Abrasive Conditions Research Articles

Features of cutting force database formation for modeling of pendulum grinding of flat surfaces of tools made of R9M4K8 and X12 steels

The purpose of the article is to create a database on cutting forces P z , P y to enable the simulation of loads on the tools made of R9M4K8 and X12 steels and on machine-tool parts and components using computer programs. forces additionally allow to simulate thermal phenomena in the grinding zone, which being an adverse factor in abrasive processing reduce the performance of cutting tools and dies. The cutting forces are measured using the Kistler dynamometer system and the output of the obtained information is presented in the computer. Correction factors to the basic model taking into account the idle passes by the width of the processed surface are obtained. It is found out that the increase in the operational allowance when grinding with cubic boron nitride wheels is not accompanied by an increase in cutting forces, which is typical for traditional abrasive wheels (in particular for electrocorundum). The cutting forces at grinding of die steel X12 are greater than those at grinding high-speed steel R9M4K8: P y - by 1.2 times, P z - by 1.36 times. The results obtained will increase the efficiency of using CAE-systems (Computer-aided engineering systems) in mechanical engineering, particularly in grinding. It is confirmed that the increase in the grinding coefficient K gr =P z /P y reflects the improvement in the abrasive wheel operating conditions. In particular, it increases when the wheel comes out of contact with the workpiece from 0.32 to 0.46 at the reverse motion in the same zone from 0.46 to 0.64.

STELLITE 19PM

Abstract STELLITE 19 PM is a cobalt-base alloy recommended for handling severe conditions of abrasion, heat and corrosion. The PM designation indicates prealloyed atomized powders and parts made from the powder. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on wear resistance as well as heat treating, machining, and joining. Filing Code: Co-87. Producer or source: Deloro Stellite Inc.. Originally published December 1993, corrected December 2019.

Chopped Carbon Fiber Reinforced Polymer Composites : Effect of Nanoclay on Adhesive and Abrasive Wear Properties

The present work investigates the wear properties of nanoclay-modified carbon fiber reinforced polymer (CFRP) composites when sliding under adhesive and abrasive wear. The specimens were fabricated using epoxy resin, short carbon fiber, and nanoclay filler of 1.0wt%, 3.0wt%, and 5.0wt% content. The wear tests were conducted using pin-on-disc and abrasion resistance test rig for adhesive and abrasive wear condition, respectively. Operating parameters were fixed at 30N load, 300rpm speed and 10km distance for both tests. Pure CFRP composite exhibited lower wear performance compared to pure epoxy in both test conditions. However, with nanoclay incorporation, the wear properties of CFRP composite have improved up to 56% and 44% under adhesive and abrasive wear, respectively. Therefore, the composite reinforced polymer of carbon fiber and nanoclay filler in epoxy matrix provides a synergistic effect under adhesive and abrasive wear conditions. The experimental findings suggest that the CFRP composite has the potential for tribological components and application such as sliding-contact and rolling-contact bearings.

Making migrant identities on social media: a tale of two neoliberal cities on the Pacific Rim

The copper mining city of of Alto Hospicio, Chile and GoodPath town, a factory city in China both seem to be archetypal neoliberal cities. They epitomize the circulation of goods, people, and ideas through their export-based economies, large migrant populations, and high penetration of Internet and social media use. Yet, we find that in migrants’ social media use, there are stark contrasts in the significance they place on their movement and the identities they form around these migrations. In China, factory workers take to the ‘online world’ to escape harsh realities and engage in identity formations that privilege cosmopolitan aspirations. In Chile, mining workers express the harshness of their lived reality, using social media to build identities around a sense of pride in their abrasive conditions. This comparative essay reveals how processes associated with neoliberal capitalism – including migrations of people, goods, and information, and the commodification of identities – is preconditioned by local contexts. We find that the processes of neoliberal capitalism sometimes yield starkly different consequences, even when local circumstances seem to be similar. This demonstrates that even as media (and particularly social media) connect people more closely, their effects are anything but homogenizing.

Assessment of 3D printed steels and composites intended for wear applications in abrasive, dry or slurry erosive conditions

The design of earth cutting and machining tools generally requires the application of several types of materials with different wear resistance: (1) base metal with low wear resistance, (2) extremely resistant cutting inserts made of ceramics (or even diamond), cemented carbides or cermets and (3) thick coatings with average wear resistance to protect base metal or thin (PVD or CVD) coatings to improve wear resistance of inserts. The production of such tools is complicated, tedious and not very efficient (tool life depends on the interface bonding, brazed inserts can be severely damaged after impact, base material wear, etc.). The novel approach is to exclude the steps of brazing or coating and to produce steels or composites with similar wear resistance as that of inserts or coatings using the promising approach of additive manufacturing (AM i.e. 3D printing). Moreover, benefits of AM like near net shape part building with complex internal features (internal cooling channels) are desired for cutting tools. The aim of the current research is to assess novel commercially available 3D printed steels and composites in several relevant tribological conditions where these materials could be applied. The comparison with conventional Hardox 400 wear resistant steel and AISI 316 stainless steel is provided. Results report significant improvement in the wear resistance of AM produced steels and composites against reference materials. The performance of 3D printed materials lie between WC- based bulk cemented carbides and hardfacings. The characteristic features of wear mechanisms are presented and discussion is supported by Scanning Electron Microscope images.

Microstructural and tribological characterization of molybdenum–molybdenum carbide structures produced by spark plasma sintering

Abstract Pure molybdenum is one of the most important refractory metals owing to its high melting point, low thermal expansion coefficient and good thermal conductivity. Molybdenum carbide exhibits superior wear resistance to molybdenum owing to its low friction coefficient and high hardness; therefore, in this study, to endure abrasive conditions, the surface of molybdenum was modified as molybdenum carbide. In accordance with this purpose, pure molybdenum powder was sintered under constant pressure (40 MPa), various temperatures (1 650 °C, 1 700 °C and 1 725 °C) and holding periods (180 s, 360 s and 540 s) using the spark plasma sintering technique. The effects of sintering temperature and holding period on relative density, microhardness, microstructure and wear properties of the specimens were investigated. Moreover, carbide formation on the surface due to carbon diffusion was also investigated. Relative density values decreased with increasing sintering temperature and period, obtaining the highest value of 97.55 % at 1 650 °C and 180 s. A microhardness value of 15.20 GPa was reached on the surface while the maximum value measured at the cross-section was 2.17 GPa, showing the formation of molybdenum carbide structure on the surface of all specimens. Furthermore, microstructural analysis supported the microhardness results and showed a minimum 288-μm thick molybdenum carbide layer on the surface. In addition, a typical eutectic microstructure was observed between molybdenum and molybdenum carbide layers; however, the decrease in temperature decreased the thickness of the eutectic layer and it gradually disappeared from the centre to edge of disc-shaped specimens. Wear resistance of surfaces was improved by decreasing holding period where a non-porous carbide layer and highest microhardness values were achieved. The cross-sectional analysis corresponding to molybdenum base metal proved that the formation of molybdenum carbide layer because of carbon diffusion improved the wear properties of the sample with the low friction coefficient and low wear depth.

Usage of powder pinus brutia cone and colemanite combination in brake friction composites as friction modifier

Friction composites are materials used in places such as braking systems of highways and rail transportation vehicles. Composites that are resistant to abrasion and environmental conditions such as temperature and humidity and with high resistance to friction are preferred in brake systems. Therefore, friction composites are formed by the combination of many materials with different properties. In this study, five friction composite samples were prepared with various combination of powder Pinus Brutia cone and colemanite. The amount of other ingredients of samples are constant. Samples were produced by conventional dry mixing method. Friction and wear tests were determined by a full-scale brake friction tester. The specific wear rate, friction coefficient and friction stability parameters of the samples were investigated and friction performance was evaluated. The hardness of the samples was calculated by Brinell hardness tester and the density was determined according to Archimedes' principle. According to the test results, all samples are compatible with the literature, applicable in industry and comply with the standards.

Influence of various airborne-particle abrasion conditions on bonding between zirconia ceramics and an indirect composite resin material

Statement of problemIndirect composite resins (ICRs) have been suggested as veneering materials for implant-supported zirconia-based fixed dental prostheses; however, obtaining a durable bond between the zirconia ceramic and the ICR is a challenge. PurposeThe purpose of this in vitro study was to evaluate the influence of airborne-particle abrasion conditions on the bond strength between 2 kinds of zirconia (yttria-stabilized tetragonal zirconia polycrystal [Y-TZP] and ceria-stabilized tetragonal zirconia/alumina nanocomposite [Ce-TZP/A]) and an ICR. Material and methodsZirconia disks were prepared by using computer-aided design and computer-aided manufacturing (CAD-CAM) systems. Specimens were airborne-particle abraded with different particle sizes (25, 50, 90, 125 μm) and jet pressures (0.1, 0.2, 0.3, 0.4 MPa). The control group (CO) was not subjected to airborne-particle abrasion. The surface roughness (Ra) of the specimens was measured. Subsequently, the specimens were treated with a primer and bonded with a light-activated composite resin, and the shear bond strength (SBS) was tested. The obtained data were analyzed by using multivariate analysis of variance, the Spearman rank-order correlation, and the Mann-Whitney U test (α=.05). After the SBS test, the interface failure modes were observed by scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical changes of the zirconia surface. ResultsThe Ra values increased significantly (P<.05) after airborne-particle abrasion with a positive correlation with both particle size and jet pressure. The airborne-particle abraded specimens exhibited significantly higher bond strength after thermocycling (P<.05) than the CO. Nevertheless, the bond strength was not significantly different among different airborne-particle abrasion treatments (P>.05). Additionally, Y-TZP had higher mean bond strength values than Ce-TZP/A. The XPS results revealed that after airborne-particle abrasion, the alumina particles mechanically adhered to the zirconia surface. ConclusionsWithin the limitations of this in vitro study, airborne-particle abrasion improved the bond strength between zirconia and ICR; however, particle size or jet pressure were not influencing factors.

Feature extraction method of abrasive belt wear state for rail grinding

Abrasive belt has the advantages of high removal efficiency and high waste collection; furthermore, it does not easily damage the rail when applied in rail grinding. However, the poor wear consistency and short service life restrict its development in this field. It is important to explore the theory and technology of monitoring the abrasive belt wear condition to evaluate the means of improving the grinding performance of the belt. This article discusses the contact stress state between the belt and the rail surface. In addition, the study establishes the belt rail grinding force model during operation using the abrasive grain distribution function. The analysis of the force model proposes that the belt abrasion condition be monitored by using the force ratio parameter of the abrasive belt in the grinding process. The extraction method of the force ratio information is proposed in accordance with the grinding environment. The results of experiments successfully verified the validity of the method.

Identification and modelling of applicable wear conditions for stir cast Al-composite

A comprehensive study of the tribological performance of the Al-Zn-Mg-Cu/Al2O3 composite and its matrix alloy is presented in this paper, with a specific emphasis to identify and model the applicable wear conditions where the composite provides a minimum of 50% reduction in wear rate and 25% lowering of the friction coefficient. Two-body abrasion experiments following Taguchi L27 orthogonal design have been performed separately on alloy and composite materials, both prepared by the stir casting method. The influence of crucial control factors including silicon carbide (SiC) abrasive size, load, sliding distance, and velocity on the percentage variations of wear rates and friction coefficients between alloy and composite have been studied using the analysis of variance technique and full quadratic regression method. The dominant control factors are identified as abrasive size, load, and the interaction between abrasive size and load. This has been verified by establishing the influence of abrasive size and load on variations of wear mechanisms like microcutting, microploughing, and delamination, identified by means of in-depth characterization of worn surfaces and generated debris for both alloy and composite. The selection of applicable tribological condition for the composite has been accomplished by adopting the multi-response optimization technique based on combined desirability approach to obtain concurrent optimization of the percentage variations of wear rates and friction coefficients. Predictive models correlating the superiority of tribological performance of composite with abrasion conditions have been developed, and these are found to be accurate (errors <10%), as determined by confirmatory experiment.

Effect of surface polishing on the tribological performance of hard coatings under lubricated three-body abrasive conditions

The present study investigates the effect of surface polishing on the tribological performance of two notably different coatings, namely chromium carbide and aluminized, under three-body abrasive conditions. Surface polishing altered the topographical and mechanical properties of the coatings. Detailed analysis of the most relevant roughness parameters highlighted the significance of surface topography under the tested conditions. Polished and unpolished coatings were tested on a pin-on-disk configuration under lubricated three-body abrasive conditions. Silica sand particles were added to the hydraulic oil to model contaminated lubricant conditions. In-situ friction coefficient and wear rate were obtained experimentally. The importance of surface roughness and core void volume in alleviating the abrasive wear was shown. It was found that the dominant wear mechanisms are independent of the coating roughness, however surface polishing increases wear, and does not significantly affect friction.

Fabrication, Thermo-Mechanical Processing and Characterization of a Ti-6% Al-1.5% V-1.0 Mo-0.5% Zr-0.1% C Alloy with Addition of Ru and Modifications of Small Amounts of V and Mo

ABSTRACTPseudo-α or near-α titanium alloys are being widely used in the power generation industry due to their stability at high temperature service, good mechanical characteristics and corrosion resistance. Particularly Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C alloy is mainly used in turbines components, heat exchangers and pipes for steam conduction, among others; these are subjected to critical conditions of temperature, abrasion and corrosive environments. A good performance of such devices depends on the chemistry and of the material processing story.Effects on microstructure and wear resistance with the addition of Ru and small variation of V and Mo amounts in the Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C alloy were analyzed. Three different alloys were melted in a vacuum induction furnace with a cooled copper skull under an argon protective atmosphere for this studyFour alloys were melted “Alloy 1” Ti-6% Al-1.5% V-1.0Mo-0.5% Zr-0.1% C-0.3% Ru, “Alloy 2” Ti-6%Al-0.5%V-1.6%Mo-0.5%Zr-0.1% C-0.3% Ru, “Alloy 3” Ti-6%Al-2.2%V-0.5%Mo-0.5%Zr-0.1%C-0.3%Ru. After melting, all alloys were homogenized at 1200°C for two hours, followed by hot rolling above β transition temperature with a reduction of 50% in thickness.All alloys were analyzed by using scanning electron microscopy (SEM) and Vickers Micro hardness (HV). Results shown that Mo and V variations modified the micro hardness by microstructure refinement. In contrast, the addition of Ru showed no microstructure modification.

Use of Acoustic Emissions to detect change in contact mechanisms caused by tool wear in abrasive belt grinding process

Abrasive belt tools are widely used for finishing processes, where the abrasive grains on the belt tool serve as the cutting edge to remove materials. The interaction between abrasive grain and the material surface might result in three contact mechanisms, i.e. rubbing, ploughing and cutting, where their nature are not fully understood. On the other hand, the performance of a coated abrasive belt tool is highly affected by the grain wear. A single grain scratch test with different abrasive grain wear conditions is conducted to explore the three contact mechanisms. Through scratch experiments of prismatic Aluminium Oxide (A12O3) grain on Aluminium 6061 workpiece, Acoustic Emission (AE) frequency signatures that correspond to the three mechanisms are examined. Dominant frequencies and energy signatures occupied by the three contact mechanisms are analysed using Short-Time Fourier Transform (STFT). The energy content of the dominant frequency signatures revealed that the cutting mechanism is more predominant on belt tool with new grains, which gradually becomes less significant as the grain wears. A similar trend is also observed in ploughing and rubbing modes with respect to the wear flat level of the belt tool. The general conclusion suggests that the intensity of contact mechanisms changes according to the condition of the abrasive grain, i.e. tool wear, and can be correlated with AE sensor data.

Tribological performance of graphite-filled polyimide and PTFE composites in oil-lubricated three-body abrasive conditions

Graphite filled polytetrafluoroethylene (PTFE) and polyimide (PI) composites were tested against tool steel under nominal contact pressure of 6.32 MPa and sliding speed of 1.91 m/s in clean ISO 46 lubricant, and also contaminated lubricant with 4200 ppm of silica sand. Pin-on-disk test results show higher friction and wear of the tribopair in the contaminated condition. Micromechanical properties of the bulk polymers were measured using nanoindentation technique, and softening of the material at elevated temperatures was measured. SEM analysis of the contacting surfaces before and after testing showed abrasive wear as the dominant wear mechanism, and microcutting was a less pronounced wear mechanism in the case of PI composite in contaminated test condition. EDS analysis showed that there was no film transfer from polymers to the countersurface, however it indicated higher oxidation on the wear track of the steel disk slid against PI. Particle embedding in the polymer was shown by EDS and is the reason for scratches seen on the steel disk wear tracks. Both polymers are found to be suitable materials from a tribological standpoint for bearing pad applications.

FORECASTING THE WEARING OF PLOUGHSHARES PARTS UNDER OPERATING CONDITIONS

This study presents an analysis of the process of wear of ploughshares subjected to different types of technological processing. The experiment was conducted under real-life operational conditions. Tests were performed on operating parts made of three types of steel and of steel enhanced by pad welding. Changes in the geometrical dimensions of an operating part that were implemented into the Holm-Archard model to verify its suitability by determining the wear of materials used under abrasive conditions were adopted as a measure of wear.

Influence of Shot Peening Treatment in Erosion Wear Behavior of High Chromium White Cast Iron

High alloy white cast irons (WCI) play an important role in many industrial fields such as mining, cement industry, or grinding due to their high hardness and wear resistance. In all these processes, white cast iron components must work under erosion and abrasion conditions. Many investigations have been carried out with the aim of improving the mechanical properties of this type of alloys. Wear resistance depends on the mechanical properties, mainly hardness. Thus, the WCI are typically heat treated in order to modify its microstructure, improving its tribological and wear behavior. The aim of this study is to propose a mechanical surface treatment, shot peening, as an alternative to global heat treatments, due to its capacity to induce phase transformation and microstructural modification, at the same time that it improves the mechanical properties of materials. Characterization of different treated samples was performed by means of microstructural characterization, X-ray diffraction analysis, SEM observation, hardness and roughness measurements, and erosion tests. The results show that shot peening treatment is able to transform residual austenite and increase hardness in the top surface layer of the material. Both effects contribute to improve the erosion wear behavior of the WCI.

Operation indices of the new cored wire of Fe−C−Si−Мn−Сr−Ni−Mo system

To protect and repair details of equipment, subjected to abrasive and shock-and-abrasive wear, a build-up of hard alloy is widely used to increase the wear resistance of details, operating under abrasion conditions. Cored wires of Fe−C−Si−Мn−Сr−Ni−Mo system of type A and B by MIS classification are the main wires used for wear-resistant build-up in Russia. For effective application of building-up wires it is necessary to know the dependence of built-up layer hardness and its wear resistance on mass share of elements included into the composition of the cored wires systems. Influence of chemical composition of he built-up layer, obtained by the building-up with application of new powder systems of Fe−C−Si−Мn−Сr−Ni−Mo, protected by RF patents, on its physical and mechanical properties studied. Based on the results of the multifactor correlation analysis accomplished, dependences of the built-up layer hardness and its wear resistance on mass share of elements included into the composition of the cored wires of Fe−C−Si−Мn−Сr−Ni−Mo system determined. The dependences obtained were used for forecasting of the built-up layer hardness and its wear resistance at changes of the chemical composition of the built-up layer. The tests of JOY 4LS20 mining machine screw protective plates at Kemerovo region mines, built-up by the elaborated cored wire, showed an increase of the resistance by 19.3% comparing with the analog plates built-up by DRATEC wire.

A dynamics condition of coastal environment in Padang City-Indonesia

Padang City is located on the West coast of Sumatra Island that borders directly with the Indian Ocean. The coastal region of the city stretches from Pasia Jambak beach, Muara Anai in the Northto Sungai Pisang in the South. The coast of South section is different from the coast of Northsection, because the Southern coastline is heterogeneous because there are many small bay, small islands and narrow beaches directly adjacent to the volcanic hills. This research aims to determine the dynamics condition of a coastal environment based on the characteristic (length, velocity, energy, and height), sediment transport value, accretion/abrasion factor value, and coastal equilibrium in Padang City.The method used in this study is the calculation of wavelength (L0), wave velocity (C), wave energy (E), run-up height (Hb), and sediment transport (Q) to determine accretion/abrasion factor and equilibrium (G0). Furthermore, it is done by Geographic Information System (GIS) approach to spatial information of research location. Research result shows that coastal region(beach)in Padang City tends to experience accretion along the beach of Pasia Sabalah, Panjalinan North, Panjalinan South, Parkit, Purus South, Purus North, Muaro Padang, Air Manis North and Pasia Putih. While the abrasion conditions occur inPasia Jambak, Parupuk Tabing, Bung Hatta University beach, Air Manis South and Sungai Beremas.

Wear behaviors of WC and TiC on co matrix composites under three-body impact abrasive wear condition

PurposeThe purpose of this paper is to investigate the tribological properties of the WC/TiC-Co substrate under different loading conditions under three impact abrasive wear conditions.Design/methodology/approachThe three body collisional wear behavior of Co alloy with WC and TiC at three impact energy was studied from 1 to 3 J. Meanwhile, the microstructure, hardness, phase transformation and wear behavior of these specimens were investigated by scanning electron microscopy, Rockwell hardness (HRV), EDS and impact wear tester. The resulting wear rate was quantified by electronic balance measurements under different pressures.FindingsThe specific wear rate increases with the increase of the nonlinearity of the impact energy and the increase in the content of WC or TiC. The effect of TiC on wear rate is greater than that of WC, but the hardness is smaller. The wear characteristics of the samples are mainly characterized by three kinds of behavior, such as cutting wear, abrasive wear and strain fatigue wear. The WC-Co with fewer TiC samples suffered heavier abrasive wear than the more TiC samples under both low and high impact energy and underwent fewer strain fatigue wears under high impact energy.Originality/valueThe experimental results show that the wear resistance of the Co alloy is improved effectively and the excellent impact wear performance is achieved. The results can be used in cutting tools such as coal mine cutting machines or other fields.

Fabrication of flower clusters‐like superhydrophobic surface via a UV curable coating of ODA and V‐PDMS

ABSTRACTIn this work, a flower clusters‐like superhydrophobic surface was fabricated via an ultraviolet (UV) curable coating of octadecylamine (ODA) and vinyl‐terminated polydimethylsiloxane (V‐PDMS). ODA self‐assembled into many flower clusters‐like structures on the surface of the coating, increasing the roughness of the coating surface without additional nanoparticles. V‐PDMS formed a highly crosslinked network under a UV lamp, which would be helpful for a robust superhydrophobic surface. The obtained PDMS/ODA fabric showed water contact angle of 161° and sliding angle of 5°. The durability of the superhydrophobic surface was tested by water impacting, tube brush scrubbing, knife scratching, hand twisting, finger pressing, tape adhesion, abrasion, continuous rinsing, and chemical conditions. The experimental results indicated that the superhydrophobic surface have good durability for long service life. Moreover, the PDMS/ODA fabric could selectively absorb oils from water with good separation performance. This work will provide a facile, low cost, and versatile method to prepare superhydrophobic surfaces, and enhance their efficiency of oil–water separation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48210.