Surface Roughness Characteristics Research Articles

Exploring the influence of surface roughness on the interface phenomenon between an air bubble and a glass bead: An experimental and theoretical investigation

The effect of surface roughness on the detachment between the bubbles and the glass beads (soda-lime) was comprehensively investigated. Glass beads with dimensions of −1.20 + 1.12 mm were acid etched to achieve varying degrees of surface roughness, followed by silanation reactions conducted for different immersion times. The characterization of surface roughness was conducted using a ContourGT-K 3D optical microscope. Measurements of receding contact angle, induction time and detachment force were conducted to assess the influence of surface roughness on bubble and glass bead attachment/detachment. It is observed that the etching surface of glass beads with uniform protrusions and depressions, the hydrophobic glass beads exhibited shorter induction time, larger contact angle and higher critical detachment force. However, the stability of aggregates of bubbles and hydrophilic glass beads was reduced, making them prone to detachment. Moreover, larger protrusions and depressions on hydrophobic glass bead surfaces with increasing etching time, resulted in an increase in induction time, a decrease in receding contact angle and critical detachment force. The stability of bubbles and hydrophilic glass bead aggregates remained unchanged.

On the Effect of Randomly Oriented Grain Growth on the Structure of Aluminum Thin Films Deposited via Magnetron Sputtering

The microstructure of aluminum thin films, including the grain morphology and surface roughness, are key parameters for improving the thermal or electrical properties and optical reflectance of films. The first step in optimizing these parameters is a thorough understanding of the grain growth mechanisms and film structure. To investigate these issues, thin aluminum films with thicknesses ranging from 25 to 280 nm were coated on SiOx/Si substrates at ambient temperature under high-vacuum conditions and a low argon pressure of 3 × 10−3 mbar (0.3 Pa) using the radio frequency magnetron sputtering method. Quantitative analyses of the surface roughness and nanograin characteristics were conducted using atomic force microscopy (AFM), transmission electron microscopy (TEM), and X-ray diffraction. Changes in specular reflectance were measured using ultraviolet–visible and near-infrared spectroscopy. The low roughness values obtained from the AFM images resulted in high film reflectivity, even for thicker films. TEM and AFM results indicate monomodal, randomly oriented grain growth without a distinct columnar or spherical morphology. Using TEM cross-sectional images and the dependence of the grain size on the film thickness, we propose a grain growth mechanism based on the diffusion mobility of aluminum atoms through grain boundaries.

Influence of Detonation Spraying Parameters on the Microstructure and Mechanical Properties of Hydroxyapatite Coatings.

The process of osteointegration depends significantly on the surface roughness, structure, chemical composition, and mechanical characteristics of the coating. In this regard, an important direction in the development of medical materials is the development of new techniques of surface modification and the creation of bioactive ceramic coatings. Calcium-phosphate materials based on hydroxyapatite have been proposed as bioactive ceramic coatings on titanium implants for the effective acceleration of bone tissue healing. To obtain bioactive ceramic coatings, pulse power sources are best suited, namely detonation spraying, in which the energy of the explosion of gas mixtures is used as a source of pulse action. The pulse mode of operation in the detonation spraying method is preferable for the formation of bioactive ceramic coatings. It provides a high velocity of hydroxyapatite particles, which promotes their effective fixation on the titanium substrate, while minimizing the heating of the material. This approach preserves the substrate structure and improves the coating adhesion. Four different types of coatings with varying O2/C2H2 molar ratios, ranging from 2.6 to 3.7, were obtained using detonation spraying. Powders and obtained coatings of hydroxyapatite were studied by Raman spectroscopy and XRD structural analysis. The results of XRD phase analysis showed the partial conversion of the hydroxyapatite phase to the α-tricalcium phosphate (α-TCP) phase during the detonation spraying process. The results obtained by Raman spectroscopy indicate that hydroxyapatite is the main phase in coatings. All hydroxyapatite-based coatings exhibited hydrophobic properties, which was confirmed by contact-angle values above 90° in wettability tests, characteristic of hydrophobic surfaces. The adhesive strength of the coatings was measured by the scratch test method. Tribological tests were conducted using the ball-on-disk method under both dry conditions and in Ringer's solution. This approach enabled the evaluation of wear resistance and friction coefficient of the coatings in different environments, simulating both lubrication-free conditions and those resembling physiological environments.

Characterization of micro-wire electrical discharge machining surface texture by empirical mode decomposition

Surface roughness is a critical factor for the operational efficacy and lifespan of the manufactured components, often serving as a key metric for evaluating manufacturing processes and determining acceptance of a component. Traditional surface roughness measurements are highly sensitive to the fixed standard cut-off length, influencing the scale at which surface texture features are analyzed. Thus, developing techniques with more reliable filtering of surface features is essential for accurate surface metrology. This research proposes a novel method that combines Empirical Mode Decomposition (EMD) and Fast Fourier Transform (FFT) for surface roughness characterization. We applied our method to Nitinol shape memory alloy (equal atomic proportions of nickel and titanium) surfaces processed using micro-Wire Electrical Discharge Machining (μ-WEDM). Our results demonstrate that the EMD-FFT method significantly outperforms traditional filtering, especially for surfaces without distinct patterns like μ-WEDM. This improvement is particularly valuable for materials like Nitinol, which is widely used in critical applications where precise surface roughness control is essential. By accurately assessing the effects of μ-WEDM parameters on surface roughness, the proposed method reveals that for a constant pulse on time and a constant discharge current, the variation of pulse off time is more important than servo voltage. Thus, this method can contribute to optimizing manufacturing processes and producing higher-quality components with improved performance and durability.

Surface condition driven fatigue performance of laser powder bed fusion H13 steel

Surface variation is an inherent imperfection in the laser powder bed fusion (LPBF) processed samples, comprising of primary roughness (PRR) from the melt pool solidification and secondary roughness (SER) from adhered powder particles. Components under cyclic loading are sensitive to surface defects, making surface finishing crucial for fatigue-bearing parts. However, this undermines LPBF’s advantage of creating high-performance and geometrically complex components. This study examines the effect of surface roughness on fatigue crack initiation in LPBF H13 steel, a high-strength alloy with a tensile strength of 1800 MPa. The focus is on scenarios where contour scanning strategies are not employed. Vertically deposited samples were subjected to three surface conditions: as-built (AB) with PRR + SER, half-polished (HP) with only PRR, and well-machined (M) with no PRR or SER. Optical and digital surface roughness characterization and stress-controlled fatigue testing were performed. Results revealed that while AB-samples showed significantly rough surface compared to HP-samples, their fatigue performance did not reduce. In contrast, M-samples had a slight improvement in roughness but exhibited a fatigue life increase by a factor greater than 17. This was attributed to the PRR, specifically the solidification valleys between the neighboring melt pools. Factographic analysis showed that the PRR-driven fatigue crack initiation is a critical determinant of fatigue performance.

Experimental Analysis of Terahertz Wave Scattering Characteristics of Simulated Lunar Regolith Surface

This study investigates terahertz (THz) wave scattering from a simulated lunar regolith surface, with a focus on the Brewster feature, backscattering, and bistatic scattering within the 325 to 500 GHz range. We employed a generalized power-law spectrum to characterize surface roughness and fabricated Gaussian correlated surfaces from Durable Resin V2 using 3D printing technology. The complex dielectric permittivity of these materials was determined through THz time-domain spectroscopy (THz-TDS). Our experimental setup comprised a vector network analyzer (VNA) equipped with dual waveguide frequency extenders for the WR-2.2 band, transmitter and receiver modules, polarizing components, and a scattering chamber. We systematically analyzed the effects of root-mean-square (RMS) height, correlation length, dielectric constant, frequency, polarization, and observation angle on THz scattering. The findings highlight the significant impact of surface roughness on the Brewster angle shift, backscattering, and bistatic scattering. These insights are crucial for refining theoretical models and developing algorithms to retrieve physical parameters for lunar and other celestial explorations.

Investigation of surface structuring and oxidation performance of Inconel 718 superalloy by laser remelting with different patterns

The current paper deals with the effect of CO2 laser remelting on the surface structuring and oxidation performance of Inconel 718 superalloy, pointing out different laser-induced surface patterns that make a difference in their oxidation properties vital for high-temperature applications. Surface roughness, microstructure, and oxidation behavior characterization were performed using 3D optical profilometry, SEM, and XRD techniques. The oxidation tests conducted at 1000 °C for 24 h have revealed that remelted surfaces offered better oxidation resistance compared to untreated samples. Notably, the patterned sample showed the lowest weight gain under oxidation, and a parabolic regime in oxidation occurred after 100 min; while in an untreated reference sample, this appears only after 200 min. This improvement in performance results from the formation of a chromium-rich oxide layer on the melt pools, which acts as an effective barrier against further oxidation. The findings show that laser remelting, especially with grid-like surface patterns, results in an improvement in both durability and high-temperature performance of Inconel 718; therefore, it is apparently a very promising technique for lifespan extension of industrially relevant materials.

Microstructure analysis of SS316L using Selective Laser Melting

Abstract Additive manufacturing has emerged as a prominent and expanding domain in materials engineering, driven by a rising need for customized, highly accurate, and readily available production. Applying the selective laser melting (SLM) technique further is delayed by the layer-by-layer melting and solidification of the metal powder. The impeller constructions were extracted from a substrate, with the bending curvature as an indicator of the stress level. This research aims to analyze the quality of impeller components, surface roughness, and microstructural features of components made for the SS316L. The microstructure examinations show the part is free from the surface and internal defects are verified.

Using bearing ratio curves to quantify the surface roughness parameters of fly ash-teff straw ash-based geopolymer mortars

Considering the prominent attributes of surface roughness parameters, the closer their solutions are to real surfaces, the more appropriate they are for civil engineering applications. One of the steps that can be considered for such applications is to incorporate the bearing ratio curve (BRC) parameters in the study of civil engineering materials. In this research, the bearing ratio curves have been used for the first time to quantify the surface roughness attributes of fly ash-teff straw ash-based geopolymer mortars. For various cases, the roughness parameters in the V-group are compared with the roughness parameters in the Rk group, which contributes to the attractiveness of this research. The fly ash-teff straw ash-based geopolymer mortar specimens in this study are dominated by smooth surfaces, as evidenced by the Rvk and Rpk values of less than 0.21 μm for all specimens. The study highlights that if such surfaces are to be used in mortar-to-mortar bonding, imposed surface roughness could be required to enhance the bond strength of the layers. In addition, the results indicate that critical roughness parameters can be identified from the bearing ratio curves when a surface is undergoing roughness transformations. These findings provide a step towards the understanding of BRC parameters for fly ash-teff straw ash-based geopolymer mortar surfaces. Overall, the approach demonstrated in this study could also accelerate and promote the surface roughness characterisation for geopolymer mortars and could be extended to unlock peculiar surface roughness properties for other civil engineering materials.

Low-Reynolds-number droplet motion in shear flow micro-confined by a rough substrate

A three-dimensional spectral boundary element method has been employed to compute for the dynamics of the droplet motion driven by shear flow near a single solid substrate with a rough surface. The droplet size is comparable with the surface features of the substrate. This is a problem that has barely been explored but with applications in biomedical research and heat management. This work numerically investigated the influences of surface roughness features, such as the roughness amplitude and wavelength, on the droplet deformation and velocities. We observe that a greater amplitude or wavelength leads to larger variations in droplet velocity perpendicular to the substrate. The droplet velocity along the substrate increases when the amplitude is reduced or when the wavelength increases. The effects of capillary number and viscosity ratios have also been studied. The droplet deformation and its velocity increases as we increase the capillary number, while the viscosity ratio shows a non-monotonic influence on the droplet behavior. The predicted droplet behaviors, including deformation, velocities, and trajectories, can provide physical insight, help to understand the droplet behavior in microfluidic devices without a perfectly smooth surface, and contribute in the design and operation of those devices.

Multicycle Characterization of Surface Roughness in Stereolithography-based Additive Manufacturing Using a Methacrylate-based Thermoresponsive Copolymer

Multicycle Characterization of Surface Roughness in Stereolithography-based Additive Manufacturing Using a Methacrylate-based Thermoresponsive Copolymer

Optimizing surface properties in pure titanium for dental implants: a crystallographic analysis of sandblasting and acid-etching techniques

Surface roughness is a critical factor affecting the performance of dental implants. One approach to influence this is through sandblasted, large grit, acid-etched (SLA) modification on pure titanium implant surfaces. In this study, SLA was performed on grade IV pure titanium. Sandblasting was conducted at distances of 2, 4, and 6 cm. Subsequently, the samples were etched with a mixed acid solution of HCl, H2SO4, and H2O for 0, 30, and 60 min. Surface roughness and X-ray diffraction (XRD) characterizations were conducted on the samples. The results revealed that surface roughness increased but was not too significant as the sandblasting distance decreased. Longer etching durations for sandblasted with acid-etched samples led to reduced surface roughness (Sa and Sz). It was found that a 60 min-etched sample resulted in optimal Sa, Sz, and Ssk values, i.e., 1.19 μm, 13.76 μm, and −0.60, respectively. The XRD texture was significantly influenced by sandblasting, with compressive residual stress increasing as the sandblasting distance decreased. Normal stress causes hill formations at shorter sandblasting distances. For etched samples, the residual stress decreased with longer etching durations. Normal stress-decreasing trend aligns with the initial reduction in hill and valley within the samples and subsequent hill enhancement at extended etching duration.

Study of the Characteristics of Ba0.6Sr0.4Ti1-xMnxO3-Film Resistance Random Access Memory Devices.

In this study, Ba0.6Sr0.4Ti1-xMnxO3 ceramics were fabricated by a novel ball milling technique followed by spin-coating to produce thin-film resistive memories. Measurements were made using field emission scanning electron microscopes, atomic force microscopes, X-ray diffractometers, and precision power meters to observe, analyze, and calculate surface microstructures, roughness, crystalline phases, half-height widths, and memory characteristics. Firstly, the effect of different sintering methods with different substitution ratios of Mn4+ for Ti4+ was studied. The surface microstructural changes of the films prepared by the one-time sintering method were compared with those of the solid-state reaction method, and the effects of substituting a small amount of Ti4+ with Mn4+ on the physical properties were analyzed. Finally, the optimal parameters obtained in the first part of the experiment were used for the fabrication of the thin-film resistive memory devices. The voltage and current characteristics, continuous operation times, conduction mechanisms, activation energies, and hopping distances of two types of thin-film resistive memory devices, BST and BSTM, were measured and studied under different compliance currents.

Comparative investigation of heat extraction performance in 3D self-affine rough single fractures using CO2,N2O and H2O as heat transfer fluid

The type and thermophysical properties of heat transfer fluids significantly impact the heat extraction rate of Enhanced Geothermal Systems (EGS). Studies based on field-scale stochastic discrete fracture network geometric models have certain limitations and uncertainties. To compare the heat extraction performance of heat transfer fluids H2O, CO2, and N2O in a core-scale (φ50 × 100 mm) rough single fracture in hot dry rock, we first constructed the fracture geometry with rock surface roughness characteristics using a fractal self-affine function, with a joint roughness coefficient (JRC) of 12.38. Then, at temperatures ranging from 37 to 300°C and a pressure of 30 MPa, we established a thermo-hydraulic (TH) coupling model based on the thermophysical parameter equations of the three heat transfer fluids. Finally, we conducted a comparative study of the changes in the outlet mean temperature and heat extraction rate after flowing through the fracture, as well as the temperature distribution on the fracture surface, under conditions of constant inlet flow velocity with varying inlet temperature and constant inlet temperature with varying inlet flow velocity. The results indicate that (1) with the increase in inlet flow velocity and temperature, the outlet mean temperature and heat extraction rate of CO2 and N2O at the fracture outlet are essentially the same and lower than those of H2O. (2) When the inlet flow velocity increases from 0.005 m/s to 0.025 m/s, the thermal convection effect from the rock matrix to the fluid in the fracture predominates, and flow velocity is the main factor affecting the heat transfer process between the fluid and the rock matrix. When the inlet temperature increases from 37°C to 57°C, the thermal conduction effect from the rock matrix to the fluid in the fracture predominates, and temperature is the main factor affecting the heat transfer process between the fluid and the rock matrix.(3)When maintaining constant inlet temperature, increasing inlet flow velocity from 0.005 m/s to 0.025 m/s results in CO2 experiencing a maximum heat extraction rate increase of 118.85 W. In contrast, N2O experiences 117.05 W, and H2O experiences 266.4 W.(4) When the inlet flow rate is constant, the maximum increase in heat extraction rate for CO2 is 15.34 W as the inlet temperature increases from 37 °C to 57 °C; for N2O, it is 13.9 W; and for H2O, it is 45.45 W.

A visual measurement method for grinding surface roughness combining filter and branch convolution network

ABSTRACT The visual measurement method of grinding surface roughness is mainly predicted by designing image feature indicators. In contrast, the self-extraction method of grinding surface features based on deep learning has problems such as noise, low resolution and poor perception of details. This paper proposes a visual measurement method for grinding surface roughness to address these problems by combining filters and branching convolutional networks. The method adopts a two-branch convolutional neural network, inputs the images using filter denoising and the original grinding workpiece surface images simultaneously, self-extracts roughness correlation features and fuses them to achieve feature enhancement, effectively improves the recognition accuracy and generalisation ability of the model, and verifies the robustness of the model in the case of rusting on the workpiece surface. The experimental results show that the method can effectively solve the problem of the grinding process’s weak and difficult recognition of surface roughness feature information and provide a basis for automated visual online measurement of grinding surface roughness.

Experimental study of abrasive water jet drilling parameters on UHMWPE for biomedical implant applications

ABSTRACT This study addresses this issue by exploring the effectiveness of abrasive water jet drilling (AWJD) as an unconventional machining approach for UHMWPE. The research employs a full factorial analysis to examine various hole characteristics, including machining time (MT), surface roughness (Ra), taper angle (TA), material removal rate (MRR), and taper ratio (TR). The study aims to understand the effect of the process features, namely abrasive water jet pressures (p), traverse rates (v), and abrasive mass flow rates (ma), on the geometry and position of the drilled holes. The results show that (v) and (p) affect the drilled hole characteristics of surface morphology, roughness, MT, MRR, TA, and TR. The microstructural characteristics of the drilled-hole surfaces are analyzed by scanning electron microscopy (SEM). It revealed that the smooth surface is attained at the lower v of 150 mm/min and ma of 250 g/min.

Improving the suppression of charge movement by porous chromium oxide coating

A chromium trioxide coating was prepared on the surface of electronic ceramics by screen printing, and solid-phase sintering was carried out at 1350 °C. The surface roughness and surface resistance characteristics of composite coatings with different chromium trioxide contents were studied. The analysis results indicate that the average thickness of Cr2O3 coating is about 19.89 μm. The main crystal phase is (Al0.9Cr0.1)2O3. SEM shows that the surface "pores" and surface roughness of the coating change with the content of Cr2O3. AFM shows that when the Cr2O3 content in the coating is 0.0921 mol, the surface roughness changes the most, and the corresponding surface resistivity of Al2O3 insulating ceramics decreases to the lowest, from 1016 Ω to 1012 Ω. An increase in surface roughness can lead to changes in the incidence angle of electrons, reducing the probability of electron surface collision. The lower the surface resistivity, the better the high-voltage breakdown resistance of vacuum ceramic devices, thereby improving the surface flashover performance of ceramics.

Experimental investigation of the distribution patterns of micro-scratches in abrasive waterjet cutting surface

The existence of striations, and scratches in Abrasive waterjet (AWJ) cutting surface necessitates an exploration of these features for enhancing the cutting accuracy of AWJ machining. This article investigates surface roughness and micro-scratch morphology characteristics on brass cutting surfaces. According to the variation law of surface roughness values, the cutting section can be divided into three regions: the initial region, smooth region, and rough region. Numerous micron-scale scratches were observed in the cutting section. The scratch length, width, and depth values all show an increasing trend as the cutting depth increases, with the scratch length experiencing the greatest growth and variability. The influence of position and traverse speed on scratch size was studied using variance analysis. Furthermore, the length and width of the scratches on the cutting surface are significantly influenced by their position, accounting for 89.19% and 81.13%, respectively. Traverse speed had a minor effect on scratch length and width, accounting for 0.01% and 2.64% respectively. The depth of the scratches is influenced by their position on the cutting surface at a rate of 41.12%, while traverse speed had an impact of 38.10%. Finally, a mathematical method based on standard scores was proposed to assess the quality of the cutting section based on micro-scratch dimension.

On the surface roughness properties of fly ash-based geopolymer mortars with teff straw ash from the image analysis viewpoint

Fly ash (FA)-based geopolymer mortar is being considered for sustainability since it enjoys peculiar properties such as high mechanical properties and environmental benefits. However, the high curing temperatures of FA-based geopolymer mortar play a complex role in its outstanding mechanical behaviour thereby requiring other precursors, such as teff straw ash (TSA). In this study, we develop surface roughness properties of FA-based geopolymer mortars with TSA, where the ambient temperature is used for curing. The surface roughness characteristics of the FA-based geopolymer mortars with TSA exploit the surface roughness simulations from Gwyddion and the approach is demonstrated here in the contexts of spatial, hybrid and amplitude roughness parameters. The results show that some roughness parameters, including Ra and Rq values for FA-based geopolymer mortars with TSA, exhibit significant decreasing trends as the TSA contents increase. However, in comparison with the CA specimens (ambient temperature curing) and CE specimens (elevated temperature curing), the trends among the majority of the roughness parameters for FA-based geopolymer mortars with TSA turn out not to be very good probably due to changes in the internal structures of the mortars. Moreover, without the kurtosis values (Rku) of less than 3, it is easy to demonstrate that all the profiles of the investigated specimens reflect sharp valleys and peaks. The findings of surface roughness properties allow one to grasp the roughness parameters of FA-based geopolymer mortars with TSA. The approach for generating surface roughness properties of FA-based geopolymer mortars with TSA offers significant quantitative and qualitative information required for the bonding of mortar layers.

Dynamics of acoustically levitated ice impacts on smooth and textured surfaces: Effects of surface roughness, elasticity, and structure

Atmospheric ice collisions on exposed outdoor infrastructure are a rarely explored surface design challenge. A primary obstacle to realistic ice particles in the laboratory setting is freezing a droplet without a solid surface present and then allowing it to impact a substrate without physical intervention. Using acoustically levitated ice formation with subsequent release onto a controlled area, a third class of ice-countering system called “ice-impacting” is introduced. Stainless steel 316 (SS), epoxy resin-coated (ER), and laser-textured (LT) surfaces with known surface roughness, hardness, and structural characteristics were subjected to 40 ice droplet impacts each. The impact effect on surface properties and the effect of these properties on solid-solid interfacial impact dynamics, in turn, were examined using an analysis framework based on fundamental conservation laws. Elasticity was the most significant factor in droplet behaviour as the ER surface exhibited rebounding for 78 % of impacts, nearly double the rates of the stainless steel surfaces. However, surface roughness also played a role, particularly for droplets with rotational motion, as immobilization occurred for 66 % of impacts on the rougher LT surface. Moreover, the nanostructures on that textured surface resulted in droplet redirection perpendicular to the surface directionality. In contrast, the other surfaces experienced no consistent change in rebound angle. Elasticity also affected momentum retention: the ER surface had a translational restitution coefficient of 0.32 compared to 0.17 for the SS/LT surfaces. Surface roughness was a predominant aspect of energy retention, as the LT surface had a translational-to-rotational energy transfer coefficient of 0.07 (0.23 for the smoother surfaces), resulting in an overall energy retention coefficient of 0.09 compared to 0.28 for the SS and ER surfaces on average. The results show that the interplay between elasticity, roughness, and structure at a dynamic solid-solid interface must be considered to optimize their effectiveness when designing ice-countering surfaces.