Average Wear Research Articles

In Situ Generation of TiCN Ni‐Based Coatings by Laser Cladding and Study of Their Structure and Properties

The influence of the ratio of TiN powder, graphite powder, and Ni60 powder on the phase composition, microstructure, microhardness, and wear properties of the TiCN Ni‐based coating on H13 steel is investigated. The findings indicate that varying proportions of TiN powder, C powder, and Ni60 powder have a minimal impact on the coating's phase composition. The diffraction peak intensity of TiC0.3N0.7 increases with the addition of (C + TiN) in the blended powder, while the crystallinity of TiC0.3N0.7 in the Ni‐based coating with a 30% (C + TiN) mass fraction decreases. The grain structure of the 20% Ni‐based coating is fine and uniform, while the microstructure of the 30% Ni‐based coating is characterized by a large polymerization phase‐containing Ti elements, with the TiCN‐reinforced phase exhibiting irregular grain morphology. The microhardness HV0.5 of the coating with a 20% (C + TiN) mass fraction ranges from 725 to 772, with an average hardness of 747.8 HV0.5, which is 3.4 times the hardness of the substrate material and 1.3 times the hardness of the Ni‐based coating. As the mass fraction of (C + TiN) in the hybrid powder increases, the friction loss mass of the coating tends to decrease and then increase. The average wear of the Ni‐based coating with a 20% (C + TiN) mass fraction is ≈22.4% of that of the substrate and 50% of that of the Ni‐based coating, demonstrating excellent wear resistance. The wear mechanism is primarily characterized by brittle spalling and abrasive wear.

Investigation of curve minimum radius in heavy-haul railway to improve wheel wear evolution and wheel-rail contact geometry

To determine the minimum and reasonable radius of horizontal curve for reducing wheel wear in heavy-haul railway design, a HXD locomotive with the wheel arrangement of C0-C0 is taken as the research object. Both the corresponding locomotive dynamic model and wheel wear model are established. Based on the measured wear data in a specific line, the simulation model is verified with the prediction error of wheel wear depth below 0.5 mm in general. The wheel wear evolution rules in 400∼1000m radius curves are studied and compared. The results indicate that, the wheel wear is large and sensitive to curve radius within 400∼600 m. The larger radius curve will be helpful to reduce wheel flange contact and wheel wear. For curve radius increasing from 600m to 1000m, the wheel average wear reduces slowly. Especially for curve radius below around 740 m, the wheel flange wear will be predominant. For radius above 740m, the wheel tread wear becomes the main wear form and the wheel flange wear can be reduced significantly. The increase of curve radius will also improve the wheel-rail equivalent conicity. If the minimum curve radius is set as 800m, the equivalent conicity difference between new wheelset and 1st ∼ 3rd worn wheelset can be kept below 21%, 52% and 9% respectively. In this case, the equivalent conicity is closest to the initial state and reaches a steady state, which will not change significantly with the radius further increasing. Viewed from the aspects of reducing wheel wear, avoiding wheel flange contact and keeping conicity stable simultaneously, the minimum radius of horizontal curve should be limited to 800 m. The research results validate the minimum curve radius suggested in Code for Design of Heavy-haul Railway in China, and provide a scientific explanation for the determination of this value.

Force and wear prediction model of disc cutter under compression shear failure mode based on dense core–cavity expansion theory (U-713)

Calculating disc cutter wear and predicting wear life are long-standing issues affecting the efficiency and cost of tunnel boring machines (TBMs). During the TBM excavation process, the wear of the disc cutter is a comprehensive outcome of the interaction between the tool and rock. Studying the mechanisms of tool rock breaking and wear can assist in developing a more precise model for predicting cutter wear. Therefore, based on the rock-breaking and wear mechanisms of a cutter, this study developed a model for predicting the cutter wear rate and life. The model is based on the theory of dense core–cavity expansion combined with the motion state of a cutter. First, the TBM excavation process and rock-breaking mechanism of a cutter were analyzed in detail. A cutting force model under the compression shear failure mode based on the dense core–cavity expansion theory was established. Based on the force model, a prediction model for the wear rate and life of the disc cutter was established, considering the working characteristics and wear mechanism. Furthermore, the impact of penetration on the prediction model was investigated. In addition, to demonstrate the practicality of the method, this study conducted a comprehensive examination using engineering examples. The results showed that the average difference in the cutter average wear rate using the developed model was less than 3% compared with the actual engineering result. In addition, the average difference in the wear life rate was less than 5%. Finally, the developed prediction method was compared with other models. The wear rate fitting accuracy was improved by 4.91–10.85% and the wear life fitting accuracy was improved by 5.11–12.19% by the developed method. This improvement confirms the reasonableness and reliability of the method. This method can estimate the wear rate and lifespan of a cutter more accurately and reliably than other methods, providing a practical tool to TBM engineers to make informed decisions and optimize tool replacement programs.

Bias voltage-induced structural change in PECVD-deposited diamond-like carbon coatings for optimizing the tribological performance

To improve the adhesion strength and enhance the wear resistance of diamond-like carbon (DLC) coatings, different negative bias voltages were utilized to deposit a-Si:C:H/H-DLC/DLC composite coatings on the 45 steel substrates using direct current plasma enhanced chemical vapor deposition technology. Influences of negative bias voltages on the surface morphology, microstructure, mechanical properties, and tribological performance were investigated. The results showed that as the bias voltages increased from −400 V to −600 V, the surface roughness and thickness of the coatings increased, reaching a maximum roughness of 0.426 μm and a maximum total thickness of 9.9 μm. Raman data illustrated the decrease of hydrogen contents and the increase in sp3 bonds content, matching well with the increasing hardness and elastic modulus. The residual stress tended to increase as the bias voltages, while the adhesion strength reached the maximum value of 62.45 ± 2.65 N at −550 V. Under the synergistic effects of surface roughness, interfacial adhesion strength, hardness and elastic modulus, the average friction coefficient and wear rate of the coatings initially decreased and then increased, reaching the best tribological performance at −550 V.

A novel organic-inorganic two-dimensional filler for composite coating with excellent mechanical and high-pressure CO2 anti-corrosion performance

organic-inorganic composite fillers were successfully prepared by a simple one-pot film-like coating of poly (α-cyanoethyl acrylate) (PECA) on mica. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TG) were used to analyze the structure, morphology, and chemical composition of the organic-inorganic composite filler and pure mica in detail. The organic-inorganic composite filler was added to epoxy resin to prepare a composite coating with long-lasting anti-corrosion and wear-resistance properties. The composite coating was characterized by electrochemical impedance spectroscopy (EIS), high-pressure CO2 corrosion tests, friction performance tests, differential scanning calorimetry (DSC), and adhesion performance tests. The mechanical test results showed that the average wear quality of the EP/P30&M(8/2) composite coating prepared with the modified filler was reduced to 65.7 % of that of the EP/MICA(8/2) coating. The addition of the modified filler to the coating substantially improved the wear resistance and crosslinking of the composite coating, reduced the porosity, increased the density, and effectively improved the overall performance of the composite coating. The results of high-pressure CO2 corrosion tests in harsh environments and electrochemical impedance spectroscopy showed that the composite coating had excellent barrier capacity. After high-pressure CO2 corrosion tests, the EP/P20&M(9/1) composite coating still has a high impedance modulus value of 6.348 × 1010 Ω/cm2 at 0.01 Hz, which is 5 orders of magnitude higher than that of the pure epoxy coating, and showsed excellent long-lasting corrosion resistance in EIS tests. This study provides new ideas for the industrial application of mica and the preparation of long-lasting anti-corrosion coatings.

Tribological Behavior of GTL Base Oil Improved by Ni-Fe Layered Double Hydroxide Nanosheets

The layered double hydroxide (LDH) has been practically applied in the field of tribology and materials science due to its unique physicochemical properties, weak bonding, flexible structural composition, and adjustable interlayer space. In this work, a series of ultrathin and flexible composition of Ni-Fe LDH samples were prepared via a cost-effective room-temperature co-precipitation process. Then, they were mechanically dispersed into GTL base oil and their lubricating performance were tested by a four-ball tribometer. It is found that the variation of Ni-Fe ratio of Ni-Fe LDH has a great influence on the improvement of lubricating performance of GTL base oil. At the same concentration (0.3 mg/mL), the Ni-Fe LDH with Ni/Fe ratio of 6 was demonstrated to exhibit the best lubricating performance and the AFC, WSD, the wear volume, surface roughness and average wear scar depth decreased 51.3%, 30.8%, 78.4%, 6.7% and 50.0%, respectively. SEM-EDS and X-ray photoelectron spectra illustrated that the tribo-chemical film consisting of iron oxides and NiO with better mechanical properties formed and slowly replaced the physical film, which resists scuffing and protect solid surface from severe collisions.

A Novel growth guidance system for early onset scoliosis: a preliminary in vitro study

PurposeThe purpose of the study was to describe a novel growth guidance system, which can avoid metal debris and reduce the sliding friction forces, and test the durability and glidability of the system by in vitro test.MethodTwo major modifications were made to the traditional Shilla system, including the use of ultra-high molecular weight polyethylene (UHMWPE) gaskets to avoid direct contact between the screw and rod, and polishing the surface of the sliding part of the rod. We tested the durability of the system by a fatigue test, which the samples were test on the MTS system for a 10 million cycle of a constant displacement. Pre and post-testing involved weighing the UHMWPE gaskets and observing the wear conditions. The sliding ability were measured by a sliding displacement test. The maximum sliding displacement of the system was measured after a 300 cycles of dynamic compressive loads in a sinusoidal waveform.ResultsAfter the fatigue test, all the UHMWPE gaskets samples showed some of the fretting on the edge of the inner sides, but its still isolated and avoided the friction between the screws and rods. There was no production of metallic fretting around the sliding screws and rods. The average wear mass of the UHMWPE gaskets was 0.002 ± 0.001 g, less than 1.7% of the original mass. In the sliding test, the novel growth guidance system demonstrated the best sliding ability, with an average maximum sliding distance(AMSD) of 35.75 ± 5.73 mm, significantly better than the group of the traditional Shilla technique(AMSD 3.65 ± 0.46 mm, P < 0.0001).ConclusionIn conclusion, we modified the Shilla technique and designed a novel growth guidance system by changing the friction interface of sliding screw and rod, which may significantly reduce the metallic debris and promote spine growth. The fatigue test and sliding dislocation test demonstrated the better durability and glidability of the system. An in vivo animal experiment should be performed to further verify the system.

Exploring tribological characteristics of ZrN-MoSN composite films fabricated via RF magnetron sputtering: Insights from microstructure and performance analysis

Achieving the stringent demands of sustainable tribological industrial applications poses a significant challenge, particular in optimizing the self-lubricant performance of nitride-based films. This paper tackled this challenge by designing and depositing a series of ZrN-MoSN composite films with varying (Mo + S)/Zr ratios, employing RF magnetron sputtering, aimed to enhance the tribological properties through utilizing the high loading capacity of the ZrN matrix and the exceptional self-lubricating attributes of Mo-S-N additives. After conducting thorough investigations on the microstructure, and tribological properties, the results revealed that the dense columnar structured ZrN-MoSN composite films displayed a polycrystalline composition comprising fcc-ZrN and hcp-MoS2 phases, intertwined with amorphous phases of Mo(SN)x and MoS2(N2). (Mo + S)/Zr ratios below 1.08 exhibited a minor impact on the room temperature (RT) tribological properties, while higher ratios led to degradation on RT average friction coefficient (COF) and wear rate (WR). However, the synergistic effect of ZrN matrix and the tribo-phases of layered MoO3 and hard ZrO2 contributed to the significant enhanced 500 °C tribological properties, particularly with an optimized (Mo + S)/Zr ratio of 0.43.

Adolescent Idiopathic Scoliosis Minimum Data Set: Towards Standardization of Data Elements in History and Physical Examination.

Nonoperative care represents a cornerstone of adolescent idiopathic scoliosis (AIS) management, although no consensus exists for a minimal data set. We aimed to determine a consensus in critical data points to obtain during clinical AIS visits. A REDCap-based survey was distributed to Pediatric Orthopedic Society of America (POSNA), Pediatric Spine Study Group (PSSG), and International Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT). Respondents ranked the importance of data points in history, physical examination, and bracing during AIS visits. Results: One hundred eighty-one responses were received (26% response rate), of which 86% were physicians and 14% were allied health professionals. About 80% of respondents worked at pediatric hospitals or pediatric spaces within adult hospitals, and 82% were academic, with the majority (57%) seeing 150+ unique AIS patients annually. Most respondents recommended six-month follow-up for patients under observation (60%) and bracing (54%). Most respondents (75%) considered family history and pain important (69%), with the majority (69%) asking about pain at every visit. Across all time points, Adam's forward bend test, shoulder level, sagittal contour, trunk shift, and curve stiffness were all considered critically important (>60%). At the first visit, scapular prominence, leg lengths, motor and neurological examination, gait, and iliac crest height were also viewed as critical. At the preoperative visit, motor strength and scapular prominence should also be documented. About 39% of respondents use heat sensors to monitor bracing compliance, and average brace wear since the prior visit was considered the most important (85%) compliance data point. This study establishes recommendations for a 19-item minimum data set for clinical AIS evaluation, including history, physical exam, and bracing, to allow for future multicenter registry-based studies.

Synthesis of long straight‐chain alkane substituted ferrocene with ultra‐robust oil solubility as multifunctional organometallic additive

Tailoring of organometallics structure toward desirable properties continues to be both fascinating and challenging in the field of materials science. Herein, a novel ferrocene derivative with long straight‐chain alkane mono‐substituent is synthesized and used as multifunctional organometallic additive in the base oil. This ferrocene‐based organometallic compound (MFc) is synthesized via the Friedel‐Crafts acylation of ferrocene with myristyl chloride, followed by reduction with sodium borohydride. The chemical structure, crystallizability, surface morphology, and the thermal properties of the as‐synthesized compound are systematically characterized. As the iron‐containing standard substance, the MFc was preferable dissolve in lubricating oil with the iron element content as high as 2*105 ppm. Resultantly, the MFc/oil solutions exhibited excellent stability even after high‐speed centrifugal treatment, long‐term storage up to 3 months, and ultra‐low temperature treatment at −40°C for 24 h. Moreover, the MFc as a functional lubricant additive could reduce the average wear scar diameter, wear volume, and coefficient of friction with 40%, 73%, and 18%, respectively, as compared to the corresponding pure base oil. This synthetic strategy provides a novel perspective for the design of functional organometallics, and the as‐synthesized novel ferrocene derivative may find a wide range of advanced potential applications in analytical chemistry, tribology, and interfacial science.

Study on Wear Characteristics of a Guide Vane Centrifugal Pump Based on CFD–DEM

Guide vane submersible centrifugal pumps are a kind of submersible pump, and the fluid inside the pump is often mixed with gravel and other impurities during operation, affecting the pump’s operating efficiency and life expectancy. However, past studies on solid–liquid two-phase flow (STF) and wear characteristics in guided vane centrifugal pumps have been limited to the particle trajectory and wear region distribution. These studies have lacked research on the effect of particles on the fluid flow and the specific amount of wear on the overflow components. Additionally, most of them have used the DPM discrete-phase model, which does not consider the particle–particle and particle–wall interactions. This paper is based on the CFD–DEM method, combined with the Archard wear model. A solid–liquid two-phase flow simulation is carried out for pumps with different particle sizes and particle shapes to analyze the particle movement inside the pump, the wear distribution and average wear amount of the overflow components, and the effect of particles on the turbulent kinetic energy of the fluid. The results show that the particles mainly collide with the leading and trailing edges of the impeller blades and the leading edge of the guide vane blades and form a buildup at the trailing edge of the concave surface of the guide vane blades, resulting in the wear being mainly distributed in these regions. With an increase in particle size and a decrease in sphericity, the average wear on the overflow components increases. The change of particle size directly affects the resistance of the fluid and the structure of the flow field, which has a large impact on the fluid flow pattern and generates large turbulent kinetic energy fluctuations. The shape of the particles only changes the structure of the local flow field, which has a small impact on the fluid flow pattern.

Effect of microtexture morphology on the tribological properties of PI/EP-PTFE-WS2 coating under starved oil and dry sliding wear

The limited wear resistance of aluminum alloys constrained their applications and longevity. Surface microtexture combined with polymer coating technology can prolong the service life of aluminum alloy materials under extreme conditions of aerospace. A370 aluminum specimens were textured with three types of microtexture surfaces including circular pits, rectangular grooves and cross grids. A PI/EP-PTFE/WS2 coating was designed and prepared on the surfaces of these textures by liquid spraying to improve the tribological properties of A370 aluminum under starved oil and dry sliding wear. The influences of different micro-texture morphology on the tribological performances of these coatings were experimented. The results indicated that the surface qualities of the micro-textures are improved by coating deposition on their surfaces. The friction coefficients of the coated surfaces on all micro-texture are effectively reduced under the relatively stable wear stage compared to the sample without micro-texture coating. The coating on the pitted texture exhibits superior performance in friction tests, reducing average coefficients and wear rate by 13.58% and 35.34% in dry sliding wear, and by 16.18% and 83.98% under the starved oil lubrication compared to the non-textured substrate, respectively. This is followed by the coating on cross-mesh texture and the rectangular groove texture. The reason is that the pitted texture facilitates the local stress release of coating during the process of coating deposition due to its smaller spacing between pits and higher density of pits per unit area. The bearing capacity of the pitted texture is highest and its deformation is the lowest. The wear debris created in the friction process is more easily accumulated in the pit units, which results in a reduction in wear.

Constructing multi-layer Ti3C2Tx/rGO heterojunctions: Synergistic effect and unique lubrication mechanism

Two-dimensional materials, such as Ti3C2Tx and graphene oxide (GO), are considered candidates for a new generation of lubricating materials due to their unique physical and chemical properties. However, the dispersion stability of Ti3C2Tx and GO in non-polar oils is insufficient, hindering their potential as lubricating additives. Herein, 1,12-Dodecanediamine (DDM) was used as a bridge to connect Ti3C2Tx and GO, and to reduce graphene oxide (rGO) for forming the stacked two-dimensional multilayer Ti3C2Tx/rGO heterostructures. The multilayer Ti3C2Tx/rGO heterostructure exhibits excellent dispersion stability in PAO 20, ensuring its continuous integration into the tribo-interfaces throughout the friction process. The addition of 0.06 wt% multilayer Ti3C2Tx/rGO to the base oil reduced the average friction coefficient and wear volume by 35.3% and 41.6%. The enhanced lubrication performance is mainly due to the unique multilayer heterostructure of Ti3C2Tx/rGO. During friction, the disintegration of Ti3C2Tx into small fragments effectively safeguards the structural integrity of rGO, thereby facilitating the formation of a robust and smooth multilayer lubrication film. Additionally, Ti3C2Tx is adhered to the wear surface in smaller sizes or evolved into the form of Ti oxides. The emergence of this new composite material is not only expected to solve the problem of insufficient performance of traditional lubricating materials under extreme conditions, but also laid the foundation for expanding the application of two-dimensional materials in the field of lubrication.

Effect of carbon quantum dots’ surface functional groups on tribological performance of polyethylene glycol

Nano additives play an important role in improving the lubricating properties and enhancing the bearing capacity of lubricants. However, traditional nano-additives contain harmful elements such as heavy metals, sulfur, phosphorus, which have a non-negligible impact on the green production of modern industry. In this study, four kinds of carbon quantum dots (CQDs) were prepared by hydrothermal synthesis method, namely CQDs, amino modified CQDs (CQDs-NH2), alkyl modified CQDs (CQDs-CH3), and hydroxyl modified CQDs (CQDs-OH). The microscopic morphology, chemical structure and luminescence of CQDs were characterized. The effects of four kinds of CQDs additives on the tribological properties of polyethylene glycol (PEG) were studied. The results showed that compared with PEG, the average friction coefficient and wear volume of PEG containing 3% CQDs-OH decreased by 60.50% and 95.05%, respectively. A composite protective film containing carbon, nitrogen, FeO, Fe2O3 forms on the worn surface, due to the end hydroxyl group of CQDs-OH has good adsorption. In addition, after 3 months of dispersion experiment, the PEG containing 3% CQDs-OH showed the best dispersion stability, and the antifriction effect was still better than that of pure PEG. Therefore, CQDs-OH is a new type of environmentally friendly lubricating additive with great potential.

Studying the Performance of Reinforced Polymer Gear Wheels: Development of an Advanced Test Bench for Wear Analysis

In recent years, polymeric materials have gained prominence as a competitive option for gear manufacturing. Nevertheless, the absence of comprehensive literature addressing the wear due to the coupling of these materials presents a real challenge in response to this innovative trend. Wear of plastic gearwheels represents, in fact, a key issue, traditionally assessed using standard formulations under optimal dry operating conditions. These calculations often rely on coefficients derived from specialized gear tests, but their applicability is constrained to specific polymer–metal combinations. This research was dedicated to the development of a test bench tailored to evaluate the wear of glass fiber-reinforced self-lubricating polymer gearwheels under different operating conditions. This study commenced with a comprehensive exploration of wear phenomena in thermoplastic gearwheels and the inherent challenges associated with utilizing existing standards and the scientific literature for wear analysis. This was followed by a careful evaluation of the operational needs of the test bench, which, starting from a basic solution already implemented, improved its use in various aspects. Finally, this study introduced an optical-based methodology for average linear wear control. This research strived to establish a testing approach that minimizes uncertainties when assessing the wear of thermoplastic gears.

Unique synergistic effects of ternary multi-dimensional CNT/g-C3N4/MoS2 hybrid as a paraffin oil additive for improved tribological properties

Graphitic carbon nitride (g-C3N4) nanomaterials have drawn much interest in the lubrication and friction fields owing to their excellent self-lubrication and mechanical performances. However, the easy agglomeration and poor dispersion stability of single g-C3N4(CN) have always been a headache. In the work, multi-dimensional ternary carbon nanotube, graphite carbon nitride, and molybdenum disulfide (CNT, CN, and MoS2) hybrids were fabricated by hydrothermal method. The microstructure and its reinforcement impact on the tribological properties of the corresponding paraffin oil were systematically studied. The results showed that the zero-dimensional spherical MoS2, one-dimensional tubular CNT, and two-dimensional lamellar CN are uniformly compounded. The tribological test results display that average friction coefficient and wear rate of the 0.2 wt% CNT/CN/MoS2 are decreased by 39.23% and 91.97% lower than those of pure paraffin oil, CNT and CN/MoS2 with the same concentration, respectively. The significantly improved tribological properties of lubricating oil is ascribed to even dispersion of CNT, CN, MoS2 in CNT/CN/MoS2 hybrids, self-lubricating effect of MoS2 and CN, and load-bearing ability of CNT and CN nanosheets, and also the generation of lubricating film between friction pairs during the wear process.

Ni-Cr Based Self Lubricating Composite Performance for High Speed Engineering Application

Developed High speed-rotating machinery is used in agriculture for various processes. This machinery runs using the tractor PTO operated at variable speed. Operating systems of machinery were depends on the skill of the driver. Due to jerks during operation and lack of maintenance such machinery gets fails. To increase the life of rotating components, Ni-Cr based self-lubricating composite bearings were developed and used for the actual application. Self-lubricating composite was tested under the different velocities of 3.14, 3.77, 4.71, and 6.28m/s up to a maximum of 8 Hours. The average wear rate of 7.2%MoS2 content composite is less than the other compositions of Ni-Cr-wt% of MoS2 self-lubricating composite. The result of the actual trial shows that the average wear rate of Ni-Cr- 7.2 wt%MoS2 at velocities 3.14m/s,3.77m/s,4.71m/s, and 6.28m/s is 5.74*10-9mm3/Nm, 6.09*10-9mm3/Nm, 6.30*10-9mm3/Nm, and 6.44*10-9mm3/Nm respectively.

A two-step data-driven method for predicting the wear of train wheel treads using GA-BPNN and LSTM algorithms

ABSTRACT During train operations, the changing of wheel tread profile due to wheel-rail contact has a significant impact on the safe operation of the train and passenger comfort. Therefore, it is crucial to timely monitor the condition of the wheels and accurately predict wheel wear. In addition, wheel wear prediction can also guide wheel re-profiling, thereby extending the service life of wheels and minimizing operating costs. In this paper, a two-step data-driven wear prediction method was proposed to comprehensively predict wheel wear from two perspectives: the overall train and individual wheels. Firstly, Density-Based Spatial Clustering of Applications with Noise (DBSCAN) and Radial Basis Function neural network (RBFNN) were used to preprocess historical data, remove outliers, and construct time series data. By analysing the wear trend of wheels, a two-step data-driven prediction method was proposed. The first step is to predict the average Wear of wheels in the future time, and the second step is to predict the deviation between each wheel Wear value and the mean in the future time. Different prediction models were utilized and compared to obtain the best predictive performance. Results show that back propagation neural network (BPNN) optimized by genetic algorithm (GA) and long short-term memory (LSTM) based model yield better performance for predicting the wear trend of the overall train and individual wheels respectively. In addition, comprehensive contour parameters were utilized in the prediction model to enhance the accuracy and robustness.

Preparation and performance study of electroplated Ni–W/diamond ultrathin dicing blades

In this study, Ni–W/diamond ultrathin dicing blades with various tungsten contents were fabricated using a composite electrodeposition technique by adding different concentrations of sodium tungstate to a nickel sulfamate plating solution utilizing a self-developed cathodic autorotating plating apparatus. The results showed that the tungsten content in the dicing blades increased, the deposition rate accelerated, the distribution uniformity of the diamond particles improved, and the mechanical properties were noticeably enhanced with an increase in the sodium tungsten concentration in the plating solution. The performance of the dicing blade reached its peak at a sodium tungstate concentration of 6 g/L. At this point, the diamond content in the Ni–W/diamond dicing blade was higher and more uniformly distributed; the base metal of the dicing blade, a Ni–W alloy, increased in hardness by 47% and in Young's modulus by 26.8% when compared to Ni; the dicing blade's microhardness reached a maximum of 12.4 GPa, an increase of 49.4% over Ni/diamond dicing blades. The average friction coefficient and wear of the dicing blades decreased by 23.4% and 46.5% respectively. The cutting test results also showed that all aspects of the cutting performance of the dicing blade were greatly improved, with the deviation coefficient of Ni–W/diamond dicing blade decreased by 47.9% compared with that of the Ni/diamond dicing blade, the chipping size decreasing by 30.6%, and the radial wear reducing by 31.6%.

Прогнозирование и оценка триботехнической эффективности азотированного слоя деталей машин

Following the laws of tribology and tribotechnics, also the results of experimental studies of reality of structure and properties change in the zone of contact tribodeformation of structural steels and alloys of different structural classes subjected to nitriding, an approach to forecasting and comprehensive assessment of the tribotechnical efficiency of nitriding of structural materials and products made of them has been developed. Analysis of the patterns of changes in the structure of the diffusion zone of nitriding steels: abnormal, martensitic and austenic, and relative wear resistance tests, taking into account their composition and technological parameters of the treatment process, showed that maximum wear resistance was provided by a nitration coating containing hardening dispersed particles of incoherent nitrides, ensuring a lower liability to brittle behavior of the nitration case due to low level of matrix level microdeformation. At the same time, preliminary types of treatment (thermal treating and deformation processing) of nitriding steels contribute to structural and phase state of the surface layer, which has added tribological performance. For nitrided ferroalloys with different matrix lattices, the most significant characteristics of the structural state and properties of the surface layers affecting the level of surface fracture under friction have been found empirically: the particle size of nitrides of alloying elements, the distance between them, the density of their distribution, the matrix lattice microdeformation, the values of X-ray lines intrinsic broadening for structural components of the material in the friction deformation zone, the hardness of the nitration case and its changes under friction. These experimental results are taken as a principle of the proposed method for forecasting and assessment of metal tribotechnical efficiency. This principle of method is based on a tribological criterion containing micro- and macroscopic characteristics of the material in the zone of contact deformation under friction, the choice of fabricating methods for the product takes place to ensure an acceptable level of wear intensity. Then, by measurement, using surface large deformation method, the ability of the nitration case formed as a result of treatment according to the selected treatment schedule to perceive surface nondestructive plastic deformation is evaluated. It affords a basis for the selected nitriding treatment schedule. The completion of the assessment is the determination of the values of the maximum operability of the nitriding material under conditions of friction and wear (alarm pressure when a tribocouple operates steadily; critical pressure when it is inoperable, but its operation is possible with short-term overloads; the average total wear intensity of the couple combined). The totality of the identified parameters allows recommending the material, its working and predicting operating modes and durability of tribounit.