Variation Of Surface Roughness Research Articles

Effects of abrasive grain size of flexible body-armor-like abrasive tool (BAAT) on high-shear and low-pressure grinding for zirconia ceramics

Zirconia ceramics exhibit remarkable performance. However, the high hardness and brittleness poses enormous challenges for machining. This study is integrally focused on preparing a flexible body-armor-like abrasive tool (BAAT) with enhanced tangential-to-normal force ratio. The rheological characteristics of the BAAT abrasive system with different abrasive grain were investigated. A series of grinding tests were conducted on a precision grinding machine. The grinding performance of the BAAT with different abrasive grain sizes was examined. Surface roughness (Ra) variation and tangential-to-normal force ratio were analyzed, together with the investigation of the three-dimensional surface morphology and surface hydrophilicity. It was found that smaller abrasive grain sizes ultimately generated lower surface roughness values after grinding. Under the optimal grinding conditions, the surface roughness (Ra) of zirconia ceramics decreased from 102 nm to 1.7 nm after 5 grinding strokes (∼1 min). Meanwhile, uniform grinding textures were obtained.

Experimental investigation on the influence of temperature on the fracture surface variations of granite after Brazilian splitting tests

Understanding the variation in the morphology of rock fracture surfaces after high-temperature is of great significance for evaluating the strength, deformation, and seepage characteristics of deep engineering rock masses. In this study, the variations in the granite fracture surface roughness after exposure to different temperatures (25–800 °C) were investigated, and the damage deterioration mechanism was revealed. The results showed that the maximum fluctuation (Z) and root mean square of the first derivative (Z2) of the granite fracture surface tended to increase with increasing temperature, whereas the fractal dimension (D) decreased, suggesting that the higher temperature contributed to greater roughness of the fracture surface. The anisotropy of the fracture surface was more evident at higher temperatures and had greater roughness in the 45°–75°, 105°–135°, and 155°–170° directions after different temperatures. Physicochemical reactions, such as dehydration, quartz phase transformation, and mineral oxidation, occurred in the granite owing to high temperatures. These reactions changed the crystalline state of the minerals and facilitated the increase and expansion of microcracks, thereby weakening the cementing property between mineral particles. Fracture surfaces with higher roughness were formed after tensile failure of the rock. The research results may provide theoretical references for the construction and operation of deep engineering.

Freezing of sessile water droplets on titanium alloy surfaces with various roughness: An in-situ experimental study

The threat of icing caused by supercooled water droplets on aircraft components such as wings and compressors is a serious concern for aviation safety, and the surface roughness of these components can experience alterations due to environmental corrosion or damage. However, the potential impact of surface roughness variation on their susceptibility to icing remains unclear. In this study, the freezing experiments of sessile water droplets on the surfaces of a typical aero-engine titanium alloy (ZTC4) with varying roughness were conducted using a laser confocal micro-Raman spectrometer with a heating/freezing stage. Three freezing stages were captured via an optical microscope, and the temperature changes of water droplet during the cooling process were explored through heat transfer simulation. In addition, the relationship between Raman peaks and temperatures of frozen droplets was quantified. The results of 200 repeated experiments demonstrated that the freezing temperatures of sessile water droplets exhibited a two-parameter Weibull distribution, and there was a nonlinear positive correlation between the mean freezing temperature and surface roughness, which implied that environmental corrosion or damage leading to an increase in surface roughness may significantly elevate the probability of component icing and safety issues.

Development of New Polyimide/Spirulina Hybrid Materials: Preparation and Characterization

This study presents the synthesis and characterization of polyimide (PI-2) films incorporated with spirulina powder for potential biomedical applications. The synthesis of PI-2 was achieved through a two-step polycondensation reaction using N-methyl-2-pyrrolidone (NMP) as the solvent. The incorporation of spirulina was systematically varied to investigate its effects on the structural and surface properties of the hybrid materials. Scanning electron microscopy revealed a tightly bound interface between spirulina and the PI-2 matrix, indicating effective dispersion and strong interfacial adhesion. Profilometry and Raman spectroscopy confirmed the homogeneous integration of spirulina within the polymer matrix, with resulting variations in surface roughness and chemistry. Contact angle measurements demonstrated altered wettability characteristics, with increased hydrophilicity observed with spirulina incorporation. Furthermore, blood component interaction studies indicated the variations in adhesion behavior observed for red blood cells, platelets, and plasma proteins. Water uptake studies revealed enhanced absorption capacity in PI-2 films loaded with spirulina, highlighting their potential suitability for applications requiring controlled hydration. Overall, this comprehensive characterization elucidates the potential of PI-2/spirulina hybrid materials for diverse biomedical applications, offering tunable properties that can be tailored to specific requirements.

In Vitro Evaluation of Surface Roughness and Color Variation after Two Brushing Protocols with Toothpastes Containing Different Whitening Technologies

The aim was to evaluate the effect of different whitening toothpastes on the enamel surface roughness and color variation. Twenty-four molars were sectioned and divided into eight groups (n = 3) considering the following two factors under study: toothpaste type (Colgate® Total Original, Oral B® 3D White Luxe Perfection, Curaprox® Black is White, and Signal® White Now) and brushing protocol (short- and long-term). Surface roughness was examined by atomic force microscopy (AFM), and color change (ΔE) was measured using the CIE L*a*b* system. Data were statistically analyzed using comparative parametric tests at a 5% significance level. In the short-term protocol, only the Signal® White Now toothpaste increased surface roughness (p = 0.038) compared to the Colgate® Total Original group. No significant differences (p > 0.05) were observed in surface roughness in the long-term protocol. Regarding color variation, no statistically significant differences (p > 0.05) were observed in either protocol. Overall, the whitening toothpastes did not affect enamel surface roughness or color, except for Signal® White Now, which caused increased roughness in the short-term protocol. However, all toothpastes induced a visual change in color.

Evaluation of plasma parameters’ impact on MRR and surface roughness in plasma polishing of fused silica: An investigation of surface characterization

Advanced fabrication methods with high efficiency are needed to meet the rising demand for precision optical components. This study proposes a plasma-based isotropic polishing method to remove fused silica's surface defects and subsurface damaged layers. Hence, a medium-pressure plasma process is developed to serve this purpose. The qualitative analysis of the plasma and atom emission spectrum explores the plasma generation and scattering of the activated fluorine (F*) radicals inside the plasma chamber. Material removal rate (MRR) and surface roughness variations with different total pressures of 5–30 mbar and substrate dimensions (i.e., varying length between 5 and 45 mm with fixed width and thickness of 5 and 2 mm) at fixed process parameters, i.e., radio-frequency power of 80 W, pressure ratio of 1:1, gas composition of 90:10, have been investigated. The highest and lowest MRR, i.e., 0.039 mm3/min and 0.0061 mm3/min, are achieved at 5 and 30 mbar total pressures on substrates having lengths 45 and 5 mm, respectively. The highest and lowest percentage change in surface roughness observed are 86.4 % and 17.1 % at 5 mbar and 30 mbar for substrates with 5 and 45 mm lengths, respectively. Surface morphology analysis shows the micro-cracks are reduced after plasma processing. The presence of elements, i.e., F and C, through EDX analysis, confirms the reactions on the plasma processed surface. Moreover, The XPS findings demonstrated that minimal radicals could be incorporated onto the fused silica surface during He/O2/SF6 plasma processing. At lower pressure, the surface roughness value increases due to the increased excitation and ionization rate caused by more interaction between the fluorine and surface atoms. The MRR increases with substrate dimension with constant pressure. Larger substrate dimensions result in increased MRR at lower pressure.

Comparative study on graphene oxide and sulfonated graphene oxide reinforced polyethersulfone-based cation-exchange membrane

In this research, polyethersulfone/sulfonated graphene oxide (PES/SGO) heterogeneous cation exchange membranes were fabricated by the mold casting method. The sulfonation of GO was carried out using the diazonium salt of sulfanilic acid. The properties of the synthesized GO and SGO were compared in terms of chemical structure, morphology, surface charge, crystallinity, and thermal stability. The variations in surface morphology and roughness, hydrophilicity, dimensional stability, and ionic conductivity of the PES-based membranes as a function of GO and SGO content were investigated. Results revealed that SGO enjoyed a higher level of oxygenated groups contributing to its higher surface charge. SGO also tolerated a higher temperature before being fully decomposed due to the presence of the sulfur-containing groups. A finer nanostructured morphology was observed in the SGO-containing membranes, resulting in a considerably lower surface roughness of these membranes than the corresponding GO-based membranes. The membrane comprising 10wt% SGO showed the lowest surface roughness of 88nm, and the highest water uptake of 16.66%, ion-exchange capacity of 1.12meqg-1, and the lowest charge transfer resistance of 3.6 Ω and area resistance of 0.9 Ωcm2. This was accompanied with a considerable increment in the permselectivity and cation (Na+) transport number of this membrane to 95.9% and 97.5%, respectively, due to the higher surface adhesion energy of 94.57Jm-2 and higher Na+ flux of 4.43×10-7 mol m-2 s-1, which were significantly higher than that obtained for the corresponding PES-based membrane containing 10wt% GO. Furthermore, a lower weight loss and resistance change were observed for PES/SGO after being exposed to the Fenton reagent for 9h, indicating the impact of the sulfonated groups on the oxidative stability enhancement of the membrane.

Material removal modes and processing mechanism in microultrasonic machining of ball ceramic tool

Microelectrochemical systems (MEMSs) have important applications in electronic information, aerospace, national defense and other fields. The microhemispherical concave die is the manufacturing foundation for the MEMS system. To clarify the forming mechanism of microhemispherical concave dies machined by microultrasonic machining with ceramic whole ball tools, a material removal model was presented. Furthermore, the kinetic energy model of a spherical abrasive under the action of microultrasonic and whole ball ceramic tools was also established. The model of the brittle-plastic transition removal mode is correlated with the kinetic energy of the abrasive model. The surface morphology of miniature molds exhibits significant variations attributed to the altered material removal mode, the removal mechanism was analyzed. The theoretical model is verified by experiments. Experiments were performed with lower and higher viscosity polishing fluids. The surface roughness of the plastic removal area in each group was 96.4 and 60.1 nm. Due to the high viscosity polishing fluid eliminating some of the cavitation phenomena, the overall surface quality is improved; hence, the surface roughness decreases by 37.6% under the same processing conditions. In the low-viscosity experimental group, the surface roughness was 113.61, 302.28 and 367.24 nm, respectively. The experimental verification confirmed that variations in surface morphology occur, even with the same removal mode applied at different locations on the microconcave die. The reasons for the surface roughness variation in different areas of the microconcave die are analyzed and reveal the influence of ultrasonic cavitation on the material removal mode in microultrasonic machining.

Experimental Analysis of the Time-Wise Compressor Fouling Phenomenon

Abstract Compressor fouling is still an unforeseen phenomenon. Gas turbines for heavy-duty and propulsion applications are subject to performance degradation due to fouling, erosion, and corrosion mechanisms. Unlike the last two, the fouling phenomenon is recoverable depending on weather, operating conditions, and operator actions. It is generated by the adhesion of micro-sized particles on the relevant surfaces, generating blade shape and surface roughness variations. Fouling could affect the machine performance differently. The interaction between machine characteristics, airborne contaminants, and environmental conditions determines fouling prediction challenges. An experimental campaign has been carried out in the present analysis to study the overtime modification of compressor performance and mass deposits on the blade and vane surfaces. The axial unit has been operated to control the performance and deposition process by keeping the contamination and the relative humidity constant during the time. The test matrix has been based on two relative humidity values and four exposure time intervals. The results have shown the action of the competitive phenomena as adhesion and detachment, generating a non-linear trend of the deposited mass−time relation depending on impact characteristics and humidity values. Compressor performance follows similar behavior and shows a non-linear trend instead of constant contamination. Data interpretation and generalization are reported to increase the possibility of better predicting the effects of particle adhesion on gas turbine performance degradation.

Interlaboratory Comparison on Absolute Photoluminescence Quantum Yield Measurements of Solid Light Converting Phosphors with Three Commercial Integrating Sphere Setups.

Scattering luminescent materials dispersed in liquid and solid matrices and luminescent powders are increasingly relevant for fundamental research and industry. Examples are luminescent nano- and microparticles and phosphors of different compositions in various matrices or incorporated into ceramics with applications in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. The key parameter to characterize the performance of these materials is the photoluminescence/fluorescence quantum yield (Φf), i.e., the number of emitted photons per number of absorbed photons. To identify and quantify the sources of uncertainty of absolute measurements of Φf of scattering samples, the first interlaboratory comparison (ILC) of three laboratories from academia and industry was performed by following identical measurement protocols. Thereby, two types of commercial stand-alone integrating sphere setups with different illumination and detection geometries were utilized for measuring the Φf of transparent and scattering dye solutions and solid phosphors, namely, YAG:Ce optoceramics of varying surface roughness, used as converter materials for blue light emitting diodes. Special emphasis was dedicated to the influence of the measurement geometry, the optical properties of the blank utilized to determine the number of photons of the incident excitation light absorbed by the sample, and the sample-specific surface roughness. While the Φf values of the liquid samples matched between instruments, Φf measurements of the optoceramics with different blanks revealed substantial differences. The ILC results underline the importance of the measurement geometry, sample position, and blank for reliable Φf data of scattering the YAG:Ce optoceramics, with the blank's optical properties accounting for uncertainties exceeding 20%.

Thermo-mechanical aging of carbon-black reinforced styrene-butadiene rubber under cyclic-loading

PurposeThe research aims to investigate the impact of thermo-mechanical aging on SBR under cyclic-loading. By conducting experimental analyses and developing a 3D finite element analysis (FEA) model, it seeks to understand chemical and physical changes during aging processes. This research provides insights into nonlinear mechanical behavior, stress softening and microstructural alterations in SBR compounds, improving material performance and guiding future strategies.Design/methodology/approachThis study combines experimental analyses, including cyclic tensile loading, attenuated total reflection (ATR), spectroscopy and energy-dispersive X-ray spectroscopy (EDS) line scans, to investigate the effects of thermo-mechanical aging (TMA) on carbon-black (CB) reinforced styrene-butadiene rubber (SBR). It employs a 3D FEA model using the Abaqus/Implicit code to comprehend the nonlinear behavior and stress softening response, offering a holistic understanding of aging processes and mechanical behavior under cyclic-loading.FindingsThis study reveals significant insights into SBR behavior during thermo-mechanical aging. Findings include surface roughness variations, chemical alterations and microstructural changes. Notably, a partial recovery of stiffness was observed as a function of CB volume fraction. The developed 3D FEA model accurately depicts nonlinear behavior, stress softening and strain fields around CB particles in unstressed states, predicting hysteresis and energy dissipation in aged SBRs.Originality/valueThis research offers novel insights by comprehensively investigating the impact of thermo-mechanical aging on CB-reinforced-SBR. The fusion of experimental techniques with FEA simulations reveals time-dependent mechanical behavior and microstructural changes in SBR materials. The model serves as a valuable tool for predicting material responses under various conditions, advancing the design and engineering of SBR-based products across industries.

Spatially resolved lock-in micro-thermography (SR-LIT): A tensor analysis-enhanced method for anisotropic thermal characterization

While high-throughput (HT) computations have streamlined the discovery of promising new materials, experimental characterization remains challenging and time-consuming. One significant bottleneck is the lack of an HT thermal characterization technique capable of analyzing advanced materials exhibiting varying surface roughness and in-plane anisotropy. To tackle these challenges, we introduce spatially resolved lock-in micro-thermography, an innovative technique enhanced by tensor analysis for optical thermal characterization. Our comprehensive analysis and experimental findings showcase notable advancements: We present a novel tensor-based methodology that surpasses the limitations of vector-based analysis prevalent in existing techniques, significantly enhancing the characterization of arbitrary in-plane anisotropic thermal conductivity tensors. On the instrumental side, we introduce a straightforward camera-based detection system that, when combined with the tensor-based methodology, enables HT thermal measurements. This technique requires minimal sample preparation and enables the determination of the entire in-plane thermal conductivity tensor with a single data acquisition lasting under 40 s, demonstrating a time efficiency over 90 times superior to state-of-the-art HT thermology. Additionally, our method accommodates millimeter-sized samples with poor surface finish, tolerating surface roughness up to 3.5 μm. These features highlight an innovative approach to realizing HT and accurate thermal characterization across various research areas and real-world applications.

Effect of Surface Roughness on Aerodynamic Loads of Bluff Body in Vicinity of Smoothed Moving Wall

This paper contributes to a new Lagrangian vortex method for the statistical control of turbulence in two-dimensional flow configurations around a rough circular cylinder in ground effect when considering higher subcritical Reynolds numbers, namely 3 × 104 ≤ Re ≤ 2 × 105. A smoothed moving wall (active control technique) is used to include the blockage effect in association with the variation in cylinder surface roughness (passive control technique), characterizing a hybrid approach. In contrast with the previous approaches of our research group, the rough cylinder surface is here geometrically constructed, and a new momentum source term is introduced and calculated for the investigated problem. The methodology is structured by coupling the random Discrete Vortex Method, the Lagrangian Dynamic Roughness Model, and the Large Eddy Simulation with turbulence closure using the truncated Second-Order Velocity Structure Function model. This methodological option has the advantage of dispensing with the use of both a refined near-wall mesh and wall functions. The disadvantage of costly processing is readily solved with Open Multi-Processing. The results reveal that intermediate and high roughness values are most efficient for Reynolds numbers on the orders of 105 and 104, respectively. In employing a moving wall, the transition from the large-gap to the intermediate-gap regime is satisfactorily characterized. For the conditions studied with the hybrid technique, it was concluded that the effect of roughness is preponderant and acts to anticipate the characteristics of a lower gap-to-diameter ratio regime, especially with regard to intermittency.

Enhancing the Tribological Properties of Low-Density Polyethylene Using Hard Carbon Microfillers.

The application of low-density polyethylene (LDPE) has been confined to packaging applications due to its inadequate mechanical and tribological characteristics. We propose enhancing LDPE by integrating hard carbon spheres (CSs) to improve its strength, frictional characteristics, and wear resistance. LDPE/CS composites were created by blending LDPE with varying CS amounts (0.5-8 wt.%). Analysis using scanning electron microscopy and Raman spectroscopy confirmed CS presence in the LDPE matrix, with X-ray diffraction showing no microstructural changes post-blending. Thermal characterization exhibited notable improvements in thermal stability (~4%) and crystallinity (~7%). Mechanical properties such as hardness and Young's modulus were improved by up to 4% and 24%, respectively. Tribological studies on different composite samples with varying surface roughness under various load and speed conditions revealed the critical role of surface roughness in reducing friction by decreasing real contact area and adhesive interactions between asperities. Increased load and speed amplified shear stress on asperities, possibly leading to deformation and failure. Notably, integrating CSs into LDPE, starting at 1 wt.%, effectively reduced friction and wear. The composite with the highest loading (8 wt.%) displayed the most significant tribological enhancement, achieving a remarkable 75% friction reduction and a substantial 78% wear reduction.

A nonlinear stress-strain relationship for soil and rock

While many employ a hyperbolic stress-strain relationship for soils, it is known that such a relationship is accurate over either the small strain range as encountered in earthquake and soil dynamics problems or a relationship with different input parameters that are needed over large strains as is required for finite element analyses of large deformation behavior. The two characterizations do not become one. A proposed power relationship is presented that was developed to characterize the triaxial test stress-strain behavior of cohesionless material from lubricated or “frictionless” cap and base tests (some 144 tests) covering a range in the natural variation in particle size, particle shape and surface roughness, over low to high confining pressure. This relationship covers the range in strain from 10−6 to soil failure. It has been used successfully to date in laterally loaded pile response characterization (the Strain Wedge Model) and shallow foundation load-settlement-bearing capacity response. Most recently, it has been extended to assess the behavior of rock-like material (caliche). The relationship and its comparison with the hyperbolic relationship for large strain and the shear modulus reduction curve for seismic behavior are presented here.

Enhancing the Cooling Efficiency of Aluminum-Filled Epoxy Resin Rapid Tool by Changing Inner Surface Roughness of Cooling Channels.

In low-pressure wax injection molding, cooling time refers to the period during which the molten plastic inside the mold solidifies and cools down to a temperature where it can be safely ejected without deformation. However, cooling efficiency for the mass production of injection-molded wax patterns is crucial. This work aims to investigate the impact of varying surface roughness on the inner walls of the cooling channel on the cooling efficiency of an aluminum-filled epoxy resin rapid tool. It was found that the cooling time for the injection-molded products can be determined by the surface roughness according to the proposed prediction equation. Employing fiber laser processing on high-speed steel rods allows for the creation of microstructures with different surface roughness levels. Results demonstrate a clear link between the surface roughness of cooling channel walls and cooling time for molded wax patterns. Employing an aluminum-filled epoxy resin rapid tool with a surface roughness of 4.9 µm for low-pressure wax injection molding can save time, with a cooling efficiency improvement of approximately 34%. Utilizing an aluminum-filled epoxy resin rapid tool with a surface roughness of 4.9 µm on the inner walls of the cooling channel can save the cooling time by up to approximately 60%. These findings underscore the significant role of cooling channel surface roughness in optimizing injection molding processes for enhanced efficiency.

The Study on Corrosion Resistance of Ti-6Al-4V ELI Alloy with Varying Surface Roughness in Hydrofluoric Acid Solution

The corrosion resistance of titanium alloy poses a crucial challenge, significantly affecting its prospect for service and application. The present study aimed to investigate the corrosion resistance of Ti-6Al-4V ELI alloys with varying surface roughness in hydrofluoric acid solution, in order to assess the influence of roughness on their corrosion resistance performance. The weight loss percentage, surface morphology evolution, and roughness variation of Ti-6Al-4V ELI alloys before and after exposure to hydrofluoric acid corrosion were characterized. While the weight loss and weight loss percentage of the Ti-6Al-4V ELI alloy increased with prolonged corrosion, the overall weight loss rate decreased. The accumulation of TiF3 phases and depletion of the Ti-6Al-4V ELI matrix mutually led to the alterations of the surface roughness. Due to the inability to prevent fluoride ions from contacting with the Ti-6Al-4V ELI alloy, continuous corrosion occurred in hydrofluoric acid. Based on these experimental results and analysis, the corrosion mechanism of the Ti-6Al-4V ELI alloy corroded by hydrofluoric acid solution was elucidated. Furthermore, an analysis was conducted to explore the influence of corrosion time on mechanical properties by analyzing the decay in compressive properties of the Ti-6Al-4V ELI titanium alloy after hydrofluoric acid corrosion treatment. The bearing capacity of the Ti-6Al-4V ELI alloy deteriorated over the corrosion time.

Build Plate Roughness Study on Part Bonding for the Laser Powder Bed Fusion Process

AbstractAdditive manufacturing (AM) processes have emerged as valuable partners in conventional manufacturing, facilitating the production of low-batch components with complex geometries across diverse industries. However, despite ongoing advancements in various AM technologies, consistently achieving reliable and defect-free components remains a challenge. In powder metal AM, the use of substrates or build plates to support the entire build plays a crucial role in ensuring build stability. Build plate preparation typically involves surface grinding followed by finishing sanding, leading to variations in surface roughness between different manufacturing runs. This study aimed to elucidate the bonding characteristics at the build plate-part interface by investigating the porosity and build plate-part strength at different substrate surface roughness. To this end, a multi-roughness build plate was designed and fabricated for tensile testing via laser powder bed fusion (LPBF) processing of upright specimens. The specimens were subjected to computed tomography (CT) scans for porosity assessment, followed by tensile tests to evaluate the mechanical performance at the build plate-part interface (bp-p). CT inspection revealed no porosity at the interface for any roughness level. Furthermore, analysis of the tensile behavior in relation to substrate roughness (Ra values of 0.8 μm, 1.4 μm, 3.5 μm, and 4.4 μm) did not reveal statistically significant differences.

Friction injury of the central vein caused by catheter for hemodialysis: an in vitro study

Vascular injury such as central venous stenosis (CVS) is a common complication in hemodialysis patients with central venous catheters (CVCs), yet the impact of the microstructure and partial physic characteristics of catheter surface on the chronic injury of central vein has not been elucidated. In this study, the microscopic morphology of tips and bodies of six different brands of polyurethane CVCs was observed and their roughness was assessed. Subsequently, an in vitro model was established to measure the coefficients of friction (COF) between CVCs (tips and bodies) and the vena cava intima of Japanese rabbits under the same condition in a linear reciprocating mode, and changes in the intima of vessels after friction were observed. The study found that there was a significant variation in surface roughness among different brands of CVCs (tips P < 0.001, bodies P = 0.02), and the COF was positively correlated with the catheter surface roughness (tips P = 0.005, R = 0.945, bodies P = 0.01, R = 0.909). Besides, the endovascular roughness increased after friction. These findings suggest that the high roughness surface of CVCs may cause chronic mechanical friction injury to the central venous intima, which is one of the potential factors leading to CVS or occlusion. This provides a breakthrough for reducing complications, improving patient prognosis, and advancing catheter surface lubrication technology.

Corrosion-induced changes in surface properties and roughness of orthodontic wires

This study aimed to investigate the surface free energy and surface roughness (SR) of metallic alloys under the influence of acid solutions. The experiment involved the use of 270 rectangular wire samples measuring 0.019 × 0.025-in. These samples were sourced from 3 different commercial brands: Dentsply GAC, American Orthodontics, and Orthoclassic. This invitro study categorized the samples into 3 groups based on the solutions employed: deionized water, citric acid, and phosphoric acid. Each group consisted of 90 samples, with 30 samples representing each type of alloy-stainless steel, nickel-titanium, and titanium molybdenum alloy (TMA). The wire segments were immersed in their respective solutions for 72 hours at a controlled temperature of 37°C, with continuous orbital agitation at 130 rpm. After the immersion period, the study analyzed both surface free energy and SR. The mean values obtained were subjected to an analysis of variance at a significance level of 5%. All alloys displayed hydrophobic behavior, as indicated by interaction free energy values<0. In acidic environments (phosphoric acid and citric acid), significant differences were observed among different brands and alloys, affecting surface energy and interaction free energy. Variations in SR among metallic alloys included steel with the lowest SR variations, followed by nickel-titanium and TMA. Notably, the TMA alloy stood out with significantly higher surface energy compared with that of the other alloys (P<0.001). In this study, all examined alloys demonstrated a hydrophobic nature, suggesting a limited attraction to water. Notably, TMA exhibited the least hydrophobic behavior among the alloys studied. However, when exposed to citric acid, TMA displayed the most substantial alterations in its surface properties. These results underscored the significance of accounting for the distinctive properties of each alloy and their responses to diverse challenges, such as exposure to acidic solutions, during the selection of orthodontic wires for orthodontics treatment.