Variations In Surface Morphology Research Articles

Effect of loading current on the arc erosion behavior of in-situ composite fiber-reinforced Ag–Cu–Ni–Ce alloy

To reveal the arc erosion behavior of in-situ composite fiber-reinforced electrical contact materials, arc erosion tests of an Ag–Cu–Ni–Ce alloy with the voltage of 24 V DC and a current ranging from 10 to 20 A were performed and the surface morphology, elemental distribution, and mass variations caused by arc erosion were investigated. The results found that, with the increase of load current, the arc erosion ratio and mass loss of contacts gradually increase. With a load current of 10 A, the contact resistance was lower, approximately one mΩ. The direction of material transfer was from the anode to the cathode, and the erosion mechanism was dominated by splashing and evaporation of the anode metal by short arc action. When the load current increased to 12 A, the contact resistance reached the maximum value of 5 mΩ. Then, it gradually decreased with increasing load current. The direction of material transfer was from the cathode to the anode, and the mechanism of erosion was mainly the bombardment of the cathode by gaseous positive ions by the long arc. At the same time, the results of the comparative analysis demonstrate that the in-situ composite fiber-reinforced Ag–Cu–Ni–Ce alloy has excellent arc erosion resistance.

Study on the working performance of CrAlCN coated and uncoated carbide twist drill

A drilling test was carried out for a 6 mm diameter carbide twist drill with CrAlCN coating and an uncoated carbide twist drill to grasp the effect of CrAlCN coating on the tool performance. Drilling and machining tests on ASTM1045 steel workpieces using CrAlCN coated and uncoated tools. Observe the pattern of variation of surface morphology and roughness of holes with the number of drilled holes using SEM and optical microscope. The effect of CrAlCN coating on carbide twist drill on drilling quality was analyzed by comparing the wear, surface roughness and chip shape of twist drill at different periods and parameters of drilling. The study concluded that using CrAlCN coated tools improved the wear resistance of the drill and significantly reduced BUE. Compared to the uncoated bit, the diameter of the drill decreased to 5.91 mm for the coated tool and 5.79 mm for the uncoated tool after 80 holes. The roughness of the coated bit was 3.324 µm at a feed rate of 0.12 mm/r and several holes of 40, which was significantly lower than that of the uncoated bit. Chip analysis showed that the coated tool maintained well-broken and tightly spiraled chips. In contrast, the uncoated tool produces tightly spiraled chips and short ribbon chips at a feed rate of 0.18 mm/rev, and the edges of the chips can appear significantly serrated. The research results improve the understanding of the drilling wear mechanism, provide new technical means to improve the analysis of working tool performance and provide a reference basis for the design of new coating tools.

Investigation on Intermittent Failure Phenomenon of Electrical Connectors Under Repetitive Mechanical Insertion and Withdrawal Operations

Electrical connectors play an indispensable role in electrical and electronic systems. The frequently occurred intermittent failure events seriously affect the reliability of application systems. In this article, the repetitive mechanical insertion and withdrawal experiment of electrical connector is carried out by using our designed test rig and the intermittent failure phenomena recurs. The typical waveforms of contact resistance and force during the mating operation are presented. The variation laws of static contact resistance and dynamic contact resistance under intermittent failure condition are counted and analyzed. And the dynamic contact resistance is proven to be a suitable sensitive parameter to characterize the intermittent failure event. Based on the mathematical model, variation of surface morphology, and element analysis, the failure mechanism of electrical connectors under repetitive operation is proposed.

Numerical modeling of Ti-6Al-4V alloy orthogonal cutting considering microstructure dependent work hardening and energy density-based failure behaviors

Numerical modeling of the cutting process provides an effective method to obtain the micro-scale and instantaneous process information which is difficult to be measured by experiments. A new microstructure (grain size) dependent work hardening plastic (JCM-ms) model was developed to characterize the effect of grain refinement on the cutting process. An energy density-based failure law was applied to control the chip formation and material removal mechanisms ahead of the cutting edge. Orthogonal cutting experiments with different edge radii and uncut chip thickness values for Ti-6Al-4V alloy were carried out to validate the finite element (FE) simulation results. The simulation results were thoroughly validated by the measured principal and thrust forces, segmented chip morphology, and the grain refinement within the machined surface layer. The distribution of grain refinement of the chips and machined surface agreed well with the experimental results. The positions of stagnation points with different edge radii and uncut chip thickness values were measured by the FE simulation results. The variation of surface morphology along the speed direction with larger edge radius is related to the variation of the stagnation points, which will affect the ratio of material being compressed to the machined surface by the tool, during the formation of the adiabatic shear band. The degree of the subsurface shear deformation determines the final distribution of the micro-hardness. Larger shear displacement at the top surface will lead to thicker layer of grain refinement. Residual stresses along the depth from machined surface are mainly related to the displacement normal to the machined surface. The height of the stagnation point is in proportion to the peak compressive stresses induced by the material flow ahead of cutting edge for different conditions. This work provides an effective method to characterize the forces, grain refinement and surface integrity for the orthogonal cutting of Ti-6Al-4V alloy.

High temperature CO2 capture performance and kinetic analysis of Na4SiO4 ceramics

Alkali silicate-based ceramics sorbents were regarded as particularly suitable materials for CO2 capture at high temperatures, however, the CO2 capture behaviors of Na4SiO4 had been seldom investigated. In this work, the Na4SiO4 ceramics samples were prepared using the one-step synthesized method, and the CO2 sorption/desorption performances at high temperatures, the thermal stability, and the cycling stability of Na4SiO4 were systematically investigated. It was demonstrated that the maximum CO2 sorption capacity of SO-3 sample reached 19.4 wt% at 725 °C, and the optimal condition of cycling tests were 750 °C for sorption and 800 °C for desorption based on the sorption/desorption capacity and rate, which exhibited good thermal stability and high cyclic stability. Besides, the kinetic analysis results showed that the diffusion process was the rate-determining step of CO2 adsorption, which was more dependent on temperature than the chemisorption process. The structure and surface morphology variations were also investigated, it was interesting that there was a special “fish scale” surface structure after the sorption process, revealing that the melting phenomenon happened during the chemisorption reaction process. By comparing with common sorbent Li4SiO4, the material and CO2 capture costs of Na4SiO4 were much lower. These results proved that Na4SiO4 was expected to be a suitable high temperature CO2 capture material as a good supplement to alkali silicate-based ceramics sorbents.

Investigation into the evolution of the microcosmic surface of bainitic wheel steel material suffering polygonal wear

With the rapid development of high-speed railway, it is imperative to develop highly comprehensive wheel/rail materials to improve the safe and stable operation of trains. Even though bainitic steel shows excellent resistance to rolling contact fatigue (RCF), its wear resistance is not good enough and whether it is qualified for high-speed wheel materials still needs further investigation. Through conducting rolling wear experiment on carbide-free bainite (FCB) wheel steel, this paper observed the changes of the surface profile lines of the worn specimens regularly and the wear morphology in different stages, and analyzed the changes of the microstructures and hardness on the surface layer, in order to explore the formation of polygonization wear (PolyW) from the angle of the microcosmic surface of bainitic wheel steel. The research revealed that during the process of rolling wear, the nonuniform load caused by mechanical vibration could lead to the appearance of PolyW on the surface of the two-disc specimens of FCB wheel steel. Based on the surface morphology and size variations, three stages could be divided to explain the formation of PolyW: The incubation stage where macromorphology underwent cyclic changes, the development stage where PolyW appeared in some regions and the mature stage where PolyW spread all over the circumference. The wear mode in wave crests was mainly featured by oxidative wear and adhesion wear, and the one in wave troughs was marked by fatigue wear with wear rotations increasing, PolyW on the surface was exacerbated. Compared with wave crests, wave troughs had a larger slip ratio and the additional impact load, so the microstructures experienced severer deformation, the hardness increase was higher and the depth of the hardening layer was greater.

The Influence of the Substrate and External Magnetic Field Orientation on FeNi Film Growth

The magnetic field-assisted electrodeposition of iron–nickel thin films on different substrates (aluminum, silver, and brass) was investigated. The process was performed galvanostatically in a sulfate solution. The same chemical and electrical conditions were applied for each sample growth, but the time restrictions and the external magnetic field orientation were changeable. The obtained results show a variation of surface morphology and composition dependence on the selected surfaces as a consequence of the presence and orientation of the external magnetic field. We discussed that the FeNi crystal structure depends on the film thickness. The results show the reduction of the film thickness after the external magnetic field application—a decrease of deposition rate.The FeNi alloy’s morphology, composition, and magnetic properties were investigated by scanning electron microscopy (SEM), X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), and Mössbauer spectroscopy (MS).

Microstructures and optical properties of porous PbSe film prepared by ion exchange process

PbSe films can be widely applied in many fields involving industrial temperature measurement, military guidance, agriculture detection and celestial observation due to their high reliability and sensitivity. The porous PbSe film with a grain size of ∼0.5 μm was firstly transformed from flaky pastry-like plumbonacrite (Pb10O(OH)6(CO3)6) precursor film by ion exchange process, where the precursor film was prepared by a low-toxicity chemical bath deposition (CBD) process. The variations of phase composition, surface morphology, and binding state of main surface elements, as well as the optical properties of films with immersion time were mainly investigated. The experimental results show that the flaky pastry-like Pb10O(OH)6(CO3)6 film can be fully converted to cubic PbSe film as the immersion time is over 1.5 h, and the grain size of PbSe is further increased with the immersion time prolonging from 1.5 to 2.5 h. Moreover, the presence of a large number of pores in PbSe film can produce low reflectance, leading to the improvement of optical performance of PbSe film in the infrared wavelength range. The XPS, Raman and TEM analyses demonstrate the presence of trace impurities and lattice defects, which can be related to the oxidation, incomplete transformation and mutual extrusion between grains. The calculated bandgap is decreased from 2.68 eV for Pb10O(OH)6(CO3)6 film to 0.39 eV for PbSe film.

Utilising micron scale 3D printed morphologies for particle adhesion reduction

In the pharmaceutical industry, the ability to improve the understanding of the effect of surface roughness on interparticulate interactions is critical. Dry powder inhalers often possess poor efficiency, as the powder formulations are inherently adhesive and cohesive due to their size. The complex interplay of factors that affect interparticulate interactions, means it has been difficult to isolate the effect of surface morphology. Using two photon polymerisation, this study shows the fabrication of bespoke sub-micron geometric structures, with a consistent surface chemistry. These are used to investigate the effect of surface morphologies on particle adhesion by utilising AFM force-volume mapping, to model spheres and carrier particles. This demonstrates the significant effect varying surface morphology can have on particle-surface adhesion. This approach allows for the first time an in-depth examination of the local variation effect of surface features on particle adhesion and may facilitate the design and optimisation of powder processes.

Hydrophobic agents and pH modification as comparative chemical effect on the hydrophobic and photocatalytic properties in SiO2-TiO2 coating

The SiO2-TiO2 composite has been studied through several techniques obtaining different morphologies and specific properties of SiO2 and TiO2. Nevertheless, the modification of the synthesis pH and the addition of different hydrophobic agents, such as hexamethyldisilazane (HDMS) and polydimethylsiloxane (PDMS), have not been thoroughly studied and reported. This work assessed the presence of two different hydrophobic agents and the pH modification. The SiO2-TiO2 coating was synthesized through two vias, basic and acid environment, employing the sol–gel method coupled to the sonochemistry technique. Moreover, the change of pH and use of P25 TiO2 nanoparticles and TiO2-synthesized nanoparticles allows establishing a relationship with the self-cleaning properties. The samples of SiO2-TiO2 composite were analyzed by AFM, indicating a variation in surface morphology and roughness concerning the PDMS and HMDS hydrophobic agent. ATR-FTIR analysis exhibit changes in intensity in vibrations of the Si-O, PDMS, and HMDS bonds. Raman spectroscopy results show the vibrations of the anatase and rutile phases of the TiO2 and the corresponding vibrations to the hydrophobic agents. The evaluation of self-cleaning properties demonstrated changes from the hydrophobic state to the hydrophilic state due to the addition of the nanoparticles of TiO2 to the SiO2. The photocatalytic activity was modified and improved in the HMDS-1 coating due to the hydrophobic agent and type of nanoparticles. To compare the effect of the pH in the PDMS and HMDS coatings, carried out with cyclic voltammograms and Differential Capacitance spectra. Finally, the storage time of SiO2-TiO2 coating was improved using the HMDS hydrophobic agent.

Important Role of Concave Surfaces in Deposition of Colloids under Favorable Conditions as Revealed by Microscale Visualization.

This study conducted saturated column experiments to systematically investigate deposition of 1 μm positively charged polystyrene latex micro-colloids (representing microplastic particles) on negatively charged rough sand, glass beads, and soil with pore water velocities (PWV) from 4.9 × 10-5 to 8.8 × 10-4 m/s. A critical value of PWV was found below which colloidal attachment efficiency (AE) increased with increasing PWV. The increase in AE with PWV was attributed to enhanced delivery of the colloids and subsequent attachment at concave locations of rough collector surfaces. The AE decreased with further increasing PWV beyond the threshold because the convex sites became unavailable for colloid attachment. By simulating the rough surfaces using the Weierstrass-Mandelbrot equation, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) interaction energy calculations and torque analysis revealed that the adhesive torques could be reduced to be comparable or smaller than hydrodynamic torques even under the favorable conditions. Interestingly, scanning electron microscopic experiments showed that blocking occurred at convex sites at all ionic strengths (ISs) (e.g., even when the colloid-colloid interaction was attractive), whereas at concave sites, blocking and ripening (i.e., attached colloids favor subsequent attachment) occurred at low and high ISs, respectively. To our knowledge, our work was the first to show coexistence of blocking and ripening at high ISs due to variation of the collector surface morphology.

Gamma ray effects on the properties of PbI2 thin films

This study reports the impact of γ-ray exposure on the nanostructural, morphological, and optical characteristics of lead iodide (PbI2) thin films (TFs). These PbI2 were deposited on glass substrates using a spin coating technique. The γ-ray irradiation was carried out using Co-60 gamma source with dose range from 0 to 100 kGy. The X-ray diffraction (XRD) results revealed a decrease in crystallinity and an increase in crystallite size of PbI2 as a function of γ-ray dose. Field emission scanning electron microscopy (FESEM) exhibited the variations in surface morphology with increasing γ-ray dose. The elemental composition of as prepared TFs was confirmed by energy dispersive X-rays (EDX) analysis. The optical transmission of PbI2 TFs was evaluated with varying the γ-ray doses. The estimated energy band gap (Eg) reduced from 2.54 to 2.45 eV with γ-ray dose. Photoluminescence (PL) spectra represent a broad peak centered at 507.64 nm with a hump present at 519.73 nm in the as prepared sample, which grow gradually with increasing the γ-ray dose. The maximum value of mobility was found to be 10.48 cm2 V−1 s−1 at 50 kGy. The change in the mobility is associated with the density of structural defects influenced by γ-ray doses. These effects conclude that γ-irradiation played a key role in structural, electrical and optical properties of the PbI2 TFs and proposes that the γ-irradiation response makes it a good candidate for radiation detecting material application.

A comprehensive study and extensive review of morphological variations of liver with new insights.

Liver is divided into four anatomical lobes presenting minor fissures and invisible major fissures. The prevalence of Accessory Fissures in liver ranges widely from 6 to 94%. The morphometric analysis of individual lobes is also scarce in literature. There have been instances where the surgeon has experienced some of these variations as a surprise during surgery as the existing data on the surface variations of liver is still contradictory. A sound knowledge of these variations would aid the surgeons and radiologists to circumvent the misdiagnosis and complications during surgeries. The study was conducted in 93 cadaveric livers. Minor liver fissures, Accessory fissures and lobes were noted and measured. The livers were classified according to the Netter's classification. The morphology of caudate and quadrate lobes was studied. Any other variations in the appearance of groove for Inferior vena cava, gall bladder and its fossa were also studied. The results are tabulated. The study revealed several variations in the morphological features of liver. Accessory fissures were noted in 51.61% of livers, distributed on various liver surfaces. Accessory lobes were noted in 27.9%. Pons hepatis was present in 22.5%. Gall bladder variations that were noted include the Hartmann's pouch (n = 14; 15.05%) and the Phrygian cap (n = 2; 2.15%). 65.6% livers (n = 61) had the sulcus of the caudate process or fissure of Gans or Rouviere sulcus which is a normal fissure present in majority of normal healthy livers. The current study provides a complete understanding and a thorough knowledge of surface morphological variations in liver. We hope that this will be greatly helpful for surgeons and radiologists to avoid possible errors in interpretations, to plan appropriately and assist during liver surgeries and to do radiological interventions.

Effect of Ni Concentration on the Surface Morphology and Corrosion Behavior of Zn-Ni Alloy Coatings

This research work aims to develop electrodeposited Zn-Ni alloy coatings with controlled dissolution tendencies on a mild steel substrate. The varying Ni concentration in the electroplating bath, i.e., 10, 15, 20 and 25 g·L−1, affected the surface morphology and electrochemical properties of the deposited Zn-Ni alloy coatings. SEM and EDS analysis revealed the resulting variation in surface morphology and composition. The electrochemical behavior of different coatings was evaluated by measuring the open circuit potential and cyclic polarization trends in 3.5 wt.% NaCl solution. The degradation behavior of the electrodeposited Zn-Ni coatings was estimated by conducting a salt spray test for 96 h. The addition of Ni in the coating influenced the coating thickness and surface morphology of the coatings. The coating thickness decreased from 38.2 ± 0.5 μm to 20.7 ± 0.5 μm with the increase in Ni concentration. Relatively negative corrosion potential (<−1074 ± 10 mV) of the Zn-Ni alloy coatings compared to the steel substrate (−969 mV) indicated the sacrificial dissolution behavior of the Zn-rich coatings. On the other hand, compared to the pure Zn (26.12 mpy), ~4 times lower corrosion rate of the Zn-Ni coating (7.85 mpy) was observed by the addition of 25 g·L−1 Ni+2 in the bath solution. These results highlighted that the dissolution rate of the sacrificial Zn-Ni alloy coatings can effectively be tuned by the addition of Ni in the alloy coating during the electrodeposition process.

Digital analysis of tooth microwear, a potential application for dental microwear monitor

In general, tooth wear is difficult to be noticed until it leads to toothache in vivo. Developing a dynamic dental wear monitoring system to predict tooth wear in daily life is a necessity. The translation between complex surface wear morphology and corresponding digital signal source is a technical limitation to develop this kind of monitoring system. Microwear texture analysis has been widely employed in predicting diet by a palaeontologist. The main question is whether the microwear texture analysis has potential development space to develop a sensor for monitoring tooth wear. According to obtained results, the microwear texture analysis had enough sensitivity to display the surface morphology variations for different chewing foods and various angles. The corresponding sensitive digital signal of tooth microwear surface morphology makes it possible to develop a dental microwear sensor.

Modification in the physical properties of nanocrystalline ZnO thin films by Sn/Ni co-doping for transparent conductive oxide applications

In this paper, the modification in the physical properties of spin-coated ZnO thin films upon Sn/Ni co-doping has been presented. All the films possess the hexagonal wurtzite structure of ZnO with varying surface morphologies. Among all the films, the optical transmittance beyond 550 nm wavelength is maximum for the 1 at% Ni-doped ZnO (1NZO) and (1 at% Sn + 1 at% Ni) co-doped ZnO (1T1NZO) films. The optical band gap for the pristine ZnO film is 3.26 eV, which decreases upon doping and co-doping. The PL spectra of the films exhibit the UV emission corresponding to excitonic transitions and the blue and green emissions related to native defects in the ZnO structure. The room-temperature electrical conductivity is found maximum in the 1T1NZO film. The existence of 1T1NZO film with improved optical transmittance and high electrical conductivity supports its use in transparent conductive oxide applications.

Analysis of device performance and thin-film properties of thermally damaged organic light-emitting diodes

This paper reports the variation in the optical and geometrical properties of individual organic layers to be used for thermally damaged top-emission organic light-emitting diodes (TEOLEDs). The copper deposited on the back of TEOLEDs is employed as a thermal facilitator, and a certain thermal damage occurs to the organic layers and devices. The phosphorescent host material 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) is rapidly damaged to a significant extent owing to the low glass transition temperature (T g ), which also changes its optical and geometrical surface properties. Although the optical properties of the hole transport layer, N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) were changed slightly, the surface morphology was changed significantly. Despite having a higher T g , the exciton blocking layer, tris(4-carbazoyl-9-ylphenyl)amine (TCTA), shows notable variations in optical properties and surface morphology due to heat exposure. Surprisingly, the electroluminescence spectra and micro-cavity are affected by increasing temperature without any considerable changes in device performance. Hence, this study reveals that besides T g , the surface morphologies and thicknesses of the organic layers are also important factors in the annealing process and play a vital role in causing thermal damage to TEOLEDs. • Surface morphology variations with respect to temperature in the TEOLEDs. • The variation in optical and geometrical properties of organic layers depending on the thickness. • CBP, TCTA and NPB showing notable damage to the properties by thermal exposure. • The color purity of TEOLEDs was affected by micro-cavity after thermal exposure.

Comparative studies of variation in cutting conditions and cutter nomenclature on the surface morphology and the integrity of slot milled nimonic 263 alloy

Cutter nomenclature and machining conditions has invoke critical impact on the machining behavior and surface integrity of machined samples. In this investigation, the slot milling operation has been performed under various cutter terminology or nomenclature (cutter with the RRA of −7°, 0° and 7°) and cutting conditions (spindle speed, table feed and MQL flow rate) to analyze its resulting outcome on the surface morphological features such as surface roughness (Sa), skewness (S sk ) and kurtosis (S ku ), etc Because the examination of these characteristics are important and significant to analyze the behavioral changes of asperities such as decohesion, wear resistance and adhesion, etc during in its relative motion. Additionally, the plasticity index and surface morphology of machined samples are helps to predict the variation in surface morphology under various machining behavior and through this study, it is found that the interactive effect of MQL flow rate and table feed offer higher and significant impact over the surface characteristics followed by the MQL flow rate during slot milling process.

The growth of nitrosobenzene adlayers on an Au(111) surface: The effect of experimental parameters

Dimerization of nitrosobenzenes also occurs at metal-solution interface which enables the design of azodioxy self-assembled bilayers. Formation of self-assembled adlayers is a dynamic process, dependent on various parameters. To gain new insights into the key experimental parameters governing a complex process of on-surface self-assembly and dimerization of nitrosobenzenes, here we studied the growth of adlayers of nitrosobenzene derivatives containing thiocyanate headgroup for adsorption on an Au(111) as a function of solution concentration and adsorption time. Ellipsometry revealed an increase in film thicknesses with increasing solution concentration and adsorption times, suggesting formation of more ordered adlayers and a greater tendency towards bilayers. This was supported by AFM and STM microscopy which showed variations in local surface morphology of adlayers in dependence on experimental parameters. It was found that higher solution concentration and longer adsorption times lead to formation of more ordered separate domains which were attributed to monolayers and bilayers.

Fractal variation of three-dimensional surface topography during sliding wear under mixed elastohydrodynamic lubrication

The surface morphology variation of the friction pair during the wear process directly affects the local lubrication effect and contact strength, and this variation is difficult to quantify in mixed lubrication. In this study, a numerical simulation and characterization model method of sliding wear surface morphology evolution based on deterministic elastohydrodynamic lubrication (EHL) model and surface three-dimensional morphology fractal method is established. The effectiveness of the lubrication model is verified by the film thickness measurement, and the actual surface wear coefficient is obtained through the wear experiment. On this basis, the variation of surface morphology and fractal parameters in the sliding wear process is investigated, and the effect of contact load and sliding speed on surface lubrication characteristics and fractal parameters is analyzed. The results show: wear will cause the higher wave peaks on the ground surface to be gradually worn away and the fine structure of the surface is reduced, and the fractal dimension of the morphology is therefore reduced. In addition, the contact area ratio and contact load ratio, as well as the coefficient of friction and surface evolution under different loads and sliding speeds are consistent.