Ring Surface Research Articles

Effect of vanadium addition on the microstructure and properties of NiCuBSi-WC60 composite coatings deposited by laser direct deposition

There is an urgent need to extend the tool life of shield boring machines for complex working conditions. Here, NiCuBSi-WC60 composite coatings with different vanadium contents were prepared by laser direct deposition on the surface of shield boring machine cutter rings, and the influence mechanism of vanadium(V) addition on the microstructure and properties of the coatings was studied. The microstructure of the coatings was analyzed by SEM, XRD, EBSD and TEM to reveal the mechanism of microstructure evolution during laser deposition. The microhardness was tested by Vickers hardness tester, and the wear resistance was tested in practical engineering applications. The results show that the addition of V can promote the formation of W2C and VC, and with the increase of V content, the W2C precipitated in the coating gradually grows and changes from flocculent to plate. The coating containing V mainly consists of Ni(Cu) bonded phase, WC, W2C and VC reinforced phase and Ni10(WC)3 transition phase. HRTEM found that the orientation relationship between W2C and VC interface is W2C (111) // VC (001), W2C [011¯] // VC [11¯0], the angle difference between the Ni(Cu) (111) direction and the Ni10(WC)3 (101¯2) direction is 5.13°, and the lattice mismatch is 12.35%. The average hardness of the coating at the locations without spherical WC particles was statistically analyzed and the highest hardness of 739.90 ± 82.58 HV was found for the coating with 2 wt% V. A small amount of V addition effectively improves the distribution of the reinforcing phase in the coating, thus increasing the wear resistance of the coating. Practical engineering application shows that the wear rate of V-modified NiCuBSi-WC60 coated cutter ring is only 4.6% of that of ordinary 5Cr5MoSiV1 steel ring in the same trajectory line during the boring process of 1521 m in Chengdu sand and pebble strata.

Определение участка нарезания мелкомодульных зубьев в эксцентриковых механизмах свободного хода

Normal forces use to transfer the load makes it possible to increase load capacity and reliability of the free running mechanisms. Normal forces in the eccentric free running mechanisms are realized in engagement of the fine-module teeth that are cut on the outer cage inner surface and the outer surface of the eccentric rings. To ensure correct operation of the mechanism in jamming and wedging, value of the fine-module teeth cutting section angle should be selected from the equality condition of the radial clearance between the outer cage teeth and the eccentric ring in the entire working section. To solve the problem, calculation scheme is proposed and mathematical model is obtained that describes relationship between the fine-module cutting section angle and the mechanism geometric parameters. The nature of the main geometric parameters influence (radius, eccentricity, radial clearance, module, etc.) on the value of the teeth cutting section angle was established. It is shown that eccentricity provides the greatest influence on the working area size, radial clearance and module influences are less pronounced.

Improving the technology of nitridation by the electro-spark alloying method

The work shows studies aimed at developing methods for protection of structural steels on the example of steels 20 and 40, from wear, using the electricity spark alloying (ESA), by applying the nitrogen-like mixture on the treated surface with subsequent vanity of steel electrode appropriate to the material of the workpiece. To increase the thickness of the surface layer and the best adhesion of the coating is offered in front of the ESA electrode-tools made of steel of the corresponding brand, to form a mold of aluminum, using an electrode from the aluminum bar of the brand of blood pressure. Metrolographic studies were performed and the distribution of microtrandomness in the coating. Studies have shown that nitrogen -containing coatings consist of a "white" layer ", which smoothly goes into the diffusion zone and base metal. The obtained coatings have the highest thickness of "white layer" 110-130 microns. The results of the study of the micro-hardness of the obtained nitrogen-containing coatings indicate an increase in hardness to 9700-9910 MPa. The phase composition of nitrogen coatings is represented by a alloy solid and cubic iron nitride, aluminum dissolves in nitride and ferrite. The considered methods of application of nitrogen -containing coatings can be used to strengthen the surface of responsible parts and elements of pumping and compressor equipment: end surfaces of rings, for protective bushings; piston machines, mechanisms that have increased wear of the product, etc. Keywords: electro-spark alloying, microstructure, nitriding, steel, phase analysis.

Superior Gain and Polarization Control in MIMO Circular Ring Surface Plasmonic Planar Differential Antenna for Wireless Systems

Superior Gain and Polarization Control in MIMO Circular Ring Surface Plasmonic Planar Differential Antenna for Wireless Systems

Influence of Pits on the Tribological Properties and Friction-Induced Vibration Noise of Textured Tapered Roller Bearings

This study analyzed the influence of pits on the tribological properties and friction-induced vibration noise of textured tapered roller bearings under starved lubrication. Laser marking equipment was used to fabricate pits on the outer ring surface. A vertical universal friction and wear testing machine was used to measure the friction force, vibration acceleration, and noise signals of tapered roller bearings. The difference between the pit texture surface and smooth surface in terms of friction wear and vibration noise performance was studied. The results show that the friction force and wear loss of the pit-textured surfaces are markedly lower than those on the smooth surface. Compared to smooth surface bearings, the friction force and wear loss were reduced by 45.1 and 62.5%, respectively, when the diameter, depth, and area density of the pit were 200 μm, 10 μm, and 24%, respectively. The pit-textured surface exhibited good potential for vibration absorption and noise suppression. The friction force of the pit-textured tapered roller bearings is crucial for generating the vibration noise of the friction pair system. It can effectively interfere with the self-excited vibration of the tapered roller-bearing friction pair system. It thereby reduces the degree of vibration noise of the tapered roller bearings.

Staphylococcal biofilm on wedding rings worn by laboratory workers.

Hands of healthcare workers play essential role in the spreading of antimicrobial-resistant microorganisms in and out of the healthcare settings. Less is known about the role of laboratory workers (LWs). The aim of our study was to evaluate the presence of biofilm-forming staphylococci on the surface of jewelry rings of LWs and their antimicrobial susceptibility pattern.A total of 79 LWs from eight different microbiology laboratories that process and analyze specimens from the tertiary care hospitals in Belgrade, Serbia participated in the study. The study was reviewed and approved by the institutional review boards at hospitals. Samples were taken after hand washing. Bacteria on LWs wedding rings were detected with the rolling method, and further analyzed in order to determine the number of colony forming unit (CFU) per ring, species of bacteria and their antimicrobial susceptibility pattern, methicillin resistance and biofilm-producing capacity in vitro.Staphylococci were recovered from 60.8% of wedding rings. All strains produced biofilm (25% weak, 56.2% moderate and 18.8% large amount), with significant difference between species (P < 0.001). Staphylococcus aureus and Staphylococcus epidermidis formed the largest amount of biofilm and had the largest number of CFU per ring. Staphylococci were most commonly resistant to penicillin (66.7%), tetracycline (50.0%), and erythromycin (45.8%); 41.7% of isolates was multidrug resistant and mecA gene was detected in five strains. All strains were susceptible to linezolid, vancomycin, teicoplanin and tigecycline.Staphylococci colonize LWs wedding rings, form biofilm on it, have multidrug resistant phenotype and/or carry mecA gene, representing a significant reservoir for the spreading of microorganisms and resistance. As far as we know, our study is the first that address this topic in laboratory workers.

The Ultrashort Spike–Ring Interaction in Substituted Iron Maiden Molecules

The in forms of molecular iron maidens are known for their unique ultrashort interaction between the apical hydrogen atom or its small substituent and the surface of the benzene ring. It is generally believed that this forced ultrashort X⋯π contact is associated with high steric hindrance, which is responsible for specific properties of iron maiden molecules. The main aim of this article is to investigate the influence of significant charge enrichment or depletion of the benzene ring on the characteristics of the ultrashort C-X⋯π contact in iron maiden molecules. For this purpose, three strongly electron-donating (-NH2) or strongly electron-withdrawing (-CN) groups were inserted into the benzene ring of in-[34,10][7]metacyclophane and its halogenated (X = F, Cl, Br) derivatives. It is shown that, despite such extremely electron-donating or electron-accepting properties, the considered iron maiden molecules surprisingly reveal quite high resistance to changes in electronic properties.

Перстни из вещевого комплекса парного захоронения детей-подростков на Сунгирской верхнепалеолитической стоянке

The article presents the results of a technical and morphological study of a series of ivory finger rings discovered in 1969 by O. N. Bader during his excavations of a unique double burial of teenagers at the Sungir Upper Palaeolithic site (35—29 thousand years ago), situated at the eastern suburb of the city Vladimir in Vladimir province of Russia. The objects under study are nine artifacts in the shape of small rings made of mammoth ivory, including six intact finger rings found on the fingers of two buried teenager boys. The newly obtained technological and use-wear evidence makes it possible to better understand how the rings were produced and used. In particular, it suggests that both closed and disconnected rings were carved from short and massive ivory chips. Special attention was given not to the aesthetic of the outer surface but rather to the morphometric properties of the inner surface. The character of pitting on the ring surfaces, peculiarities of their position on the fingers, and the character of the archaeological context of these finds point to the possibility that they were probably not only personal ornaments of ancient hunters, but had also some strictly utilitarian function associated with the use (throwing) of projectiles.

Anticancer Efficacy of Antibacterial Quinobenzothiazines

The antitumor potency of a series of designed and prepared antibacterial quinobenzothiazines was evaluated against different types of human cancer cell lines, such as glioblastoma SNB-19, lung adenocarcinoma A549 and breast cancer T47D, and the activities of the compounds were compared to cisplatin and doxorubicin. 9-Propoxy-5-methyl-12H-quino[3,4-b][1,4]benzo- thiazinium chloride (4a), 9-allyloxy-5-methyl-12H-quino[3,4-b][1,4]benzothiazinium chloride (4d) and 11-benzyloxy-5-methyl-12H-quino[3,4-b][1,4]benzothiazinium chloride (4l) were the most active compounds; their IC50 values against all three cell lines ranged from 5.3 to 9.3 µM. The effective derivatives showed no cytotoxic effect up to 100 µM on normal human dermal fibroblasts (NHDFs). To explore the structure–activity relationship, the effect of the type/nature and position of the substituents on the tetracyclic quinobenzothiazine system on the anticancer activity was investigated. Additionally, the receptor-dependent approach was used to specify the mutual ligand–enzyme (bio)compositions that might be potentially valid for the antitumor characteristics of new quinobenzothiazine derivatives. In particular, the molecular docking procedure was applied for the most potent agents against the human breast cancer line T47D in order to obtain comprehensive knowledge about the aromatase–inhibitor binding mode. The docking study revealed that some regularities in the spatial atomic distribution and nonbonding interactions (e.g., hydrophobic patterns) can be observed for the most active molecules. The surface of the electron-rich aromatic rings of 4d and 4l molecules could also contribute to π–π stacking interactions with protoporphyrin IX (HEM) as well as to the formation of π–cation interactions with the adjacent iron cofactor.

Medium-term clinical results in patients with floating hip injuries

BackgroundThe objective of this study was to evaluate the effectiveness of our strategy for managing floating hip injuries.MethodsFrom January 2014 and December 2019, all patients with a floating hip underwent surgical treatment in our hospital were included in the retrospective study, with a minimum follow-up of 1 year. All patients were managed according to a standardised strategy. Data on epidemiology, radiography, clinical outcomes and complications were collected and analysed.ResultsTwenty-eight patients were enrolled, with an average age of 45 years. The mean follow-up was 36.9 months. According to the Liebergall classification, Type A floating hip injuries predominated (n = 15, 53.6%). Head and chest injuries were the most common associated injuries. When multiple operative settings were required, we prioritized the fixation of the femur fracture at the first operation. The mean time from injury to definitive femoral surgery was 6.1 days, with most (75%) femoral fractures treated with intramedullary fixation. More than half (54%) of acetabular fractures were treated with a single surgical approach. Pelvic ring fixation included isolated anterior fixation, isolated posterior fixation, combined anterior and posterior fixation, of which isolated anterior fixation was the most common. Postoperative radiographs suggested that the anatomic reduction rates of acetabulum and pelvic ring fractures were 54% and 70%, respectively. According to grading system of Merle d’Aubigne and Postel, 62% of patients achieved satisfactory hip function. Complications included delayed incision healing (7.1%), deep vein thrombosis (10.7%), heterotopic ossification (10.7%), femoral head avascular necrosis (7.1%), post-traumatic osteoarthritis (14.3%), fracture malunion (n = 2, 7.1%) and nonunion (n = 2, 7.1%). In the patients with complications described above, only two patients underwent resurgery.ConclusionsAlthough there is no difference in clinical outcomes and complications among different types of floating hip injuries, special attention should be paid to anatomical reduction of the acetabular surface and restoration of the pelvic ring. In addition, the severity of such compound injuries often exceeds that of an isolated injury and often requires specialised multidisciplinary management. Because of no standard guidelines for treatment of such injuries, our experience in the management of such a complex case is to fully assess the complexity of the injury and formulate an appropriate surgical plan based on the principles of damage control orthopaedics.

Light energy distribution of submicron charged particles based on the scattering-enhancing effect

Magnetic microspheres, charged soot and other charged sub-micron particles are widely used, and the accurate measurement of their particle size is crucial to biomedical, environmental monitoring and other fields. During light scattering measurements, the light energy distribution projected onto each ring surface of the photodetector is the core data for particle size inversion calculations. When the measured particle is charged, the light energy distribution will be different from its neutral state due to the scattering-enhancing effect of surface charges. Therefore, it is necessary to confirm the extent of the scattering-enhancing effect on the light energy distribution by numerical simulation, before actual measurement. In this paper, calculation models of scattered light energy distribution are established for charged single particle, monodisperse particle system and polydisperse particle system respectively. Considering the difference between the complex refractive indices of charged particles, the forward scattering of silica and polystyrene with different monodisperse degrees are taken as an example to analyze the light energy distribution. The results show that the scattering-enhancing effect of surface charges can affect the light energy distribution of submicron particles, and the smaller the median diameter of the particle system and the lower the monodisperse degree, the more significant the effect is. At a median diameter of 0.1 μm, the light energy of charged particles with different monodisperse degrees increased by an average of about 3.5 times, near the scattering angle of 45° This research realizes the forward deduction of the light energy distribution for charged particles, and provides the necessary theoretical support for the visible light measurement of charged submicron and nanoparticles.

Measurement and analysis of vibration characteristics of nanocrystalline magnetic core under symmetrical/asymmetrical waveforms

PurposeBecause the nanocrystalline core is widely used in power electronic equipment, and the excitation waveform of its working mode is complex, the vibration at medium and high frequencies cannot be ignored. Therefore, this study aims to study the vibration mechanism of nanocrystalline strip and the vibration characteristics of nanocrystalline magnetic ring under different excitation waveforms.Design/methodology/approachFirst, the electromagnetic vibration mechanism between nanocrystalline strips is analyzed by finite element analysis, and the force of the magnetic ring with and without air gap is compared and analyzed. Then, the vibration of nanocrystalline magnetic ring under different excitation waveforms such as sine wave, triangular wave, symmetric rectangular wave and asymmetric rectangular wave is analyzed by experimental method. The acceleration time domain waveform measured by the experiment is analyzed by fast Fourier transform, and the vibration is analyzed according to the spectrum.FindingsBecause of the increase of magnetic flux leakage, the volume force density and the Maxwell force on the surface of the nanocrystalline magnetic ring will increase after the air gap is opened, resulting in the intensification of vibration. Under symmetric/asymmetric rectangular wave excitation, the vibration acceleration varies with the duty cycle. Due to the influence of harmonic excitation, the relationship between the main frequency of vibration and the excitation frequency is not two times, and its multiple decreases with the increase of excitation frequency.Originality/valueThe research and analysis of this paper can promote the application of new magnetic materials in electrical equipment in small and medium-sized and medium- to high-frequency fields.

Revealed pathways of furan ring opening and surface crosslinking in biobased polyfurfuryl alcohol

Poly(furfuryl alcohol) – (PFA) is a biobased thermoset known for its highly crosslinked structure. Bidimensional NMR (2D-NMR) was employed to give new insights on the complex structural organization in PFA with a special emphasis on the side structures resulting from furan ring-opening. Interestingly, the presence of aldehyde functions was for the first time clearly highlighted and quantified in PFA resins. Overall, the aldehydes account for about 20 % of the total carbonyls present in PFA. Results from HSQC and HMBC sequences allowed proposing two pathways for the furan ring opening reactions. The first one is an hydrolytic-ring opening leading to levulinic like species. The second one is rather an oxidative furan-ring opening leading to conjugated aldehydes. These conjugated aldehydes are prone to crosslink via Diel-Alder cycloadditions with furanic entities thus leading to crosslinking. At macroscopic scale, this newly proposed crosslinking pathway would explain the formation of the rigid shell formed at the external surfaces of PFA resins.

Study on the frictional properties of the top ring-liner conjunction for different-viscosity lubricant

In modern internal combustion engines, the lubricant viscosity affects greatly the friction power loss. To obtain maximum fuel economy of the engines, the lubricants with different viscosities are considered to evaluate the friction properties of the compression ring-cylinder liner conjunction in the engines in this study. To conduct the evaluation, an improved mixed lubrication model is developed with considerations of the cylinder liner deformation, the lubricant thermal effect &amp; transportation, and the change of lubrication condition from full flooded to starve. On this basis, the influence of different viscosity lubricants on the minimum oil film thickness, friction, power loss, FMEP, and wear load are investigated. The numerical result indicates that the low viscosity lubricant is more beneficial to facilitate the change of lubrication condition from starve to fully flooded. Furthermore, the low viscosity lubricant will result in large wear load on the compression ring surface while reducing the friction power loss.

Design, manufacturing, and testing of a laser textured piston ring surface reinforced with a CuCoBe–diamond composite by hot-pressing

A CuCoBe–diamond composite was used to reinforce a laser textured 410 stainless steel piston ring by hot-pressing. Different hot-pressing parameters were used to optimize the sintering process of the CuCoBe particles (P = 25 and 50 MPa, T = 820 and 980 °C, and t = 15 and 30 min). The results showed an increase in the hardness of the hot-pressed samples (50.5% and 48.5% for P = 25 and 50 MPa, respectively). Three textures with different track widths and distances between them were produced by laser on the compression piston rings’ surface. The composite powders were used for the reinforcement of the textures by hot-pressing at the optimized sintering parameters (T = 980 °C, P = 25 and 50 MPa, and t = 15 min). The tribological results revealed that larger texture dimensions led to enhanced tribological performance.

Design of Thin Wideband Absorber Based on Lossy Capacitive Surface of Dipole Square Ring Crossed Element

Design of Thin Wideband Absorber Based on Lossy Capacitive Surface of Dipole Square Ring Crossed Element

Quantification of oil film thickness on the top ring sliding surface by visualization

The oil film thickness of the piston ring at the sliding surface affects oil consumption, friction loss and wear of the ring and liner in internal combustion engines. It is important to know the oil film thickness on the piston ring sliding surface in order to improve the engine efficiency. Accurate measurement of oil film thickness on the piston rings is difficult because the oil film thickness is extremely thin. A modified method is proposed for measuring thin oil film. The authors have measured the oil film thickness on the piston skirt and land to contribute. The optical measurement system and analytic method are improved. The presented method present the oil film thickness on the sliding surface of the top ring from the oil film visualization images. The verification of the measured oil film thickness carried out by comparing with the data obtained from the numerical calculation. For evaluating the effect of the oil characteristics, 0W-20 oil and #8 oil were tested with different engine speeds and different crank angle where different ring loads. It was confirmed that the top ring oil film thickness became thick due to the high engine speed. A large load on the top ring reduces the oil film thickness. The oil film became thick when the oil viscosity was high. The effect of oil viscosity on the oil film thickness of the top ring was clarified. The effect of the viscosity index improver was also discussed. It is shown from the experimental results that the present measurement system for the top ring oil film thickness has enough accuracy.

Рост пленок SiC, AlN и GaN на кремниевых изделиях произвольной геометрии для микроэлектромеханических применений

A technique is proposed for the formation of epitaxial films of silicon carbide, gallium and aluminum nitrides on the surface of non-planar silicon parts. Using the technique, a GaN/AlN/SiC/Si heterostructure was grown on the surface of a silicon ring. The samples were studied by scanning electron microscopy, as well as raman and energy dispersive spectroscopy. It is shown that the preliminary deposition of a SiC layer on silicon by the atomic substitution method, in which (111) facets are inevitably being formed regardless of the local crystallographic orientation of the substrate surface, makes it possible to efficiently grow subsequent layers of III-nitrides of both wurtzite and sphalerite types on silicon parts.

Optimization Analysis of Meshing Worm Drive Structure with Roller Enveloping Ring Surface

Based on the meshing theory of the worm drive with the roller enveloping ring surface and the mathematical model of transmission efficiency of transmission mechanism, the mathematical calculation model of transmission efficiency for simultaneous meshing of multiple teeth has been set up; the geometrical parameters of transmission countershaft, the influence of friction parameters on transmission efficiency of transmission pair have been analyzed. The analysis and optimized results are that the transmission efficiency is negatively correlated with friction parameters and with other structural geometric parameters and positively correlated with the center distance in the structural geometric parameters. Thereinto, friction parameters and throat-neck coefficient have a great influence on transmission efficiency, and the roller radius and center distance have little influence on it. After structure optimization, the transmission efficiency is improved by 3.86% compared with before optimization.

MR-YOLO: An Improved YOLOv5 Network for Detecting Magnetic Ring Surface Defects

Magnetic rings are widely used in automotive, home appliances, and consumer electronics. Due to the materials used, processing techniques, and other factors, there will be top cracks, internal cracks, adhesion, and other defects on individual magnetic rings during the manufacturing process. To find such defects, the most sophisticated YOLOv5 target identification algorithm is frequently utilized. However, it has problems such as high computation, sluggish detection, and a large model size. This work suggests an enhanced lightweight YOLOv5 (MR-YOLO) approach for the identification of magnetic ring surface defects to address these issues. To decrease the floating-point operation (FLOP) in the feature channel fusion process and enhance the performance of feature expression, the YOLOv5 neck network was added to the Mobilenetv3 module. To improve the robustness of the algorithm, a Mosaic data enhancement technique was applied. Moreover, in order to increase the network's interest in minor defects, the SE attention module is inserted into the backbone network to replace the SPPF module with substantially more calculations. Finally, to further increase the new network's accuracy and training speed, we substituted the original CIoU-Ioss for SIoU-Loss. According to the test, the FLOP and Params of the modified network model decreased by 59.4% and 47.9%, respectively; the reasoning speed increased by 16.6%, the model's size decreased by 48.1%, and the mAP only lost by 0.3%. The effectiveness and superiority of this method are proved by an analysis and comparison of examples.