Sample Surface Research Articles

A SARS-CoV-2 outbreak in a public order and safety training facility in England, June 2021.

The public order and safety (POS) sector remains susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks, as workplace attendance is typically compulsory and close physical contact is often needed. Here, we report on a SARS-CoV-2 outbreak with an attack rate of 39% (9/23), which occurred between 19 and 29 June 2021 among a cohort of new POS recruits participating in a mandatory 18-week training programme in England. The COVID-OUT (COVID-19 Outbreak investigation to Understand Transmission) study team undertook a multidisciplinary outbreak investigation, including viral surface sampling, workplace environmental assessment, participant viral and antibody testing, and questionnaires, at the two associated training facilities between 5 July and 24 August 2021. Environmental factors, such as ventilation, were deemed inadequate in some areas of the workplace, with carbon dioxide (CO2) levels exceeding 1,500ppm on multiple occasions within naturally ventilated classrooms. Activities during safety training required close contact, with some necessitating physical contact, physical exertion, and shouting. Furthermore, most participants reported having physical contact with colleagues (67%) and more than one close work contact daily (97%). Our investigation suggests that site- and activity-specific factors likely contributed to the transmission risks within the POS trainee cohort. Potential interventions for mitigating SARS-CoV-2 transmission in this POS training context could include implementing regular rapid lateral flow testing, optimizing natural ventilation, using portable air cleaning devices in classrooms, and expanding use of well-fitted FFP2/FFP3 respirators during activities where prolonged close physical contact is required.

Study of the dielectric properties of decomposing materials during heating

The dielectric properties of materials when heated at ultrahigh frequencies are determined by methods based on the use of waveguide cavity resonators. However, as the sample is in the closed volume during measurements, the dielectric properties of destructive material thus determined can contain errors attributed filling of the resonator volume and depositing products of the sample decomposition on the internal conducting surfaces of the resonator. We present the results of studying the dielectric properties of destructive materials under heating in waveguide resonator cavity using methods that exclude the impact of destruction products on the accuracy of measurement. To reduce the influence of destructive vapors rising from the surface of the sample during the destruction process, additional thin quartz plates, placed on the sample surface were used. In addition, cuvettes with a lid were also used to prevent destruction products from entering the resonator volume. A method for taking into account the effect of plates and cuvettes in calculating the dielectric constant and dielectric loss tangent of a material sample when heated in a cavity resonator is presented. Changes in the dielectric properties of a composite material consisting of quartz fabric impregnated with an aluminochromophosphate binder and fiberglass laminate made of quartz fabric impregnated with a phenol-formaldehyde binder were studied in a temperature range above the onset of the destruction (up to temperatures at which loss of the structural strength of the material is observed). The developed method can be used in studying the thermophysical properties of destructive materials to assess changes in their dielectric characteristics under operation conditions of high-temperature heating.

Sulfated CeO2-TiO2 as H2 evolution photocatalyst: Synergic effects of heterojunction and sulfation on catalyst performance

SO42−/CeO2/TiO2 composite oxides are successfully fabricated via sol-gel method and impregnation process for photocatalytic H2 production. The characterization results from XRD, FTIR and TEM revealed that the heterojunctions were formed by the formation of Ti-O-Ce bond across the SO42−/CeO2/TiO2 interface, which was contributed significantly to separation of photo-generated carriers. Py-FTIR spectra and XPS results indicated that Lewis acid and Brønsted acid sites were formed over the surface of SO42−/CeO2/TiO2 composite, which was owing to SO42− coordinated to the metal on the sample surface. The induced Lewis acid sites could enhance the separation of photogenerated carriers, and Brønsted acid sites could provide protons for photocatalytic H2 production. In addition, the Lewis acidity could facilitate the shift of conduction band minimum to a more negative value, which improves the photocatalytic H2 production capacity of SO42−/CeO2/TiO2. The results of photocatalytic H2 production revealed that SO42−/CeO2/TiO2 composite exhibits superior photocatalytic activity compared to bare CeO2, TiO2 and CeO2-TiO2 composite. Notably, it achieves the average H2 yield rate of 6295.2 μmol·g−1 h−1 over a period of 5 h. Combine the results of spectra analysis and photocatalytic activity H2 evolution, it can be concluded that the synergetic effects of heterojunction structure of CeO2/TiO2 composite and acid impregnation promoted the photocatalyst activity.

利用水文化学和稳定同位素追踪南非白云石采石场中矿井水流动

AbstractSouth Africa has a growing population, a relatively dry climate, and abundant mining activity, all of which increase the importance of water management. The Mooiplaas Dolomite Quarry, south east of Pretoria, has been mining metallurgical grade dolomite since 1969, within the productive karst aquifers of the Malmani Subgroup, Transvaal Supergroup. This study was conducted to elucidate the flow of water around the site, including the mine water and groundwater. The site was investigated by sampling precipitation, surface water, groundwater, and mine water for hydrochemical and stable isotope analysis from 2011 to 2017, totalling over 400 samples. Levels of nitrate in groundwater and mine water were marginally above drinking water limits, from explosives residues, and ammonia in the nearby Hennops River was unacceptably high due to municipal sewage outfalls, but otherwise, water quality was very good. Alkalinity from rock weathering, aided by crushing of dolomite, was the main control on water chemistry. Combined analysis of dissolved matter (TDS, nitrate, Mg, etc.) suggested that the dewatering of the mine and resultant recharge from the slimes dams caused an aerated zone of groundwater, which mixed with regional groundwater flowing beneath the site. Stable isotopes, with an evaporated signature from the mine open water bodies, also showed how mine operations cause recharge to groundwater and subsequent seepage back into the pit lakes. The mine appears not to contaminate the regional groundwater; however, mine designs should avoid situations where process water flows via groundwater back into pits, causing excessive dewatering costs.

Global flattening realization and kinematic analysis of UV-assisted low-speed 3D dynamic friction-polished diamonds

Diamond has attracted extensive attention from many scholars because of its unique properties. However, there are still bottlenecks in how to achieve high efficiency polishing and global flattening of diamond which restrict its application. The aim of this study is to obtain a globally homogeneous flattened diamond surface in macro dimension by introducing a compound motion of the polished workpiece. It is shown that ultra-smooth diamond surface machining with global flattening can be realized by UV-assisted low-speed dynamic friction polishing technique, and the typical roughness is 0.175 nm as measured by 3D optical surface profiler. These experimental results demonstrate that the catalytic phase transition process of UV light is the underlying mechanism to realize the diamond surface polishing under low rotational speed conditions. Additionally, the composite motion of the diamond sample with the metal disk brings large enhancement to the effect of polishing global flattening on the sample surface. The theoretical and experimental studies in this paper provide novel ideas for achieving efficient and polished global flattening of diamond.

A simple DIY electrical resistivity apparatus for students

A simple do-it-yourself (DIY) apparatus is designed and built for the measurement of the electrical resistivity of materials. The tool is portable and easy to operate, and students/new researchers can build their own apparatus with a minimum amount of time and raw materials. The apparatus’ spring-loaded four-point probes help provide a good electrical contact between the sample surface and the probes. It has been checked for its reliability by comparing the resistivity data with literature values and the measurements match well with the previous data. The apparatus is suitable for measurements from room temperature to ∼100 °C.

Ambient mass spectrometry imaging of food natural products by angled direct analysis in real time high-resolution mass spectrometry

Direct surface analysis in ambient conditions provides information on the position and chemical composition of an object at the time of investigation. An angled sampling probe is developed in this work for direct analysis in real time (DART) ionization high-resolution mass spectrometry. The DART ion source and the interface were modified for improved surface resolution, increased ion transfer efficiency, as well as enabling two-dimensional surface scanning. The angled probe DART-MS system was used for investigating a variety of food samples including fruit peels, ginseng root, plant leaves and sections of radish. Abundant signals and distinct chemical profiles are obtained in seconds, and spatial distribution of different molecules across the sample surfaces can be observed. In addition, the developed system can quickly identify the chemical changes when the surfaces were treated. The method is capable of directly evaluating food sample surfaces with different shapes, hardness, and conditions, without any sample pretreatments.

Assessing the Antifouling Effectiveness of the Novel Organic Coating for Adherent Species in the Seawater of the coastal area of Ha Long City, Quang Ninh Province (Vietnam)

This paper presents the results of a 12-month testing period in seawater at Vung Oan, Ha Long City marine area, Quang Ninh Province (Vietnam), assessing the fouling organism’s removal effectiveness of polysiloxane (PS)/Ag-Zn zeolite/Cu2O nanocomposite coatings. This experiment is a substantial base to evaluate impact of Ag-Zn/zeolite and Cu2O nanoparticles (NPs) on growth of bacteria and macro-fouling organisms compared to a control coating without the above additives. The results indicated that the coating loaded with Ag-Zn/zeolite and Cu2O NPs exhibited a lower bacterial count than the coating without biocide additives. Specifically, the bacterial count was 9.6 × 105 for the coating with biocide and 2 × 107 for the coating without biocide. Regarding macro-fouling species, the analysis and identification of organisms attached to the coating samples revealed the presence of three fouling species: Perna viridis, Balanus amphitrite, and Haliclona cinerea. Modiolus barbatus, Nereis sp., and Xanthidae were only observed on surface of the control samples, suggesting that Ag-Zn/zeolite and Cu2O NPs can impede the development of Modiolus barbatus, Nereis sp., and Xanthidae on the coating surface. Furthermore, the average weight of macro-fouling organisms on the coating containing Ag-Zn/zeolite and Cu2O NPs was significantly lower (90 g/sample) than that of the macro-fouling organisms on the control coating (333 g/sample). Notably, one of the three samples with the Ag-Zn/zeolite and Cu2O NPs had the lowest weight of macro-fouling organisms, measuring only 35 g. Based on these findings, it can be concluded that polysiloxane/Ag-Zn/zeolite/Cu2O nanocomposite coatings show promise as antifouling paints for marine work applications.

Comparative study of morpholine-based ligands on corrosion inhibition of C-steel in 0.5 M H2SO4 solution: Chemical and electrochemical exploration

The inhibition of carbon-steel (C-steel) corrosion in 0.5 M H2SO4 media using three morpholine-based compounds, N1-(2-morpholinoethyl)-N1-([pyridine-2-yl]methyl)propane-1,3-diamine (H1), 2-((3-(2-morpholinoethylamino)-N3-((pyridine-2-yl)methyl) propylimino) methyl)pyridine (H2), and N1-(2-morpholinoethyl)-N1,N3-bis(pyridine-2-ylmethyl)propane-1,3-diamine (H3), at room temperature (RT) and higher temperatures, was investigated using electrochemical and chemical methods. The Tafel results showed that the highest corrosion current density (Icorr) is related to the sample without an inhibitor, with a value of 6.3 × 10−5 A.cm−2, and adding inhibitors reduced the values. The lowest Icorr is associated with the sample containing H3 with a concentration of 2.0 mM, which is 0.3 × 10−5 A.cm−2. According to the electrochemical impedance spectroscopy (EIS) results, with an increase in the concentrations of inhibitors H1, H2, and H3 from 0.2 to 2.0 mM, the value of charge transfer resistance (Rct) increases. In addition, Tafel and EIS results confirm that the inhibitor H3 shows better results in corrosion protection. The immersion results of C-steel in a 0.5 M H2SO4 solution without the inhibitor also showed that the highest corrosion rate occurs at 30 and 50 °C. At 30 °C, inhibitors H1, H2, and H3 offer stability for one, two, and three days, respectively. However, at 50 °C, inhibitors H1 and H2 decompose on the first day and do not provide good protective conditions, while sample H3 shows relatively good stability in a 0.5 M H2SO4 environment at 50 °C. In general, inhibitor H3 offers better corrosion protection performance at 30 and 50 °C compared with H1 and H2. According to the R2 values, the adsorption isotherm model of inhibitor H1 follows the Freundlich model, while inhibitors H2 and H3 follow the Langmuir model. The scanning electron microscopy (SEM) results also suggest that the surface of the C-steel sample after corrosion in the inhibitor-free solution has the highest corrosion and surface roughness. Adding inhibitors H1, H2, and H3 significantly reduces the corrosion, and sample H3 shows better surface conditions than the other samples.

Monitoring of enteropathogenic Gram-negative bacteria in wastewater treatment plants: a multimethod approach.

The wastewater treatment processes are associated with the emission of microbial aerosols, including enteropathogenic bacteria. Their presence in this work environment poses a real threat to the health of employees, both through the possibility of direct inhalation of the contaminated air and indirectly through the pollution of all types of surfaces with such bioaerosol particles. This study aimed to investigate the prevalence of enteropathogenic bacteria in the air, on surfaces, and in wastewater samples collected in four wastewater treatment plants (WWTPs). The effectiveness of conventional culture-biochemical, as well as spectrometric and molecular methods for the rapid detection of enteropathogenic bacteria at workstations related to particular stages of wastewater processing, was also evaluated. Bioaerosol, surface swab, and influent and effluent samples were collected from wastewater plants employing mechanical-biological treatment technologies. The air samples were collected using MAS-100 NT impactor placed at a height of 1.5m above the floor or ground, simulating aspiration from the human breathing zone. Surface samples were collected with sterile swabs from different surfaces (valves, handles, handrails, and coveyor belts) at workplaces. The raw influent and treated effluent wastewater samples were aseptically collected using sterile bottles. The identification of bacterial entheropathogens was simultaneously conducted using a culture-based method supplemented with biochemical (API) tests, mass-spectrometry (MALDI TOF MS), and molecular (multiplex real-time PCR) methods. This study confirmed the common presence of bacterial pathogens (including enteropathogenic and enterotoxigenic Escherichia coli, Salmonella spp., Campylobacter spp., and Yersinia enterocolitica) in all air, surface, and wastewater samples at studied workplaces. Higher concentrations of enteropathogenic bacteria were observed in the air and on surfaces at workplaces where treatment processes were not hermetized. The results of this study underline that identification of enteropathogenic bacteria in WWTPs is of great importance for the correct risk assessment at workplaces. From the analytical point of view, the control of enteropathogenic bacterial air and surface pollution using rapid multiplex-PCR method should be routinely performed as a part of hygienic quality assessment in WWTPs.

Wear characteristics of cold tool steels for recycling plastic preprocessing

Abstract Eight type of commercial cold work tool steels were heat treated to achieve the equal hardness of 650 HV. Heat-treated samples were investigated by optical and scanning electron microscopy (SEM), microhardness, and X-ray diffraction (XRD) to identify microstructural features and phases. The samples were examined in three distinct wear modes: adhesion, two-body wear using pin wear on SiC, and recycling plastic cutting machine, respectively. The wear surfaces of samples were analyzed by 3D scanning technology. The microstructure of steels determined their wear characteristics. For low sliding and higher cutting speeds, the order of adhesive wear performance of the steels was reversed due to the stress occurring in the cutting line. The wear rate of all samples was commensurate with load. In the recycling plastic cutting process, the sample with the minimum and homogeneously dispersed carbides exhibited the best wear performance. Tempering the S3 sample prevented crack formation and improved fracture toughness.

Experimental Study on Evolution of Chemical Structure Defects and Secondary Contaminative Deposition during HF-Based Etching

Post-processing based on HF etching has become a highly preferred technique in the fabrication of fused silica optical elements in various high-power laser systems. Previous studies have thoroughly examined and confirmed the elimination of fragments and contamination. However, limited attention has been paid to nano-sized chemical structural defects and secondary precursors that arise during the etching process. Therefore, in this paper, a set of fused silica samples are prepared and undergo the etching process under different parameters. Subsequently, an atomic force microscope, scanning electron microscope and fluorescence spectrometer are applied to analyze sample surfaces, and then an LIDT test based on the R-on-1 method is applied. The findings revealed that appropriate etching configurations will lead to certain LIDT improvement (from initial 7.22 J/cm2 to 10.76 J/cm2), and HF-based etching effectively suppresses chemical structural defects, while additional processes are recommended for the elimination of micron- to nano-sized secondary deposition contamination.

High-Speed Surface Property Recognition with a 140 GHz Frequency

In the field of integrated sensing and communication, there is a growing need for advanced environmental perception. The terahertz (THz) frequency band, significant for ultra-high-speed data connections, shows promise in environmental sensing, particularly in detecting surface textures crucial for autonomous systems’ decision-making. However, traditional numerical methods for parameter estimation in these environments struggle with accuracy, speed, and stability, especially in high-speed scenarios like vehicle-to-everything communications. This study introduces a deep learning approach for identifying surface roughness using a 140-GHz setup tailored for such conditions. A high-speed data acquisition system was developed to mimic real-world scenarios, and a diverse set of rough surface samples was prepared for realistic high-speed datasets to train the models. The model was trained and validated in three challenging scenarios: random occlusions, sparse data, and narrow-angle observations. The results demonstrate the method’s effectiveness in high-speed conditions, suggesting terahertz frequencies’ potential in future sensing and communication applications.

Photothermal Superhydrophobic Surfaces with Dual Self-healing Capabilities

In this study, superhydrophobic coatings with dual self-healing functions were constructed by spraying fluorosilane-modified SiO2 aerogel powders and multi-walled carbon nanotubes on composite films composed of polycaprolactone and epoxy resin. The synergy between the thermally healable polycaprolactone/epoxy resin layer and the photothermal effect of the multi-walled carbon nanotubes allows the coating to repair scratches on the coated surface under light. The porous surface, composed of fluorinated SiO2 aerogel powders and multi-walled carbon nanotubes, provides surface roughness while acting as a storage site for low surface energy healing agents, creating the conditions for surface chemical energy repair. After oxygen plasma etching, the samples were exposed to a solar intensity for 30 min to restore the superhydrophilic state to the superhydrophobic state. The scratches on the sample surface of about 80 μm can be repaired after 20 min of light exposure. The dual healing of chemical energy and the rough structure of the material surface is expected to solve the problem that superhydrophobic surfaces are prone to damage and fail in practical applications. In addition, the material has excellent antifouling and self-cleaning properties. In synergy with the self-healing properties, the material is expected to be recyclable in the long term.

Zr-based bulk metallic glasses in PBF-LB/M: near-polished surface quality in the as-built state

This study investigates the relationship between varying contour scanning parameters and their impact on both surface characteristics and mechanical performance of the glass-forming Zr59.3Cu28.8Al10.4Nb1.5 produced via PBF-LB/M. Near-polished surface states with Ra values below 1 µm were achieved. The study identifies increased laser power as a key factor in reducing the surface roughness, while repetitive scanning exhibits only marginal improvements in surface quality. Partial crystallization on the surface of the amorphous samples is found on the as-built surfaces. However, it appears to be confined to depths below 50 µm. Impressively, the material showcases large mechanical strength in the as-built condition, evidenced by a high flexural strength of 2.2 GPa combined with approximately 1% plastic deformation. These findings offer initial insights into optimizing additive manufacturing processes for BMGs, guiding the enhancement of both surface quality and mechanical robustness in Zr-based metallic glass fabricated via PBF-LB/M techniques.

Spatiotemporal and multi-isotope assessment of metal sedimentation in the Great Lakes

This study investigates spatiotemporal dynamics in metal sedimentation in the North American Great Lakes and their underlying biogeochemical controls. Bulk geochemical and isotope analyses of n = 72 surface and core sediment samples show that metal (Cu, Zn, Pb) concentrations and their isotopic compositions vary spatially across oligotrophic to mesotrophic settings, with intra-lake heterogeneity being similar or higher than inter-lake (basin-scale) variability. Concentrations of Cu, Zn, and Pb in sediments from Lake Huron and Lake Erie vary from 5 to 73 mg/kg, 18–580 mg/kg, and 5–168 mg/kg, respectively, but metal enrichment factors were small (<2) across the surface- and core sediments. The isotopic signatures of surface sediment Cu (δ65Cu between −1.19‰ and +0.96‰), Zn (δ66Zn between −0.09‰ and +0.41‰) and Pb (206/207Pb from 1.200 to 1.263) indicate predominantly lithogenic metal sourcing. In addition, temporal trends in sediment cores from Lake Huron and Lake Erie show uniform metal concentrations, minor enrichment, and Zn and Pb isotopic signatures suggestive of negligible in-lake biogeochemical fractionation. In contrast, Cu isotopic signatures and correlation to chlorophyll and macronutrient levels suggest more differentiation from source variability and/or redox-dependent fractionation, likely related to biological scavenging. Our results are used to derive baseline metal sedimentation fluxes and will help optimize water quality management and strategies for reducing metal loads and enrichment in the Great Lakes and beyond.

High-performance Ga2O3 solar-blind UV photodetectors via film growth regulation and surface state engineering

Gallium oxide (Ga2O3) with a wide bandgap is emerging as one of the most promising candidates for solar-blind photodetectors (SBPDs). However, the practical application of Ga2O3-based SBPDs is impeded by substantial defects-related leakage currents, sluggish response speed, and high-cost, making their practical applications face great challenges. Here, we proposed strategic films growth regulation and surface state engineering to grow high-quality yet economical β-Ga2O3 films, thereby achieving high-performance SBPDs. High-resolution transmission electron microscopy revealed the presence of high-quality films with an extremely regular arrangement of β-Ga2O3 (2‾01) planes. The full width at half maximum and root mean square roughness values are 0.07° and 0.716 nm, respectively. The β-Ga2O3 films demonstrated a significant reduction in VO concentrations after O2/N2 plasma treatment. This process can effectively minimize thermal damage to the sample surface while retaining highly reactive free radicals. The photocurrents of devices can be further enhanced, leading to a larger PDCRs of 8.6 × 107, through N2 plasma treatment. Moreover, the films effectually suppress the persistent photoconductivity effect with τr and τd values of 5.31/0.97 s and 0.49/0.87 s before and after N2 plasma treatment, respectively. We have demonstrated the influence mechanism of O2/N2 plasma treatment on photoelectronic performance. This study provides a practical approach to growing high-quality β-Ga2O3 films and preparing high-performance but low-cost Ga2O3-based SBPDs.

Enhancing ferroelectric characterization at nanoscale: A comprehensive approach for data processing in spectroscopic piezoresponse force microscopy

Switching Spectroscopy Piezoresponse Force Microscopy (SSPFM) stands out as a powerful method for probing ferroelectric properties within materials subjected to incremental polarization induced by an external electric field. However, the dense data processing linked to this technique is a critical factor influencing the quality of obtained results. Furthermore, meticulous exploration of various artifacts, such as electrostatics, which may considerably influence the signal, is a key factor in obtaining quantitative results. In this paper, we present a global methodology for SSPFM data processing, accessible in open-source with a user-friendly Python application called PySSPFM. A ferroelectric thin film sample of potassium sodium niobate has been probed to illustrate the different aspects of our methodology. Our approach enables the reconstruction of hysteresis nano-loops by determining the PR as a function of applied electric field. These hysteresis loops are then fitted to extract characteristic parameters that serve as measures of the ferroelectric properties of the sample. Various artifact decorrelation methods are employed to enhance measurement accuracy, and additional material properties can be assessed. Performing this procedure on a grid of points across the surface of the sample enables the creation of spatial maps. Furthermore, different techniques have been proposed to facilitate post-treatment analysis, incorporating algorithms for machine learning (K-means), phase separation, and mapping cross correlation, among others. Additionally, PySSPFM enables a more in-depth investigation of the material by studying the nanomechanical properties during poling, through the measurement of the resonance properties of the cantilever–tip–sample surface system.

The effect of heat treatment on the anisotropic mechanical properties of metastable β titanium alloy

The effect of heat treatment on the anisotropic mechanical properties of metastable β titanium alloy is investigated in this work. The anisotropic deformation behaviour is mainly due to the formation of band-like macrozone and texture during forging, which can be effectively weakened by solution + aging treatment. Both the microstructure and texture of the heat treated samples are favourable for the lower strength, higher ductility and impact toughness of axis direction (AD) samples than circumferential direction (CD) ones. Besides, the CD impact samples have stronger anisotropy than AD samples. The delamination along different directions happens in the impact fracture surface of CD samples.

Assessing charge accumulation and flashover phenomena on silicone rubber surface exposed to salt-containing droplets under direct current voltage

In damp and salt-fog environments, silicone rubber composite insulators are prone to forming dispersed droplets that absorb airborne salt nuclei, leading to charge accumulation and potentially causing flashovers that threaten transmission line stability. Regrettably, these concerns have not yet received sufficient attention from relevant researchers. This study examines the surface charge accumulation and flashover characteristics of silicone rubber insulators with droplets of varying electrical conductivity. The droplets can fix charges, as the conductivity of droplets on insulator surfaces increases, the migration rate of surface charges accelerates, causing distortion of the electric field and a significant increase the area of high-density charge regions on the sample surface. Compared with dry surfaces, increasing the equivalent salt density of salt-containing droplets attached to the surface from mild to severe (with conductivity increasing from 800 μS/cm to 2800 μS/cm) leads to a 25 %-40 % increase in the average surface charge density. After adsorbing charges, the salt droplets shorten the discharge development path, making it easier to trigger interface discharge. Compared with dry surfaces, the average flashover voltage of the salt droplets is reduced by at least 30 %. This study offers valuable analysis on charge accumulation and flashover for silicone rubber insulators in salt-fog environments.