Abrasive Powder Research Articles

Experimental Investigations on the Effect of Relative Particle Sizes of Abrasive and Iron Powder in Polishing Fluid Composition for Ball End MR Finishing of Copper

Demand for ultra-finished copper mirrors is very high in defence and laser optics industries due to their high heat conductivity and durability. In ultra-finishing, soft materials require gentle finishing for scratch free highest degree of surface quality. Ball end magnetorheological finishing is an advanced finishing process that confirms both the requirements of optical industries, i.e., finishing of complex surfaces and up to nanometre level of surface finish. In this study it is explored that the relative particle sizes of the abrasive and the ferromagnetic substance in magnetorheological fluid affect the chain structure and in turn the quality of the finished surface. The study has been carried out over magnetorheological polishing fluids composed of different sizes of iron particles and abrasives. The results show that magnetorheological polishing fluid having iron particles of 300 mesh size and alumina powder of 1,000 mesh size is most suitable combination for best surface finishing on copper samples.

Polishing of paramagnetic materials using atomized magnetic abrasive powder

ABSTRACTThis paper reports on the polishing of paramagnetic materials in the magnetic abrasive finishing (MAF) process by using atomized-type magnetic abrasive powder (MAP). After atomization process, a spherical MAP with captured Al2O3 hard particles was obtained. The MAF process was experimented on two plane workpieces with different hardnesses. An orthogonal array containing five factors with three levels was applied in the experiment. Based on analysis results, the model of surface roughness was obtained, and the rotational speed of the MAPs played the most dominant role in the surface quality of both finished experimental materials. By comparing the value of the finished surface roughness at different process parameters, the influence of single process parameter on processing quality was analyzed. Furthermore, the minimum surface roughness of both materials was obtained at the best combination of process parameters. Finally, the experiment of the material removal and the produced surface morphology was examined in order to understand the finishing characteristics of the atomized MAPs during the MAF process.

Самораспространяющийся высокотемпературный синтез тугоплавких порошковых материалов на основе диборида циркония из борсодержащего минерального сырья Республики Казахстан

The goal of the present work is the synthesis of the refractory zirconium diboride powder in the combustion mode. One of the most effective methods of synthesis of the refractory zirconium diboride powder is the self-propagating high-temperature synthesis method (SHS) with a preliminary mechanical activation of the initial components. Initial components of the SH-synthesis are borate ore, zircon, aluminum powder and magnesium. After the SH-synthesis obtained products were processed by 37.5% HCl and were washed with distilled water. Final composition and microstructure of SHS products were investigated with X-ray phase analysis and SEM. Boron-containing SHS-powders can be used as bio-protection in nuclear engineering, production of abrasive powders, ceramic, composite materials and coatings.

Durability and Biological Response of a New Posterior Dynamic Stabilization System Using Polyethylene with Vitamin E.

Objective The purpose of this study was to evaluate the durability and biological response of a new Posterior Dynamic Stabilization system using polyethylene with vitamin E on the sliding surface. Summary of Background Data The use of polyethylene with vitamin E on the sliding surface in Posterior Dynamic Stabilization has not been reported previously. Methods A developed pedicle screw-based Posterior Dynamic system consists of four parts: a set screw, a rod, a ball, and a pedicle screw. The rod is inserted into the through hole of the ball, and the ball is sandwiched by the set screw. (1) Fatigue Wear Test. Testing was conducted under a dynamic compressive load of 50N at a speed of 1 Hz for 1 million cycles. We examined the loss of polyethylene due to abrasion in 3 units. (2) Biological Response in Pigs. In two pigs, a new pedicle screw and a conventional pedicle screw were inserted in L2 and L3/4, and L4 and L2/3, respectively. After breeding for 6 months, autopsies were performed. CT imaging was used to evaluate bone union of the facet joint. Abrasive specimens were prepared, and abrasion powder and inflammatory cell infiltration were evaluated microscopically. Results The average loss of polyethylene due to abrasion was -0.01 mg. In all units, polyethylene showed a decrease of 0.1 mm or less at the contact point with the set screw. The facet joints between the conventional screws exhibited bone fusion, but the facet joint between the conventional and the new screw retained mobility with no bony fusion. No abrasion powder was found and inflammatory cell infiltration was only minimally observed. Conclusion The new Posterior Dynamic Stabilization system exhibited a high level of durability and biological safety.

Separation of ultrafine ceria-based abrasive particles from glass polishing powder waste through liquid–liquid–powder extraction

Glass polishing powder waste comprises ultrafine particles of ceria-based abrasive and polished glass powder. This study investigated the separation of ceria-based abrasive particles from glass polishing powder waste through liquid–liquid–powder extraction. Kerosene was used as the oil phase, and sodium oleate (NaOL) was used as the surfactant collector. First, the properties of the ceria-based abrasive/glass powder particles transferred from the water phase to the kerosene phase and the effect of surfactant collector addition were investigated individually. Then, separation of ceria-based abrasive from an artificial particle mixture of ceria-based abrasive and glass powder was carried out to determine the optimal extraction conditions. Finally, the method was applied to a glass polishing powder waste.The results indicated that with the addition of 2 kg/ton NaOL, more than 90% of the ceria-based abrasive particles were extracted from the water phase to the kerosene phase at a pH of 5–9. The pH and NaOL addition had negligible effect on the extracted fraction of the glass powder, which remained at approximately 10–15%. The optimal extraction conditions for the separation of ceria-based abrasive from an artificial particle mixture of ceria-based abrasive and glass powder were obtained at pH 7. Both the grade and recovery of the ceria-based abrasive in the kerosene phase solid were higher than 90% when more than 5 kg/ton NaOL was added. With the addition of 10 kg/ton NaOL, the grade was 98.5% and recovery was 97.1%. Similar results were obtained after applying this technique to a glass polishing powder waste.

Development of magnetically assisted lapping process for nano-finishing of alumina balls

The advanced ceramics have emerged as a successful alternative to the conventional materials used in ball bearing industry. However, extreme hardness and lower toughness of the ceramic balls make their finishing a challenging task. To address this problem, a novel process is developed and results are presented in this article. The process is termed as magnetically assisted lapping (MAL) wherein the lapping and the polishing action are supported by magnetic levitation. The process parameters are identified. The capability of the process in terms of surface finish, roundness and material removal rate of alumina balls is assessed. The process is carried out in two stages. In the first stage, the main focus is on material removal and sphericity while the second stage focuses on achieving nano level surface finish. A very high material removal rate of 2.5 µm/min is achieved in the first stage. In the second stage, diamond abrasive powder (0.25–1 µm) mixed with silicone oil is used as a polishing medium for fine finishing of balls. The final surface finish of 20 nm and roundness of 0.23 µm is achieved which meets the requirement of G10 grade bearings (as per ISO3290). Atomic force microscope images show remarkable improvement of the surface up to 8 nm. The developed process is capable of producing nanometric finish in quite lesser time as compared to conventional and eccentric lapping processes. The underlying mechanism of material removal is proposed with the help of scanning electron microscope and atomic force microscope images.

Magnetic field assisted finishing process for super-finished Ti alloy implant and its 3D surface characterization

Titanium alloy is used in medical industries due to its biocompatibility. Requirement of implant’s surface roughness and surface topography depends mainly upon its application. In the present study, application of titanium alloy is considered as femoral knee joint implant. The capability of magnetic field assisted finishing (MFAF) process and the polishing tool to provide implant worthy surface is analyzed here. In MFAF process, magnetorheological fluid mixed with abrasive powder in acidic base medium is used as the finishing medium. Characterization of the finished surface is carried out by analyzing 3D surface roughness parameters. The selected 3D surface parameters ( Sa, Spk, Sk and Svk) are considered due to their importance concerning load-bearing articulating surface of knee joint implant. Statistical design of experiment is used for experimental study and subsequently process parameters are optimized. From experimental investigation, the values of Sa, Spk, Sk and Svk are obtained as 11.32 nm, 15.82 nm, 6.51 nm and 41.15 nm, respectively, at optimum process parameter condition. The optimum process parameter values are 901 rpm of the tool, 0.60-mm working gap and 4.30 hrs of finishing time. The obtained values of 3D surface roughness parameters are in the nanometer range and the surface topography will render better wear properties, performance and longer implant life. Further confirmation experiments support the optimized values. The effect of individual process parameter on output responses is also analyzed.

Low-temperature synthesis of high-purity boron carbide via an aromatic polymer precursor

Abstract

Experimental and theoretical analysis of solid particle erosion of a steel compressor blade based on incubation time concept

Abstract This paper considers experimental and theoretical study of a compressor blade steel (EI-961 grade), subjected to solid particle erosion. Material samples were cut from the first stage compressor blades and then tested in a modified wind tunnel, capable of mixing abrasive media into an accelerated airflow. Velocity of the abrasive stream vas varied and additionally abrasive powders with different average particle sizes were used. Erosion resistance was assessed in two ways: measurements of the sample mass degradation and investigation of the surface roughness change due to erosion. Moreover, data fitting was used to calculate approximate threshold velocities for the abrasive powders used in the tests. Incubation time concept was applied in order to obtain dependence of the threshold particle velocity on the particle radius and to perform theoretical analysis of the material's resistance to the solid particle erosion.

Effects of process parameters on the Surface Finish of Flat Surfaces in Magnetic assist Abrasive Finishing Process

Study for advanced and cost efficient finishing processes like magnetic abrasive finishing (MAF) process has been an area of research in order to enhance the performance of existing finishing processes and makes the process more efficient for industrial utilization. Magnetic abrasive finishing (MAF) is one of the finishing process which can finish the surface of both magnetic and non-magnetic materials up to Nano-scale. Intent of this paper is to study all operating parameters (machining gap, current supply, input voltage, machining time, rotational speed, mesh size of abrasive, weight of abrasive, percentage of oil or binder in MAP, composition of MAP, type of abrasives), machining forces and their effects on the quality of surface finish achieved. In the view of existing literature, magnetic abrasive finishing for finishing of plane surfaces has undergon less attention. This paper reviews the results reported in past and recent researches. These results are used to study the performance of magnetic abrasive finishing process for flat surfaces and effect of variation in composition of magnetic abrasive powder on surface texture of work piece

Study of wear resistance of diamond grinding tool, a layer which contains the dispersed abrasive powders of composite materials

The results of the study opportunities of application compacted structured by nanocarbon bond dispersed powders of synthetic, natural diamond and boron carbide in the grinding wheels for the processing of cemented carbide. For this purpose were selected Diamond powders AC 6 125/100 and on their surface was damaged composite material based on sub-micron (3/0) fractions of natural diamond powders, as well as boron carbide micropowders, compacted carbon pile method physicochemical synthesis at a pressure lower than atmospheric pressure. In this paper, the main task was to compare features of the operational characteristics of the diamond community, primarily their durability when used in their working layer dispersed of abrasive powders of new composite materials based on natural diamond and boron carbide and set conditions for their effective application in grinding wheels. In this paper, the main task was to compare features of the operational characteristics of the diamond community, primarily their durability when used in their working layer dispersed of abrasive powders of new composite materials based on natural diamond and boron carbide and set conditions for their effective application in grinding wheels. It is shown that partial (50 %) or total replacement of synthetic diamonds compacted powders that contain diamonds, surrounded by the original coating of mìcropowders natural diamond or boron carbide mìcropowders structured by nanocarbon bond, allows you to significantly increase wear resistance diamond grinding wheels.

Effects of variation in the particle size of the rock abrasion powder and standard rotational speed on the NTNU/SINTEF abrasion value steel test

Ten potentially abrasive rock samples selected from various locations of Pakistan covering igneous, metamorphic and sedimentary rocks were subjected to a comprehensive laboratory testing program. The experimental work includes the NTNU/SINTEF abrasion value steel (AVS) and Sievers’ J-miniature drill (SJ) tests accompanied by CERCHAR and LCPC rock abrasivity tests. The results of SJ tests and AVS tests were further utilized to compute the cutter life index (CLI), which estimates the life of tunnel boring machine (TBM) disc cutter rings in boring hours. In this research, a comparative study was performed on an NTNU/SINTEF rock abrasivity device by varying the particle size of rock abrasion powder and rotational test speed of the steel disc. The NTNU/SINTEF AVS test results showed a gradual decrease in abrasivity with the corresponding decrease in grain size of test fractions. An increase in the wear of the test piece was observed at a test speed of 10 rpm as compared to the standard test speed of 20 rpm. Relevant correlations of CLI, SJ-value and AVS with CERCHAR abrasivity index (CAI) and LCPC abrasivity coefficient (ABR, g/t) were also discussed.

Micro-abrasive wear mechanisms of P/M AISI M2 steel with different surface treatments

Boriding, heat treatment (quenching and tempering) and PVD (Physical Vapor Deposition) film deposition were applied to P/M (Powder Metallurgy) AISI M2 steel. Four sample conditions were produced: Quenched and tempered AISI M2 (QT), Borided AISI M2 (B), Quenched and tempered AISI M2+Film (QTF) and Borided AISI M2+Film (BF). The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the Vickers microhardness test. The load applied in the micro-abrasion tests (fixed-ball) was 0.49N and abrasive slurry concentration was 0.1g/cm3. Silicon dioxide (SiO2) abrasive powders (approximately 80% of particles between 1 and 5μm) were used in the abrasion experiments. Wear coefficient and mechanisms of all conditions were compared. The XRD analysis revealed the presence of a biphasic layer of borides (FeB and Fe2B phases) on the borided samples. The film thickness was 2.1±0.4μm and the hardness of the multilayered AlTiN/CrN film was about 3912HV0.025. The borided layer thickness was 46.5±5.1μm and the hardness average of 2162HV0.025. The wear mechanism for the QT and QTF samples was two-body abrasion (grooving abrasion). There was a reduction on the signs of grooving abrasion for the B and BF samples due to the increase in plastic deformation resistance.

Reduction of diamond-coated cutting tool wear during graphite cutting

To investigate wear characteristics of diamond-coated inserts when cutting carbon based materials, lathe-turning tests were conducted using diamond-coated cemented carbide inserts and a graphite round bar at various cutting speeds in an air or a nitrogen blowing atmosphere. Tests were conducted with constant cutting length, but at different cutting speeds of 23–495m/min. Wear to the insert was observed using a microscope after the tests. Then the wear volume was measured using coherence scanning interferometry. After cutting in air, only small wear volume was found for low speeds of 36m/min or less and for high speeds of 328m/min or more, but greater wear volume was found for medium speeds of 54–208m/min. During cutting in air at high speeds, oxidation of diamond was thought to be a main wear factor because sparks were observed in the abrasion powder from the graphite round bar. Wear to the diamond-coated insert decreased with shortened time of contact to the hot graphite chips. At low speeds, the wear volume decreased concomitantly with decreased cutting speed, probably because of decreased heat generation, which is proportional to the cutting speed. For most cutting speeds investigated, cutting with nitrogen blowing produced less wear than cutting in air. The tendency was remarkable at 54–208m/min. These results indicate oxidation as the main cause of wear to the diamond-coated insert during graphite cutting in air. Wear can be reduced considerably by cutting in an atmosphere with blowing nitrogen.

Comparison of two different techniques used for the maintenance of peri-implant soft tissue health: a pilot randomized clinical trial

Objectives: The aim of this pilot study was to compare the effectiveness of two different methods of debridement on maintaining and improving peri-implant soft tissue health over a period of 12 months.Materials and methods: Twenty adult patients (25 implants) were enrolled in a randomized, single-blinded, parallel group clinical trial. All implants included showed no signs of pathologic bone loss. Patients were scheduled to be reviewed every 3 months over a 12 months period. Nine patients (15 implants) were randomly allocated to a test group and treated with a low abrasive air polishing powder (Air-Flow® Perio, EMS) (AFP) and another nine (10 implants) to a control group and treated with titanium curettes (TC). Peri-implant crevicular fluid samples were analyzed to quantitatively measure the concentration of six interleukins (IL-6, IL-8, IL-1β, TNF, IL-10 and IL-12). A multilevel analysis was used to test the comparison between the two treatments. The same analysis was used to study the relationship between clinical parameters and cytokines while controlling for confounding factors.Results: There was no significant difference in bleeding on probing (BOP) between the two treatment methods (p = .35). Both debridement techniques resulted in a similar reduction of BOP (40.04% and 39.93%). IL-6 was the only cytokine of the six investigated that demonstrated a correlation with a clinical parameter (BOP) (p = .05).Conclusions: Both treatment methods were proven to be effective in reducing peri-implant inflammation and preventing further disease progression. Some cytokines may act as markers for peri-implant disease as the present study showed a significant relationship between IL-6 and BOP.

Modeling of normal force and finishing torque considering shearing and ploughing effects in ultrasonic assisted magnetic abrasive finishing process with sintered magnetic abrasive powder

Ultrasonic assisted magnetic abrasive finishing process (UAMAF) is a precision manufacturing process that results nano-scale level finish in a part. Normal force on a particle helps indenting the particle in the work surface whereas horizontal force provides finishing torque that in-turn helps the particle to perform micro-machining. Better understanding of the effect of these forces on material removal and wear pattern of the work-piece necessitates mathematical modeling of normal force and finishing torque and subsequently its validation with experimental results. In the present study, single particle interaction concept is considered to develop a model which is subsequently applied for all active particles of magnetic abrasive powder (MAP). Separation point theory is applied to consider the effect of ploughing below a critical depth and shearing above that depth. Normal components of shearing and ploughing forces are considered for calculating normal force and horizontal components of shearing and ploughing forces are taken to calculate finishing torque. Johnson-Cook model is applied to calculate shearing strength of the work material during UAMAF. The impact of ultrasonic vibrations is considered while calculating strain rate. Images are taken with the help of scanned electron microscope and atomic force microscope to study the material removal and wear mechanism during UAMAF process. Predicted values of force and torque model are validated with the experimental values.

Parameters Optimized Specifying for EDM with PM/Conventional Electrodes on M2 Tool Steel using Taguchi and TOPSIS

Objectives: The scope of this experimental work of electrical discharge machining (EDM) process with and without the addition of abrasive powder while executed on M2 tool steel for the advancement in surrounding safety factors to meliorate the surface quality. Methods/Statistical Analysis: Taguchi’s L36 mixed orthogonal array is used after identification of most appropriate six input parameters (polarity, electrode type, concentration of abrasive, discharge current, and gap voltage and duty cycle) for maximum MRR and minimum TWR, and SR. Findings: To recognize the significant factors ANOVA is used and TOPSIS determine the 10.47% overall improvement in all responses with the optimal level of process parameters after confirmatory test. Energy dispersive X-ray (EDS) and Scanning electron microscope (SEM) analysis applied to examine the surface quality. Application/Improvements: This study finds the downfall of titanium from powder metallurgy tool electrode (CuTi) and deposition of aluminium material from PMEDM may also be implemented to improve the method of computation and precision.

Micro-abrasive wear mechanisms of borided AISI 1020 steel

A boriding treatment was applied to AISI 1020 steel at 1000°C for 4h. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the Knoop microhardness test. The loads and abrasive slurry concentrations used in the micro-abrasion tests (fixed-ball) were 0.49–0.98N and 0.5–1.0g/cm³, respectively. Silicon carbide (SiC) abrasive powders (5µm) were used in the abrasion experiments. The wear coefficient and mechanisms were compared with those obtained from untreated samples. The XRD analysis revealed the presence of the Fe2B phase on the borided samples. The iron borided layer was 177µm thick and had a hardness of 2100 HK0.01. The wear mechanism for the borided samples was rolling abrasion while grooving abrasion with micro-rolling occurred in the untreated samples.

Обоснование механизма доминирующего государственного участия в освоении ресурсов высоколиквидных полезных ископаемых Арктики

For a scientific discussion the authors present proposals on the formation in Russia of a new form of effective mineral resource base development of the strategic solid mineral resources in the Arctic zone of Siberia and the Far East. The mechanism is based on the prevailing govenmental participation in projects of development and exploitation of highly liquid metals (rare earth elements, Tomtor ore cluster in Yakutia) and minerals (diamond abrasive materials, Rock Popigai meteorite crater deposit in Krasnoyarsk region) in the Siberian Arctic, carried out under conditions of high risk. Shown, that due to the unique parameters of both rare earth and diamond ores flow of hi-tech products and semi-products is formed. With the extension of the technological and value chain - delivery to the domestic and the global markets of highly liquid products (oxides of rare earth metals and high-purity metals, technical super abrasive diamond powders and products for the treatment of materials). Thus, a cluster for the production of final products based on rare-earth metals and super abrasive rough diamonds with high added value can be created. Milestones and additional exploration operations, preparations for the operation and development of deposits are carried out by the State Corporation for Mineral Resources with the joint participation, investment, technological cooperation of private companies and research organizations. The Corporation could be considered as a platform for international cooperation and foreign investment in technological chains of a presented mega-project of development of two closely located deposits. Introduced organizational and economic mechanism allows to: a) carry out public administration of complex resource projects in the Arctic and to develop them to an economically efficient level with a gradual sale of business projects to the private sector; b) to initiate and stimulate long-term scientific and technological development in conditions of high risk; c) to form a system of preferences for the development of Russian high-tech exports; d) ensure Russia’s economic presence and increased geopolitical and geo-economic interests in the Arctic.

Behavior of the grade 5 titanium alloy in different structural states in conditions of high-speed erosion

Behavior of a Grade 5 titanium alloy after high pressure torsion (HPT) and equal channel angular pressing (ECAP) under conditions of high-speed erosion was studied. Samples of the alloy in the ultrafine-grained state after the HPT and ECAP treatment were tested in an abrasive flow with various velocities using a technique similar to those presented in article Petrov et al. (2017). Two abrasive powders were used: with 109 and 230 μm average particle size. The tests were carried out at room temperature. Fracture surface parameters were studied for all tested specimens and fracture type (ratio of viscous and brittle fracture) was evaluated in each case. Additionally, surface roughness mass loss dependencies on particle flow velocity was investigated for both HPT and ECAP samples.