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To improve the roughness prediction accuracy of Al2O3-based ceramic insulation coating on bearing surfaces, a method based on the spectral confocal principle was proposed for measuring the surface of grinding wheels and quantifying the characteristic parameters of abrasive particles. The abrasive characteristic parameter K of the grinding wheel surface, the grinding wheel line speed vs, the workpiece feed speed f, the cutting depth ap, and the normal grinding force F were taken as input parameters. A BP neural network prediction model of workpiece surface roughness, which directly reflects the time-varying state of the grinding wheel surface, was established. The prediction performance of the network model was verified using known grinding samples and four groups of unknown samples after grinding wheel wear. The results show that the predicted roughness results of the BP network model with known samples are consistent with the actual roughness results in terms of regularity and numerical values, with network output errors are all less than ± 0.04 μm. The network prediction accuracy for the four unknown samples decreases, but the absolute value of the maximum relative error does not exceed 20.00%. The neural network prediction model, which includes the characteristic parameters of abrasive particles on the grinding wheel surface , can be used to predict the roughness of Al2O3-based ceramic insulation coating on the bearing surface under the time-varying state of abrasive wear on the grinding wheel. It also demonstrates a certain generalization ability for unknown samples.

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Steel Pipe is the property of Steel Pipe Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The abrasive wear characteristics of large length to diameter ratio CBN single-pass honing tools during ultrasonic dressing process were studied by single abrasive test with 4Cr13 stainless steel as dressing material. The test results show that the average cutting force during ultrasonic cutting is reduced by 60%～80% compared to that during ordinary cutting. However, the abrasives break in a short time and the grinding ratio is seriously reduced. The abrasive-workpiece contact ratio during ultrasonic cutting is mainly between 0.6 and 0.8, and the abrasives are mainly in the intermittent cutting process. Moreover, the maximum cutting width during ultrasonic cutting increase by 2.7 times compared with that during ordinary cutting, leading to an increase in the maximum cutting force on the abrasives. According to the point cloud information, the abrasive was modeled inversely, and a single abrasive cutting simulation model was established to quantitatively analyze the maximum cutting force. The simulation results show that, compared with that during ordinary cutting, the maximum cutting force during ultrasonic cutting is more than 20% higher, and the fluctuation of cutting force is more than 80%.

The pantograph copper impregnate carbon strip with abnormal wear in the winter operation of a domestic subway line was studied. The differences in surface morphology, microstructure and chemical composition between the carbon sliding plate surface with normal wear and the carbon sliding plate surface with abnormal wear were compared with a variety of microscopic testing methods, so as to explore the causes and mechanism of the abnormal wear of the carbon strip. The results show that, compared with the carbon sliding plate in normal wear state, the three--dimensional surface topography of the carbon sliding plate in abnormal wear state is rugged and rough, the friction conditions deteriorate significantly, and mechanical abrasion wear, abrasive wear, arc ablation and material transfer are increased. When at the autumn and winter seasons, the surface lubrication conditions of carbon strip change, the number and diameter of the abrasive particles increase, and the temperature of the contact pair rises, which aggravates the abrasive wear and arc ablation, resulting in abnormal wear of the carbon strip. After tracking and monitoring the operation process of subway, it is found that the occurrence of abnormal wear of the carbon strip is related to the decrease of environmental humidity in the tunnel. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rolling-sliding dry friction properties of AZ91 and AZ91-Y (1.0% Y) (mass fraction)were studied with 45 steel as friction pair. The experiment was carried out under different normal loads (100,200,300 N), respectively. The worn surfaces of AZ91 and AZ91-Y samples were investigated by energy dispersive spectrometer (EDS),scanning electron microscopy (SEM) and X-ray diffraction (XRD) so as to analyze wear mechanism. The results indicate that the wear rates of AZ91 and AZ91-Y samples boost linearly but the friction coefficients are decreased gradually with the increase of normal loads. Al2Y particles can refine grains, weaken the tendency of interface cracking to improve the wear resistance.Hence,the wear rates of AZ91-Y are decreased by 21.7% and 5.9% compared with AZ91 alloy when normal loads are 100, 300 N, respectively. Meanwhile,the main wear mechanisms of AZ91-Y alloy are abrasive wear and delamination wear, which is the same with AZ91 alloy.

The friction and wear behavior of NM400 and NM500 steels in the temperature range from room temperature to 300℃ were investigated, including the formation of interface oxide, wear surface morphology, and microstructures. A high-temperature sliding friction tester was used to study the behavior of sliding friction between wear-resistant steel and Al2O3 ceramic balls under different loads of 200-300 N and speeds of 100-400 r·min-1. A ball-disc friction pair containing mix-sintered Al2O3 ceramic balls with a diameter of 5 mm was mounted on the holding tool and steel plate. The friction coefficients of the two materials from room temperature to 300℃ are determined to be in a range of 0.27-0.40, whereas the average friction coefficients of NM400 and NM500 steels are found to decrease gradually from 0.337 to 0.296 and from 0.323 to 0.288. The generation of oxides is the primary reason for slight decrease in the friction coefficient at a high temperature of 300℃. The friction behavior is controlled by the abrasive wear mechanism, and then the phenomenon of pressure-into-peeling-oxidation of oxide gradually occurs at a higher temperature, which slightly reduces the wear rate. Larger amount of oxides are produced on the interface as the temperature increases, but this is not sufficient to form a continuous oxide layer. The main wear pattern at this time is still abrasive wear, although the wear rate and friction coefficient are affected by oxides. The main factors influencing the wear behavior are the hardness, oxide volume fraction, and oxidation activation energy of the wear-resistant steel, as found through the analysis of high-temperature frictional wear behavior and micro-oxidation model. In conclusion, the wear mechanisms of NM400 and NM500 steels from room temperature to 300℃ are influenced by the combined effect of abrasive wear, extrusion deformation wear, and trace oxide wear. NM500 steel exhibites better wear resistance than NM400 steel, and this can be mainly attributed to higher level of its hardness. A small amount of additional alloying elements in the high-strength microalloyed martensitic wear-resistant steel can reduce the wear rate to some extent, due to the formation of a certain amount of stable attached oxides that are produced during the high-temperature friction process.

Aiming at studying the wear mechanism of a single PCBN abrasive grain at high-speed grinding of Inconel718, the grinding force, the material pile-up ratio and the wear of the abrasive grains during the high-speed grinding experiment were studied. The MV - 40 CNC machining center was employed in the process of High-speed grinding Inconel718 with single abrasive grain. The grinding force was measured by a dynamometer, the grinding crack and abrasive wear were observed with a 3D profilometer and super depth-of field microscope, and the material pile-up ratio and abrasive grain wear change law were analyzed. The wear of abrasive grain was analyzed from the angle of grinding force ratio, cross section of grinding cracks and pile-up ratio. The results indicate that during the initial wear stage, the tip of the abrasive grain appeared macro-fracture, material adhesion and crack, and during the stable wear stage, the crack expanded along the cutting edge until new cutting edges were formed. The grinding force ratio (Fn/Ft) and pile-up ratio will be increased by the passivation of the abrasive grain at the initial wear stage, while the grinding force ratio (Fn/Ft) and pile-up ratio will be decreased by the formation of new cutting edges at the stable wear stage. The increase of grinding depth will aggravate the wear of abrasive grain, and the grinding force ratio (Fn/Ft) will appear earlier than the inflection point [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Assisted drilling with non-liquid technologies,such as supercritical CO2 jet, are more and more important in natural gas exploration, especially in coal-bed methane exploration. As a kind of non-liquid technologies, abrasive gas jet is widely used to drill metal and glass. It is also powerful enough to break coal and rock, which is the primary precondition of its usage in coal-bed methane exploration.To understand the rock erosion wear mechanism of abrasive gas jet is critical important to apply the technology preferably and widely. However, the existing erosion mechanism mostly neglects the effect of rebound abrasive. To this end, the experiments of limestone erosion by the abrasive gas jet under different kinds of abrasives and different stand-off distances were carried out. The experiment results show that the ero-sion pit has an approximate inverted cone-shape. The bottom of erosion pit is of hemispherical. There is an annular platform above the hemispherical bottom, which connects the bottom and side of erosion pit. The primary reason that induces the peculiar shape of erosion pit is the specific flow field of abrasive gas jet. There is an annular region between the axis and boundary of the abrasive gas jet, and there is no abrasive in the annular region. The abrasive around the axis induces the formation of hemispherical bottom. After rebounding, the abrasive around axis moves to the annular region. The rebound abrasive with high velocity enlarges both the diameters of hemispherical bottom and erosion pit and induces the formation of annular platform. The failure characteristics of different areas of the erosion pit were analyzed by Scanning Electron Microscopy(SEM). It can be concluded that the failure models of different spots are different. The failure is caused by the impact stress wave of the incident abrasive at the base of the hemispherical bottom. Plastic deformation is the primary failure model induced by the rebound abrasive at the side of hemispherical bottom. The plastic deformation induced by incident abrasive and fatigue failure induced by rebound abrasive are the primary failure model at the annular platform. Fatigue failure induced by rebound abrasive is the primary model failure at the side of erosion pit. The rock failure reason of abrasive with different hardness is the same, but the rock damaged by hard abrasive has rougher surface and higher rock breakage efficiency. [ABSTRACT FROM AUTHOR]

Aiming at the problems that the constant rotation angel and uneven distribution trajectory while manufacturing with concentric circles, the process parameters for material removal of high-precison balls was investigated. The high precision balls can be manufactured by using spiral groove lapping plate and changing rotation angel. The processing trajectory can be distributed over the entire spherical surface after a single processing cycle. After the analysis of the load with different diameters of the same batch balls, the mechanical model was established. The numerical analytic method was presented to influences on load distribution of balls grinding. The material removal with different pressure and rotation speed were tested. The experimental results indicate that small processing load has a certain advantage in "size-selective". The large load is used to improve the material removal rate in rough stage, and the small load is used to get optimal accuracy in finishing stage. [ABSTRACT FROM AUTHOR]

The abrasive-wear properties of 8Mn-2Cr-Si steel were tested under different impact energy conditions. XRD (X-ray diffractometer) was used to investigate the structural transformation of the impacted wear surface， and SEM (scanning electron microscope) was used to investigate the morphology of wear surface and subsurface in order to study wear mechanism. The results show that impact-induced martensite phase transformation occurs during the wear. With the impact energy growing， the amount of martensite transformation increases， the work hardening effect improves and the wear loss increases. The reason is the wear mechanisms are different under different impact energy conditions. Besides， the grains embedded in the substrate during the plastic deformation will become sources of stress concentration. Thus the fatigue cracks will grow and propagate to the wear surface gradually under the circulation impact， causing large impact-flaking， finally making the material failure. [ABSTRACT FROM AUTHOR]

Single grain abrasive wear model is established for the micro grinding process. The abrasive wear at different stages in micro-grinding process is analyzed by the observation toward the diameter variation and the surface appearance of the micro-grinding tools as well as the surface quality variation of the workpieces. Tool wearing influence rules caused by various grinding influence factors are also studied through single-factor experiments on soda-lime glass， with #500 particle size micro-grinding tools adopted. The experiment results indicate that the wear and breakage of abrasive grains are increased as long as the feed speed and feed rate increase during the micro grinding process. In addition， as the material removal volume increases， the diameter of the micro grinding tool decreases sharply at first， and then decreases linearly. Generally， a decrease trend of the roughness value is observed form the machine surface. The achievements of this paper provides theoretical and experimental basis for increasing working life and improving processing performance of micro-grinding tool. [ABSTRACT FROM AUTHOR]

Microstructures and properties of 42CrMo steel and dual-phase wear-resistant steel after a quenching and tempering treatment were investigated, where water and quenching oil were used as quenching medium, respectively. The results show that both microstructures of the water-quenched+tempered and oil-quenched+tempered dual-phase wear-resistant steels are lath martensite, needle-like bainite and carbide. The microstructures of the water-quenched+tempered and oil-quenched+tempered 42CrMo steels are tempered martensite and retained austenite, and tempered martensite, ferrite and bainite, respectively. The optimum heat treatment and properties of 42CrMo steel and dual-phase wear-resistant steel can be obtained after the comparison of their microstructures and properties. As a result, the wear-resistant property of 42CrMo steel after water-quenching and tempering at 280℃ treatment is the best one, which is 1.558 times higher than that of a high manganese steel in a 480h low-stress abrasive wear experiment. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The wear of plant abrasive is the main reason to roller wear failure in wheat roller milling industry, while the heat treatment is the general strengthening means of surface hardness of low chromium white iron which is usually used as roller material. In this paper, 3 principles of abrasive wear were applied, and low chromium white iron was chosen as the test samples and wheat powder was chosen as abrasive. The wear test was conducted on wear test machine under the similar work process of industrial roller milling. The test was divided into 2 phases. In the first phase, 9 groups of samples were heat treated with different process parameters according to the design of orthogonal test, and then cooled to the room temperature by air cooling. The wear tests of wheat powder were conducted for all 9 groups of samples under room temperature condition for 2 h. The wear tests repeated 3 times and the average quality losses were recorded. The various factors of heat treatment process were sorted by SPSS (statistical product and service solutions) statistical analysis software. The effects of the factors in heat treatment process were analyzed, and the optimum process was obtained using Duncan multiple comparison. In the second phase, 2 groups of samples under identical conditions were contrasted. The first group of samples had not been heat treated, and the second had been heat treated according to the optimum heat treatment process. The wear test in the second phase contained 5 test cycles, and each cycle was conducted for 2 h. The various wear characteristics were analyzed, such as wear quality losses, and feature of wear surface; the metallographic examination, the energy dispersive spectrometer analysis and the scanning electron microscope morphology were performed. Then the reinforcement effects of heat treatment under the optimum heat treatment technology were investigated. The results showed that the optimum heat treatment technology is 960 °C with 1 h air quenching and 250 °C with 2 h tempering. The recommendation for roller production is that roller surface hardness should be strengthened according to the heat treatment process of 960 °C air quenching and 250 °C tempering. The wear quality loss of low chromium white iron samples under the optimum technological combination was about 42% of its original quality loss. The network broken phenomenon of eutectic carbide was obvious in cast structure, which existed in the form of semi-continuous networks or isolated blocks in the matrix. The groove trace of the worn surface was shallow and narrow, and the peak-to-valley value of ridges was low. The content of metal elements decreased while the non-metallic element content increased. The hardness increased significantly. The wear mechanism was mainly the micro-cut abrasive wear because wheat powder abrasive formed the "incompressible group", and the worn surface had obvious plough-cutting and furrow. Otherwise, if the wheat powder abrasive did not form the "incompressible group", the wear mechanism would be mainly the multiple plastic deformation and low cycle fatigue wear. The metal was finally separated from the sample matrix because of strengthening and exceeding plastic deformation. The research results can provide references for strengthening the roller wear-resistant performance and reducing the metal contamination during flour roller milling process. [ABSTRACT FROM AUTHOR]

According to the observation and analysis of the hinge joint（ friction pair） among pin,sleeve and roller in the chain of bucket coal elevator by means of scanning electron microscope,it shows that the wear mechanism of pin and sleeve is mainly abrasive wear accompany with fatigue wear after choosing the martensitic stainless steel material to produce parts. When the material of rollers is medium carbon alloy steel,the wear mechanism is corrosion wear and fatigue wear due to the effect of environmental medium,which is different from the dual sleeve.

As one of the important biomass resources in China, straw plays an important role in energy utilization. While straw solidifying technology provides an effective utilization route which has been widely used. After densification, both density and intensity of the straw fuel were improved, making it easier to transport, store and use. And this efficient utilization is also crucial for providing bio-energy, releasing the risk of environmental pollution caused by crop straw burning. But there are still some problems, such as easy wear of ring die, which will shorten its service life. In this paper, the wear behavior of ring die has been studied based on experimental test and theoretical analysis. After the shape of the worn ring die was tested, the microscopy morphology was obtained by scanning electron microscopy (SEM), and then the wear mechanism was analyzed. By testing it is found that abrasion mainly occurs in the middle part and lower side of the die, and abrasion gradually weakens along the feed direction. Hard abrasive wear plays a leading role in the wear process; the material loss of the die surface is caused by the cutting fracture mechanism. According to conclusions above, the calculation model of this abrasive wear was deduced based on fractal theory. It shows that the wear rate of the ring die is related to the particle size silhouette coefficient G, contact area Ar, forming speed v and material properties. Then the effect of the forming speed and the hardness of the ring die to this abrasive wear was investigated by using finite element analysis software DEFORM. The forming speed was set as 7, 8, 9 and 10 mm/s four levels, and the die hardness was set as 42.5, 45, 47.5 and 50 HRC four levels. The forming temperature was 110°C while the extruded material length was 45 mm. Simulation results show that the wear depth of the ring die increases with increasing forming speed and decreases with increasing die hardness. Range analysis results of the above two factors are RHRC=2.846, RV=1.822, RHRC >RV, which means that die hardness plays a more important role than forming speed to the die wear. To verify these conclusions, 45 steel dies were divided into four groups for heat treatment to obtain different hardness (36.2 HRC, 42.8 HRC, 47.9 HRC and 52.6 HRC). The heat treatment method was tempering after whole quenching, different hardness was achieved by controlling the tempering temperature. Then these ring dies were installed into the machine for production testing after being weighed and the forming speed was set as 9 mm/s. The experiment results indicate that the wear resistance of the ring die increases with increasing hardness, while the die hardness is between 36.2 and 47.9 HRC. Because it is more difficult for the abrasive to press into the metal with a higher die hardness. Its brittleness will be enhanced if the surface hardness is too high for the same material, this may lead to die failure directly under the high pressure working environment. The die with a hardness of 52.6 HRC was broken shortly after the experimental test started. While the forming speed is 9 mm/s, the interior of the fuel combines relatively close, and the product density is 0.96 g/cm3 with a better ignition performance. In addition, the fractal dimension of the worn working surface decreases with increasing die hardness. [ABSTRACT FROM AUTHOR]

During the process of drilling carbon fiber reinforced plastics (CFRP), it tends to effectively reduce or eliminate manufacturing deficiency, such as burr and delamination using electroplated diamond step-core drill whose service life mainly depends on the service life of electroplated diamond abrasive. Therefore, systematic statistical observation was carried Out on the abrasive wear patterns of electroplated diamond. Investigations show that using the electroplated diamond step-core drill, three unique stages of diamond abrasive wear can be observed during the process of drilling T300 CFRP, which involves initial instable wear stage, mixed-wear stage and normal wear stage. The wear patterns of diamond abrasive and drilling thrust force have a significant linear relationship. With the growing of hole numbers, the thrust force gradually increases, but diameter tolerances of the holes are still stabilized in a range of 0. 024 mm after the initial instable wear stage. [ABSTRACT FROM AUTHOR]

A new wearability hardfacing electrode was developed by using the core of H08A and the coat contents of Fe-Ti, Fe-V, graphite, rutile, etc. The microstructure and properties of hardfacing metal were systemically researched. The results show that the carbides formed by high temperature arc metabllurgic reaction are dispersedly distributed in the base structure and basically distributed along the verge of crystal grain. The carbides are compression aggregation of TiC, VC and present irregular block, angle and stick. The base microstructure of hardfacing metal is lath martensite. The lath martensite and dispersedly distributed carbides are the micro-base of the hardfacing layer with satisfactory wearability and well cracking resistance. The constitutive phases of hardfacing metal are α-Fe-γ-Fe+VC+TiC+Fe3C. The hardness of hardfacing metal increases with the increase of contents of Fe-Ti, Fe-V, graphite, while the cracking resistance and welding technique are worsen off. The hardness of surfacing metal can be more than HRC60, and its relative wearability is five times that of D667. [ABSTRACT FROM AUTHOR]