Observation Of Surface Topography Research Articles

Effects of carbon content and heat treatment on wear-resistance and impact properties of novel cast steels with bainitic and martensitic structure

Abstract The traditional material for caterpillar boards is mainly Hadfield steel. The wear resistance of the Hadfield steel cannot be fully exerted due to insufficient work hardening during the operation of the caterpillar board. The effects of carbon content and heat treatment on the wear-resistant and impact properties of a novel caterpillar board cast steels with bainitic and martensitic structures have been investigated. The microstructural observation of worn surface topography was performed by scanning an electronic microscope, and the impact toughness was carried out by an impact tester, in a bid to improve the wear-resistant properties and its impact toughness. The results demonstrate that the hardness and wear-resistant properties of cast steels increase with the increase of carbon content, whereas the impact properties reduce because the brittle phases, such as the carbide precipitation and the martensite, are more. The heat treatment temperature of steels can change the relative ratio of bainitic and martensitic structures, thus affecting the wear-resistant properties of the steels. By controlling the carbon content and heat treatment processing of the steels, the optimal combination of toughness and wear-resistant properties can be achieved. The wear mechanism of dual-phase cast steel was analyzed through wear resistance tests, and it also shows that dual-phase cast steel with bainitic and martensitic structures had better wear-resistance properties compared to the Hadfield steel at low-impact wear conditions.

A new accelerated thermal fatigue experiment method of pistons and its application

This study proposed a new test method to take the piston instead of the internal combustion engine as the experimental object and use electromagnetic induction heating and auxiliary cooling to simulate the actual operating conditions of the piston during engine start-stop, to achieve accurate control of the temperature of the heating and cooling cycles. The experimental process can be accelerated by worsening the service conditions. In order to prove the feasibility of this scheme, the temperature field distribution, fatigue life, and failure mode of the piston are compared and analyzed using finite element simulation, theoretical calculation, and surface topography observation. The results show that the error between the simulated temperature value of the key point of the piston and the experimental value of the actual operating condition is less than 5%, the position and value of the maximum temperature of the piston under the thermal fatigue test condition are consistent with the actual engine operating condition, the error between the fatigue life test results and the theoretical calculation results is less than 10%, and the location and cracking mode of the main crack is consistent with the actual working condition. It is proved that the test method is reasonable and feasible, which can provide an important guarantee for the fast and efficient design of high-performance pistons.

Incorporation of cellulose nanocrystals to improve the physicochemical and bioactive properties of pectin-konjac glucomannan composite films containing clove essential oil

This study aimed to investigate the effectiveness of cellulose nanocrystals (CNC) isolated from cotton in augmenting pectin (PEC)/konjac glucomannan (KGM) composite films containing clove essential oil (CEO) for food packaging application. The effects of CNC dosage on film properties were examined by analyzing the rheology of film-forming solutions and the mechanical, barrier, antimicrobial, and CEO-release properties of the films. Rheological and FTIR analysis revealed the enhanced interactions among the film components after CNC incorporation due to its high aspect ratio and abundant hydroxyl groups, which can also prevent CEO droplet aggregation, contributing to form a compact microstructure as confirmed by SEM and 3D surface topography observations. Consequently, the addition of CNC reinforced the polysaccharide matrix, increasing the tensile strength of the films and improving their barrier properties to water vapor. More importantly, antibacterial, controlled release and kinetic simulation experiments proved that the addition of CNC could further slow down the release rate of CEO, prolonging the antimicrobial properties of the films. PEC/KGM/CEO composite films with 15 wt% CNC was found to have relatively best comprehensive properties, which was also most effective in delaying deterioration of grape quality during the storage of 9 days at 25 °C.

Operando Nanomechanical Mapping of Amorphous Silicon Thin Film Electrodes in All-Solid-State Lithium-Ion Battery Configuration during Electrochemical Lithiation and Delithiation.

An operando bimodal atomic force microscopy system was constructed to perform nanomechanical mapping of an amorphous Si thin film electrode deposited on a Li6.6La3Zr1.6Ta0.4O12 solid electrolyte sheet during electrochemical lithiation/delithiation. The evolution of Young's modulus maps of the Si electrode was successfully tracked as a function of apparent Li content x in lithium silicide (LixSi) simultaneously with real-time surface topography observation. At the initial stage of lithiation, the average modulus steeply decreased due to the generation of LixSi from intrinsic Si, followed by a moderate modulus reduction until the electrode capacity reached 3300 mAh g-1 (Li content x = 3.46). In the following delithiation, the gradual recovery of the average modulus of LixSi was observed up to 1467 mAh g-1 (Li content x = 1.54) at which delithiation stopped due to the significant volume change induced by phase transformation of LixSi.

Bistatic Rough Surface Scattering at P-Band in Grand Mesa Based on Lidar Observations of Surface Roughness and Topography

Bistatic Rough Surface Scattering at P-Band in Grand Mesa Based on Lidar Observations of Surface Roughness and Topography

Synergistic effect between cavitation erosion and corrosion of Monel K500 alloy in 3.5 wt% NaCl solution

Cavitation erosion-corrosion simultaneously damaged the material through mechanical attack and electrochemical corrosion. In this work, experiments were performed on Monel K500 alloy in deionized water and 3.5 wt% NaCl solution using an indirect ultrasonic vibration system to investigate the synergistic effect between cavitation erosion and corrosion. Mass loss measurement and surface topography observation were used to identify the different stages of cavitation erosion. The electrochemical properties at different cavitation stages were analyzed by EIS technique. Results showed that the synergistic effect between cavitation erosion and corrosion exacerbated cavitation damage, and the weight loss rate in 3.5 wt% NaCl solution was about 10% higher than that in deionized water. The increase in ion diffusion and oxygen supply caused by violent agitation accelerated the surface corrosion process, resulting in corrosion-enhanced erosion. Mechanical damage to the material surface during the cavitation process also accelerated the corrosion process, indicating that cavitation-enhanced corrosion was the primary synergistic mechanism. Pure cavitation accounted for 90.75% of total mass loss, suggesting that mechanical deterioration dominated the overall cavitation erosion and corrosion process. Cavitation-enhanced corrosion accounting for 96.12% of the synergistic effect，was the main synergistic mechanism.

Influence of Inorganic Additives on the Surface Characteristics, Hardness, Friction and Wear Behavior of Polyethylene Matrix Composites.

The aim of this research was to analyze the effect of inorganic additives on the tribological properties of the high-density polyethylene (HDPE) matrix composite surface. Titanium (Ti) and hexagonal boron nitride (hBN) were added in different mass fractions. The samples were produced by pressing a pre-prepared mixture of granules. The composite samples with the following mass fractions of additives were fabricated: 5% hBN, 10% hBN, 28% Ti-2% hBN, 23% Ti-7% hBN, and 20% Ti-10% hBN. An even distribution of individual additives' concentrations was confirmed. Observations of morphology, surface topography, hardness, and tribological measurements were conducted using reciprocating motion tests with the "pin-on-flat" and rotational tests with the "pin-on-disc" configuration. Subsequently, microscopic observations and measurements of the wear track profile were carried out. Additionally, geometry parameters of the contacting elastic body were calculated for various counter-samples. It was found that the Shore D hardness of samples containing Ti and hBN increased with the Ti content, while the coefficient of friction (COF) value decreased. The addition of hBN alone did not significantly affect the hardness, regardless of the ratio, while the COF increased with the increasing hBN content. The COF value doubled with the addition of 10% hBN (COF = 0.22), whereas the addition of 90% Ti-10% hBN resulted in a decrease in the COF value, to COF = 0.83. The highest hardness value was obtained for the sample containing 28% Ti-2% hBN (66.5), while the lowest was for the sample containing 10% hBN (63.2). The wear track analysis, including its height and width caused by deformation, was detected using a focal differentiation microscope and scanning electron microscopy. Additionally, EDS maps were generated to determine the wear characteristics of the composite.

Using the Rods as Collector and Study of its Effect on Morphology and Uniformity of Nanofibers via Electrospinning

Nanotechnology research has lacked to provide new studies on nanofibers using the electrospinning method, the reasons are attributed that all parameters have been covered by previous studies. Believing that science is in a state of constant renewal leads to the possibility to study a parameter that has not been studied before, which affects the morphology of nanofibers. One of the disadvantages of nanofibers manufacturing is the formation of beads, and controlling the parameter helps reduce these beads. Field emission scanning electron microscope (FESEM) images reveal the formation of nanofibers and surface topography observations by atom force microscopy (AFM) indicates that the roughness is improved by changing the distance between rods of the collector. The rods function as a collector for nanofibers, changing this parameter improves the morphology and diameter of the nanofibers.

Development and printability of diamond-containing composite filament for material extrusion

PurposeMaterial extrusion technology is considered to be an effective way to realize the accurate and integrated manufacturing of high-performance metal diamond tools with complex structures. The present work aims to report the G4 binder that can be used to create metal composite filament loading high concentrations of large diamond particles through comparative experiments.Design/methodology/approachThe quality of filaments was evaluated by surface topography observation and porosity measurement. And the printability of filaments was further studied by the tensile test, rheological test, shear analysis and printing test.FindingsThe results show that the G4 binder exhibits the best capacity for loading diamonds among G1–G4. The L4 filament created with G4 has no defects such as pores, cracks and patterns on the surface and section, and has the lowest porosity, which is about 1/3 of the L1. Therefore, the diamond-containing composite filament based on G4 binder exhibits the best quality. On the other hand, the results of the tensile test of L5–L8 filaments reveal that as the diamond content increases from 10% to 30%, the tensile strength of the filament decreases by 29.52%, and the retention force coefficient decreases by 15.74%. This can be attributed to the formation of inefficient bonding areas of the clustered diamond particles inside the composite filament, which also leads to a weakening of the shear strength. Despite this, the results of the printing test show that the diamond-containing composite filament based on the G4 binder has reliable printability.Originality/valueTherefore, the G4 binder is considered to solve the most critical first challenge in the development of diamond-containing filament.

Ultrastructure, surface topography, morphology and histological observations of a new parasitic cnidarian of the marbled swamp eel from the world's largest tropical wetland area, Pantanal, Brazil

Myxosporeans are a diverse group of microscopic cnidarians of wide distribution that evolved into a parasitic lifestyle. A new myxosporean species, Myxobolus sp., is herein described infecting the mandible of wild specimens of Synbranchus marmoratus, caught in the world's largest tropical wetland area, Pantanal, Brazil. Light, scanning, transmission electron microscopy and histological observations unveiled detailed taxonomic information of the new myxosporean cnidarian. Ultrastructural analysis revealed a detailed description of plasmodia structures which can be used for comparison with plasmodia from other species of myxobolids. Both histological and ultrastructural observations evidenced a connective tissue capsule surrounding the plasmodia of Myxobolus sp. as a histopathological host reaction to the infection of this parasitic cnidarian. Histology showed that tissue tropism of the new myxosporean occurs in a well-defined part of the mandible, with development of plasmodia occurring in the epidermis layer. Mature myxospores from the valvular view featured an ovoid shape and had a short prolongation of the spore valves in the posterior end. Myxospores measured 22.7 ± 1.2 µm (21.5–23.9 µm) in length, 12.5 ± 0.4 µm (12.1–12.9 µm) in width and 11.3 ± 0.5 (10.8–11.8 µm) in thickness. Polar capsules were pyriform equally-sized and measuring 4.6 ± 0.3 µm (3.9–4.3 µm) in length and 2.9 ± 0.1 µm in width (2.8–3.0 µm). Finally, this study substantiates the still hidden myxosporean diversity from South America.

Laser assisted surface conditioning of a residual pattern on single crystal silicon induced by ultra-precision cutting

Fabrication of a silicon lens using an ultra-precision machining tool generates a periodic cutting texture, which can cause light diffraction and scattering, resulting in a significant degradation of the optical performance. This phenomenon usually appears in the form of rainbow patterns. In this study, a single-crystal silicon wafer, after diamond turning, is polished by a nanosecond laser mounted on a four-axis ultra-precision machine lathe. It’s found that the rainbow pattern has been effectively eliminated after laser irradiation through the observation of surface topography. Effects of defocus, scanning velocity, and pitch on polishing were investigated. This polishing method is able to obtain surface roughness Sa better than 1 nm for silicon surface without removing or adding material to the workpiece, and high throughout can be achieved through easy integration with the existing cutting process.

The Influence of Blade Type and Feeding Force during Resin Bonded Dentin Specimen Preparation on the Microtensile Bond Strength Test.

This paper presents the effect of blade type and feeding force during resin-bonded dentin specimen preparation on the microtensile bond strength (μTBS) test. Forty resin-bonded flat middle dentin specimens were divided into four groups. The specimens of each group were sectioned according to type of blade and feeding force as follows: fine grit/20 N, fine grit/40 N, medium grit/20 N, and medium grit/40 N to obtain resin-dentin sticks with a cross-sectional area of 1.0 mm2. Four sticks from the center of each tooth were subjected to the μTBS test. Five remaining sticks of each group were selected for surface topography observation under a scanning electron microscope (SEM). As a result, the bond strength of the medium-grit group was higher than that of the fine-grit group (p < 0.001), whereas the feeding force had no influence on bond strength values (p = 0.648). From the SEM, sticks prepared with the fine-grit blade showed a smoother surface integrity and fewer defects on the specimen edges in comparison with the sticks prepared with the medium-grit blade. The grit type of the blade is one of the considerable factors that may affect the bond strength and the surface integrity of resin-dentin specimens for microtensile testing.

Roles of pH in the NH4+-induced corrosion of AZ31 magnesium alloy in chloride environment

Corrosion behavior of AZ31 magnesium alloy in NH 4 + -bearing chloride solution with controlled pH was investigated by weight loss experiment, hydrogen collection, and electrochemical test combined with surface morphology and topography observation. The results show that NH 4 + and pH of the solution can affect the corrosion of AZ31 magnesium alloy. The existence of NH 4 + affects the formation and dissolution of corrosion products, which makes the protective effect of the corrosion product layer weaker. The change of pH value not only affects the corrosion mechanism of AZ31, but also alters the concentration of NH 4 + ions in the solution, which further influences the corrosion product layer of AZ31, and finally makes the corrosion of AZ31 change significantly.

Motion bias analysis of sea surface height measurement by near-nadir interferometric Synthetic Aperture Radar (SAR) and its compensation method research

ABSTRACT High-precision observation of ocean surface topography is of great significance in studying the ocean mesoscale and sub-mesoscale processes. Spaceborne near-nadir interferometric synthetic aperture radar (InSAR) is capable of measuring sea surface height with centimetre-level accuracy and over a wide swath. It differs from terrestrial height measurement because the constant movement of the dynamic ocean surface creates biases in synthetic aperture radar imaging and leads to height measurement inaccuracy. This study investigates the bias due to the motion of ocean surface waves and establishes a theoretical model of the height measurement motion bias related to the ocean wave spectrums and InSAR system parameters. The motion bias model was simulated in different SAR modes, including Stripmap and Terrain Observation by Progressive Scans (TOPS) modes in various oceanic states. The results showed that the motion biases are smaller in Stripmap mode than TOPS mode under the same oceanic conditions. By adopting the total zero steering technology in Stripmap mode, the motion bias can be significantly decreased. In the same oceanic state, the motion bias increases with increasing angle of incidence. In the TOPS mode, the Doppler centroid frequency of the antenna’s signal changes linearly with the azimuth time, and thus, the biases change significantly in the azimuth direction. The motion bias model is validated by the interferometric full-link experimental simulation and the results are consistent with the theoretical values. This study provides a compensation method with millimetre level accuracy to compensate for the height measurement bias caused by sea surface motion. The theoretical derivation of motion bias models and simulation results provide feasible suggestions for the design of InSAR systems and bias compensation for sea surface height measurement.

Thermocapillary Marangoni Flows in Azopolymers.

It is well known that light-induced multiple trans-cis-trans photoisomerizations of azobenzene derivatives attached to various matrices (polymeric, liquid crystalline polymers) result in polymer mass movement leading to generation of surface reliefs. The reliefs can be produced at small as well as at large light intensities. When linearly polarized light is used in the process, directional photo-induced molecular orientation of the azo molecules occurs, which leads to the generation of optical anisotropy in the system, providing that thermal effects are negligible. On the other hand, large reliefs are observed at relatively strong laser intensities when the optofluidization process is particularly effective. In this article, we describe the competitive thermocapillary Marangoni effect of polymer mass motion. We experimentally prove that the Marangoni effect occurs simultaneously with the optofluidization process. It destroys the orientation of the azopolymer molecules and results in cancelation of the photo-induced birefringence. Our experimental observations of polymer surface topography with atomic force microscopy are supported by suitable modelings.

Optical image amplification in dual-comb microscopy

Dual-comb microscopy (DCM), based on a combination of dual-comb spectroscopy (DCS) with two-dimensional spectral encoding (2D-SE), is a promising method for scan-less confocal laser microscopy giving an amplitude and phase image contrast with the confocality. However, signal loss in a 2D-SE optical system hampers increase in image acquisition rate due to decreased signal-to-noise ratio. In this article, we demonstrated optical image amplification in DCM with an erbium-doped fiber amplifier (EDFA). Combined use of the image-encoded DCS interferogram and the EDFA benefits from not only the batch amplification of amplitude and phase images but also significant rejection of amplified spontaneous emission (ASE) background. Effectiveness of the optical-image-amplified DCM is highlighted in the single-shot quantitative nanometer-order surface topography and the real-time movie of polystyrene beads dynamics under water convection. The proposed method will be a powerful tool for real-time observation of surface topography and fast dynamic phenomena.

AFM Characterization of Stir-Induced Micro-Flow Features within the AA6082-T6 BFSW Welds

Bobbin Friction Stir Welding (BFSW) is a thermomechanical process containing severe plastic deformation by mechanical stirring and Dynamic Recrystallization (DRX) during recooling. Here we report the three-dimensional characteristics of the micro-flow patterns within the aluminium weld structure. The Surface topography observations by Atomic Force Microscopy (AFM) show the stirred-induced microstructural evolution where the rearrangement of dislocations at the sub-grain scale, and the subsequent High- and Low-Angle Grain Boundaries (HAGBs, LAGBs) exhibit specific alterations in grain size and morphology of the weld texture. The dislocations interaction in different regions of the weld structure also was observed in correlation to the thermomechanical behaviour of the BFSW process. These micro-flow observations within the weld breadth give a new insight into the thermomechanical characteristics of the FSW process during the stirring action where the plastic flow has a key role in the formation of the weld region distinct from the base metal.

The utilization of activated carbon as micronutrients carrier in slow release fertilizer formulation

In many plantations, fertilizers were often added in high dosage and applied several times to get maximum productivity. But processes in soil caused not all nutrients in fertilizer could be uptaken by plants. Besides, the high dosage can be toxic to plants. The use of slow release fertilizer can overcome this case. This research was aimed to obtain the data of adsorptive capacity of activated charcoal to the nutrients mixed and gathering the information about nutrients release rate of fertilizer produced. The study was conducted by converting materials into activated charcoal. SRF was formulated by soaking fine activated charcoal CuSO4, FeSO4 or ZnSO4 solution for 24 hours. Analysis conducted were the observation of surface topography, qualitative analysis using EDX, and determination of total Cu, Fe and Zn in SRF. The optimal treatment was chosen to determine its release rate by extracting fertilizer with distilled water and 2% citric acid. The results showed the activated charcoal could be used to adsorb nutrients mixed as shown by SEM and EDX results. Nutrients in the charcoal could be released slowly and could not be easily leached out.

Global Observations of Fine-Scale Ocean Surface Topography With the Surface Water and Ocean Topography (SWOT) Mission

The future international Surface Water and Ocean Topography (SWOT) Mission, planned for launch in 2021, will make high-resolution 2D observations of sea-surface height using SAR radar interferometric techniques. SWOT will map the global and coastal oceans up to 77.6° latitude every 21 days over a swath of 120 km (20 km nadir gap). Today’s 2D mapped altimeter data can resolve ocean scales of 150 km wavelength whereas the SWOT measurement will extend our 2D observations down to 15-30 km, depending on sea state. SWOT will offer new opportunities to observe the oceanic dynamic processes at these scales, that are important in the generation and dissipation of kinetic energy in the ocean, and act as one of the main gateways connecting the interior of the ocean to the upper layer. The active vertical exchanges linked to these scales have impacts on the local and global budgets of heat and carbon, and on nutrients for biogeochemical cycles. This review paper highlights the issues being addressed by the SWOT science community to understand SWOT’s very precise SSH / surface pressure observations, and it explores how SWOT data will be combined with other satellite and in-situ data and models to better understand the upper ocean 4D circulation (x,y,z,t) over the next decade. SWOT’s new SAR-interferometry technology aims to observe ocean SSH scales down to 15-30 km in wavelength. At these scales, SSH includes “balanced” geostrophic eddy motions and high-frequency internal tides and internal waves. This presents both a challenge in reconstructing the 4D upper ocean circulation, or in the assimilation of SSH in models, but also an opportunity to have global observations of the 2D structure of these phenomena, and to learn more about their interactions. At these small scales, the ocean dynamics evolve rapidly, and combining SWOT 2D SSH data with other satellite or in-situ data with different space-time coverage is also a challenge. SWOT’s new technology will be a forerunner for the future altimetric observing system, and so advancing on these issues today will pave the way for our future.

Testing and evaluation of adhesive bonded joints of unreinforced and glass fiber–reinforced polyoxymethylene treated with low-pressure plasma

The effect of surface treatment of polyoxymethylene (POM) using low-pressure plasma (LPP) on its adhesive bonding was investigated. Three different types of adhesives were used. Examinations of single lap shear, scanning electron microscopy, contact angle measurements, and energy dispersive X-ray analysis were carried out. The results showed that the adhesion strength was apparently enhanced when treating surfaces by LPP using argon or oxygen plasma which increased with the treatment time. This increase was also dependent on the adhesive type. Moreover, glass fiber–reinforced POM showed better adhesion strength compared to that of unreinforced POM. An increase in the surface free energy exceeding 50 mN/m was observed after 600-s treatment time compared to untreated samples (39 mN/m), where the increase in polar component was more predominant. Surface topography observations showed a significant increase in the surface roughness with increasing the treatment time, mainly when using oxygen plasma. Finally, an increase in polarity and wettability due to changes in the chemical composition of the surface was also reported.