Abrasive Action Research Articles

Effects of oxidizer concentration and abrasive type on interfacial bonding and material removal in 4H-SiC polishing processes.

Determination of chemical effects involved in material removal during the polishing process of 4H-SiC has been a challenge. In this study, the polishing processes of 4H-SiC under the action of diamond and SiO2 abrasive in different concentrations of H2O2 solutions are investigated by reactive force field molecular dynamics simulations. It is found that 4H-SiC can be oxidized by H2O2 solution at the atomic scale, but the chemical reaction alone does not lead to material removal. An increase in the concentration of H2O2 solution and the mechanical action of abrasives can promote the oxidation of 4H-SiC. Since the mechanical removal dominates material removal when polishing 4H-SiC with diamond abrasive, there is no clear pattern in the effect of H2O2 solution concentration on material removal. Nevertheless, the removal of atoms associated with chemical bonds dominates material removal when polishing 4H-SiC with SiO2 abrasive. Therefore, the damage and atomic removal of 4H-SiC are lower. Since the H2O2 solution can increase the total number of bonds between 4H-SiC and SiO2 abrasive, an increase in the concentration of H2O2 solution can improve the material removal rate. These findings can provide guidance for the 4H-SiC polishing process in terms of abrasive and oxidizer selection.

Influence of cryogenic treatment and tempering temperature on microstructural evolution and dry sliding wear behavior of AISI D3 cold-work tool steel

Abstract AISI D3 cold work steel was shallow and deep cryogenically treated and double tempered at 150, 250, and 350 °C temperatures. Cryogenic processes transformed the retained austenite into martensite, while double tempering produced Fe, Cr, and W-rich carbides. The wear losses of cryogenically treated specimens decreased by up to 60% compared to conventionally heat-treated samples. Worn surfaces mainly experienced abrasive and adhesive wear mechanisms. Due to the formation of homogeneously dispersed fine carbides at 250 °C, oxidative wear occurred at the matrix phase, resulting in the lowest wear rate. The samples tempered at 150 °C suffered from the severe abrasive action of hard carbide particles, while the samples treated at 350 °C failed because of carbide coarsening.

Study on the damage mechanism of hydraulic concrete under the alternating action of freeze-thaw and abrasion

This study investigates the damage mechanism of hydraulic concrete under the alternating action of freeze–thaw (F) and abrasion (W) in cold regions. To this end, three groups of working conditions were established with a constant water-binder ratio. The mass loss and relative dynamic elastic modulus (RDEM) of each cycle were evaluated using the fast-freezing method and underwater method. The phase composition and relative content change of hydration products, pore characteristic parameters and pore size distribution, morphology and microstructure of interfacial transition zone (ITZ) were analyzed by X-ray diffraction (XRD), mercury intrusion porosimeter(MIP), scanning electron microscopyn (SEM) and image recognition technology, respectively. The results indicate that the alternating effect will accelerate the mass loss of concrete and the reduction of the RDEM compared with the single factor. Following four consecutive alternating cycles, the mass loss rates of working conditions W and F group were found to be 4.61 % and 97.66 % lower, respectively, than those of working condition F-W group. The RDEM damage coefficient (γ < 1) was also observed. At the micro level, the freeze-thaw effect will result in the formation of a considerable number of micropores and the expansion of microcracks, with the abrasion effect continuing to promote this process. In the process of alternating action, the dissolution of Ca(OH)2 by external water through microcracks and interconnected pores is accelerated. Concurrently, the pores and microcracks in the ITZ expand, the morphology is roughened, and the microstructure is complicated. The interfacial bonding ability and compactness of different material components decrease. Under the action of external disturbance, cement paste and aggregate fall off, resulting in mass loss and a decreased RDEM.

Effect of abrasion level on surface handling and thermal conductivity of blended suit fabrics

The tactile comfort of garments is of great interest for researchers to achieve their performance efficiently. This research aims to study the ability of blended worsted fabrics to be used as men’s suits by checking the thermal conductivity (k) and surface handling properties that are represented in surface roughness deviation (SMD), surface mean friction (MIU), and electrostatic properties before and after abrasion actions. Different levels of weft yarn counts (16 Ne and 24), weft density (19 and 21 per cm) and fabric weave structures (stripped twill 2/2 and stripped satin 4) were used. Abrasion weight loss percentage, thermal conductivity, surface roughness, and friction in warp and weft directions, and electrostatic properties were measured. Results showed that all the fabric factors studied are significant to affect abrasion weight loss percentages, thermal conductivity, and fabric roughness in the weft and warp directions. Fabric friction behavior follows the fabric roughness, but there is a difference between weft direction and warp direction. In addition, the fabrics achieved a reasonable resistance to form static charges after abrasion actions, and the fabric factors studied are not significant to affect the electrostatic properties except for abrasion cycles as P-value equals 0.03.

Material deformation and chip formation under single abrasive grain action

The purpose of the work is to determine the volume of material destroyed by a single grain (microasperity), which produces elastic and plastic deformation of the material when an abrasive tool interacts with the treated surface. To calculate the intensity of deformation of the plastically displaced material of the workpiece under the action of a single grain, the slip-line technique (method of characteristics) was used. To determine the volume of material destroyed by a single grain as a result of polydeformation when moving in the tangential direction, the following is determined: area of the deformed material; intensity of the shear deformation; speed of the shear deformation rate; number of plastic deformation cycles necessary for the destruction of the material in various zones of the sliding line field. The solution to these problems is found using the radii of curvature of the sliding lines in the physical planes and in the planes of the velocity hodographs for the meridional and normal to the axis planes of the grain section. The determination of the elastic deformation of the material is taken into account when calculating the roughness of the treated surface. Chip formation under the action of a single grain is considered taking into account the determination of the cross-sectional area of chips. This formed the basis for a determination of material removal during abrasive processing. The theoretical provisions for the determination of the above indicators are confirmed by experimental data. Thus, the studies carried out by the slip-line method formed a basis for determining the volume of plastically deformed material, the magnitude and rate of deformation under the action of a single grain, as well as the volume of the removed material as a result of repeated plastic deformation and in the form of chips. The performed investigation forms an integral part of studies into the process performance and roughness of the machined surface when finishing workpieces with elastic polymer-abrasive tools and free abrasive particles.

Deterioration of interfacial bonding performance between metal mortar and concrete under the coupling effect of freeze-thaw cycle and abrasion

In cold regions, hydraulic concrete structures are often severely damaged by the combined effects of freeze-thaw cycle and hydraulic abrasion, and it is critical for safe operation of the structure to repair the damage. The actions of freeze-thaw cycles (0, 25, 50, 75, 100, 125, and 150 cycles), abrasion (24, 48, 72, 96, 120, and 144 h), and the coupled action of freeze-thaw cycles and abrasion on the metal mortar-concrete interface were investigated. The apparent damage, mass loss, abrasion resistance, and interfacial splitting tensile and shear strengths of metal mortar-concrete are discussed. The changes in the bond properties of metal mortar-concrete interface were also investigated from a microscopic point of view. The results showed that the alternating action of freeze-thaw cycles and abrasion resulted in more apparent damage and mass loss, and the coupling damage became more pronounced as the number of alternations increased. The interfacial bond strength was reduced by 33.7 %–50.06 % under a single freeze-thaw or abrasion action. And interfacial bond strength decreases by 54.94 %–66.33 % under coupled freeze-thaw and abrasion. The interfacial splitting tensile and shear strengths have a good linear relationship under various actions (the correlation coefficients are higher than 0.97). The microscopic tests showed that the maximum width of the interface under the coupled action of freeze-thaw cycles and abrasion reaches 80–110 μm, which is significantly higher than the single action (30–45 μm).

Study of the wear resistance of hardened harrows of agricultural machines

The conducted research is devoted to the analysis of the wear resistance of materials used in reinforcing coatings of working bodies of agricultural machines subjected to friction under abrasive action in soil conditions. The aim of the study was to determine the degree of wear of the hardened teeth of the disc under the load of their impact on the soil in real operating conditions. The disk of a toothed harrow, which is a hardened working body of agricultural machinery, was used as an object of research. The individual teeth of this disc were the test samples. To increase the wear resistance of the teeth, a variety of reinforcing coatings were applied. The results of the study made it possible to comparatively evaluate the effectiveness of various reinforcing coatings and identify their effect on the wear resistance of the teeth of the disc. This study provides important data for further improvement of materials and technologies in agricultural engineering in order to increase the durability and efficiency of working bodies.

The choice of the magnetic abrasive action method for processing cutting plates

The existing methods of processing workpieces between two pole tips are described in detail. It is proved that the addition of movements in the process of magnetic abrasive treatment significantly increases the production capabilities, and the plates are obtained with a radius specified by technologists and other geometric parameters. The developed method and device make it possible to process plates on different machines and at different technological parameters. Graphs of the dependence of roughness, material removal and plate radius on processing parameters are described in detail. In conclusion, conclusions are drawn about the viability of the method, as well as the prospects for the development of the magnetic abrasive treatment method. Key words. Operating surfaces, regular microgeometry, material removal per unit area, magnetic abrasive polishing, rounding of the tool cutting edge, two-pole tips

Machinability and tool wear studies on AZ91/B4C metal matrix composites using uncoated and CVD diamond coated WC-Co turning inserts

AZ91/B4C metal matrix composites (MMCs) comprising three different amounts of B4C particulates, 12, 18, and 24 wt% were fabricated using a melt stirring-squeeze casting technique. Machinability studies were conducted on the cast composites using uncoated and CVD diamond coated WC-Co turning inserts. The tool life of these turning inserts was calculated at different cutting speeds of 30, 60, and 90 m/min. Results revealed that with the increasing cutting speed, the surface roughness of the MMCs decreased and the magnitude of the main cutting forces increased. The increased magnitude in the cutting speed and particle proportion significantly reduced the tool life. The abrasive action of the hard B4C particles caused severe tool wear during the machining of AZ91–12%B4C, AZ91–18%B4C, and AZ91–24%B4C composite materials. From the tool flank wear results, it was evident that diamond coated inserts outperformed uncoated WC-Co inserts at all machining conditions. The tool life of the CVD diamond coated insert at the cutting speed of 30 m/min was found to be the highest.

The effect of mechanical action on the release of microplastic fibers during washing

The release of microplastic fibers (MPFs) during washing is the main source of microplastic pollution in water environment. Mechanical action is the principle factor affecting the release of MPFs during washing. In order to better understand the effect of washing mechanical action on the release of MPFs, a washing simulation device was designed to study the effects of abrasion action, hydrodynamic flow action and beating action on the release of MPFs. The results show that there is a certain amount of floating MPF in the fabric due to the production process. The floating MPFs can be released in large quantities even though the mechanical action is weak, accounting for about 28% of the total MPF release. In addition, the release of secondary MPFs increases with the mechanical action. The increase of the abrasion times between fabric and fabric has the most significant effect on the release of MPFs. Compared with 60 abrasion times, the number of MPFs increased by about 16% and the average length decreased by 40% when abrasion was 5000 times. This study enhances the understanding of how mechanical action during washing affects the release of MPFs. This emphasizes the impact of floating MPFs, as well as the need to optimize the washing process to reduce the emission of MPFs.

Modelling and simulation of MRR in electro-chemical surface grinding of Al-SiC-Gr using hybrid analytical approach

Electro-Chemical Surface Grinding (ECSG) is a hybrid machining process which utilizes synergic actions of three sub-processes viz. electrochemical dissolution, grinding action of abrasive particles and erosive action of electrolyte flow in inter electrode gap. Since, occurrence of turbulence in machining zone significantly affects the machining performance, it is required to analyze the turbulence phenomenon in ECSG process. The exact solution and Numerical solution–based hybrid analytical approach has been used to predict the Material Removal Rate (MRR) in ECSG of Al-SiC-Gr. In this model, the streaming potential of electrolytic action, abrasive action of grinding wheel and shear force of electrolyte flow between inter electrode gap have been considered. Finite Element Method based Numerical modelling has been carried out to analyze the electrolyte flow in machining zone in order to evaluate the MRR due to erosive action. It was observed that the application of shear force on oxide layer rises with the increase in flow rate of electrolyte. Confirmation experiment has been performed to validate the modelling results. Validation results show a minor error of 8.21% in prediction of MRR using analytical as well as finite element model.

Technological Principles of Complex Plasma-Beam Surface Treatment of Al2O3/TiC and SiAlON Ceramics

Thermomechanical action during high-performance diamond grinding of sintered cutting Al2O3/TiC and SiAlON ceramics leads to increased defectiveness of the surface layer of the deposited TiZrN and CrAlSiN/DLC coatings. It predetermines the discontinuous and porous coatings and reduces its effectiveness under abrasive exposure and fretting wear. The developed technological approach is based on “dry” etching with beams of accelerated argon atoms with an energy of 5 keV for high-performance removal of defects. It ensures the removal of the defective layer on ceramics and reduces the index of defectiveness (the product of defects’ density per unit surface area) by several orders of magnitude, compared with diamond grinding. There are no pronounced discontinuities and pores in the microstructure of coatings. Under mechanical loads, the coatings ensure a stable boundary anti-friction film between the ceramics and counter body that significantly increases the wear resistance of samples. The treatment reduces the volumetric wear under 20 min of abrasive action by 2 and 6 times for TiZrN and CrAlSiN/DLC coatings for Al2O3/TiC and by 5 and 23 times for SiAlON. The volumetric wear under fretting wear at 105 friction cycles is reduced by 2–3 times for both coatings for Al2O3/TiC and by 3–4 times for SiAlON.

Dual composite architectonics: Behavior of ZrB2–SiC–TaB2 composites under abrasive conditions

The influence of abrasive impact on ZrB2–SiC–TaB2 ceramic composites with homogeneous distribution of components in ZrB2 matrix and with «dual composite » structure (ZrB2–SiC)-(TaB2–SiC) has been studied. It was shown that at the same content of components the abrasive wear of the ceramic with the «dual composite » structure is significantly less than that of the composite with homogeneous distribution of single-phase components in a single-phase matrix. On the surface of the studied composites there were no furrows and grooves typical for the abrasive action on the material. At abrasive impact on ceramic composite with homogeneous distribution of components there was a formation of subsurface cracks with the subsequent tearing off of material segments with the size exceeding the size of inclusions in the matrix. Abrasive wear of ceramics with the «dual composite » structure at a high content of composite inclusions occurs by "erosion" of the matrix at the interface with composite inclusions with subsequent removal of inclusions. Composites with «dual composite » structure had higher residual strength compared to ceramic with homogeneous distribution of components. It was found that the difference in the character of abrasive wear of composites is largely in relation to the distribution of residual stresses formed due to the difference in the thermal linear expansion coefficients of the components.

Mechanical properties and abrasion resistance of polyurethane mortar subjected to freeze–thaw cycles and sulfate attack

The objective of this paper is to investigate the properties of polyurethane mortar subjected to freeze–thaw cycles in sulfate environment. Na2SO4 solutions with 5% and 10% sulfate concentrations were prepared. The mass loss, compressive strength, flexural strength and abrasion resistance of the polyurethane mortar were investigated. The interface transition zone and pore structure were then analysed. Results revealed that the damage degree of the mass, compressive strength and flexural strength of polyurethane mortar subjected to freeze–thaw cycles in sulfate solution are greater than that in water, and the high concentrations of sulfate solution can cause severe damage. The polyurethane mortar subjected to freeze–thaw cycles and sulfate attack will appear to have more severe surface damage after abrasion. The abrasion resistance of polyurethane mortar decreases as the freeze–thaw cycles and abrasion time increase. The freeze–thaw cycles and sulfate attack can cause the crack width at the interface transition zone of polyurethane mortar to expand, and the abrasion action accelerates this evolution. With the increase in freeze–thaw cycles, the gel and transition pores are gradually transformed into capillary and large polyurethane mortar pores. The volume fraction of capillary and large pores gradually increases, and the fractal dimension tends to decrease. Furthermore, the fractal dimension of the pore structure is positively correlated with mechanical properties and abrasion resistance. The mechanism analysis shows that abrasion can cause the detachment of loose mortar matrix of polyurethane mortar surface and form a weak area.

Technological principles for removal of defective surface layer on grinded ceramic products by etching with accelerated argon

The article describes the technological principles and equipment for “dry” ion-plasma etching of the surface layer of SiAlON dielectric ceramics and subsequent deposition of (TiAl)N coatings. The proposed approach made it possible to ensure the high-performance removal of a defective layer formed during diamond grinding from the ceramic samples’ surface. Accelerated argon atoms with an energy of 5 keV are used as a source of energy impact on ceramic samples, which bombard the surface layer and ensure its sputtering at a rate of 9 μm/h. It is shown that the (TiAl)N coating deposition on ceramic samples after the preliminary removal of the defective layer reduces the volumetric wear under abrasive action by a factor of 2.6 compared to the initial samples subjected to diamond grinding.

The Noise of Rail Transport

The research examines the sources of rail transport noise. Noise depends on the type of locomotives, warning signals, maintenance, and construction equipment. The wheel–to–rail contact of the rolling stock and the locomotives’ propulsion systems are the noise sources. Static and dynamic loads have intensities that depend on the masses and speeds of the trainsets. In addition, static, dynamic loads of the rolling stock, thermal loads, and the action of rainwater stress the ballast. The stresses lead to tensions on the rail that can affect fatigue, wear and tear, and railway line maintenance. Fatigue and wear are related to the intensity of traffic rail traffic, developing an abrasive action of the wheels on the rail and contributing to rail-to-rail misalignment concerning the underlying ballast.

Acaricidal Biominerals and Mode-of-Action Studies against Adult Blacklegged Ticks, Ixodes scapularis.

Ticks in the USA are the most important arthropod vector of microbes that cause human and animal disease. The blacklegged tick, Ixodes scapularis, the focus of this study, is able to transmit the bacteria that causes Lyme disease in humans in the USA. The main approach to tick control is the use of chemical acaricides and repellents, but known and potential tick resistance to these chemicals requires the discovery of new methods of control. Volcanic glass, Imergard, was recently developed to mimic the insecticide mode of action of the minerals from diatoms (diatomaceous earth, DE) for the control of malaria mosquitoes in Africa. However, studies on the use of these minerals for tick control are minimal. In a dipping assay, which was put into DE (Celite), the times of 50 and 90% death of adult female I. scapularis were 7.3 and 10.5 h, respectively. Our mimic of DE, Imergard, killed ticks in 6.7 and 11.2 h, respectively. In a choice-mortality assay, ticks moved onto a treated surface of Imergard and died at 11.2 and 15.8 h, respectively. Ticks had greater locomotor activity before death when treated by dipping for both Imergard and Celite versus the no-mineral control. The ticks after making contact with Imergard had the mineral covering most of their body surface shown by scanning electron microscopy with evidence of Imergard inside their respiratory system. Although the assumed mode of action of Imergard and Celite is dehydration, the minerals are not hygroscopic, there was no evidence of cuticle damage, and death occurred in as little as 2 h, suggesting minimal abrasive action of the cuticle. Semi-field and field studies are needed in the future to examine the practical use of Imergard and Celite for tick control, and studies need to examine their effect on tick breathing and respiratory retention of water.

Influence of aging heat treatment at 180 °C on cavitation erosion for aluminum alloy type 5083 in cold rolled state

Aluminum-based alloys have wide applicability in the construction of aircraft, vehicles, and ships. Some of their components, during operation, such as the radiators and the rotors of the cooling pumps in the vehicles, and the propellers of fishing and pleasure boats are affected by the abrasive, chemical and cavitational corrosive action of the water. At certain hydrodynamic flow regimes, the most dangerous becomes the corrosion through cavitation. Operation in such regimes inevitably leads to damaging the structure, due to cyclic stresses of the micro-jets and shock waves generated by the implosion of cavitation bubbles. Although the chemical constitution and alloying with other chemical elements increase the mechanical properties, the service life is still limited when operating in high-intensity cavitation flows. Therefore, researchers are looking for solutions to improve this resistance through various treatments, such as bulk heat. Research heading the same direction, but, made on 5083 alloy, is presented in this paper. The results highlight the behavior of a modified structure compared to the semi-fabricated state (obtained by rolling), through three durations regimes (one hours, 12 hours and 24 hours) of aging heat treatment to 180 °C temperature, after hardening treatment at 450 °C. The cavitation tests were performed in the Laboratory of the Polytechnic University of Timisoara, on the standard vibrating device with piezoceramic crystals. The results were expressed by curves and parameters specific to the evaluation of cavitation resistance, and by macro and microscopic images, showing the unique aspects of the connection between the structure and the mechanical properties obtained through heat treatment regimes. Thus, comparison of the results, including with the delivery state (laminated product), shows that the highest resistance is provided by the treatment at 24 hours. At the same time, the erosion, of pitting and caverns type, and differs from one structure to another.

Surface Enhancement of Additively Manufactured Bone Plate Through Hybrid-Electrochemical Magnetorheological Finishing Process.

Additive manufacturing or 3D printing provides the benefits of individualizing the implant per patient requirements. However, the poor surface quality of additively manufactured biomaterial is a major limitation. Hence, hybrid-electrochemical magnetorheological (H-ECMR) polishing is developed to improve the surface quality of fabricated parts. H-ECMR finishing is an advanced surface polishing operation that avails the synergic action of mechanical abrasion and the electrochemical reaction to enhance the surface quality of the workpiece without hampering its surface topography. Furthermore, the developed H-ECMR finishing process reduces the finishing time and produces a uniform surface quality compared with the conventional magnetorheological (MR) finishing process. However, the surface finishing of the parts having a hole-of-pocket feature through the H-ECMR finishing process is a major challenge as MR fluid gets trapped inside those holes or pockets. A feature-based hybrid H-ECMR finishing process is developed to resolve the issue. In this case, paraffin wax is applied to the holes and pockets before the H-ECMR process occurs. In the present work, bone plates are fabricated through selective laser melting, and their surface quality is further enhanced through the H-ECMR finishing process. Bone plates are necessary to provide mechanical stability during bone fracture healing by adapting to the chemical environment. The final Ra value of 21.37 nm is attained from 9.36 μm through H-ECMR finishing. Pin-on-disk study is carried out on the biomaterial to analyze its wear resistance. The surface topography of the workpiece is analyzed through scanning electron microscopy before and after finishing, and it was observed that a uniform surface is achieved after polishing. Apart from the average surface roughness (Ra ), other roughness parameters such as skewness (R sk) and kurtosis (R ku) are analyzed to study the attribute of the surface irregularities.

Morphodynamic Types of the Laptev Sea Coast: A Review

The Laptev Sea coast has a unique high-latitude and dynamic landscape. The presence of low-temperature permafrost (below −7 °C) and its high ice content (up to 90%) determine a wide array of permafrost landforms and features. Under the actions of thermal abrasion and thermal denudation, high rates of coastal retreat are evident within this region. Local differences in the geological structure and sea hydrodynamic conditions determine the diversity of this sea coast’s types. In this review, we present the results of a morphodynamic classification and segmentation of the Laptev Sea coast. The integrated approach used in the classification took into account the leading relief-forming processes that act upon this coastal zone. The research scale of 1:100,000 made it possible to identify and characterize the morphologies of the coast and their spatial distributions within the study area. The presented original classification can be considered to be universal for the eastern Arctic seas of Eurasia; it may be used as a basis for further scientific and applied research.