Search Results (242)

Although cemented carbides have been manufactured by the powder metallurgy (P/M) technology for over a century now, systematic developmental efforts are still underway. In the present study, tool life improvements in metal grooving applications are the key objective. Four PVD-coated cemented carbides compositions, dedicated to groove steel, stainless steel, cast iron, and aluminium alloys, have been newly designed, along with their manufacturing conditions. Physical, mechanical and chemical characteristics—such as sintered density, modulus of elasticity, hardness, fracture toughness, WC grain size, and the chemical composition of the substrate material, as well as the chemical composition, microhardness, structure, and thickness of the coatings—have been studied. A series of grooving tests have also been conducted to assess whether modifications to the thus far marketed tool materials, tool geometries, and coatings can improve cutting performance. In order to compare the laboratory and application properties of the investigated materials with currently produced by reputable companies, commercial inserts have also been tested. The experimental results obtained indicate that the newly developed grooving inserts exhibit excellent microstructural characteristics, high hardness, fracture toughness, and wear resistance and that they show slightly longer tool life compared to the commercial ones. Full article

To enhance the electromagnetic performance of flat-wire permanent magnet synchronous motors, three different groove structures were designed for the rotor, and a multi-objective optimization algorithm combining a genetic algorithm (GA) with the TOPSIS method was proposed. Firstly, an 8-pole 48-slot flat-wire motor model was established, and the cogging torque was analytically calculated to compare the motor’s performance under different groove schemes. Secondly, global multi-objective optimization of the rotor groove dimensions was performed using a combined simulation approach involving Maxwell, Workbench, and Optislang, and the optimal rotor groove size structure was selected using the TOPSIS method. Finally, a comparative analysis of the motor’s performance under both rated-load and no-load conditions was conducted for the pre- and post-optimization designs, followed by verification of the mechanical strength of the optimized rotor structure. The research results demonstrate that the combined optimization approach utilizing the genetic algorithm and the TOPSIS method significantly enhances the torque characteristics of the motor. The computational results indicate that the average torque is increased to 165.32 N·m, with the torque ripple reduced from 28.37% to 13.32% and the cogging torque decreased from 896.88 mN·m to 187.9 mN·m. Moreover, the total distortion rates of the air-gap magnetic flux density and the no-load back EMF are significantly suppressed, confirming the rationality of the proposed motor design. Full article

In this study, solid particle erosion tests were conducted to evaluate the resistance of AISI 4340 (EN24) and 8620 alloy steels against silicon carbide (SiC). These steels were selected due to their high hardness, yield strength (σ_y), ultimate tensile strength (σ_uts) and elongation (%), which are significant parameters, influencing wear resistance. An erosion rig based on the ASTM G76-95 standard was used to perform the testing. Tests were carried out using different impact angles, 30°, 45°, 60° and 90°, with a particle velocity of 24 ± 2 m/s. The abrasive flow rate was 0.7 ± 0.5 g/min and the temperature was between 35 °C and 40 °C. Characterization techniques such as SEM were employed to identify the chemical composition of AISI 4340 and AISI 8620 steels and optical microscopy to determine the morphology of SiC abrasive particles. In addition, the SiC particle size was between 350 and 450 µm; it was determined by the particle size distribution technique. SEM micrographs were obtained to classify the wear mechanisms, characterized by micro-cutting, micro-ploughing, grooves, pitting actions and embedded particles on the surface at 30° and 90°. The results showed that AISI 8620 steel exhibited higher erosion resistance than AISI 4340 steel. Finally, AFM was used to evaluate the roughness variations before and after erosion tests, specifically in the central zone of the wear scars at 30° and 90° for both materials. Full article

We investigated the interaction of HspB7 and its α-crystallin domain with the wild-type (WT) C-terminal fragment of human filamin C (FLNC), containing immunoglobulin-like domains 22–24 and its three mutants associated with cardio- and myopathies. The physicochemical properties of the WT FLNC fragment and its three mutants, p.Glu2472_Asn2473delinsAsp (EN/D) located in the 22nd domain, p.P2643_L2645del (ΔPGL), and p.W2710X (Wmut) both located in the 24th immunoglobulin-like domain were analyzed. Although all FLNC fragments had similar secondary structures, WT FLNC and its EN/D and ΔPGL mutants formed dimers, whereas Wmut formed either monomers or aggregates. The surface hydrophobicity of EN/D, ΔPGL, and especially Wmut mutants was larger than that of the WT fragment. Size exclusion chromatography, native gel electrophoresis, and chemical crosslinking indicated that the efficiency of interaction with HspB7 or its α-crystallin domain decreased in the order WT~EN/D > ΔPGL. Wmut was unable to interact with either HspB7 or its α-crystallin domain. Modeling via Alphafold 3 indicated that EN/D mutation affected the orientation of two loops connecting β-strands in the 22nd domain, while the ΔPGL and Wmut mutations exposed a hydrophobic groove in the 24th domain thereby reducing their interaction with HspB7. These findings reveal the molecular mechanisms underlying filaminopathies associated with three mutations in the C-terminal region of filamin C. Full article

Electrolytic copper foil is one of the core materials in the fields of electronics, communications, and power. The cathode roller is the key component of the complete set of electrolytic copper foil equipment, and the quality of the titanium cylinder of the cathode roller directly determines the quality of the electrolytic copper foil. There typically exists a longitudinal weld on the surface of the cathode roller’s titanium cylinder sleeve manufactured by the welding method, which leads to the degradation of the quality of the electrolytic copper foil. Refining the grains in the weld zone and the heat-affected zone to close to those of the base material is a key solution for the manufacturing of welded cathode rollers. In order to effectively modify the microstructure and obtain an optimal refining effect in the weld zone of a TA1 cathode roller, a novel composite technology consisting of low-energy and fewer-pass welding combined with multi-pass rolling deformation and vacuum annealing treatment was primarily explored for high-purity TA1 titanium plates in this study. The microstructure of each area of the weld was observed using the DMI-3000M optical microscope, and the hardness was measured using the HVS-30 Vickers hardness tester. The research results show that the microstructure of each area of the weld can be effectively refined by using the novel composite technology of low-energy and fewer-pass welding, multi-pass rolling deformation, and vacuum annealing treatment. Among the explored experimental conditions, the optimal grain refinement effect is obtained with a V-shaped welding groove and four passes of welding with a welding current of 90 A and a voltage of 8–9 V, followed by 11 passes of rolling deformation with a total deformation rate of 45% and, finally, vacuum annealing at 650 °C for 1 h. The grain size grades in the weld zone and the heat-affected zone are close to those of the base material, namely grade 7.5~10, grade 7.5~10, and grade 7.5~10 for the weld zone, heat-affected zone, and base material, respectively. Meanwhile, this technology can also refine the grains of the base material, which is conducive to improving the overall mechanical properties of the titanium plate. Full article

In recent years, polycrystalline diamond compact (PDC) drill bits have seen significant advancements. They have replaced over 90% of the workload traditionally handled by roller cone bits and have become the predominant choice in energy drilling due to their superior efficiency and durability. However, PDC drill bits are susceptible to adhesion of rock cuttings during drilling in muddy formations, leading to mud accumulation on the bit surface. This phenomenon can cause drill bit failure and may contribute to downhole complications, including tool failure and borehole instability. The adhesion issue between PDC drill bits and mud rock cuttings underground is primarily influenced by the normal adhesion force between the drill bit surface and the mud rock cuttings. Therefore, biological non-smooth surface technology is applied to the prevention and control of drill bit balling. It is an optimal selection of biomimetic non-smooth surface structures with reduced adhesion and detachment properties. A non-smooth surface model for the PDC drill bit body is established through the analysis of the morphological characteristics of natural biological non-smooth surfaces. An experimental platform is designed and manufactured to evaluate the adhesion performance of non-smooth surface specimens. Indoor experiments are conducted to test the normal adhesion force of non-smooth surface specimens under varying morphologies, sizes, and contact times with clay. Finally, the anti-adhesion performance of the non-smooth surface unit structures is then analyzed. The normal adhesion force with a contact time of 12 h is as follows: 340 Pa of big square raised, 250 Pa of middle square raised, 190 Pa of small square raised, 315 Pa of big circular groove, 280 Pa of middle circular groove, 200 Pa of small circular groove, 225 Pa of big dot pit, 205 Pa of middle dot pit, and 130 Pa of small dot pit. Compared with the normal adhesion force of 550 Pa for smooth surface specimens with a contact time of 12 h, the anti-adhesion properties of the three non-smooth surface unit structure specimens designed in this paper were verified. We analyzed the anti-adhesion performance of non-smooth surface unit structures. At the critical contact time when the adhesion force tends to stabilize, the adhesion forces of different specimens are as follows: 330 Pa of big square raised, 237.5 Pa of middle square raised, 175 Pa of small square raised, 290 Pa of big circular groove, 250 Pa of middle circular groove, 160 Pa of small circular groove, 210 Pa of big dot pit, 185 Pa of middle dot pit, and 115 Pa of small dot pit. The results indicate that the anti-adhesion effect of small dot pit structures is the most effective, while the anti-adhesion effect of large square convex structures is the least effective. As the size of the unit structure decreases, it becomes more similar to the surface size of the organism. Additionally, a shorter contact time with clay leads to a better anti-adhesion effect. These findings provide new insights and research directions for the effective prevention and control of mud wrapping on PDC drill bits. Full article

Valve leakage mainly comes from worn sealing surfaces caused by abrasive particles. This study uses plasma beam spraying to create Fe55 alloy coatings with CeO₂ and TiN added to improve microstructure and wear resistance. Five coatings were prepared: Fe55 with 0.02% CeO₂ (FC2), 0.04% CeO₂ (FC4), 1% TiN (FT1), 2% TiN (FT2), and 2% TiN/0.02% CeO₂ (FC2T2). These coatings were tested for wear and erosion using wet sand and slurry experiments. Results showed that FC2T2 had the most uniform microstructure with fully equiaxed grains (20.32 μm size) and no columnar grains. This was due to CeO₂ and TiN co-working effect: CeO₂ was adsorbed onto TiN surfaces, reducing TiN decomposition and acting as nucleation sites. The FC2T2 coating also showed the highest hardness uniformity (no large changes with depth) and the lowest surface roughness after wear (41% lower than pure Fe55). In wear tests, FC2T2’s Cr₇C₃ hard phases blocked abrasive cutting, while the γ-Fe matrix prevented Cr₇C₃ from breaking off. Erosion tests confirmed FC2T2’s superior performance, as its uniform structure limited deep grooves. Adding both CeO₂ and TiN improved wear resistance by providing a balanced microstructure, reducing leakage risks in valve sealing surfaces. Full article

The research and related tests aimed to investigate the effect of different heat inputs on the microstructure and properties of the joint when using laser-backing welding for X80 steel, with the purpose of guiding a reasonable adjustment of heat inputs to obtain a sound and high-quality joint, and ultimately laying the foundation for the engineering application of laser-backing welding. The fiber-laser-backing welding is performed on a 22 mm thick X80 steel, before which a groove is prepared and assembled; joints were obtained under different heat inputs (162, 180, 210, 270 J/mm) with orthogonal combinations of laser power and welding speed. The microstructure and properties of the joints were characterized by using an optical microscope, scanning electron microscope, and microhardness tester. According to this investigation, the morphology of the joint is directly affected by the heat input, and insufficient heat input (<180 J/mm) will lead to an unacceptable weld profile. The width of the weld and heat-affected zone gets bigger as the heat input increases. The hardness nephograms of the joints under different heat inputs show that the weld has the highest hardness, followed by the coarse-grain heat-affected zone and the fine-grain heat-affected zone, sequentially. The less heat input, the lower the joint hardness; when the heat input increases to 270 J/mm, the coarse-grain zone near the fusion line shows obvious hardening. In addition, heat input also affects the impact toughness of the weld. The grain size of X80 steel with a lower content of niobium easily becomes coarse under excessive heat input (270 J/mm), resulting in the degradation of the grain-boundary slip ability; hence, the impact toughness of the joint deteriorates. The optimal heat input of 210 J/mm was identified, achieving a grain size of nearly 14 µm and providing a balanced combination of lower strength and higher impact toughness. Full article

Under mixed lubrication, the macro size is affected by the wear of the surface roughness peaks, which results in degradation of the bearing accuracy. To study the wear characteristics of rolling bearings under mixed lubrication, based on the elastohydrodynamic lubrication theory and Archard wear model, and considering the coupling of the oil film and roughness, a wear prediction model of angular contact ball bearings under mixed lubrication was established, and the influence of the working parameters and hardness on bearing wear was analyzed. The results show that the wear depth of the outer grove increases with an increase in the load, or a decrease in the rotational speed or the initial viscosity of lubricating oil. The load has the most significant effect on the wear depth of the outer grove. There is a critical value for the load, rotational speed, and initial viscosity of the lubricating oil, which varies with the parameters of other working conditions and the hardness of the materials. When the increase in load exceeds the critical value or the rotational speed and initial viscosity of lubricating oil are less than the critical value, the outer groove fails because the wear depth exceeds the critical value of wear depth. The ratio of the load on the rolling element to the hardness of the outer grove at different entrainment speeds and initial viscosities of lubricating oil can be used to predict the wear degree of the outer grove. When the ratio is greater than a certain threshold, the outer grove is faulted owing to wear, and the threshold decreases with an increase in the initial viscosity of lubricating oil or the decrease in rotational speed. Full article

As a hard and brittle material, the processing of C_f/SiC ceramic matrix composites (CMCs) faces significant challenges, especially in the processing of small-sized shapes. To address this challenge, laser processing with gas-assisted nanosecond laser (GNL) and waterjet-guided nanosecond laser (WNL) modes were applied to fabricate thin kerfs in the C_f/SiC composite. The surface morphology, microstructure, and chemical composition of the processed C_f/SiC composite were investigated comparatively. The results revealed that the coupling of helium in the GNL mode laser processing could make full use of the laser energy, but resulted in spattering in the kerf margin and a recast layer in the kerf surface, accompanied by obvious oxidation, while the coupling of the waterjet in the WNL mode laser processing decreased the oxidation significantly and removed the remelting debris, which produced a clear and flat kerf surface. Due to the taper caused by laser energy dissipation, the single-path laser processing in the C_f/SiC composite had a limited depth. The maximum depth of the kerf prepared by single-path laser processing with the GNL mode was about 328 μm, while that with the WNL mode was about 302 μm. The multi-path laser processing with the GNL and WNL modes could fabricate a through kerf in the C_f/SiC composite, but the coupling medium obviously influenced the surface morphology and microstructure of the underlying region. The kerf surface prepared by the GNL mode had a varied surface morphology, which transited from the top layer, covered with oxide particles and some cracks, to the bottom layer, featured with micro-grooves and small oxides. The kerf surface prepared by the WNL mode had a consistently smooth and clean morphology featured with broken carbon fiber and residual SiC matrix. The slow laser energy dissipation and open environment in the GNL mode resulted in a bigger HAZ and relatively serious oxidation, which caused local phase transformation and microstructure degradation. The isolation condition and rapid cooling in the WNL mode decreased the HAZ and restrained the oxidation, almost keeping the original microstructure. The thicknesses of the HAZ in the GNL- and WNL-processed C_f/SiC composite were about 200 μm and 100 μm, respectively. The WNL-processed C_f/SiC composite had a lower oxidation and thermal damage surface, which is instructive for the processing of the C_f/SiC composite. Full article

The role of notch stress and surface defects on fatigue crack initiation and small-crack propagation behavior has been investigated using groove simulation specimens. The naturally initiated small-crack growth tests have been performed on a FGH4099 superalloy at 500 °C and 700 °C. The findings indicate that elevated testing temperature significantly reduced the proportion of fatigue crack initiation life, with a less pronounced effect on the proportion of life for cracks to grow to First Engineering Crack size. Competing crack initiation modes were observed in the fatigue test of groove simulation specimens. The location of maximum principal stress was dominant fatigue crack initiation sites, and for specimens with surface inclusions, the defect location can also serve as a crack initiation site. Furthermore, crack initiation modes were found to have a more pronounced effect on the small-crack growth rate. A turning point observed in the crack growth rate curves for specimens with multi-site crack initiation was attributed to crack shielding and subsequent coalescence. Full article

Ultrasonic vibration (UV)-assisted forming technology has emerged as a significant advancement in the field of bulk micro-forming. This study presents a comprehensive experimental investigation into the micro-scale deformation behavior of metallic materials and its influence on size effects under UV, with a specific focus on the UV-assisted T-shaped micro-upsetting of T2 copper. Utilizing a custom-designed UV-assisted micro-upsetting apparatus, the flow stress, filling height, and microstructural evolution of T2 copper are systematically examined, considering various grain sizes, die opening angles, and ultrasonic amplitudes. The findings demonstrate that UV significantly mitigates the influence of grain size effects. Notably, the softening effect induced by UV becomes more pronounced with decreasing grain size, concomitantly leading to increased filling height. As the die opening angle expands, the required forming load increases. The enhancement of ultrasonic amplitude not only increases the V-groove filling height but also improves the surface quality. The optimal V-groove filling performance is achieved at an ultrasonic amplitude of 8.01 μm. It is crucial to note that increased ultrasonic amplitude generally improves forming performance, while excessive ultrasonic amplitude may lead to micro-crack formation within the material, thereby decreasing the formability of T2 copper. These results provide valuable insights into the complex interplay between ultrasonic parameters and material response in micro-forming processes, offering significant implications for the optimization of UV-assisted forming technologies in precision manufacturing applications. Full article

The extension direction of welding defects is random and uncontrollable, while magneto-optical imaging detection has a good imaging effect on defects perpendicular to the magnetic field direction. At present, magneto-optical detection methods may fail to detect small weld defects parallel to the direction of the magnetic field. To overcome this problem, a non-destructive testing method based on magneto-optical imaging under a vertical combined magnetic field (VCMF) is proposed. The paper first establishes a simulation model to compare and analyze the magnetic leakage characteristics of cross grooves under a constant magnetic field (CMF), an alternating magnetic field (AMF), a rotating magnetic field (RMF), a parallel combined magnetic field (PCMF), and VCMF excitation, proving that detection does not easily fail under VCMF. Secondly, by changing the size of the CMF in the VCMF simulation model, it was found that, as the CMF intensity increases, a new maximum value will appear on the side of the defect contour close to the sample area. This maximum value increases with the increase of the CMF intensity, which can lead to misjudgment of the defect contour, that is, false contours. Finally, magneto-optical imaging was used to verify the imaging effect of weld defects under VCMFs. The results indicate that more comprehensive defect information can be detected under VCMFs. When the maximum value of the excitation current of the AMF is at least 12 times the excitation current of the CMF, there will be no false contour defects. Full article

Skull base meningiomas present considerable challenges in surgical management due to their proximity to critical neurovascular structures. Anterior skull base meningiomas encompass olfactory groove, supra- and parasellar, anterior sphenoid ridge, cavernous sinus, and spheno-orbital tumors. The success of surgical resection and the likelihood of complications are influenced by several key factors, including the presence of an intact arachnoid plane, tumor size and consistency, peritumoral brain edema, cranial nerve involvement, vascular encasement, and invasion of critical areas such as the optic canal or cavernous sinus. These factors not only affect the feasibility of gross total resection but also play a pivotal role in determining functional outcomes and postoperative recovery. With the vast array of imaging modalities available, selecting the most appropriate investigations to assess these parameters and tailoring surgical strategies accordingly remain complex tasks. This review examines the critical surgical parameters, identifies the most effective imaging modalities for evaluating each, and provides key insights into how this analysis can guide surgical decision-making, mitigate risks, and minimize complications. Full article

This paper develops a composite weaving structure, combining hexagonal micro-bumps and hexagonal grooves, in the design of the rubber surface of the screw pump. This allows us to solve the problem of high torque and fast wear of the rubber stator during the operation of screw pump lifting oil recovery, based on the bionic hexagonal surface structure, traditional surface damping principle, and fluid dynamic pressure lubrication theory. Finite element analysis is first conducted to quantitatively analyze the impacts of the parallel side distance, groove width, and groove depth on the surface flow field and wall pressure field of the composite hexagonal structure. Based on the simulation law, the rubber surface laser structure is then designed and prepared by nanosecond laser processing. Afterward, tribological experiments are conducted under the condition of long-term immersion in the actual extraction fluid of shale oil wells. This aims at simulating the actual downhole oil production conditions and quantitatively studying the impact of the size of the composite hexagonal structure on the lubrication characteristics of the friction part of the stationary rotor, as well as the effect of abrasion reduction. The results show that, within the simulation range, the smaller the parallel side distance, the higher the load-carrying capacity. In addition, the hexagonal weave with a parallel side distance of 3 mm has a higher wall load carrying capacity than that with distances of 4 mm and 5 mm. When the groove width is equal to 0.4 mm, the oil film load carrying capacity is higher than that in the case of 0.2 mm. When the groove depth increases, the oil film pressure first increases and then stabilizes or decreases after reaching 0.3 mm. In the hexagonal weave, the friction ratio of the rotor is equal to 0.4 mm. In the tribological experiment of hexagonal weave, the smaller the parallel side distance, the smaller the friction coefficient, and the 0.5 mm weave has the highest performance. Full article