Ice abrasive particles are promising environmentally friendly media for abrasive jet machining, but their application is limited by low preparation efficiency, irregular morphology, and insufficient hardness. This study developed a nanofluid-assisted cryogenic atomization method for preparing ice-bonded abrasive (IBA) particles. Al2O3 and SiO2 nanofluids were characterized by differential scanning calorimetry. The 0.25 wt% Al2O3 nanofluid reduced the crystallization duration from 2.01 to 0.91 s, corresponding to a 54.7% decrease, and exhibited the largest peak heat-flow magnitude. Its thermal conductivity reached 0.6722 ± 0.0030 W·m−1·K−1 at 25 °C, 11.06% higher than that of pure water. These results suggest that the improved crystallization behavior may be associated with interfacial effects and enhanced heat transfer. COMSOL simulations indicated that a 45° nitrogen inlet angle produced a relatively uniform cooling field. After 900 s of pre-cooling, the tank temperature reached approximately −160 °C, while the collected particles remained below −60 °C. The Shore D hardness increased by 24.0%, and more than 300 particles exhibited near-spherical morphology with a mean diameter of 173.26 μm. The proposed method provides a feasible route for controlled IBA preparation.

In this study, a bolt installation tool loading mechanism has been developed to overcome the constraints posed by compact space in the assembly of aero-engines and airframes. The loading mechanism features a thin-walled structure, allowing it to adapt to compact working space, and achieves high torque output through the coordinated drive of the ratchet-pawl mechanism and the hydraulic cylinder. A detailed design was carried out for the thin-walled structure, force arm dimensions, and ratchet tooth profile in the loading mechanism. Through dynamic simulation analysis, the strength safety of key components under a torque of 120 Nm and the rationality of symmetrical design were verified. Experimental results demonstrated that the tool can deliver an average torque of 136.3 Nm within a space as narrow as 4 mm, fulfilling the design requirements. The findings of this paper provide a reliable solution for the assembly of high-strength bolts in the compact space of a lean engine, significantly enhancing assembly efficiency and safety.

The S-shaped test piece is an effective workpiece for evaluating the machining accuracy and dynamic performance of five-axis CNC machine tools. Addressing the lack of precise mathematical models and systematic geometric analyses for the third-version S-shaped test piece specified in ISO 10791-7:2020, this study constructs a set of cubic quasi-uniform rational B-spline (QURBS) basis functions via the de Boor-Cox recurrence formula for the first time. A parametric ruled surface model integrated with control vertex coordinates is established. Model analysis reveals four curvature peaks on the upper and lower directrices of both ruled surfaces A and B, with a maximum curvature of 0.032 mm⁻¹ for surface A and 0.042 mm⁻¹ for surface B. The opening/closing angles exhibit two dynamic transitions within the 300–400 mm arc length interval. A novel twist angle calculation formula based on normal vector projection angles is proposed, revealing maximum twist angles at the Z = 0 mm directrix: 3.794° for ruled surface A and 3.288° for ruled surface B. By introducing a concavity/convexity criterion for the lower directrix, the machining principle error computation is optimized, confirming a positive correlation between tool-workpiece contact length and machining principle error.

The yield strength of FCC high-entropy alloys is low, which seriously restricts its application. In order to significantly improve the strength while without significantly sacrificing ductility, a new and efficient processing strategy was adopted in this study, including two-stage thermomechanical processing and flash annealing. Based on this, a heterogeneous grain structure high-entropy alloys composed of recrystallized coarse grains, recrystallized fine grains and residual deformed grains was prepared. The complex structure formed by flash annealing has a good strength-plastic synergistic effect. The results show that with the increase of annealing time, the phase structure of the alloy always maintains a single-phase FCC structure. When the annealing time is 10 s, the yield strength and uniform elongation are 950.8 MPa and 13.9 %, respectively. Especially when the annealing time is 15 s, the yield strength is still maintained at 835.5 MPa, and the uniform elongation is greater than 20 %. The high yield strength is not only due to the strengthening caused by high density dislocations, but also due to the back stress hardening caused by the combination of hard and soft domains. The excellent combination of strength and plasticity is the combined effect of heterogeneous deformation induced strengthening and strain hardening, deformation twins and stacking faults.

Marine components often face severe challenges due to high friction, wear, and corrosion in saline environments. In this work, graphite-like carbon (GLC) films reinforced with nano high-entropy carbide (HEC) layers were designed to enhance durability. The insertion of nano HEC layers intensified the bias-induced etching effect, increasing the sp3 bonding fraction and improving hardness. Meanwhile, interfacial passivation developed each HEC layer effectively slowed the diffusion of corrosive ions. As a result, the multilayer architecture provided superior electrochemical stability and tribo-corrosion resistance. Notably, the optimized eight-period (HEC/ GLC)8 multilayer film exhibited excellent corrosion resistance, with the corrosion current density reduced 4.51 & times; 10-8 A/cm2. It also maintained structural integrity under tribo-corrosion tests and achieved an ultralow friction coefficient of 0.03.

To enhance the service stability of cemented carbides in marine and other corrosion-wear coupled environments, a series of Si-DLC coatings was fabricated via magnetron sputtering by adjusting the acetylene flow rate. The chemical structure, mechanical properties, and electrochemical and tribocorrosion behaviors in 3.5 wt% NaCl solution were systematically evaluated. The results showed that an acetylene flow rate of 8 sccm enabled optimal silicon incorporation, enhancing the H/E* and H3/E*2 ratios, reducing residual stress and porosity, resulting in a denser structure with the highest pore resistance (1.0 x 107 Omega & sdot;cm2) and lowest corrosion current density (2.0 x 10_8 A/cm2). This condition also resulted in excellent wear resistance and a minimum coefficient of friction of 0.09. SXAS further revealed the evolution of coating porosity, confirming that the sample deposited at 8 sccm acetylene exhibited the lowest porosity and the most uniform pore size distribution. By contrast, although the coating deposited at 10 sccm showed the highest hardness, its tribocorrosion performance declined due to pore agglomeration and increased residual stress.

Cracks are a common form of subsurface damage (SSD) in optical glass grinding, directly affecting the positioning accuracy and lifespan of hemispherical resonator gyroscopes (HRGs). This study presents a predictive model for SSD in hemispherical resonator grinding, based on indentation fracture theory. The SSD and surface roughness average (Ra) data, obtained from grinding experiments under various conditions, were used to optimize the model's accuracy. Material scratching tests under different loads revealed that only surface plastic deformation occurred, with no observable SSD at 120 mN. The characteristics of surface damage (SD) transitioned from plastic deformation to brittle fracture between 120 mN and 300 mN, with subsurface cracks propagating in the direction of maximum stress. The model's practical applicability was further verified through precision grinding trials conducted on hemispherical resonators. A minimum error of 1.41 % and a mean error of 14.94 % demonstrate the model's predictive capability within a specific range.

Abstract Cr/Cr–WC/WC–DLC composite coatings were sequentially deposited on Cr12MoV alloy substrates via a hybrid process combining high-power impulse magnetron sputtering and chemical vapor deposition. The influence of different bias voltage parameters (−300 V, −400 V, −500 V, −600 V, −700 V) on the fabrication of WC–DLC coatings was systematically investigated, with a focus on evaluating how bias voltage affects the coatings’ microstructure, mechanical properties, tribological behavior, and corrosion resistance. The results demonstrate that the variations in bonding configurations induced by different bias voltages directly modulate the tribological performance and corrosion resistance of the WC–DLC coatings. Comparative analysis of the carbon bonding structures revealed that as the bias voltage increased from −300 V to −400 V, the sp 3 bond content peaked while the I D / I G ratio remained relatively low. This significantly enhanced the coating’s deformation resistance and stability in corrosive environments, thereby improving its wear and corrosion resistance. However, when the bias voltage was further increased to −700 V, the sp 2 -C content increased, and a graphitized carbon structure formed in the deposited coating. This led to a reduction in hardness and a decline in chemical stability, which accelerated coating corrosion and the degradation of mechanical properties.

Additively manufactured special-shaped waveguides with continuous blind cavities often exhibit rough internal surfaces, non-uniform finishing on boss surfaces, and excessive edge removal. This study regulates abrasive-medium viscosity to improve boss surface finishing while preserving edge morphology. A power-law fluid model was established to analyze viscosity effects on velocity distribution and near-wall velocity difference. Numerical simulations obtained near-wall velocity, PV value, and strain rate distributions on boss surfaces and edge regions. Single-factor abrasive flow finishing experiments were conducted at 1000-3000 Pa·s. Finishing performance was evaluated using the surface roughness reduction rate of boss surfaces, edge removal height, and machining uniformity among key boss surfaces. With increasing viscosity, the average surface roughness reduction rate of boss surfaces decreased from 83.80% to 67.76%, while the post-finishing, Ra increased from 1.838 μm to 4.222 μm. The average edge removal height decreased from 0.1537 mm to 0.0417 mm, and the roughness dispersion among the key boss surfaces also decreased. These results indicate that higher viscosity weakened boss surface material removal and local edge removal, while improving machining uniformity. Considering finishing efficiency, edge preservation, and uniformity, 2000-2500 Pa·s was selected as the preferred viscosity range. Within this range, the roughness reduction rate remained above 70%, Ra decreased from above 10 μm to below 3.7 μm, and the average edge removal height was 0.0951-0.0641 mm. This study clarifies the coupled effect of medium viscosity on boss surface material removal, edge removal, and machining uniformity in continuous blind-cavity waveguides.

To improve the durability of cemented carbides in corrosion-wear coupled environments, a series of Cr/Si co-doped DLC coatings was deposited by magnetron sputtering, in which the Si content was maintained while the Cr content was systematically varied. The results reveal a pronounced structure-property correlation governed by Cr incorporation. With increasing Cr content, the coating evolves from a dense, homogeneous amorphous structure to a heterogeneous, nanocomposite-like structure with higher nanocluster density and defect connectivity. At moderate Cr content, the coating exhibits optimal performance, characterized by a high coating resistance (3.8 × 105 Ω·cm2), low corrosion current density (1.6 × 10-7 A/cm2), low friction coefficient (0.101), and minimum wear rate (2.5 × 10-7 mm3/N·m). This behavior is attributed to the formation of Cr-C bonds and a more compact structure, which effectively suppresses defect connectivity and inhibits electrolyte penetration, resulting in barrier-controlled corrosion. In contrast, excessive Cr induces structural heterogeneity and the formation of defect-connected pathways, promoting electrolyte transport and accelerating degradation. Consequently, the corrosion mechanism transitions from barrier-controlled to transport-dominated behavior, while the tribocorrosion failure evolves from mild wear to severe delamination due to the synergistic coupling between corrosion and mechanical damage.

Tribocorrosion is a common and highly challenging service condition for marine engineering equipment, and improving the durability of cemented carbides in corrosion-wear coupled environments is of great significance. In this study, a-C:H(Si, Cr) coatings were prepared by dual-target magnetron sputtering, and their tribological behavior was investigated. The a-C:H(Si, Cr) film with a Cr concentration of 7 at.% exhibited excellent lubricating behavior, with a coefficient of friction of 0.1. Compared with the a-C:H(Si, Cr) film containing 12 at.% Cr, its wear rate was reduced by 90%, mainly due to the microstructural changes induced by Cr incorporation. The results show that Cr incorporation promotes the formation of ordered sp2-C clusters in the a-C:H(Si, Cr) film, which is beneficial for constructing a more ordered carbon network. The Cr-mediated carbon network reconstruction and the formation of Cr-C bonds help release internal stress, enhance film-substrate adhesion, and promote the formation of a stable transfer film. During corrosive sliding, the synergistic effect of stable interfacial bonding and the transfer film reduces mechanical shear damage and restricts electrolyte penetration along defect channels toward the coating/substrate interface, thereby weakening the coupled failure between corrosion and wear. This mechanism links atomic-scale bonding and interfacial stability with macroscopic tribocorrosion performance, highlighting a-C:H(Si,Cr) films as promising corrosion-resistant lubricating coatings.

This study focuses on rhenium nitride (ReNx) coatings (x = 0.37-0.50) deposited on YG8 cemented carbide via magnetron sputtering, investigating nitrogen content's regulation of their microstructural evolution and comprehensive properties. By adjusting the N2/Ar flow ratio (S1:1:1 to S4:1:4), coatings with varying nitrogen contents were prepared. Characterizations via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nanoindentation, tribological/ electrochemical tests, and first-principles calculations confirm all coatings exhibit a face-centered cubic (fcc) ReNx phase. High nitrogen (S1, x = 0.50) promotes dense, low-roughness (Sa (surface roughness parameter) =1.43 nm) microstructures via lattice contraction and strong Re-N bonding; low nitrogen (S4, x = 0.37) causes metallic Re accumulation, increasing roughness (Sa = 1.75 nm) and deposition rate. Mechanically, hardness peaks at 27.66 GPa for S3 (x = 0.40)-supported by TEM observations of dense columnar grains, dislocation walls, and refined grains (19.7 nm)-while elastic modulus rises from 537.0 GPa (S1) to 589.5 GPa (S4) with decreasing nitrogen. Tribologically, minimum friction coefficient (0.1) and wear rate (9.0 x 10-8 mm3/(N & sdot;m), S2) come from tribo-induced ReO2/ReO3 lubricants and dense structure. Electrochemically, S1 shows corrosion current density (1.93 x 10-6 A/cm2) two orders lower than YG8 (2.23 x 10-4 A/cm2) due to the dense structure's barrier effect. This work clarifies nitrogen-driven structure-property relationships of ReNx coatings, supporting their optimization for friction-corrosion coupled extreme environments.

The excellent physical and chemical stability of single-crystal 4H-SiC slices renders them challenging to process. Laser modification processing is an effective approach to enhance the machinability of single-crystal 4H-SiC slices. The control variable method was conducted to investigate the evolution of SiC cutting sheets surface quality and structural characteristics under picosecond laser modification. Picosecond laser-modified SiC cut sheets were characterized using both pre-analytical and experimental methods: The optimal process parameters under these experimental conditions were determined to be 7.96 J/cm2 for energy density, 180 mm/s for scanning speed, and 18 mu m for scanning spacing. Laser modification significantly improves the mechanical properties and machinability of SiC slices. These substances were deposited on the surface in the form of SiO2 smoke particles and crystalline Si (c-Si). Obvious residual tensile stresses were observed on the surface, along with subsurface defects caused by heat transfer during the laser modification process. Additionally, upon conclusion of the laser modification, rapid cooling promotes the recrystallization of SiC vapours on the subsurface, isolated from the atmosphere and deposited there. This work will provide a theoretical basis and practical guidance for the efficient processing of single crystal SiC cutting sheets in laser synergistic CMP.

Tool edge preparation can eliminate edge defects and customize edge geometry to improve cutting performance, which has become essential in the manufacturing of high performance tools. Developing a novel edge preparation process is particularly urgent as the quality and controllability of edge preparation become increasingly demanding. This study presents a process for preparing carbide tool edges using magnetorheological fluids containing abrasives. An equivalent multiphase flow simulation of the preparation process is developed to investigate the interaction between the abrasive and the tool edge, and the mechanism and critical conditions for material removal are elucidated. Response surface methodology was employed to investigate the effects of the process parameters on the edge material removal amount and surface quality. The results show that magnetorheological preparation is a reliable edge treatment method that significantly improves the edge surface quality, achieving a surface roughness of 0.15 μm and an increase in the edge radius of approximately 1.48 μm/min in the optimization experiment. Normal force-assisted shear scraping of the abrasive particles is the dominant mechanism for edge material removal, and an appropriate abrasive particle area ratio ensures edge material shear failure. Adjusting the process parameters can change the material removal amount and surface roughness. This study contributes to a deep understanding of the magnetorheological preparation mechanism of cemented carbide tool edges and will provides an invaluable reference for determing process preference and achieving controlled tool edge preparation.

To address the problems associated with the preparation of traditional epoxy resin-bonded magnetic abrasives, such as incomplete solvent evaporation and poor environmental compatibility, as well as the problems of brittleness and short service life in the abrasives, a novel glass fiber-reinforced magnetic abrasive (GFMA) was developed using a curing-demolding method. The incorporation of glass fibers into the resin matrix forms a reinforced composite structure and the microstructure and composition were characterized. Three experiments were conducted using a planar magnetic abrasive finishing setup to polish 3D-printed AlSi10Mg workpieces. Results showed that compared with traditional epoxy resin-based abrasives, GFMA exhibits higher finishing efficiency and a longer service life. Specifically, using 3 g of 10-20 mesh GFMA reduced the surface roughness of the AlSi10Mg workpiece by 97.83% and removed 77 mg of material. Compared to traditional magnetic abrasives, material removal rates increase by approximately 56%. The reinforced composite matrix enhances the mechanical strength and service life of abrasives, and also improves preparation reliability and environmental compatibility. This method has engineering value for precision finishing of complex internal cavity components, and provides a promising strategy and reference for developing composite magnetic abrasives.

Silicon carbide (SiC) exhibits exceptional hardness and brittleness that severely limit machining efficiency and surface quality. This work reports, for the first time, the electro-plastic softening of single-crystal SiC under direct current fields and proposes a novel mechanism: the effect originates synergistically from radial electric fields generated by surface charge accumulation and electron wind forces. Indentation experiments demonstrate current-dependent hardness reductions governed by surface treatment, electrode geometry, sample dimensions, loading rate, and applied load. Moreover, the reduction in hardness exhibits a clear correlation with the distribution of surface charge density. Furthermore, this study provides the quantitative calculations of surface and space charge densities distributions near the semiconductor surface under direct current fields, establishing theoretical foundations for predicting internal current intensity and radial electric field strength across material systems. Results reveal a critical doping-dependent transition. First-principles calculations establish that the radial electric field reduces the bandgap, thereby lowering dislocation nucleation energy barriers and facilitating plastic deformation. Besides, the effect intensity is inversely proportional to doping concentration and directly proportional to current density. This work provides both experimental evidence and theoretical insight for achieving efficient and high-quality machining of SiC through current-field-assisted methods.

Diamond-like carbon (DLC) films are regarded as highly competitive surface films for marine service environments owing to their excellent lubricity, wear resistance, and corrosion protection. In this work, a series of (NbTaMoWAl)(x)-DLC films were developed by systematically tuning the multi-element co-doping levels. We investigated its effects on microstructural evolution and tribo-corrosion mechanisms. At low doping levels ( similar to 4 at%), multi-element additions promoted the formation of a stable carbonate-type passive film and preserved high compactness with the sp(3) carbon network, thereby increasing the charge transfer resistance (R-ct), lowering the friction coefficient, and suppressing the tribo-corrosion failure. With further enrichment in multi-element content (similar to 12, 24, 35 at%), the films exhibited intrinsic features of carbide ceramics: increased columnar gaps and grain-boundary channels and stronger interfacial galvanic effects. It led to the OCP shifting toward more negative values, and the COF showed larger fluctuations. Such microstructural evolution caused by excessive multi-element doping accelerated the penetration of corrosive media along columnar grain boundaries and channels, thereby undermining the overall protective efficacy.

The excellent combination of strength and plasticity of heterostructures high-entropy alloys (HEAs) has attracted much attention, but it is only impossible to achieve further engineering applications. Therefore, the corrosion resistance of FeCoCrNiMn HEAs with different heterogeneous grain structures (HGS) and Si contents in sodium chloride solution was studied in this paper. Experimental results revealed that except for Si-free alloy, pitting corrosion occurred in other alloys. Moreover, with the increase of volume fraction and Si content in the residual deformed grain region, the pitting corrosion gradually increases. Si improves the self-corrosion resistance of the alloy. The p-n heterojunctions are observed in all HEAs. The thickness or composition of the passivation film can be changed by changing the composition of the alloy structure or adding Si. The high activity of the residual deformed grain region in the heterogeneous grain structure HEAs makes it preferentially undergo anodic reaction and be eroded by chloride ions. Si promotes the diffusion of metal elements and accelerates the pitting reaction. This study establishes the correlation between heterogeneous grain structure and corrosion behavior, and provides insights for the design of high-entropy alloys with excellent comprehensive properties.