Variation Of Surface Roughness Research Articles

Classification of surface roughness for CNC face milling of Inconel 625 superalloy utilizing cutting force signal features with SVM and ANN

Superalloys, commonly referred to as high-performance alloys, possess remarkable characteristics that enable them to operate effectively at temperatures significantly surpassing their melting points. These alloys exhibit exceptional strength properties (i.e., corrosion resistance, high tensile strength, creep resistance, rupture strength, and the ability to retain their strength even at elevated temperatures). These inherent properties of superalloys introduce intricate challenges during the machining or cutting process, resulting in unforeseen and abrupt modifications to the interaction between the workpiece and the cutting tool. The fluctuations in interactions can give rise to inconsistencies in the surface finish of the work material. This research focuses on the characterization/classification of variations in surface roughness during face milling of INCONEL 625 using cutting force signals. Additionally, the study investigates the influence of machining parameters on cutting forces and surface roughness. The research considers five levels for each cutting parameter, including feed rate, cutting speed, and depth of cut. Interaction plots are generated to analyze the relationship between machining parameters and responses, namely surface roughness and cutting forces. In order to classify the surface roughness, a proposed methodology is employed, aiming to identify different classes such as refined, good, and satisfactory surface finishes during milling. Both time domain and frequency domain characteristics of the cutting force data collected during milling are utilized to determine surface quality. Bayesian optimized Support Vector Machine (SVM) and Artificial Neural Network (ANN) models are employed, and a comparison is conducted between them. The SVM model achieved an accuracy of 99.61%, while the ANN model slightly outperformed with an accuracy of 99.74%.

Experimental evaluation of the effect of ozone treatment on the oxidation and removal of dry soot deposits of the exhaust gas recirculation system

The integration of alternative energy sources as a replacement for fossil fuels across various industrial sectors, including power generation, emergency systems, or marine applications, is uncertain. As a result, the utilization of traditional fuels is not anticipated to be fully phased out in the near future. To address this, new technologies, such as those that employ oxidising atmospheres, have been explored as a means to enhance the pollution control capabilities of existing technologies, as the Exhaust Gas Recirculation (EGR) system. In this regard, the present study has assessed the efficacy of ozone atmosphere exposure in mitigating the formation of undesired fouling deposits within the system, with the aim of facilitating more efficient operation of EGR devices and extending their service life. To this end, dry soot samples have been exposed to various ozone atmospheres at different temperatures and ozone concentrations through the utilization of an experimental test bench. The oxidation potential of these atmospheres has been evaluated through the analysis of the deposit mass loss. Likewise, confocal microscopy techniques have been employed to obtain the 3D topography of the fouling samples before and after the ozone treatment, allowing the assessment of the deposit thickness reduction, as well as the surface roughness variation. Additionally, thermogravimetric analysis has been conducted to examine the effects of the oxidation processes on fouling samples composition. The findings of this study have revealed that ozone atmospheres have been effective in reducing deposit mass at ozone treatment temperatures above 100 °C. The reduction in mass has reached 78.5% and 91.8% with treatment temperature of 140 °C with ozone concentrations of 30 gO3/m³ and 50 gO3/m³, respectively. It has also been established that treatment conditions with ozone concentrations of 30 gO3/m³ and 50 gO3/m³ are effective in reducing the thickness of deposits even at intermediate treatment temperatures, resulting in a thickness reduction of 78.6% and 81.1% at 80 °C, respectively. Additionally, it has been observed that the ozone exposure leads to the increase in the proportion of volatile material within the deposit.

Performance analysis of annular disks with non-Newtonian Rabinowitsch fluid model: Influence of squeeze film pressure, surface roughness, porosity and viscosity variation

In various systems of energy, such as turbo-machinery and viscous-lock system, squeeze film plays a crucial role for improving transport systems. The importance of the aforementioned applications led us to explore the physical behavior of Rabinowitsch fluid flow for several values of viscosity, [Formula: see text], load capacity [Formula: see text], nonlinear factor, [Formula: see text], dimensionless film thickness [Formula: see text], dimensionless radius of the capillary tube [Formula: see text], dimensionless thickness of porous pad [Formula: see text]), inner and outer radius ratio [Formula: see text], roughness parameter [Formula: see text] through a squeeze film with two rough porous annular discs. Five-point Gauss quadrature integral formula has been used to examine the characteristics of annular discs, and small perturbation method has been used to discretize the governing Rabinowitsch fluid flow (RFF) equations. The modified Reynolds equation for rough, porous and viscosity change with film thickness is developed using Christensen’s stochastic theory, modified Darcy’s theory and the association between viscosity and film thickness agreement. The impacts of [Formula: see text] on the behavior of porosity and viscosity variability of RFF have been visually depicted in terms of film pressure, load capacity and squeeze reaction time of annular discs. It has been determined that for RFF with variable viscosity and roughness parameter on a porous media, the performance of the annular disks enhances for [Formula: see text] (dilatant lubricant), and diminishes for [Formula: see text] (pseudo-plastic lubricant). It has been found that the film pressure in case of dilatant lubricant is increased by the influence of Rabinowitsch fluids on porous walls, but the behavior of pseudo-plastic lubricants has an opposite tendency relative to Newtonian lubricants. It has also been found that the impact of variability in porosity, roughness and viscosity diminishes the load-carrying capacity (LCC) with increased film thickness than the case of nonporous, smooth surface and constant viscosity of Rabinowitsch fluid.

Investigations on Oxidation Behavior of Free-Standing CoNiCrAlYHf Coating with Different Surface Roughness at 1050 °C.

MCrAlYHf bond coats are employed in jet and aircraft engines, stationary gas turbines, and power plants, which require strong resistance to oxidation at high temperatures. This study investigated the oxidation behavior of a free-standing CoNiCrAlYHf coating with varying surface roughness. The surface roughness was analyzed using a contact profilometer and SEM. Oxidation tests were conducted in an air furnace at 1050 °C to examine the oxidation kinetics. X-ray diffraction, focused ion beam, scanning electron microscopy, and scanning transmission electron microscopy were employed to characterize the surface oxides. The results show that the sample with Ra = 0.130 µm demonstrates better oxidation resistance compared to Ra = 7.572 µm and other surfaces with higher roughness in this study. Reducing surface roughness led to a decrease in the thickness of oxide scales, while the smoothest surface exhibited increased growth of internal HfO2. The β-phase on the surface with Ra = 130 µm demonstrated faster growth of Al2O3 compared to the γ-phase. An empirical model was suggested to explain the impact of surface roughness on oxidation behavior based on the correlation between the surface roughness level and oxidation rates.

Water flow tuned by micro/nano hierarchical structures fabricated through two-photon polymerization

Two-photon polymerization (TPP) is a sub-classification of vat photopolymerization. It has been widely used to fabricate micro/nano hierarchical structures that have the potential to be used to tune the fluid flow in chips. The present work first studied the influence of laser power on the feature size of TPP-fabricated 2D structures. It was found that the increase of laser power from 1.0 μW to 1.4 μW leads to the feature size increasing from 203 nm to 307 nm. Then, the effect of scanning parameters on the accuracy and surface quality of 3D structures was investigated. The arrangement of the voxels at different scanning strategies explains the mechanisms of the variation of accuracy and surface roughness. Finally, the pinecone structures with micro/nano hierarchical features were built and evaluated for their water repellence. The increase in the number of rows of pinecone structures significantly enhances the water-repellent performance.

Design and Additive Manufacturing of Acetabular Implant with Continuously Graded Porosity.

Porous structured metallic implants are preferable as bone graft substitutes due to their faster tissue integration mediated by bone in-growth and vascularization. The porous scaffolds/implants should also mimic the graded structure of natural bone to ensure a match of mechanical properties. This article presents a method for designing a graded porous structured acetabular implant and identifies suitable parameters for manufacturing the model through additive manufacturing. The design method is based on slice-wise modification to ensure continuity of gradation. Modification of the slices was achieved through the binary image processing route. A geodesic dome-type design was adopted for developing the acetabular cup model from the graded porous structure. The model had a solid shell with the target porosity and pore size gradually changing from 65% and 950 µm, respectively, in the inner side to 75% and 650 µm, respectively, towards the periphery. The required dimensions of the unit structures and the combinations of pore structure and strut diameter necessary to obtain the target porosity and pore size were determined analytically. Suitable process parameters were identified to manufacture the model by Direct Metal Laser Sintering (DMLS) using Ti6Al4V powder after carrying out a detailed experimental study to minimize the variation of surface roughness and warping over different build angles of the strut structures. Dual-contour scanning was implemented to simplify the scan strategy. The minimum diameter of struts that could be manufactured using the selected scanning strategy and scanning parameters was found to be 375 µm. Finally, the model was built and from the micro-CT data, the porosities and pore sizes were found to be closely conforming to the designed values. The stiffness of the structures, as found from compression testing, was also found to match with that of human trabecular bone well. Further, the structure exhibited compliant bending-dominated behaviour under compressive loading.

Study on the effect of the strengthen grinding process surface coverage on the micro-morphology, micro-hardness, roughness, and residue stress of GCr15 bearing steels

In this study, the surface integrity of GCr15 bearing steels processed by different surface coverage of the strengthen grinding process (SGP) has been theoretical and experimentally investigated. OpenCV-Python-based image processing algorithm was used to extract the evolution of the shot peening coverage. The surface morphology, roughness, equivalent plastic deformation (PEEQ), microhardness, and residual stress were analyzed. Results show that as surface coverage increase from 100 % to 400 %, the PEEQ and microhardness, and theoretical and actual residual stress, behave similarly. The highest microhardness and residual stress reach 851.3 HV and − 1182 MPa, respectively. The variation of surface roughness shows a significant difference, especially at the surface coverage of 300 %, the measured roughness is reduced by approximately 65 % compared to simulation. The possible mechanisms were further discussed. This work demonstrated that the proposed theoretical modeling method could be an efficient approach for controlling the process parameters of multiphase jet flow in practical applications.

Ionized Jet Deposition of Calcium Phosphates-Based Nanocoatings: Tuning Coating Properties and Cell Behavior by Target Composition and Substrate Heating.

Calcium phosphate-based coatings are widely studied in orthopedics and dentistry for their similarity to the mineral component of bone and their capability to promote osseointegration. Different calcium phosphates have tunable properties that result in different behaviors in vitro, but the majority of studies focus only on hydroxyapatite. Here, different calcium phosphate-based nanostructured coatings are obtained by ionized jet deposition, starting with hydroxyapatite, brushite and beta-tricalcium phosphate targets. The properties of the coatings obtained from different precursors are systematically compared by assessing their composition, morphology, physical and mechanical properties, dissolution, and in vitro behavior. In addition, for the first time, depositions at high temperature are investigated for the further tuning of the coatings mechanical properties and stability. Results show that different phosphates can be deposited with good composition fidelity even if not in a crystalline phase. All coatings are nanostructured and non-cytotoxic and display variable surface roughness and wettability. Upon heating, higher adhesion and hydrophilicity are obtained as well as higher stability, resulting in better cell viability. Interestingly, different phosphates show very different in vitro behavior, with brushite being the most suitable for promoting cell viability and beta-tricalcium phosphate having a higher impact on cell morphology at the early timepoints.

Influence of Immobilization Strategies on the Antibacterial Properties of Antimicrobial Peptide-Chitosan Coatings.

It is key to fight bacterial adhesion to prevent biofilm establishment on biomaterials. Surface immobilization of antimicrobial peptides (AMP) is a promising strategy to avoid bacterial colonization. This work aimed to investigate whether the direct surface immobilization of Dhvar5, an AMP with head-to-tail amphipathicity, would improve the antimicrobial activity of chitosan ultrathin coatings. The peptide was grafted by copper-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry by either its C- or N- terminus to assess the influence of peptide orientation on surface properties and antimicrobial activity. These features were compared with those of coatings fabricated using previously described Dhvar5-chitosan conjugates (immobilized in bulk). The peptide was chemoselectively immobilized onto the coating by both termini. Moreover, the covalent immobilization of Dhvar5 by either terminus enhanced the antimicrobial effect of the chitosan coating by decreasing colonization by both Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. Relevantly, the antimicrobial performance of the surface on Gram-positive bacteria depended on how Dhvar5-chitosan coatings were produced. An antiadhesive effect was observed when the peptide was grafted onto prefabricated chitosan coatings (film), and a bactericidal effect was exhibited when coatings were prepared from Dhvar5-chitosan conjugates (bulk). This antiadhesive effect was not due to changes in surface wettability or protein adsorption but rather depended on variations in peptide concentration, exposure, and surface roughness. Results reported in this study show that the antibacterial potency and effect of immobilized AMP vary greatly with the immobilization procedure. Overall, independently of the fabrication protocol and mechanism of action, Dhvar5-chitosan coatings are a promising strategy for the development of antimicrobial medical devices, either as an antiadhesive or contact-killing surface.

Study on force-thermal characteristics and cutting performance of titanium alloy milled by ultrasonic vibration and minimum quantity lubrication

Ti-6Al-4V alloys are widely utilized in aerospace field because of its excellent physical and mechanical performance. Nevertheless, titanium alloy has high strength and low thermal conductivity, which leads to poor processability. Therefore, in the titanium alloys cutting processing, decreasing cutting force and cutting temperature are reliable ways to improve its cutting machinability. The high-frequency intermittent cutting effect of ultrasonic vibration be beneficial to reduce the milling force, and the minimum quantity lubrication (MQL) technology can efficiently improve the friction environment and decrease the cutting temperature. Combined with the technological superiority of ultrasonic vibration assisted machining (UVAM) and MQL, this paper proposes to use UVAM&MQL technology for titanium alloy milling. Firstly, theoretical analysis shows that the separation property of UVAM can enhance the cooling/lubrication of MQL, and the coupling action of UVAM and MQL can improve the force and temperature generated in the cutting process. Then, the variation of surface roughness, surface morphology and chip morphology under this force-thermal coupling is discussed through milling experiments, and compared with conventional milling (CM) and UVAM. From the results, we make out that compared with CM, both UVAM and UVAM&MQL can reduce the cutting force. When the cutting speed is high, UVAM can't reduce the cutting temperature, while UVAM&MQL produces a smaller cutting temperature under all parameters. When the UVAM&MQL method is adopted for processing, the surface is smoother, and the surface forms a clear and uniform vibration texture. Compared with CM and UVAM, the surface roughness of UVAM&MQL is decreased by about 27–51 % and 5–44 %, respectively. In addition, UVAM&MQL method is beneficial to promote the transformation of serrated chip to non-serrated chip.

Influence of Tucupi on Enamel Surface Roughness, Microhardness, Ultramorphology and Mass Variation

The study evaluated the influence of tucupi on enamel surface roughness, microhardness, ultramorphology, and mass variation. Ninety healthy bovine incisors were divided into three experimental groups, according to the acidic challenge adopted, being: G1- tucupi, G2- cola-based soft drink, G3-distilled water. The enamel properties (surface roughness, microhardness, ultramorphology and mass variation) of all specimens were evaluated at times T0 (before any intervention), T10 (10 days after the proposed treatments), T20 (20 days after the proposed treatments) and T30 (30 days after the proposed treatments). After confirming the normality of the data (Shapiro-Wilk test), a two-way ANOVA (α = 5%) was performed, followed by Sidak post-test, with results described as mean and standard deviation. The roughness means increased for all tested groups, with no statistical difference only in G3 for all evaluated times. Microhardness of all groups showed a significant decrease over the time, with the lowest average observed in G1 in T30. Considering enamel mass variation, the lowest average was in G2 at time T3, with no statistical difference only in G3 (distilled water) over the time. Regarding ultramorphology (scanning electron microscopy - SEM), only groups G1 and G2, that were exposed to acidic challenges, showed disorganization of the enamel surface layer. It was possible to conclude that tucupi has low pH and high titratable total acidity, being able to gradually decrease enamel microhardness, increasing surface roughness and causing loss of dental enamel.

Machining of Custom-450 Grade Stainless Steel Using TiAlSiN-Coated Tungsten Carbide Tool Inserts

Turning operations using single-point cutting tools have been one of the earliest and most used methods for cutting metal. It has been widely studied for cutting forces and workpiece surface roughness to affect turning operations. When cutting metal, the cutting tool needs to be tougher than the workpiece so it can resist high temperatures and wear while the operation is conducted. The mechanical qualities of martensitic stainless steel (MSS) grade Custom-450 can be significantly enhanced by heat treatment processes, which also provide it with an outstanding corrosion-resistance material. It has excellent resistance to rusting and pitting in a saltwater environment. Nuclear power reactors, screens for the pulp and paper sector, chemical processing, and power generation are just a few industries that require Custom-450 grade steel. To increase the workpiece’s machinability, dimensional precision, and appealing surface finish, the cutting tool industries have recently demonstrated a great interest in developing hard coatings and cutting tool technology. In the present study, Custom-450 grade stainless steel was used for machining (turning operation), using a tungsten carbide tool insert coated with TiAlSiN using the physical vapor deposition (PVD) method. The machining parameters such as the speed, feed, and depth of cut (DOC) were varied Surface roughness and various forces (cutting force, thrust force, and feed force) were evaluated by varying these three parameters. The depth of cut is the main factor affecting the surface roughness. More plastic deformation may lead to a rougher surface as a result. The tungsten carbide insert wear decreased with an increase in the cutting speed. An increase in feed considerably accelerates the tool wear of the inserts. As the depth of cut grows, the likelihood of tool wear also increases. The depth of cut, however, has a greater effect on tool wear than anything else. Therefore, the surface roughness in the sample is reduced as the cutting speed is increased.

Influence of Tool Rotation and Surface Roughness on the Shear Strength of Nylon 6 - SS 304 Dissimilar Joint Resulted by Friction Lap Welding

This research was conducted to investigate the effect of variations in tool rotation and surface roughness towards shear strength on the newly developed friction lap welding (FLW) for dissimilar joints between stainless steel (SS) 304 and Nylon 6 plates. Under constant welding traverse speed at 30 mm/min, the variation of tool rotation used were 1100 and 2200 rpm and surface roughness of 0.32; 1.25; and 1.88 μm initially obtained from different surface modification methods. The shear test was conducted at FLW dissimilar joint based on AWS D8.9-97 standard. The results showed that the shear stress increased along with the higher tool rotation and at the greater surface roughness. The highest shear strength value was found at the tool rotation of 2200 rpm and surface roughness of 1.88 μm with 9.447 MPa. The tool rotation may produce a higher heat input as well as an effect on the value of nylon hardness. On the other hand, rougher SS surfaces provide a larger area for the interfacial adhesive bond between nylon and metal; therefore, they can act as an interlocking site when the shear loading was applied. These phenomena were also confirmed by fracture morphology and microscopic image analysis.

Experimental Study and Analysis of Fretting Wear and its Influence on Functionality of Mechanical Components

Fretting occurs when there is tangentially low-amplitude vibrational motion (range tens of nanometres to tens of micrometers) between nominally stationary contact surfaces. This is a common occurrence as most machines are exposed to vibration both in transit and in operation. Contacts that appear to have no relative movement, such as press-fit, can actually slide on a scale of 1 μm with alternating pendulum loads. It is very difficult to eliminate such movements and the resulting friction. Fretting wear and frictional fatigue occur on almost every machine and otherwise cause a total failure of robust components. Studies have shown that, in contrast to other forms of wear, the frequency of machine fit problems has not diminished in the last few decades. Experiments were conducted on a fretting wear testing machine of amplitude range 10–200 μm, frequency range 4–120 Hz and surface roughness were recorded for both polished and unpolished condition. The correlation was made between changing parameters and variation in surface roughness. Friction fatigue is an important but almost unknown factor when load-bearing components are damaged at very low loads. Therefore, we will conduct an experimental study of fretting and its control parameters. For unpolished specimen, the variation of amplitude with respect to the coefficient of friction (COF) increases to 0.5, then it becomes linear. For semi-polished specimen, it increases to COF 0.45 and then it starts decreasing. For a fully polished specimen, there is no change in COF to 75 μm and then it starts increasing. According to the experimental data, for all specimens’ COF constantly decrease with increasing the load.

Optimization of Machining Parameters in Mild Steel Turning Operation by Response Surface Methodology

A lot of process variables affect the surface roughness obtained in turned machine parts. One of these variables is bearing clearance. However, there is limited information on the influence of bearing clearance on surface integrity. This paper is an optimization study in which the surface roughness of AISI 1018 mild steel is minimized with the aid of the response surface methodology. In this paper, the effect of process parameters like cutting speed, feed, depth of cut, and bearing clearance is analyzed to ascertain how the surface finish properties of mild steel can be improved. The design of the experiment used for this study involves a rotatable central composite system. This design is used to find the experimental results of machining. The analysis of variance (ANOVA) was used to determine the statistical significance of the improved quadratic model developed. The numerical and graphical optimization carried out determined the optimum values of each of the parameters used in different ways. From the ANOVA, it was revealed that the most significant factor in the model was the depth of cut. This factor was closely followed by spindle speed, bearing clearance, and feed, respectively. Numerical optimization results employing the desirability function showed optimum values to be at bearing clearance of 70um, depth of cut of 2.5mm, feed of 0.01mm/rev, and a spindle speed of 450rpm. The result obtained using the graphical optimization option was similar to the results from the other options. The variation of surface roughness with the process parameters chosen for the experiment was mathematically modeled. The model developed used the response surface methodology, and it was validated with a set of experimental values. The result from the exercise undertaken revealed that the predicted values of the surface roughness were very close to measured values. The average percentage deviation of 6.20% for all sample data utilized showed that the model developed was in close agreement with the experimental results.

Chemical and Structural Assessment of New Dental Composites with Graphene Exposed to Staining Agents.

Among the newest trends in dental composites is the use of graphene oxide (GO) nanoparticles to assure better cohesion of the composite and superior properties. Our research used GO to enhance several hydroxyapatite (HA) nanofiller distribution and cohesion in three experimental composites CC, GS, GZ exposed to coffee and red wine staining environments. The presence of silane A-174 on the filler surface was evidenced by FT-IR spectroscopy. Experimental composites were characterized through color stability after 30 days of staining in red wine and coffee, sorption and solubility in distilled water and artificial saliva. Surface properties were measured by optical profilometry and scanning electron microscopy, respectively, and antibacterial properties wer e assessed against Staphylococcus aureus and Escherichia coli. A colour stability test revealed the best results for GS, followed by GZ, with less stability for CC. Topographical and morphological aspects revealed a synergism between GZ sample nanofiller components that conducted to the lower surface roughness, with less in the GS sample. However, surface roughness variation due to the stain was affected less than colour stability at the macroscopic level. Antibacterial testing revealed good effect against Staphylococcus aureus and a moderate effect against Escherichia coli.

Thermoreflectance-based approach for surface temperature measurements of thin-film gold sensors.

A novel thermoreflectance-based diagnostic tool capable of visualizing spatial and temporal changes in surface temperature is presented. The method uses narrow spectral emission bands of blue [λ = 405nm with 10nm full-width-at-half-maximum (FWHM)] and green (λ = 532nm with 10nm FWHM) light to monitor the optical properties of gold and thin-film gold sensors, relating changes in reflectivity to temperature through a known calibration coefficient. The system is made robust to tilt and surface roughness variations through the simultaneous measurement of both probing channels with a single camera. Experimental validation is performed on two forms of gold materials heated from room temperature to 200 °C at a rate of ∼100 °C/min. Subsequent image analysis shows perceptible changes in reflectivity in the narrow band of green light, while the blue light remains temperature-insensitive. The reflectivity measurements are used to calibrate a predictive model with temperature-dependent parameters. The physical interpretation of the modeling results is given, and the strengths and limitations of the presented approach are discussed.

Effects of Automotive Test Parameters on Dry Friction Fiber-Reinforced Clutch Facing Surface Microgeometry and Wear-Part 3 Tribological Parameter Correlations and Simulation of Thermo-Mechanical Tribological Contact Behavior.

Correlations among previously determined tribological properties, such as the coefficient of friction values, wear and surface roughness differences of hybrid composite dry friction clutch facings are revealed after pin-on-disk test apparatus examinations under three pv loads, where samples are cut from a reference, unused, and several differently aged and dimensioned, used-according to two different trends: dry friction fiber-reinforced hybrid composite clutch facings. In 'normal use' facings, increasing specific wear trend is detected as a function of activation energy according to a second-degree function, while a logarithmic trend line can be fitted to the values of the clutch killer facings, showing that even at low activation energy levels, significant (~3%) wear occurs. The specific wear rate also varies as a function of the radius of the friction facing, with the relative wear values measured on the working friction diameter being higher regardless of the usage trend. In terms of surface roughness variation measured in the radial direction, normal use facings show a varying roughness difference according to a third-degree function, while clutch killer facings follow a second-degree or logarithmic trend depending on the diameter (di or dw). From the statistical analysis of the steady-state, we find three different clutch engagement phase characterizing pv level pin-on-disk tribological test results for the specific wear of the clutch killer and normal use facings, and significantly different trend curves with three different sets of functions were obtained, showing that the wear intensity can be described as a function of the pv value and the friction diameter. In terms of radial direction surface roughness difference, the values of clutch killer and normal use samples can be described by three different sets of function showing the effects of the friction radius and pv.

Mechanical properties of laser powder directed energy deposited NASA HR-1 superalloy: Effects of powder reuse and part orientation

The feasibility of NASA HR-1 powder reuse for laser powder directed energy deposition (LP-DED) of thin-walled structures in the as-built surface condition was investigated in this study. Although continuously reusing the powder five times slightly reduced the number of fine particles in the powder and increased the mean particle size, changes in powder rheological properties were negligible. The similarities in powder flow between all reused conditions resulted in no variation in surface roughness, defects’ size and spatial distributions, and microstructure of the as-deposited parts and, thus no differences on tensile and fatigue properties. The effects of different specimen orientations, loading direction being perpendicular or parallel to the building direction, on mechanical properties were also investigated. While no change in tensile strength was noted, tensile ductility was lower for the parallel specimens because of surface micro-notches being perpendicular to the loading direction, which led to an early onset of fracture. Due to accelerated crack initiation from these micro-notches, parallel specimens were also less resistant to fatigue failures. The fatigue failures always initiated from the specimen surfaces, and all specimens experienced a ductile fatigue crack growth mechanism characterized by clear striations on the fracture surface.

Self-powered visible transparent mathrm{Cu}/{mathrm{Zn}}_{left(1-xright)}{mathrm{Sn}}_{left(xright)}mathrm{O} Schottky-based ultraviolet photosensors fabricated via DC magnetron sputtering

Visible transparent mathrm{Cu}/mathrm{n}-mathrm{ZnO} and mathrm{Cu}/{mathrm{Zn}}_{left(1-xright)}{mathrm{Sn}}_{left(xright)}Oleft(x=0.14right) mathrm{TZO}, Schottky junctions were successfully fabricated on ITO-coated glass substrates via direct current magnetron reactive sputtering method. The structural, morphological, optical, and electrical properties were thoroughly investigated. The polycrystalline nature of the samples was confirmed by XRD studies. FESEM images validate the changes in surface morphology after doping and annealing, and AFM analysis confirmed the variation in surface roughness. The electrical analysis reveals the presence of a Schottky barrier in the fabricated devices. In dark condition, three-order rectification ratio was observed. A two-order increase in leakage current was also observed after illuminating 365 nm UV light of power 60 µW/cm2. The figures of merits of sensors, such as responsivity, detectivity, response speed, and linear dynamic range, were thoroughly investigated. The fabricated sensor had a responsivity of about 07.80 mA/W and a detectivity of 1.39 × 1011 Jones. At zero bias, the sensor also demonstrated a transient photocurrent response of approximately 783 ms for rise and 876 ms for fall. Similarly, 33.70 dB of linear dynamic range was observed. These findings suggests that Cu/TZO Schottky diodes could be useful for self-powered, visible transparent UV photosensors in next-generation optoelectronic devices.