Wear最新文献

In highly loaded steel-bronze rolling-sliding contacts under mixed lubrication conditions, abrasive wear often occurs and limits the service life. Up to now, in applications of thermal elastohydrodynamically lubricated (TEHL) contacts with hard/soft pairing such as worm gear drives, extensive, costly, and time-consuming component wear tests need to be carried out to determine the wear performance for each tribological system. High-carrying capacity lubricants and bronze alloys with high wear resistance are expensive, so an efficient screening test method for wear performance will help to save development and product costs. For this reason, this paper covers a new and efficient method based on a twin-disk test rig to experimentally determine the wear of steel-bronze rolling-sliding contacts. The wear determination method presented is suitable for efficiently determining wear rates and shows comparable wear behavior to similar rolling-sliding contacts in the literature. The introduced method also allows conclusions about the wear performance of tribological systems from the twin disk to the worm tooth contact with a remarkably shorter test run time.

In the grinding process of 2.5D C/SiC composites by the ordered grinding wheel, the signals are more complicated due to the special structure of the material and the ordered abrasive clusters, which makes it difficult to identify the wear state of the grinding wheel. To solve this problem, this study employs the analysis methods of direct and indirect. The acoustic emission signals, grinding force and grinding temperature signals throughout the entire lifespan of the grinding wheel were collected, and the topography of the grinding wheel was photographed. The difference in wear behavior between the ordered grinding wheel and the traditional disordered grinding wheel was compared and analyzed. The corresponding relationship between the ordered grinding wheel wear behavior and various signals was studied in depth. The results showed that the initial wear occurred during the 1st-80th grinding process, the stable wear occurred during the 81st-224th grinding process, and the serious wear occurred during the 225th-350th grinding process. Additionally, this research further extracted the key features of various signals, and used the Pearson correlation coefficient to identify the features highly related to grinding wheel wear. Subsequently, LDA was used to reduce the dimension of individual signal types. By comparing the recognition effects of different signal type combinations, the optimal combination was determined. Finally, this research proposed a DBO-ELM model for the recognition and classification of ordered grinding wheel wear state. Compared to four common machine learning models, namely KNN, SVM, ELM, and BP, the proposed DBO-ELM model demonstrated a classification accuracy of 94.86 %, which was increased by 25.57 %, 16 %, 16 % and 7.86 % respectively. This demonstrates that the DBO-ELM model proposed in this research has certain advantages and potential in the wear state recognition of abrasive clusters ordered grinding wheel.

Friction and wear, specifically in automotive components, significantly impact fuel consumption, greenhouse gas emissions, material quality and lifespan, operational costs, and depleting the planet's finite resources. High-performance polymers (HPPs) like Polytetrafluoroethylene (PTFE) are used for their low friction, high wear and chemical resistance, high-temperature stability, and self-lubrication. This study investigates the effects of various reinforcing fillers on PTFE's tribological performance under a 32 N load and 0.5 m/s sliding speed for 1 h in unlubricated conditions, representing automotive air-conditioning compressors. PTFE reinforced with aromatic thermosetting copolyester (ATSP) demonstrated superior wear resistance and lower friction compared to carbon black, bronze, and graphite fillers. The enhanced performance of PTFE-ATSP blends is due to their higher mechanical strength and ability to form fluoride-rich lubricating transfer films on the 440C stainless steel counter surface. PTFE-ATSP blends offer an effective solution for unlubricated engineering applications aimed at sustainable environments.

This study investigates the potential use of additive manufacturing (AM)-produced gears in the polymer gear industry as an alternative to conventionally manufactured gears. The focus is on comparing the wear and thermal properties of polyamide 6 (PA6) gears, the most commonly used in industry, with those of polyetherimide (PEI) gears manufactured via AM. The research aims to determine whether AM offers any advantages over conventional methods, particularly with regard to wear resistance and thermal performance. The wear behaviour of both types of gears is examined under various operating conditions, with particular attention being paid to the initial wear rates and how they evolve. PEI and PA6 test gears were evaluated using a custom-built gear wear test rig. Throughout the wear test, polymer test gears were subjected to wear by running against a metal gear. The gears were tested at various rotational speeds for up to 1 million cycles. During this process, measurements were taken to determine surface roughness changes, operational noise levels, microstructure analyses using scanning electron microscopy (SEM), and chemical structure analyses using Fourier transform infrared spectroscopy (FTIR). Additionally, thermal properties such as temperature generation and stability are monitored with a thermal camera and infrared thermometer to understand the suitability of each gear material for different applications. PA6 gears demonstrate better wear resistance at low and medium rotational speeds, while PEI gears show superior performance at high speeds. Furthermore, PEI gears display enhanced thermal properties, with lower temperature increases during operation compared to PA6 gears; this can be attributed to the porous structure inherent in AM, which allows for better heat dissipation. The findings suggest that AM-produced PEI gears hold promise as an important alternative in high-speed applications due to their superior wear resistance and thermal performance compared to conventionally manufactured PA6 gears.

As an inherent attribute of asphalt pavement, texture durability is the essential reason for the change in skid resistance. However, different scale texture deterioration behavior remains unclear by tire wearing at present. To explore the influence of the durability of multi-scaled textures on skid resistance, nine pavement specimens were tested using the Harbin polishing and dynamic friction integrated experimental machine (HPFM). The pavement anti-skid texture tester (PATT-II) was used for high-precision texture scanning and reconstruction. The results show that the texture richness and skid resistance of the three types of pavements in 300 min polishing are ranked as Open-graded Friction Coarse (OGFC) > Stone Mastic Asphalt (SMA) > Asphalt Concrete (AC), while SMA presents the best durability, determined by the material skeleton structure of asphalt mixture. The macro-texture deterioration occurs slightly at first and then tends to stabilize in 300 min polishing. The micro-texture deterioration behavior is the same as the μ_HPFM, increasing rapidly at the beginning, then slowly decreasing, and finally remaining constant. This deterioration is caused by the asphalt damage and continuously wearing aggregate surface. The 2D-PSD deterioration behavior is more significant with a smaller texture scale in 300min polishing, and the most considerable contribution wavelength in the microscopic scale range is 0.15 mm–0.3 mm, which is determined by the adhesion characteristics and molecular mechanism between a mineral mixture and asphalt material. The influence of pavement texture on the dynamic friction coefficient is significantly different under different water film thicknesses, the micro-texture and macro-texture play the main roles in boundary and mixed lubrication, respectively.

Nickel-based superalloy has great potential in the aerospace industry as key components. However, difficult-to-machine characteristics have further limited its application. Thermal-barrier coatings of the titanium-based family on carbide tools offer exceptional performance in cutting superalloys, combining high-temperature stability and remarkable toughness. This work primarily concentrates on understanding cutting-edge microstructure and deformation induced by tool adhesive wear in the turning of nickel-based superalloys with experiment and modelling. The dominant tool wear mechanisms are revealed to be adhesive wear and abrasive wear by SEM/EDS. The microstructure of the cutting-edge interface is qualitatively and quantitatively investigated by SEM/EDS and EBSD. The adhesive layer thickness at cutting edge is about 10–30 μm. The GND density of WC grains at cutting edge is 15-20 × 10¹⁴/m. The nanomechanics properties of the tool wear interface were quantitatively evaluated by nanoindentation. The average hardness of WC and Ni-superalloy at cutting-edge interface is evaluated to be 15–19 GPa and 6.2–6.5 GPa, respectively. Further, the underlying deformation mechanisms induced by tool wear behaviours are revealed through the transient heat conduction model and cutting-edge stress distribution model. This research offers a framework and mechanism for the cutting tool wear surface/interface characteristics targeted to the difficult-to-cut superalloy materials.

With increasing demands for friction reduction and wear resistance in heavy-duty diesel engines, the design of surface textures in reciprocating contact zone of the cylinder liner and piston ring (CLPR) has been a major concern. Through designed orthogonal tests for optimizing the double-sided textured CLPR, a maximum reduction in the friction coefficient of 12.63 % was achieved for the superior double-sided textured CLPR compared to the untextured surface, with corresponding reductions in the wear depth of the cylinder liner and piston ring of 16.73 % and 18.25 %, respectively. The relative position variation between the CLPR microtextures at the sliding contact area caused different stress values and stress distribution. Compared to the inferior double-sided textured CLPR, superior double-sided textured CLPR with lower stress concentration and symmetrical distribution within the contact area generated smoother and flatter worn platforms and non-spalling dimple edges with less abrasive wear. It can provide some insight into the matching design of double-sided CLPR surfaces under heavy load conditions.

In order to improve antiwear properties of the cutting tool for titanium alloy, the temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM)-graphene oxide (GO) nanocomposites were developed in this work. The tribological properties of the titanium alloy/cemented carbide contact lubricated with the PNIPAM-GO nanocomposites were investigated. The results show that the PNIPAM-GO nanocomposites have stable dispersive and controllable lubricating performance. The wear of the titanium alloy decreased and the adhesive behavior was improved with the increase of GO in the nanocomposites. The tribological performances are attributed to both the controllable release of GO sheets from the nanocomposites and the formation of a protective tribofilm. A mechanical mixing submechanism counts for the decrease of friction and wear of titanium alloy/cemented carbide contact lubricated by the nanocomposites.

The focus of this study is to compare the wear characteristics of different types of micro-prismatic electrode array during EDM, and to propose a method for preparing microcylindrical electrode array based on micro-prismatic electrode array. Firstly, the characteristic of the micro-prismatic electrode that the front cross-section becomes circular after wear during EDM is clarified, and the wear form of the micro-prismatic electrode is analyzed. Then, the laws of the influence of electrode shape (triangle, square, hexagon), electrode material (pure copper, copper-tungsten alloy, pure tungsten), electrode size (200 μm, 300 μm, 400 μm) on the wear characteristics of the micro-prismatic electrode array, including the length of the wear of each part of the electrodes, the length of the area of the front cross-section that becomes rounded, the consistency of the wear of the electrode array, the machining efficiency, and electrode wear rate are summarized. After that, the process of changing the electrode array from square columns to cylinders using the new method is given, which confirms the feasibility of the method. Finally, the effects of peak current and pulse width on the size, machining efficiency, surface roughness, and surface micro-morphology of micro-cylindrical electrode array prepared by the new method are summarized. This study is of great significance for achieving mass production of microcylindrical electrode array.

An Inconel 690 alloy tube acting as a steam generator tube has been widely applied in the second and third generations of nuclear power plants using pressurized water reactors. However, its entire service process is always accompanied by high-temperature and high-pressure (HTHP) liquid medium corrosion and various fretting mechanical damage behaviors. This study first immerses the Inconel 690 alloy tube in HTHP corrosive medium for different lengths of time (0, 4, 8, and 12 h); then, a fretting tribo-corrosion test rig is used to investigate the effect of different fretting mechanical parameters on the surface damage mechanism and electrochemical dynamic response of each test sample. Results show that the corrosion rate of the Inconel 690 alloy tube has significantly increased after being treated by HTHP immersion corrosion, which is mainly due to the pre-existing corrosion products.