Hemispherical Resonator (HSR) is a typical high-performance component due to the complex coupling relationship between the machining errors and performance parameters. To understand the impact of machining errors on frequency splitting, the frequency splitting model that couples the multiple machining errors was developed to elucidate the mechanism of frequency splitting and reveal the effect of geometric error parameters on frequency splitting innovatively. In addition, a method for characterizing machining errors is established to describe the circumferential mass uniformity of the hemispherical shell. Furthermore, measurement experiments of HSRs were performed to verify the accuracy of the model, and the results showed that the predicted errors of the model were within 15%. Both theoretical and experimental results demonstrated that the direct cause of frequency splitting is the uneven circumferential mass of HSR. In particular, the radial concentricity has the most significant influence on frequency splitting, followed by the coaxiality and roundness. Within the error range of 0-0.5 lm, frequency splitting values change by 0.945 Hz, 0.098 Hz, and 0.039 Hz, respectively. Furthermore, the coupling effect of machining errors and surface quality on frequency splitting was discussed, which showed machining errors is the predominant factor contributing to frequency splitting. This work not only enhance the understanding of the mechanism of frequency splitting, but also provide theoretical guidance for the parameter optimization involved in high-performance manufacturing of HSR. (c) 2025 The Author(s). Published by Elsevier Ltd on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

The hemispherical resonator gyroscope (HRG) is a high-performance gyroscope widely used in next-generation strapdown inertial navigation systems due to its exceptional accuracy, ultra-long lifespan, and high reliability. The core component, the hemispherical resonator (HSR), is a Ψ-shaped thin-walled structure fabricated from fused silica, whose polishing quality directly influences the overall performance of the HRG. Permanent-magnet small ball-end magnetorheological polishing (PSBMRP) has demonstrated the capability for full-surface, high-precision, and non-destructive polishing of the HSR. However, its relatively low material removal rate poses a challenge for mass production of HSRs. To address this limitation, a chemical-thermal co-assisted PSBMRP method is proposed in this study. Six common alkaline substances are selected as chemical additives for magnetorheological (MR) fluids. The effects of chemical additive types on polishing efficiency and surface quality are analyzed through polishing experiments with fused silica glass rods, and the optimal chemical additive is determined to be granular NaOH. Using MR fluid with NaOH under controlled conditions (temperature: 60 ℃; pH: 14), HSRs with diameters of 30 mm and 20 mm are successfully polished. The total polishing times are reduced to 19 h and 23 h, respectively, representing nearly a 50

Due to their high refractive index, excellent transparency, and wide bandgap, hafnium dioxide (HfO2) films are vital as high-index layers in multilayer optical coatings. During the manufacturing and handling of high-power laser optics, friction-induced micro-defects can severely degrade the laser-induced damage threshold and overall component lifetime. Therefore, elucidating the tribological failure mechanisms of HfO2 films under mechanical contact is essential. To clarify the dynamic failure behavior of HfO2 films on fused-silica substrates, ball-on-disk tests were conducted on samples with different film thicknesses at discrete rotation speeds and for specific sliding durations, followed by systematic characterization and analysis. The results show that, within the tested conditions, film thickness affects both early failure and the subsequent wear trajectory. The 300nm HfO2 film exhibits larger mean wear volume and higher wear rates than the 200nm film. Notably, although late-stage contact is dominated by the exposed fused-silica substrate, the final wear responses do not converge, suggesting that the initial thickness-dependent surface damage, rather than the residual film material, likely influences subsequent substrate removal. Furthermore, film thickness and rotation speed jointly affect third-body layer (TBL) formation. Higher speeds accelerate damage accumulation, and the 300nm film exhibits poorer TBL continuity with more severe substrate exposure. By contrast the 200nm film exhibits a distinct non-monotonic, multistage coefficient of friction evolution, which corresponds closely to debris generation, temporary TBL formation, and partial film spallation. These findings provide insight into the thickness-dependent wear behavior and TBL-mediated damage evolution of HfO2 optical films.

Potassium Dihydrogen Phosphate (KH2PO4, KDP) crystals are widely used in laser systems owing to their outstanding nonlinear optical properties. However, cross-scale micro-nano surface defects inevitably introduced during ultra-precision machining severely induce laser-induced damage and propagation, especially under increasing laser energy. Thus, rapid defect detection and precise repair are critical to improve the laser damage resistance of KDP optics. This study developed a dual-station detection and repair system combining the EfficientNet-based machine vision for wide-field imaging and atomic force microscopy (AFM) for nanoscale-resolution imaging. The EfficientNet model was adopted to achieve efficient coarse detection and accurate localization, with defect coordinates transmitted to AFM for ultra-precise characterization. Furthermore, high-precision in-situ repair was realized using the condensed water bridge at the AFM tip-KDP interface. The system performance was optimized through mechanical design and finite element simulations. Full-aperture (50 & times; 50 mm) scanning was accomplished in 41 min, capturing defects from tens of micrometers to similar to 500 nm. After repair at 65%, 75%, and 80% relative humidity, the scratch depths were reduced by 92.5%, 98.7%, and 95.8%, respectively. The overall surface roughness decreased from 18.50 nm to 4.21 nm, from 14.70 nm to 1.62 nm, and from 15.60 nm to 5.61 nm, respectively. A positive correlation between the initial scratch-wall slope and the initial filling rate was further observed, with a Pearson correlation coefficient of 0.871. These results demonstrate the feasibility of a dual-station machine-vision/AFM workflow for wide-field defect localization, nanoscale morphology detection, and localized water-bridge-assisted repair of KDP surface defects.

High-volume fraction SiCp/Al composites typically exhibit poor surface quality after machining. To improve the machinability of 65 vol% SiCp/Al composites, this study proposes an innovative method combining inductively coupled plasma (ICP) with ultra-precision turning (UPT). The removal mechanism of SiCp/Al composites in the ICP process was studied, and a comprehensive comparative analysis was conducted on the surface quality, cutting force, and tool wear after ICP, UPT, and their hybrid processes. The results indicate that after UPT processing, defects such as cracks, pits, and scratches appeared on the material surface, and the content of aluminum and silicon elements is consistent with the original surface. The ICP process selectively removes the hard and brittle SiC particles from the surface, resulting in a surface with a single type of pit defect, and the silicon content decreased from 45.04 % on the original surface to 8.53 %. Notably, the ICP and UPT hybrid process can achieve high-quality surface machining of SiCp/Al composites, with no significant surface defects. Furthermore, this hybrid process shows outstanding machining performance. Compared to the single UPT process, the cutting force decreased by 40.3 %, from 12.74 N to 7.60 N, while the tool flank wear width (VB) decreased by 43.1 %, from 14.75 mu m to 8.40 mu m. This study fully validates the advantages of the hybrid ICP and UPT machining method through a comprehensive process comparison, offering new insights for ultra-precision machining of SiCp/Al composites and showing great potential for engineering applications.

Ta2O5 films prepared by ion-assisted electron beam evaporation (IEBD) are irreplaceable optical elements in high-power laser systems. However, this process is highly parameter-sensitive and involves coupled multi-physics across scales, making it prone to the formation of microscopic defects. This work addresses this challenge by elucidating how ion-beam energy field governs the formation of micro-pores and atomic defects. The aim is to enable more sustainable fabrication of defect-free films. For micro-pores, increasing Ar+ proportion broadens the incident-angle distribution via gas-phase collisions, reducing shadowing effects and surface roughness (Sa). When argon flow rate (f(a)) > 25 sccm, intensified re-sputtering causes a rise in Sa. Increasing ion flux can make film surfaces smooth by enhancing ion-bombardment-driven migration. As beam current (I-i) > 850 mA, film growth becomes roughening-dominated. Quantitatively, Sa decreases from 0.38 nm to 0.20 nm when f(a) increases from 5 sccm to 25 sccm, indicating that collision-induced incident-angle redistribution weakened the shadowing effect and improved valley filling. However, Sa increases to 0.33 nm at f(a) = 30 sccm due to enhanced Ar+-induced re-sputtering and re-deposition. With increasing I-i, Sa decreases to 0.31 nm at 960 mA, while excessive ion flux caused slight surface re-roughening. For atomic defects, PL intensity exhibits a non-monotonic evolution, reflecting the competition among collision-induced energy loss, reactive oxygen compensation, Ar+-dominated preferential sputtering, and bombardment damage. The lowest weak absorption (A) of 1.81 ppm is obtained at I-i = 850 mA, whereas A increases to 4.86 ppm at I-i = 960 mA. Correlation analysis further revealed that Sa is weakly correlated with A for micro-pores (r = 0.14-0.20), whereas PL intensity showes a strong positive correlation with A for atomic defects (r = 0.67-0.84). These results demonstrate that A in IEBD-prepared Ta2O5 films is mainly governed by atomic defect states rather than surface micro-pores, providing mechanistic guidance for defect-controlled fabrication of low-absorption oxide optical films.

While multi-laser additive manufacturing has revolutionized the throughput of large-scale component fabrication, universal protocols for spatially tailoring material properties remain elusive. Currently, as-printed parts are constrained to uniform performance, and their potential for site-specific microstructural control has not been fully exploited. Here, we report a scanning trajectory orchestration strategy that could transcend this limitation, enabling both the suppression of defects in the laser overlapping region and the customization of mechanical performance. Scanning paths parallel to the laser overlapping regions can effectively suppress defect formation. Furthermore, we demonstrated that modulating local thermal histories enables on-demand tailoring of Ti-6Al-4V mechanical properties in three dimensions, achieving a modulation range of over 25% in ultimate tensile strength or over 100% for ductility. Microstructural differences resulting from the varied thermal histories of different scanning paths form the foundation for property tuning. Notably, the key to realizing performance control in the inter-layer is ensuring that the same trajectory print height exceeds the affected zone height. This scanning trajectory orchestration strategy was also validated across three distinct alloy systems without feedstock modification or post-heat treatment. Our work provides both theoretical and experimental foundations for tailoring the mechanical properties of monolithic components via scanning trajectory programming. This capability paves the way for manufacturing functionally graded properties, which are crucial for next-generation aerospace and automotive applications.

Tantalum pentoxide (Ta2O5) films deposited on fused silica substrates are critical components of high-power laser systems. Ion-assisted electron beam evaporation (IAD-EBE) is the mainstream technique for fabricating Ta2O5 films. However, it commonly requires extensive experimental efforts for deposition quality optimization, while each coating cycle is extremely time-consuming. To solve this issue, this work establishes a dataset targeting the surface roughness (Rq) and refractive index (n) of Ta2O5 films using atomic force microscopy, as well as ellipsometer and deposition experiments. Influence of assisting ion source beam voltage (V)/current (I) and Ar (Q1)/O2 (Q2) flow rate on the n and Rq of Ta2O5 films are analyzed. Combining energy-field mechanism analysis with a Bayesian optimization approach (PI-BO), both deposition quality prediction and feature analysis of process parameters are achieved. The determination coefficient/mean absolute error for the prediction models of n and Rq reach 0.927/0.013 nm and 0.821/0.049 nm, respectively. Based on sensitivity analysis, the weight factors of V, I, Q1, and Q2 affecting n/Rq of Ta2O5 films are determined to be 0.616/0.274, 0.199/0.144, 0.113/0.582, and 0.072/0.000. V and Q2 are identified as the core factors for regulating deposition quality. The optimal ranges for V and Q2 are 600~700 V and 70~80 sccm, respectively. This study proposes a PI-BO method for predicting Rq and n of Ta2O5 films under small-data conditions, while determining the preferred parameter ranges and their sensitivity weight factors. These findings provide effective theoretical support and technical guidance for IAD-EBE strategy design and optimization of optical films in high-power laser systems.

Fused silica is a critical optics in high-power laser facilities. To extend the service life of fused silica optics, femtosecond laser repair is employed to mitigate surface defects. This technique can rapidly fabricate optically benign conical structures over the defects. However, the laser-induced damage resistance of the repaired site is highly dependent on the surface quality of these conical structures. The primary challenge lies in suppressing the complex undesirable microstructures that are inevitably introduced during the femtosecond laser ablation process. The observed surface anomalies are attributed to three primary mechanisms. First, the femtosecond laser ablation process induces localized plasma explosions, which disrupt the material. Second, the chosen laser scanning pattern leads to non-uniform material accumulation and redeposition, forming a characteristic “knife-pattern” texture. Third, this newly formed textured surface itself possesses an inherent micron-scale roughness. To address this issue, this study optimizes key femtosecond laser processing parameters, specifically the trajectory interval and scanning speed, which are identified as the most influential factors on the formation of undesirable microstructures. The optimized treatment significantly improves the surface quality of the repaired region. The processed area achieves nanoscale surface roughness and exhibits a substantially reduced concentration of atomic-scale defects. Crucially, unlike the grinding process, this laser-based repair method does not introduce new impurities or contaminants. The mechanism behind this improvement was elucidated by establishing an internal light field transmission model for fused silica under high-energy laser irradiation. The model reveals that suppressing undesirable microstructures reduces both the distribution density and the intensity of localized light field concentrations within the optic, thereby enhancing its laser damage resistance. We innovatively propose surface roughness and concentration of atomic-scale defects as key metrics for evaluating the laser damage resistance of the ablated region. The analysis confirms that the complex microstructures generated by femtosecond laser ablation are the root cause of increased fluorescence intensity and atomic defect concentrations. Notably, after the suppression of undesirable microstructures, the photoluminescence (PL) intensity of the ablated area drastically decreases. Characterization reveals a substantial reduction in the concentration of several typical atomic-scale defects. Two specific defects—the STE and the E’ center—were completely eliminated following the repair process. In conclusion, this work successfully demonstrates a parameter optimization strategy for suppressing undesirable microstructures during femtosecond laser repair, which significantly improves the laser damage resistance of fused silica optics. The findings are of great significance for achieving high-quality femtosecond laser processing of optics.

Laser processing is widely used in the field of optical material processing due to its high efficiency and high precision. However, the surface ablation textures formed by material removal under pulsed laser irradiation seriously degrade the surface quality. To reveal the formation mechanism of ablation textures, this work combines multi-physics simulation and experiments to investigate the evolution process of ablation textures during cross-dimensional ablation, and the morphological composition of the ablated surface at different spatial frequency band. The morphology and temperature evolution laws under multi-pulse single-point laser irradiation are explored, and the nonlinear evolution process of texture height and pit bottom position during variable-energy laser line ablation are obtained. Through parameter optimization, the texture height can be controlled within 40 nm. Subsequently, experiments are conducted to explore the morphological composition of the ablated surface at different spatial frequency bands. The laser-induced periodic surface structures (LIPSS) caused by photon polarization dominate the microscopic roughness. The periodic textures formed by scanning laser ablation and morphological superposition are the main contributor to the mesoscopic surface topography. Thermal deformation of the ablated surface induced by thermal accumulation is the primary factor for the formation of macroscopic surface morphology. Using optimized ablation parameters, the surface roughness Sa of fused silica material after ablation removal can be improved to better than 100 nm. This work can provide a theoretical basis for understanding the formation mechanism of ablated surface morphology, and offer parameter guidance to enhance the ablation surface quality.

Spallation and thermal damage limit the application of fused silica under extremely intense lasers. Herein, the unclear underlying mechanisms, including extreme-irradiation-induced plasticity-related behaviors were studied based on first-constructed cross-scale models, molecular dynamics simulation, and multimodal characterization. Material spallation originated from the anomalous "quasiplasticity" and phased propagation of micro-cracks under quadruplex elastoplastic waves. Although the fastest primary wave could not cause macroscopic deformation, it could lead to micro-plasticity phenomena (ring-structure transformation and point-defect proliferation) due to material phase transformation and destabilizing effects. Subsequently, conjugate secondary and head elastoplastic waves governed initialization processes of micro-cracks, where primary-wave-induced E'-Center and NBOHC defects played roles of "damage precursors". Concomitantly, transitional deformation zones containing massive strip-like-distributed cavities (similar to "immature" micro-cracks) were generated around micro-cracks. There was a cascading evolution process of point defects, cavities, and micro-cracks under phased energy input from waves, causing an anomalous "quasiplasticity" process within brittle fused silica. It differs from transient fracture processes of brittle materials. Finally, the Rayleigh waves trapped on surfaces attracted micro-cracks towards them, causing disastrous surface damage. The thermal damage originated from the volcanic vents formed within 3 similar to 4 ns, which was induced under the comprehensive action of the impact of elastoplastic waves, cascading solid-liquid-gas phase transition, GPa-level pressure difference between ablated zones and air, and fluidic flow disturbances. The whole time-evolution sequence axis diagram of the material failure process was drawn based on these. Summarily, this work could offer novel insights into the anomalous "quasiplasticity", spallation, and thermal damage phenomena of fused silica under intense lasers.

As a high-performance optical and dielectric material, Hafnium dioxide (HfO2) films prepared by electron beam evaporation occupy an important position in the field of surface protection for optical and microelectronic devices due to their combination of high hardness and high stability. Particularly in high-energy laser systems, any minor defects caused by fretting wear or mechanical scratching can lead to severe component failure under continuous high-energy laser bombardment. Therefore, deeply investigating the friction failure mechanism of HfO2 films is essential. Accordingly, based on the mechanical properties of films with different thicknesses, this study investigates the macro- and micro-friction and wear mechanisms. This is achieved through ball-on-disk friction and nano-scratch tests to explore the behavioral differences of HfO2 films with different thicknesses. Research findings indicate that the significant intrinsic hard-brittle characteristics of the 300 nm film cause rapid, large-area fragmentation during ball-on-disk friction tests. This results in a shorter running-in stage for the 300 nm film, and the initial friction rapidly rises to a high level. In contrast, the 200 nm film maintains an initial friction coefficient of around 0.2 and fully exhibits a typical three-stage friction evolution process. In 0-500 mN nano-scratch experiments, both films display three-stage evolution characteristics. However, the 300 nm film shows extensive film spallation in the middle stage, leading to premature entry into the substrate-dominated friction stage. In contrast, the 200 nm film developed a debris-rich third-body-like layer during steady wear, which helped stabilize the interface and delay substrate exposure. Nanoscratch tests under 0-50 mN reveal that the 200 nm film exhibits more pronounced plastic morphological features. The early scratch process presents a damage mode involving both crack propagation and local deformation. Meanwhile, the high hardness and residual stress of the 300 nm film make it more prone to early micro-crack propagation and fracture. Therefore, its frictional characteristics are primarily dominated by high-energy brittle damage. This study provides an experimental basis for the structural optimization and the regulation of friction and wear behaviors of HfO2 films. Additionally, it offers a reference for their subsequent application research in related optical protection scenarios.

Designing low-absorption HfO2 optical thin-film components (OTCs) on fused silica substrates (FSS) for high-power laser systems remains challenging. Electron beam evaporation (EBE) can introduce micro-defects in the HfO2 films and simultaneously alter the amorphous network of FSS, compromising optical performance. This work investigates how substrate temperature (T) and oxygen flow rate (Q) control the relationship among process, structure and properties of OTCs, and how these relationships can be utilized to guide OTC design. Reactive EBE is conducted under controlled T (23 similar to 100 degrees C) and Q (140 similar to 190 sccm). Film surface quality is quantified by AFM roughness (Sa), while the nanoscale FSS network is assessed by Raman spectroscopy. The resulting structure changes are validated at the property level using optical constants and weak absorption (beta) at the wavelength of 1064 nm. The novelty lies in a systematic cross-scale correlation that explicitly links film-induced stress and morphology with the evolution of the substrate ring structure during EBE. This aspect has not been widely explored for HfO2/fused-silica OTCs. Increasing T reduces the average compressive stress from 112 to 95 MPa, lowers Sa by 24.2%, decreases the Raman intensity by 21.6%, and reduces beta by 41.2% from 6.92 to 4.07 ppm. Increasing Q further stabilizes hydroxyl-related structures and suppresses unfavorable ring conversion, leading to additional reductions of 11.8% in Sa, 11.1% in Raman intensity, and 29.2% in beta. These results provide a critical process-parameter design guideline for co-optimizing film morphology, substrate network structure, and low-beta performance in high-reliability OTCs.

Electrochromic technology has garnered increasing attention from both academia and industry due to its expanding practical applications across diverse fields. Viologen (4,4′-bipyridinium salts), a small-molecule electrochromic material, exhibits exceptional performance and holds significant promise in electrochromic technology and devices. However, viologen-based materials are prone to degradation of properties during electrochemical reactions. Recent research has increasingly concentrated on viologen-based electrochromic devices (ECDs). This review comprehensively examines modification strategies—including structural modifications of viologen molecules, construction of viologen-containing polymers, and formation of viologen-based complexes—to enhance electrochromic performance. These advancements have not only improved the functional characteristics of viologen materials but also broadened the application potential and functional versatility of ECDs. Furthermore, this work prospects the future development of viologen-based ECDs, highlighting critical technical bottlenecks and unresolved challenges that demand urgent attention. By summarising current progress and outlining research directions, this review provides valuable insights and guidance for researchers in related fields.

During the trajectory grinding of hemispherical resonators, the grinding points of the small-diameter ball-end diamond wheel continuously migrate along the complex curved surface, resulting in dynamically changing grinding conditions. This dynamic variation induces non-uniform wheel wear, ultimately leading to form errors on the workpiece surface. To gain an in-depth understanding of the influence of wheel wear on form error, a theoretical model of wheel wear in hemispherical resonator grinding was established. The spatial distribution characteristics of wear points and the influencing factors of wheel wear were systematically analyzed, and the evolution law of wheel wear throughout the full grinding cycle was revealed. Furthermore, a model describing the effect of wheel wear on the form error of hemispherical resonators was developed to clarify the mechanism of form error formation. Grinding experiments showed that the deviation between the theoretical and measured wheel wear values was less than 9.64%, while the error rate of form accuracy ranged from 2.42% to 7.62%. Based on the established wheel wear and form error models, a support vector machine prediction model was constructed to predict form errors and evaluate wheel service life under various grinding parameter combinations. The reliability of the wheel life evaluation results was verified through comprehensive analyses of form error characteristics, wheel wear morphology, and workpiece surface quality. Overall, this study develops a unified framework that integrates wheel wear evolution, wear-induced form error formation, and rapid prediction of form error and wheel life in hemispherical resonator grinding, thereby supporting form error control, grinding parameter optimization, and wheel condition management.

Subsurface damage introduced by grinding significantly affects the energy-dissipation behaviour of fused-silica hemispherical resonator (HSR). Magnetorheological polishing and chemical etching are considered effective techniques for removing subsurface damage in fused silica HSR. However, the simultaneous achievement of high removal efficiency and superior surface quality remains a challenge. This work focuses on energy-dissipation mechanisms and subsurface-damage removal strategy for HSR. Firstly, the reaction behaviours of fused silica components that exhibit different surface qualities during chemical etching are analysed. Based on the reactivities of the different surface types with the chemical etchant, the processed areas are categorized into seven distinct reaction zones, revealing the directional nature of the chemical reaction with the surface materials. Secondly, the evolution of the surface morphologies of HSRs exhibiting different surface qualities under chemical etching is investigated. Higher initial surface roughness is found to produce greater variations and longer stabilization during etching. Further analysis demonstrates that the surface morphology and the form and distribution of subsurface damage significantly influence the energy-dissipation. Finally, a processing strategy for effectively improving the quality factor of HSRs is proposed, based on the correlation between surface quality and performance under various processing parameters. The proposed strategy reduces the fabrication time from 28 to 10.5h, and improves the quality factor from 2.05 × 107 to 2.26 × 107, achieving simultaneous enhancement of both efficiency and performance. This research advances the understanding of the energy-dissipation mechanisms in HSR and provides practical guidance for the high-efficiency and high-performance manufacturing of HSR.

In high-energy laser systems, the performance of tantalum pentoxide (Ta2O5) thin films prepared by ion-beam assisted electron beam evaporation (IAD) is extremely sensitive to deposition parameters. Due to complex physical coupling mechanisms, slight variations in any parameter can trigger micro-defects, stoichiometric deviations, and stress fluctuation, making it challenging to identify the optimal process parameter window in engineering applications for achieving high refractive index (n), low absorption (A), and low residual stress (σ). To address this issue, deposition experiments were conducted to obtain data on process parameters and film performance, which were utilized to establish the initial population for the Non-dominated Sorting Genetic Algorithm II (NSGA-II). Subsequently, machine learning was employed to construct prediction models for n, A, and σ. A voting-based ensemble model combining Random Forest (RF), Extremely Randomized Trees (ExtraTrees), and Extreme Gradient Boosting (XGBoost) was adopted, where RF improves prediction stability under small-sample conditions, ExtraTrees enhances robustness against experimental noise through increased randomness, and XGBoost captures complex nonlinear process-property relationships. Experimental validation was further performed using nine representative Pareto-optimal solutions. The average relative errors for n, A, and σ were 0.07%, 10.47%, and 1.68%, respectively, while the comparatively higher relative error for A was mainly associated with its low absolute values and greater sensitivity to microscopic defects and measurement fluctuations. Furthermore, considering diverse optical requirements, solutions prioritizing n, A and σ were obtained via the fast non-dominated sorting algorithm combined with an elite strategy. The optimized process windows were all centered near I = 850 mA, while the preferred V, FO2, and FAr ranges varied with the target priority: 600–700 V, 50–60 sccm, and 5–6 sccm for n; 300–600 V, 55–60 sccm, and 5–10 sccm for A; and 300–400 V or 790–810 V, 50–60 sccm, and 5–10 sccm for σ. Analysis of the Pareto frontier revealed that, within the studied parameter range, n and σ exhibited a weak correlation, whereas clear trade-offs existed between n and A and between A and σ. Representative XPS, XRD, and AFM characterizations of selected Pareto-favorable and comparatively poor-performing samples further showed that the performance deterioration under excessive ion-beam input was mainly associated with defect-related oxygen states and surface roughening, rather than crystallization-driven changes. These results demonstrate that the proposed surrogate-assisted optimization framework can resolve complex parameter trade-offs and provide technical support for the high-precision IAD of optical thin films with high n, low A, and low σ.

SiCp/Al composites are widely used in the aerospace field, but they still face numerous technical challenges due to processing difficulties and the rapid wear of cutting tools. This research investigates the wear mechanisms of PCD and PCBN tools in the SiCp/Al cutting process and systematically classifies and characterizes the wear features in various cutting regions of the tools. The research provides an in-depth analysis of the effect of tool wear status on chip morphology and surface quality. The results indicate that the presence of SiC particles results in both tools experiencing severe abrasive wear. Specifically, the flank face of the PCD tool shows abrasion and adhesion, while the rake face and cutting edge mainly exhibit chipping and abrasive wear. In contrast, the PCBN tool is affected by thermal damage, causing severe adhesive wear and diffusion wear on its surface. Notably, this research reveals the tool wear evolution of the rake face, flank face, and cutting edge. As tool wear progresses, the chips transition from a spiral to a fragmented shape, with the change occurring earlier in PCBN tools compared to PCD tools. Furthermore, the surface roughness of workpieces machined with PCD tools is consistently superior to that of those machined with PCBN tools in all wear states. These findings indicate that PCD tools outperform PCBN tools in machining SiCp/Al composites. This study offers significant theoretical insights into the selection and design of tools for SiCp/Al machining.

Customizable 3D-printed biopolymer hydrogels have attracted considerable interest for diabetic wound care. This study developed a novel dual-crosslinked, temperature-responsive hydrogel ink for rapid fabrication of personalized diabetic wound dressings. The robust network was pre-crosslinked via Schiff base reactions between hydroxybutyl chitosan (HBC) and quaternized-aldehyde modified chitin (OQCH), with further reinforcement from the thermosensitive hydroxybutyl groups. This design conferred excellent self-supporting properties, enabling high-fidelity, scalable 3D printing without post-processing. The ink could be directly printed onto wounds, and the positively charged quaternary ammonium groups provided effective antibacterial activity long-timely. To address key healing challenges, dysregulated macrophage balance early in inflammation and subsequent vascular dysfunction, a dual-layered bioprinted dressing was engineered. Through spatial organization and graded crosslinking density, this design allows sequential drug release aligned with distinct healing stages. Evaluations showed the HBC/OQCH hydrogel possesses favorable mechanics, reliable tissue adhesion, strong antibacterial performance, and excellent biocompatibility, alongside anti-inflammatory and pro-angiogenic functions. In vivo tests confirmed that the bilayer dressing reduced inflammation and oxidative stress, modulated macrophage polarization, promoted vascularization, and accelerated wound closure. These results underscore its potential as an advanced, personalized wound dressing with spatiotemporal regulatory capability for diabetic wound management.