa for CV, 3435±346 MPa for CAD, and 2371±197 MPa for 3D. CAD had the lowest average R value (0.29±0.16 µm) before polishing, and bacterial adhesion after 90 minutes of incubation. R value and microbial adhesion were not different amongst groups after polishing and 16 hours of incubation, respectively. The CAD group displayed the best flexural properties, except for FS, the lowest roughness before polishing and bacterial adhesion after 90 minutes of incubation. All tested PMMAs had similar surface roughness after polishing, and microbial adhesion after 16 hours of incubation.

A Correlation between Deformation-Induced Surface Roughness and In-Plane Plastic Strain in an Aluminum Alloy at the Mesoscale

Experimental and numerical studies on deformation-induced surface roughening in a commercial purity aluminum alloy are presented and discussed. Mesoscale surface profiles evolving in the experimental and numerical specimens in the course of tension are processed to reveal a correlation between roughness characteristics and in-plane plastic strains at the mesoscale. A dimensionless parameter calculated as a ratio of the rough profile length to the profile evaluation length has been used for quantitative estimations of the mesoscale roughness patterns. The dimensionless roughness parameter is shown to depend exponentially on the in-plane plastic strains at the mesoscale. The results support an early assumption that in-plane plastic strains accumulated in a loaded material can be evaluated from the estimations of mesoscale surface roughness.

Surface roughness assessment on hole drilled through the identification and clustering of relevant external and internal signal statistical features

Drilling is a continuous cutting process where two or more cutting edges remove the material, to obtain the desired feature. During the chip evacuation, it generally rubs against the generated surface. Thus, the roughness obtained differs from other machining processes such as turning or milling. Therefore, surface roughness can be different from the analytically expected one. In this research work, an analysis of the cutting conditions where a level of roughness is expected to meet specific requirements has been carried out. 600 holes were made with two different tool geometries on steel without modifying the cutting conditions. When analysing the surface generated, certain variability in the roughness profiles obtained can be observed. External signals to the machine tool were acquired with sensors (cutting forces, vibrations, and acoustic emissions) as well as internal signals (spindle power, spindle torque in the Z-axis, spindle current and positions, speeds, accelerations, and jerk of the tool tip in the three axes of the machine). The most representative statistical features of the signals regarding roughness were selected using correlation analysis. Besides that, the hierarchical clustering of statistical features of the external and internal signals of the process was compared with clusters obtained using roughness parameters. Results show that clusters appear using signals highly related to the roughness parameters obtained from the measured profiles, confirming a mapping between the acquired signals during the machining process and the roughness of the holes.