Papers by Keyword: Surface Characterization

Abstract: The long-term performance of dental implants relies on material stability and sustained osseointegration. This study analyzed titanium implant after six years of clinical function and compared it with unused implants to assess surface integrity. Field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to evaluate morphology and elemental composition, while surface roughness was measured to detect changes. SEM showed direct bone attachment, and EDX confirmed calcium, phosphorus, sodium, oxygen, and carbon associated with osseointegration. Roughness values increased slightly due to adherent bone tissue, but no evidence of surface wear or degradation was observed. These results demonstrate that titanium maintains chemical stability, biocompatibility, and reliability for long-term dental implant applications.

Abstract: Carbon steel is widely used in infrastructure, manufacturing, and structures due to its cost-effectiveness and robust mechanical properties. However, the susceptibility of steel structures to corrosion in various working environments has been a longstanding concern. In this study, we explored the potential of titanium-aluminum (Ti-Al) coating as a surface treatment to enhance the corrosion resistance of low-carbon steel. The coating was applied using the arc spraying technique, where two materials were melted by an arc and then distributed onto the substrate using compressed air. To evaluate the corrosion resistance of the coated samples, we conducted immersion tests following the ASTM G31 standard for durations of 625 and 1000 hours. Additionally, electrochemical technique was employed to assess the anti-corrosion performance of both the Ti-Al coating and the substrate. Surface characterization was carried out using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX), as well as measurements of hardness and roughness. The SEM-EDX analysis revealed uniform distribution of titanium and aluminum across the surface and within the coating. Moreover, the coating significantly altered the surface roughness. Electrochemical corrosion testing indicated that the Ti-Al coating exhibited lower corrosion current and corrosion potential, suggesting its potential to enhance the corrosion resistance of the substrate. The SEM-EDX revealed cracks on the coating surface and the oxidation level of the coating surface varied with immersion time. The hardness of the coating was found to be relatively lower than that of the substrate, while the surface roughness was higher. Overall, the findings suggest that Ti-Al coating holds promise for enhancing the corrosion resistance of steel structures, as evidenced by its low corrosion current density and corrosion potential in corrosive environments.

Abstract: Lignin, one of the interesting carbon sources which underutilized, gives great interest in transforming into value-added material, specifically as a solid acid catalyst. In this study, lignin undergoes heat treatment at temperatures 400–600 °C for 1 and 2 h, followed by sulfonation on a 1:10 (carbon-to-acid, g/mL) ratio in a reflux setup at 150 °C for 15 h to produce lignin carbon acid catalysts. The characterization of the catalysts was performed by the elemental analyzer, N₂ adsorption-desorption, Fourier transform infrared (FTIR), and acid density calculation. The effects of lignin carbon preparations on the catalyst's physiochemical properties as well as the effectiveness of sulfonation were evaluated. The selected catalyst was tested in levulinic acid esterification at selected fixed conditions; 1:10 molar ratio of levulinic acid-to-ethanol, 10 wt.% of catalyst loading, for 3 h of reaction at 80 °C and 200 rpm in a batch reaction system. At higher heat treatment temperatures and time of carbon preparation, the surface area of the catalysts was recorded to increase resulting in the acid density reduction. For the catalytic activity, 62.36 mol% (Batch 1) and 61.64 mol% (Batch 2) of ethyl levulinate yield were obtained over LCS-400-1 with a good acid density of 0.0223 mmol/m² and a surface area of 43.28 m²/g. The results of this study show that the conditions for carbon preparation significantly influence the catalyst's physical and chemical characteristics.

Abstract: The tensile deformation of NiTi alloy can proceeds in either homogeneous manner, or localized deformation via formation and propagation of macroscopic shear bands, that is commonly known as Lüders-like deformation. The high deformation strain within the localized deformed regions can result in the changes of surface characteristics of NiTi specimen. This paper studies the surface roughening effect associated with Lüders-like deformation of martensitic NiTi alloy, via surface characterization of polished surface and localized deformed region that consists of Lüders bands on tensile specimens, respectively. The surface roughness profile and roughness parameters of surface with Lüders bands are significantly different and higher as compared to the polished surface.

Abstract: This presented article focuses on surface characterization and assessing the satisfactory machining condition of WEDMed Inconel 625. This work material has been received remarkable attention to the industrial and academic organization for its end use applications. WEDM is well-known machining process for intricate shape cutting and machining hard materials. The experimental design was planned according to L₂₇ orthogonal array (OA), by varying controllable process parameter (i.e. Wire-Tension, Wire-speed, Flushing-Pressure, Discharge-Current and Spark-on Time), each parameter varied at four discrete levels, within the selected parametric domain. WEDMed surfaces have been investigated with a focus to the surface characterization of selected machined surface through captured images from scanning electron microscope (SEM). Eventually, multi-response optimization of process parameters was sought by using a combination of nonlinear regression modelling, fuzzy inference system (FIS) with Teaching Learning-Based Optimization (TLBO) algorithm. The obtained TLBO result was compared with the Genetic algorithm (GA). The results show that optimization algorithms are effective tools for getting satisfactory optimal machining conditions during WEDM process of Inconel 625.

Abstract: It will be discussed in this work how it is possible to produce latex films by evaporation induced self-assembly (EISA) process. Latex beads were synthesized in a cylindrical flask without N₂ flow. The polymerization process of styrene happens at water as solvent and with the presence of persulfate potassium as initiator. The final product was a dispersion of spherical nanometric particles (ɸ = 0.47 ± 0.06μm) whose concentration can be changed from 0.5 to 10% (V/V_o). These dispersions were spread on glassy substrates at 50°C over a square area (~1cm²) with control of solvent evaporation. The films are transparent and they show the formation of nanowire structures by scanning electron microscopy (SEM) characterization. Such structures were associated to high affinity of latex beads particles to form cylindrical arrangements due to presence of O₂ during their synthesis. It has been concluded that this self-assembly structure can be very worthy for generation of functional devices like sensors, solar cells and biomaterials.

Abstract: The topography of a surface consists of structures of different length scales. The surface roughness caused by these structures plays a decisive role in interfacial properties. Atomic Force Microscopy (AFM) can be applied to measure the surface topography with great accuracy and thus facilitates roughness quantification. Here, however, the data reduction poses a challenge. In a conventional approach, surface roughness parameters are evaluated based on averaging height differences, which leads to values dominated by the largest height differences of the surface topography. To quantify contributions of smaller structures to the roughness, a previous study presented a tunable local background correction, which eliminates structures on a larger than selected scale. Therefore, this method only considers surface structures smaller than the chosen scale. A different approach to quantify surface roughness on all length scales covered by AFM measurements uses Fourier transformation of the surface topography to calculate the power spectral density, which describes the amplitudes of different contributing spatial frequencies.In the current study, a new approach based on power spectral density is used to quantify surface roughness parameters as a function of the length scale of contributions to the surface topography. This procedure allows a comprehensive characterization of surface roughness and an intuitive comparison of different surfaces.The usefulness of this method and its compatibility to local background correction is demonstrated by analyzing several commercially available carbon fibers with and without different fiber surface treatments.

Abstract: The adsorption of bacteria onto minerals is the premise for bioleaching and plays an important role in minerals oxidation. Understanding of the adsorption kinetics onto the surface will give information on the effectiveness of bioleaching. Three kinds of mixed bacteria (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, Sulfobacillus) were cultured in different substrates - copper concentrate, elemental sulfur and ferrous iron and adsorbed onto different solid surface of elemental sulfur, silica and copper concentrate. Adsorption kinetics was examined and surface properties were investigated by Zeta-potential and FT-IR spectroscopy. Bacterial adsorption equilibrium data for bacteria grown on three different substrates were well fitted to Freundlich isotherms, indicating inhomogeneous and selective adsorption. Microorganisms grown on copper concentrate and S⁰ showed similar adsorption kinetics whereby cell adsorptions proceeded rapidly and reached equilibrium within 30 mins of interaction. With the average K_F value of 46.2, most copper concentrate-grown cells were strongly adsorbed to three solid surfaces. Microorganisms grown on copper concentrate and S⁰ also showed higher hydrophobicity and higher isoelectric point (IEP) (pH 3.4-3.8) as compared to the soluble Fe²⁺-grown cells (pH 2.1), indicating higher amount of EPS and proteins on the surfaces. The FT-IR spectra indicated the presence of COOH, NH₂, OH and PO₄ groups on all cell surfaces. However, more proteinaceous compounds were found on cells grown on copper concentrate and S⁰ substrates.

Abstract: Meta-aramid fibers were treated by sub-atmospheric pressure dielectric barrier glow discharge plasma. The effect of plasma treatment time on the fiber surface physical and chemical properties was studied by using surface characterization techniques. Scanning electron microscopy (SEM) was performed to determine the surface morphology changes. FT-IR spectroscopy measurements were performed to investigate the change of chemical structure. Dynamic contact angle analysis (DCAA) was used to examine the changes of the fiber surface wettability. SEM analysis showed that there was obvious crack along the fibers’ axial direction present on the fiber surface, which resulted in the better wetting behavior of the plasma-treated PMIA fiber. FT-IR analysis showed that plasma had little effect on the chemical structure of PMIA fibers. DCAA analysis showed that the wettability of the samples could be improved with the treatment time increasing. In addition, a slight decrease in breaking strength was observed at the treatment time ranging from 60 to 180 s in comparison with the untreated sample.

Abstract: Magnesium (Mg) is a promising implant material for orthopedic applications due to its biodegradability and desirable mechanical properties. However, in order for Mg to have widespread clinical applications, engineering solutions that address the rapid degradation in physiological environments and promote bone-forming activity are needed. The objective of this study was to develop an anodization process using a toxicant-free electrolyte to modulate nanoscale surface features and surface chemistry on Mg. Anodic polarization and potentiostatic anodization tests were used to evaluate the effect of applied potential on surface morphology of Mg in a 10 M KOH electrolyte. Nucleation of oxides as a function of anodization duration was also investigated in order to optimize the synthesis process. The alkaline electrolyte used for anodization of Mg offers an alternative to commercial processes that use hazardous elements. The anodized samples were annealed to investigate the effect of thermal treatments on surface morphology and chemical composition. The nanostructure and chemical composition of the anodized and annealed Mg substrates were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy. Our results showed that the nanostructures and chemical composition of anodically-generated oxide layers on Mg are specific to each oxidation process in a 10 M KOH electrolyte. Furthermore, results indicated that anodization durations of two hours generated surface oxide layers with homogeneous topography on the Mg substrates atapplied potentials of 0.5 V, 1.5 V and 2 V.. This study showed a promising approach for creating nanoscale surface features on Mg for improved bioactivity and degradation property.