Concentration Of Abrasive Particles Research Articles

Experimental Investigation on Chemical Mechanical Polishing of ZA27 Alloy Considering Galvanic Corrosion at Zn/Al Interface

To improve the surface integrity of ZA27 alloy, a method of chemical mechanical polishing (CMP) considering the galvanic corrosion at the Zn/Al interface is proposed to treat the surface of ZA27 alloy. Firstly, the electrochemical experiment is carried out to study the influence of the pH, H2O2 concentration, and glycine concentration on corrosion potential between zinc and aluminum. Then the Taguchi method integrated with grey relation analysis and fuzzy inference are used to optimize the CMP parameters of ZA27 alloy. Finally, the prediction model of the MRR and surface roughness Ra is established using the mathematical regression analysis method. The experimental results showed that the minimum zinc-aluminum corrosion potential difference is 14 mV when the pH is 10, H2O2 concentration is 1 wt%, and glycine concentration is 0.4 wt%. The optimum CMP parameter is the polishing pressure of 34 kPa, the polishing plate’s rotational speed of 70 rpm, and the abrasive particle concentration of 15 wt%. After polishing with the optimum CMP parameter, the MRR is 242 nm min−1, and the surface roughness Ra is 13.91 nm. This study demonstrates that the CMP considering the galvanic corrosion at the Zn/Al interface is an effective method for treating ZA27 alloy surface.

Hardening of gear teeth depending on the concentration of abrasive particles in the transmission oil

The article deals with the issues of determining the life and limiting concentration of abrasive particles in the oil of transmission units, depending on the type of hardening of gear teeth. Resource was determined after volume hardening, hardening by current of high frequency and cementation by hardness of gears materials, on the friction machine on the samples which have been made of gears material, working in oil with abrasive particles, considering coefficient of acceleration at test. Maximum allowable concentration of abrasive particles in machine oil, were estimated on the basis of expression for calculation of wear rate, providing the set life, maximum allowable wear depending on modulus of gearing, hardness of gearing material, size of abrasive particles, geometrical and kinematic parameters of gearing.

Research on influence of polishing fluids parameters on processing effects in reciprocating magnetorheological polishing

PurposeThis paper aims to study the influence of the different parameters of magnetorheological polishing fluids (MRP fluids) on the surface roughness and material removal rate (MRR) of the workpiece surface in the reciprocating magnetorheological polishing (RMRP) process.Design/methodology/approachA series of single-factor experiments are performed to evaluate the influence of the concentration of magnetic particles, concentration of abrasive particles and size of abrasive particles on surface processing effects by using the RMRP method. Moreover, the yield stress and viscosity of MRP fluids are studied based on the Bingham plastic model by varying the MRP fluids parameters.FindingsA reasonable parameter of MRP fluids is crucial to the surface roughness and MRR of the workpiece surface, and the optimized parameters are obtained by the single-factor experiments of RMRP. The results are when the concentration of carbonyl iron particles is 40 Vol.%, the concentration of CeO2 is 5 Vol.% and the size of CeO2 is 2.5 µm in the MRP fluids, the surface roughness of the workpiece remarkably decreases to 28 nm from the initial 332 nm and the MRR of the workpiece increases to 0.118 mg/min.Originality/valueIn this study, the single-factor experiments for the different parameters of MRP fluids are studied to polish K9 glass by using the RMRP device, and the yield stress and viscosity of MRP fluids are investigated by rheological experiments, which provides reference for a reasonable selection of the MRP fluids parameter in RMRP process.

Experimental Study on Shear Rheological Polishing of Si Surface of 4H-SiC Wafer

In this study, shear rheological polishing was used to polish the Si surface of six-inch 4H-SiC wafers to improve polishing efficiency. The surface roughness of the Si surface was the main evaluation index, and the material removal rate was the secondary evaluation index. An experiment was designed using the Taguchi method to analyze the effects of four critical parameters (abrasive particle size, abrasive particle concentration, polishing speed, and polishing pressure) on the Si surface polishing of SiC wafers. By evaluating the experimental results for the signal-to-noise ratio, the weight of each factor was calculated using the analysis of variance method. The optimal combination of the process parameters was obtained. Below are the weightings for the influence of each process on the polishing result. A higher value for the percentage means that the process has a greater influence on the polishing result. The wear particle size (85.98%) had the most significant influence on the surface roughness, followed by the polishing pressure (9.45%) and abrasive concentration (3.25%). The polishing speed had the least significant effect on the surface roughness (1.32%). Polishing was conducted under optimized process conditions of a 1.5 μm abrasive particle size, 3% abrasive particle concentration, 80 r/min polishing speed, and 20 kg polishing pressure. After polishing for 60 min, the surface roughness, Ra, decreased from 114.8 to 0.9 nm, with a change rate of 99.2%. After further polishing for 60 min, an ultrasmooth surface with an Ra of 0.5 nm and MRR of 20.83 nm/min was obtained. Machining the Si surface of 4H-SiC wafers under optimal polishing conditions can effectively remove scratches on the Si surface of 4H-SiC wafers and improve the surface quality.

Study on the Wear Modes of PVD Films Using Different Concentrations of Al2O3 Abrasive Particles and Textured Rotating Balls

Abrasive wear is a wear mechanism that results in a loss of material from the interaction of a surface with hard particles. This type of wear is frequently found in the surface of machining tools. Microscale abrasion equipment is often used to characterize the resistance to abrasive wear of a surface. The different parameters able to control micro-abrasion wear tests, such as ball rotation, sliding distance between ball and surface sample, abrasive slurry concentration, normal load acting on the sample, and abrasive flow rate over the sample, have been widely studied. The combination of different variables, including sliding distance, concentration of abrasive particles, their hardness, and size of abrasive particles, promotes the transition between two-body, three-body, or mixed abrasive wear modes. However, the influence of the ball surface on the dragging of abrasive particles, which is reflected in the wear modes, is still poorly studied. One of the variables possible to control and less studied is the influence of the ball surface texture on the dragging of abrasive particles in micro-abrasion wear tests. This work intends to correlate the effect of different testing times (500, 1000, and 1500 cycles) and different concentrations of 3 μm Al2O3 abrasive slurry (25, 35, and 45 g/100 mL) on the micro abrasion resistance of a TiN thin coating film, using balls of AISI 52100 steel whose texture and roughness were prepared by 60 s chemical etching. The rotation speed of each test was 80 rpm, applying a normal load of 2 N. Subsequently, the craters were carefully analyzed using SEM to evaluate the transition of the wear mode as a function of the applied load, the abrasive particle concentration, and the sliding distance. The textured ball tracks were observed via SEM to assess the particle dynamics. The results showed that, contrarily to what is reported in the literature regarding wear modes where rolling is promoted with increasing abrasive concentration, in this work grooving took place instead. This is a result of the rough balls use in the experiments which, due to the embedment of abrasive particles in the ball grooves, promotes the abrasion mechanism. The higher the abrasive concentration, the higher the grooving mechanism, since more particles are available to scratch the surface.

Toothpaste Abrasion and Abrasive Particle Content: Correlating High-Resolution Profilometric Analysis with Relative Dentin Abrasivity (RDA).

In this in vitro study, the influence of the concentration of abrasive particles on the abrasivity of toothpastes was investigated using laser scan profilometry on polymethyl methacrylate (PMMA) surfaces with the aim of providing an alternative method to developers for screening of new toothpaste formulations. PMMA plates were tested in a toothbrush simulator with distilled water and four model toothpastes with increasing content of hydrated silica (2.5, 5.0, 7.5, 10.0 wt%). The viscosity of the model toothpaste formulations was kept constant by means of varying the content of sodium carboxymethyl cellulose and water. The brushed surfaces were evaluated using laser scan profilometry at micrometer-scale resolutions, and the total volume of the introduced scratches was calculated along with the roughness parameters Ra, Rz and Rv. RDA measurements commissioned for the same toothpaste formulations were used to analyze the correlation between results obtained with the different methods. The same experimental procedure was applied to five commercially available toothpastes, and the results were evaluated against our model system. In addition, we characterize abrasive hydrated silica and discuss their effects on PMMA-sample surfaces. The results show that the abrasiveness of a model toothpaste increases with the weight percentage of hydrated silica. Increasing roughness parameter and volume loss values show good correlation with the likewise increasing corresponding RDA values for all model toothpastes, as well as commercial toothpastes without ingredients that can damage the used substrate PMMA. From our results, we deduce an abrasion classification that corresponds to the RDA classification established for marketed toothpastes.

Material Removal Characteristics of Spherical-Array-Focused Ultrasonic Abrasive Machining.

To improve the ultrasonic energy and realize far-field ultrasonic abrasive machining of complex surfaces, a spherical-array-focused ultrasonic abrasive machining system was established. By combining ultrasonic field simulation, detection and a single-factor experiment, the influences of the ultrasonic generator current, abrasive concentration, and particle size on the material removal properties and surface quality evolution of quartz glass were investigated. When the current was less than 0.4 A, the material removal showed plastic removal at the nanoscale. When the current was more than 0.5 A, the cavitation phenomenon formed micron-scale impact removal traces on the workpiece surface. The increase in abrasive concentration increased the impact density and material removal rate, while excessive abrasive concentration increased the impeding effect between abrasive particles and reduced the material removal rate. Moreover, the increase in abrasive particle concentration enhanced heterogeneous cavitation nucleation, promoted the removal of abrasive impact materials under the action of a cavitation jet, and inhibited the removal of direct surface cavitation. The abrasive particle size affects the heterogeneous cavitation nucleation and the acceleration of the cavitation jet on abrasive particles, which affects the material removal rate and surface quality. By controlling the energy of the focused ultrasound and abrasive parameters, the plastic or brittle domain removal of quartz glass can be achieved at the micro- and nanoscales.

Smoothed Particle Hydrodynamics Modeling of Thermal Barrier Coating Removal Process Using Abrasive Water Jet Technique

Abstract In this work, a new smoothed particle hydrodynamics (SPH)-based model is developed to simulate the removal process of thermal barrier coatings (TBCs) using the abrasive water jet (AWJ) technique. The effects of water jet abrasive particle concentration, incident angle, and impacting time on the fracture behavior of the TBCs are investigated. The Johnson–Holmquist plasticity damage model (JH-2 model) is used for the TBC material, and abrasive particles are included in the water jet model. The results show that the simulated impact hole profiles are in good agreement with the experimental observation in the literature. Both the width and depth of the impact pit holes increase with impacting time. The deepest points in the pit hole shift gradually to the right when a 30-deg water jet incident angle is used because the water jet comes from the right side, which is more effective in removing the coatings on the right side. A higher concentration of abrasive particles increases both the width and depth, which is consistent with the experimental data. The depths of the impact pit holes increase with the water jet incident angle, while the width of the impact holes decreases with the increase in the water jet incident angle. The water jet incident angle dependence can be attributed to the vertical velocity components. The erosion rate increases with the incidence angle, which shows a good agreement with the analytical model. As the water jet incident angle increases, more vertical velocity component contributes to the kinetic energy which is responsible for the erosion process.

Surface Planarization of CdZnTe Wafers: Effect of Slurry Formulation and CMP Processing Parameters on Surface Planarity

This study investigates the effect of chemical mechanical planarization (CMP) processing parameters such as platen velocity, the concentration of the oxidizer and abrasive nanoparticle, slurry pH and surfactant types on the surface roughness of cadmium zinc telluride (CdZnTe) substrate. It was found that these parameters have a significant effect on the quality of the polished surfaces. It was found that lower platen velocity, lesser concentration of abrasive particles, basic slurry pH, and addition of anionic surfactant (SDS) into the CMP slurry solution showed improved surface planarity. Optical Surface Profiler and atomic force microscopy (AFM) techniques were used to monitor the surface topography before and after polishing. A notable root-mean-square surface roughness, (Rq), ∼0.9 nm, has been obtained on the polished CdZnTe (CZT) surface over a scan area of 481 × 361 μm2 under the optimized conditions of 60 rpm relative velocity, slurry pH of 9, 3.75 vol% of oxidizer (H2O2) and 1.25 wt% of abrasive (SiO2 nanoparticle). A probable mechanism of the present CMP surface planarization of CZT substrate has been proposed. Unlike the conventional surface planarization processes, which involve two-step lapping followed by CMP for the CZT surfaces, we have developed a single step CMP process to obtain good surface planarity.

Study on Wear Mechanism of Helical Gear by Three-Body Abrasive Based on Impact Load.

This study aimed to explore the wear characteristics and evolution mechanisms of large-scale wind power gears under the impact load of particles of the three-body abrasive Al2O3 (0.2 mg/mL) from four aspects: oil analysis, vibration analysis, amount of gear wear, and tooth-surface-wear profile analysis. A magnetic powder brake was used to simulate the actual working conditions. Combined with the abrasive particle monitoring and the morphology analysis of the tooth-surface-wear scar, by setting quantitative hard particles in the lubricating oil, the gears are mainly operated in the abrasive wear state, and wear monitoring and wear degree analysis are carried out for the whole life cycle of the gears. Oil samples were observed and qualitatively analyzed using a particle counter, a single ferrograph, a metallographic microscope, and a scanning electron microscope. The experiments demonstrate that the initial hard particles have a greater impact in the early wear stage of the gears (<20 h), and abrasive particle concentration increases by 30%. This means that Al2O3 particles accelerate the gear wear during the running-in period. The loading method of the impact load on the oblique gear exacerbates the abrasion particle wear and expands the stress concentration, which reduces the surface of large milling particles on the surface, and reduces the width of the tooth (the part above the pitch line is severely worn), which causes the gear to break into failure. The research provides help for analyzing the mechanism of abrasive wear of gears and predicting wear life.

Evaluation of the degree of abrasive particles activity in oil of machine units involved in the wear process of toothed wheels

This article discusses the regularities of changes in the activity of abrasive particles in the oil of machine units participating in the process of gear-wheel wear at constant and increasing concentrations. They vary depending on the number of loading cycles of gear teeth, considering the share of crushed abrasive particles in one loading cycle of the gear teeth. This makes it possible to obtain regularities in the change of concentrations of active abrasive particles in the oil depending on the gear modules and the number of loading cycles, taking into the account the fraction of crushed abrasive particles per cycle of loading the gear. This technique can be used to determine the duration of the test of the gear wheel material on samples at a constant total concentration of abrasive particles in the oil change for the units of machines with gear drives operating in the presence of abrasive particles in the working environment. The case under consideration corresponds to the operating conditions of the gear transmission in the unit, which allows calculating the oil change period in the units of machines operating in an abrasive environment.

Evaluation of Wear Measurement with Radioactive Isotopes for DLC Coatings Affected by Abrasive Particles

Diamond-like carbon (DLC) coatings protect engine parts from wear and provide low-friction. Unfortunately, the nature of DLC coatings does not allow progressing wear measurement using conventional methods. Therefore, we applied a radioactive isotope-based wear measurement method (RIC method). A tribometer with oscillating contact and one with sliding contact were used to provide different loading conditions. The RIC method was evaluated for DLC coatings, and the DLC wear was investigated regarding the presence of abrasive particles. The results indicate that an increase in abrasive particle concentration leads to an increase of DLC wear rate and a decrease in usage-time until wear-off.

Расчетно-экспериментальная методика определения предотказного состояния сложнонагруженных подшипников скольжения

The article deals with the types of wear and failures of journal bearings. Based on the physics of failures, a method for determining the pre-failure state of plain bearings is proposed, including: determination of the limiting clearance in the bearing; determination of the limit value of oil viscosity; determination of the limiting value of the ovality of the shaft neck and liners; determination of the maximum area of chipping of the surface of the liners; determination of the limit value of the concentration of active abrasive particles in the lubricant. The solution of these problems is based on the calculation of the determination of the hydromechanical characteristics (HMC) of bearings using the hydrodynamic theory of lubrication, the determination of the zones of contact interaction between the elements of the rolling stock, the duration of the boundary lubrication regime, the amount of wear on the surfaces of the sleeve and the shaft neck. Calculation studies were carried out on the example of calculating the dynamics of the connecting rod bearing of the crankshaft of a heat engine. In particular, it is shown that with a diametrical clearance in the connecting rod bearing of 90–120 μm, the duration of the boundary regime of lubrication is more than 25%, which is the limiting value. Reducing the oil viscosity (measured at 100 С) below 9.5 mPa∙s is unacceptable, as it leads to an increase in the duration of the boundary lubrication regime by up to 42%. For the same reasons, the ellipticity of the liners more than 5 microns is unacceptable. A mass concentration of active abrasive particles in the oil of more than 0.1% leads to a sharp increase in the maximum wear rate of the bearing, and this concentration should be considered the limit in terms of its pre-failure state. The technique allows at the early stages of designing machines, which include hydrodynamic plain bearings, to determine the criteria for their pre-failure state.

Hand and Abrasive Flow Polished Tungsten Carbide Die: Optimization of Surface Roughness, Polishing Time and Comparative Analysis in Wire Drawing.

This research work highlights the benefits of abrasive flow polishing (AFP) applied to tungsten carbide dies compared with conventional hand polishing (HP). An indigenous experimental set-up for AFP was developed. The effect of prominent process parameters viz. extrusion pressure, number of cycles, and abrasive particle concentration on the final surface roughness, percentage improvement in surface roughness, and polishing time was investigated by Taguchi-designed experiments. The multi-objective optimization (MOO) was performed using the Taguchi-TOPSIS-Equal weight approach to find the respective optimized AFP parametric settings. A set of skilled operators performed the conventional HP of dies, and the best hand-polished (HPed) die was selected using the TOPSIS technique. The operational performance of the HPed dies and the abrasive flow polished (AFPed) dies were compared on the three-stage wire drawing operation. The results revealed that AFP’s surface resulted in a better-quality surface than hand polishing with a 27.06% improvement in surface roughness. Furthermore, AFP can reduce the dependency on costly and tricky-to-locate skilled operators, with a reasonable amount of time saving (about 87.05%). Overall, the study’s findings show that abrasive flow polishing of dies is fast and cost-effective.

Material removal characteristics of magnetic-field enhanced shear thickening polishing technology

To achieve the efficient and high-quality machining of hard and brittle ceramics used in various industries, in addition to other materials that are difficult to process, a magnetic-field enhanced shear thickening polishing technology was developed in this study. Based on the coupling effect of the magnetization enhancement and shear thickening, the proposed processing technology can improve the rheological properties of the shear thickening fluid, thus realizing an adaptive and efficient removal of microscopic materials. Herein, the microscopic material removal mechanism of this technology was analysed and the rheological properties of a magnetic shear thickening polishing fluid were studied. Based on the Preston's equation, the dynamic pressure of non-Newtonian fluids and the magnetorheological polishing theory, a material removal rate prediction model was established and it had a maximum relative error of 7.56%. The influences of the polishing head rotational speed, abrasive particle concentration and carbonyl iron powder particle concentration on the material removal function were investigated and the stability of the prediction model was verified. After polishing a zirconia workpiece for 20 min, a low-damage machining surface was obtained and the surface roughness was 8.3 nm. Therefore, the effectiveness of the material removal prediction model was verified and the findings of this study provide a theoretical basis for the realization of deterministic polishing. Moreover, the feasibility of the magnetic-field enhanced shear thickening polishing method for the ultra-precision machining of hard-to-machine materials, such as hard and brittle ceramics, was verified.

CFD analysis of slurry jet behavior after striking the target surface and effect of solid particle concentration on jet flow

Abrasive flow jet machining (ASJM) is modern manufacturing technique which uses comparatively low-pressureabrasiveflowjet for machining various machined surfaces like holes, channels and intricate shapes which is not possible from conventional machining processes. The effect of abrasive particle concentration on the impacting slurry velocity on the surface was examined in the present CFD simulation, resulting in target surface erosion. To predict the impact velocity of abrasive particles hitting the surface, a 2D CFD model was used. The depth of machined surface, surface irregularity and surface removal rate at normal incidence mainly depend on the KE of particle, impact angle, etc. in line with previously published research work on highly pressurised air and water driven abrasive jet. In the present work CFD simulation is performed to predict the effect of solid particle concentration on the impacting slurry jet velocity at the target surface and also turbulence kinetic energy near the surface is studied. As per the CFD results the simulation model predictions the velocity of impacting particle goes on decreasing due to internal frictional resistance between solid and liquid phase and it shows scope of further parametric analysis in this area.

Investigation of process parameters of AMEDM on Al/SiC composite using Taguchi approach

The present study examines the abrasive mixed electrical discharge machining (AMEDM) of aluminium composites. Taguchi method has been used to optimize the material removal rate (MRR) and tool wear rate (TWR) considered as performance response for composite machining using AMEDM. In this analysis, boron carbide (B 4 C) abrasive particles were mixed with different concentration to the kerosene oil that acts as a dielectric fluid (DF). It has been found that with the addition of B 4 C powder, MRR is increased and TWR is decreased. Based on S/N ratio analysis, results showed that the MRR in machining of through holes with AMEDM on composites is significantly influenced by abrasive concentration and peak current. Concentration of abrasive particles has a significant impact on the TWR. Optimum process parameters are found based on S/N ratio analysis, For MRR, value are specified as pulse-on-time (A2) 120 µs, peak current (B3) 9 A, concentration of abrasive particle (C2) 10 gm/l and pulse-off-time (D2) 40 µs and for TWR, value are specified as pulse-on-time (A3) 150 µs, peak current (B2) 6 A, concentration of abrasive particle (C2) 10 gm/l and pulse-off-time (D3) 50 µs.

Criterion for evaluation of erosion of aviation engine parts from polymer composite materials

A criterion is proposed for assessing the reliability of parts made of polymer composite materials in the event of sand and dust entering the compressor during take-off and landing. Conducting erosion tests with a concentration of abrasive particles corresponding to a conventional dust stream is practically impossible due to their long duration. When conducting tests with a high concentration that is several orders of magnitude higher than the concentration of a conventional stream, the reliability of the estimate is reduced due to the need to extrapolate the results to a large resource. Therefore, to improve the accuracy of the assessment of the erosion resistance of engine parts from polymer composite materials, it is proposed to conduct periodic measurements of the thickness of the part during operation. By calculating the dynamic eigenfrequencies and oscillation shapes and maximum static stresses, the critical thickness of the part is established, below which its eigenfrequency approaches the dangerous rotor harmonics.

The effect of the rumen washing mechanism in sheep differs with concentration and size of abrasive particles

Measures of tooth wear have widespread use as proxies in palaeobiological reconstructions. In order to apply these proxies, an understanding of potential influence factors on wear is important. The processes during the digestion in the ruminant organism lead, possibly inadvertently, to a washing of material before it is regurgitated for rumination chewing. Therefore, ruminants might experience less tooth wear from external abrasives such as dust and grit, which can be washed off, compared to nonruminant herbivores. Details of the washing mechanism, including its efficiency in relation to abrasive size, have not been explored so far. Here, we describe the location and quantity of external abrasives in the gastrointestinal tract of sheep fed seven diets containing external silica abrasives varying in concentration (0, 4, and 8%) and size (4, 50, and 130 μm). As typical for ruminants, external abrasives accumulated mainly in the fourth stomach section, the abomasum. Compared to the diet, the dorsal rumen contents – from where material for regurgitation and rumination is recruited – were depleted of external abrasives for the 130 μm silicates, and for the 8% concentration of 50 μm silicates, but not for the 4 μm silicates or the 4% concentration of 50 μm silicates. These results suggest that the rumen washing mechanism is probably more protective against abrasion from grit and sand, and potentially less efficient against fine dust.

Annular Surface Micromachining of Titanium Tubes Using a Magnetorheological Polishing Technique.

In this study, a novel magnetorheological (MR) polishing device under a compound magnetic field is designed to achieve microlevel polishing of the titanium tubes. The polishing process is realized by combining the rotation motion of the tube and the reciprocating linear motion of the polishing head. Two types of excitation equipment for generating an appropriate compound magnetic field are outlined. A series of experiments are conducted to systematically investigate the effect of compound magnetic field strength, rotation speed, and type and concentration of abrasive particles on the polishing performance delivered by the designed device. The experiments were carried out through controlling variables. Before and after the experiment, the surface roughness in the polished area of the workpiece is measured, and the influence of the independent variable on the polishing effect is judged by a changing rule of surface roughness so as to obtain a better parameter about compound magnetic field strength, concentration of abrasive particles, etc. It is shown from experimental results that diamond abrasive particles are appropriate for fine finishing the internal surface of the titanium-alloy tube. It is also identified that the polishing performance is excellent at high magnetic field strength, fast rotation speed, and high abrasive-particle concentration.