Surface Resistivity Research Articles

PTFE-based antistatic coatings by incorporating modified carbon black

A kind of antistatic coatings which were applied to nonconductive surfaces were prepared with Polytetrafluoroethylene (PTFE) as matrix, modified carbon black (CB) as conductive filler. Compared to sodium dodecyl sulfate, poly(vinyl pyrrolidone), the TMN-10 modified CB has better wettability, dispersion, stability and re-disperse. When CBTMN-10content is 5 wt.%, the surface resistivity of coating reach to 106Ω*cm, which denotes the coating performance good antistatic behavior. The antistatic coating of 5 wt.% CBTMN-10content is found to exhibit excellent hydrophobicity and high HV hardness. Meanwhile, the low average friction coefficients and wear rate were achieved in antistatic coating of 5 wt.% CBTMN-10content. Furthermore, compared to MXene, reduced graphene oxide, carbon nanotube, the modified CB as conductive material in PTFE antistatic materials could be an useful way not only excellent properties but also large-scale production as well as a reduction in unit cost in antistatic materials.

An Effective Method for Quantitative Interpretation of Seawater Intrusion in Shallow Aquifers from Electrical Resistivity Data

Groundwater in coastal areas is vulnerable to saltwater intrusion. Electrical resistivity is commonly used in order to detect saltwater intrusion due to its ability to distinguish the occurrence of saltwater in the pore water. In this research, a correlational approach was used to estimate percentage seawater content that was mixed with fresh water in a shallow aquifer. The study area was located in Dumai City, which was covered mainly by peat soil, but some areas were covered by sand and silt. A ground surface resistivity survey and direct soil resistivity measurements were used in the study. For both experiments, the Wenner configuration of electrical resistivity was employed. In order to determine the direct soil resistivity values, measurements of the soil's fluid content and character were made. The findings indicate that the resistivity value in the aquifer increased to 5–10 Wm at a 25% seawater content, from roughly 2–5 Wm at a 50% seawater content. The pore soil's rising salt content was the primary source of the sharp decline in resistivity values. By measuring the electrical resistivity on the surface, it is possible to accurately forecast the percentage of seawater mixture in the pore soil fluid.

Pinewood biochar antistatic polymer composites: an investigation of electrical, mechanical, rheological and thermal properties

ABSTRACT This study investigates the practical applications of biochar as an innovative and sustainable conductive filler in composite materials. Utilizing the conventional melt-blending method, we prepared conductive pinewood biochar-filled poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) composites and systematically examined their electrical, mechanical, rheological and thermal properties. Our results reveal a significant enhancement of electrical and mechanical properties upon the inclusion of conductive pinewood biochar in the PLA/PBAT matrix. With the addition of 10 wt% of conductive pinewood biochar, the average surface resistivity of the composites decreased by three orders of magnitude, measuring 4.86 × 10 10 Ω / sq , which meets the antistatic requirements for polymer composites. Additionally, the average tensile strength of the biochar filler composites improved by 53% with an addition of just 1 wt% of biochar.

Water-Polymer Slide Electrification in Polyethylene Films Coated with Amphiphilic Compounds and Its Connection to Surface Properties Dependent on Water-Polymer Interactions.

Slide electrification experiments were performed on low-density polyethylene films (PE) and PE sprayed with five amphiphilic compounds, including antistatic and slip additives. Drops of aqueous solutions were delivered on the films and after sliding spontaneously acquired a net electrical charge (Qdrop), which is dependent on the pH and ionic strength. The slide electrification was detected in pristine PE films and those with five additives. An acid-base equilibrium model, based on the adsorption of hydroxides and protons on surface sites, accounted for the dependence of Qdrop on pH, allowing recovery of the acid-base equilibrium constants and the density of adsorption sites. The model was modified to account for ionic strength effects through activity factors. The surface conductivity, wettability, and friction coefficients were strongly modified by the additives. However, the observed trends are different from those observed in slide electrification, which better correlated with zeta potential determinations. This suggests that the interaction mechanisms among surface water, the considered additives, and the polymer, which are involved in slide electrification and the generation of zeta potential, are different from those associated with other surface processes involving surface water. Although additives are required for changing surface resistivity, friction coefficients, and wettability, the generation of sliding electrical charges in polyethylene is a spontaneous and highly effective process. For one specific additive, a simultaneous decrease in friction coefficients, zeta potential, and Qdrop was observed, assigned to the blockade of hydroxide adsorption sites and water repulsion by the compound.

Xerogel synthesis from carbon materials and glue inspired by Japanese-solid-calligraphy ink

Abstract Japanese-solid-calligraphy ink is a xerogel made by mixing soot and glue followed by molding and drying. Herein, we prepare xerogels from glue and 1 or 2 carbon materials (fullerene C60, multiwalled and single-walled carbon nanotubes, nanodiamonds, graphite, graphene, and carbon nanohorns) and characterize their surface morphology, indentation hardness, surface resistivity, and other physical properties. Our ecofriendly and simple synthesis does not require special equipment and affords xerogels holding promise as electrode materials.

Correlation of residual stress on piezoresistive properties of boron-doped diamond films

To investigate the influence of residual stress on the piezoresistive behavior of boron-doped diamond (BDD) films, BDD films with varying doping concentrations were synthesized using a hot-filament chemical vapor deposition (HFCVD) system on silicon and diamond substrates. The relationship between the surface morphology, structural composition, resistivity, and piezoresistive properties of BDD electrodes was examined, along with an in-depth analysis of the impact of boron doping level on these properties. The microstructure and bonding state of the BDD films were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The piezoresistive properties of the BDD films were evaluated employing a cantilever beam bending method. Our findings demonstrate that the level of boron doping not only affects resistivity but also directly influences residual stress in BDD films, both factors having an impact on their piezoresistive properties. Despite significantly larger grain sizes observed in BDD films grown on diamond substrates compared to those grown on silicon substrates at identical boron doping concentrations, they exhibit consistent variations in residual stress and gauge factor (GF) values. With increasing doping levels, the absolute residual stress decreases initially before increasing again; moreover, at 2000 ppm doping level, it transitions from compressive to tensile stress. The GF value is closely associated with both the magnitude and type of residual stress. By utilizing a doping concentration of 2000 ppm for growth on diamond substrates, we achieved a peak GF value of 257 for BDD films which highlights their promising potential for pressure sensor applications.

Laser scanning patterns induced surface properties variations of Ti-V-Hf-Zr non-evaporable getter film with 316L stainless steel substrates

The effects of laser treatment scanning patterns on the properties of Ti-V-Hf-Zr non-evaporable getter (NEG) film on 316L stainless steel (316L SS) substrates were analyzed. 316L SS substrates were laser-treated with different patterns, which resulted in spherical structure and protrusions on the surface of the substrates. Subsequently, Ti-V-Hf-Zr NEG films were deposited on ultrasonically cleaned laser-treated 316L SS by a direct current (DC) magnetron sputtering machine. Based on the XPS results of Ti-V-Hf-Zr, it has been revealed that the atomic proportions of film elements on the surface of samples #1-1∼#3–1 were about 2.2 (Ti):1.7 (Zr):0.9 (V):1.0 (Hf). In this paper, the Ar+-induced secondary electron yield (SEY) and surface resistivity of Ti-V-Hf-Zr NEG are discussed for the first time, and it has been observed that the laser treatment leads to an increase of the substrate surface roughness, which decreases the SEY and increases the surface resistivity.

Silane modified Cr2O3/polyimide nanocomposite films with excellent surface insulation performance for space applications

The exploration of deep space significantly increases the probability of spacecraft failures due to surface electrostatic discharge, which imposes higher vacuum insulation protection requirements on polyimide (PI), the external insulation material of spacecrafts. To address this challenge, this study proposes using silane coupling agent KH550 for organic grafting treatment of Cr2O3nanoparticles, which are then used to dope and modify PI to enhance the vacuum surface insulation of PI films. The KH550 grafting improves the interface strength between the fillers and the matrix, allowing the fillers to be uniformly dispersed in the matrix. Compared to pure PI films, the prepared PI-Cr2O3@KH550 composite films exhibit significantly enhanced vacuum surface flashover voltage, improved surface/volume resistivity, and dielectric properties. The results demonstrate that PI composite films with 0.8% by mass of Cr2O3@KH550 show the most notable performance improvement, with the DC flashover voltage and impulse flashover voltage in vacuum increasing by 20.7% and 27.8%, respectively. The doping of chromium oxide nanoparticles introduces more deep traps into the PI films and reduce the surface resistivity. The higher deep trap density inhibits charge migration, thereby alleviating secondary electron emission and surface electric field distortion. Simultaneously, the lower surface resistivity facilitates dissipating surface charges and improves the surface insulation. These findings are of significant reference value for promoting the enhancement of aerospace insulation performance.

An effect of Fe atom clusters doped CNTs on resistivity of PTFE dielectrics

Polymers are of interest for use on spacecraft surfaces as dielectrics and electrical insulators, and polytetrafluoroethylene (PTFE) is a polymer with mechanical advantages, but low conductivity. Fe-doped carbon nanotubes (CNT) can be added to the polymer matrix and may improve their electrical properties. This work measures the volume and surface resistivity for PTFE and PTFE + Fe-doped CNT test specimens using the Keithley 6517B Electrometer/High Resistance Meter system, by determining current levels through the samples as a function of applied voltage. The system noise current was measured and averaged to be 4.83×10−15 Amps. The results obtained show that both volume and surface resistivities of pristine PTFE increase with increasing voltage. The volume resistivity is higher if compared to the surface resistivity at the same voltage. The conductivities of PTFE + Fe doped CNTs composites are higher as compared to the pristine PTFE, which can be contributed to the Fe-doped CNTs. The conductivity of the PTFE + Fe doped CNTs composite material increases with the concentration of the Fe-doped CNTs.

Preparation of porous composite coatings to suppress surface charge movement and reduce electrical resistivity

In this work, Cr2O3/TiO2 composite coatings were prepared on α-Al2O3 insulating ceramic matrix surface by screen printing and solid phase sintering methods to yield an average film thickness of about 14.10 μm. Scanning electron microscopy (SEM) revealed changes in the pore structures of the coatings at different TiO2 contents. The atomic force microscopy (AFM) analysis of the coating surface roughness suggested a TiO2 content of 0.025 mol to yield the best surface roughness and pore structure of the coating. The calculation showed an increase in the energy level of the deep trap center on the surface from 1.506 eV to 1.547 eV, reaching a maximum. The surface resistivity of insulating ceramics decreased from 1016 Ω to 1012 Ω. The formation of deep surface traps and the decrease in surface resistivity promoted charge dispersion and suppressed the formation of flashover channels, effectively improving the surface flashover voltage of the ceramics.

Improving the suppression of charge movement by porous chromium oxide coating

A chromium trioxide coating was prepared on the surface of electronic ceramics by screen printing, and solid-phase sintering was carried out at 1350 °C. The surface roughness and surface resistance characteristics of composite coatings with different chromium trioxide contents were studied. The analysis results indicate that the average thickness of Cr2O3 coating is about 19.89 μm. The main crystal phase is (Al0.9Cr0.1)2O3. SEM shows that the surface "pores" and surface roughness of the coating change with the content of Cr2O3. AFM shows that when the Cr2O3 content in the coating is 0.0921 mol, the surface roughness changes the most, and the corresponding surface resistivity of Al2O3 insulating ceramics decreases to the lowest, from 1016 Ω to 1012 Ω. An increase in surface roughness can lead to changes in the incidence angle of electrons, reducing the probability of electron surface collision. The lower the surface resistivity, the better the high-voltage breakdown resistance of vacuum ceramic devices, thereby improving the surface flashover performance of ceramics.

Mapping and monitoring dense non-aqueous phase liquid source zone by fused surface and cross-borehole electrical resistivity tomography

Effective characterization of dense non-aqueous phase liquid (DNAPL) source zones is crucial for remediating polluted sites. DNAPL often reside as residuals or pools within high-permeability lenses and above impermeable layers due to soil heterogeneity, gravity, and capillary barriers. Given the high cost of drilling, electrical resistivity tomography (ERT) techniques—including surface ERT and cross-borehole ERT, are commonly used for DNAPL source zone mapping and monitoring. However, the low spatial resolution of ERT increases uncertainty in source zone investigations. This study proposes a method for improving DNAPL mapping and monitoring by fusing surface and cross-borehole ERT data. Sandbox experiments were conducted to simulate a heterogeneous DNAPL source zone, employing both ERT methods for static mapping and dynamic monitoring. Reflective light imaging (RLM) was used to visualize DNAPL migration and provide saturation data, allowing for the quantification of ERT's effectiveness in characterizing DNAPL distribution. The results indicate that individual ERT methods face significant challenges in DNAPL source zone mapping due to background interference. Surface ERT alone tends to underestimate the extent of deeper DNAPL source zones. However, fusing surface and cross-borehole ERT results in a complementary enhancement of vertical spatial resolution, thereby improving the characterization of DNAPL source zones. The fusion of static and time-lapse ERT data substantially enhances DNAPL source zone mapping and monitoring capabilities. By calculating the ratio of the ERT-monitored area to the actual area using resistivity change contours (5 %, 10 %, 15 %), it was found that fusing surface and cross-borehole ERT data improved monitoring resolution by 50.48 % compared to surface ERT alone and by 22.95 % compared to cross-borehole ERT. Principal component analysis (PCA) was effective in fusing time-lapse data, while the weighted average method (WAM) outperformed PCA for static resistivity data fusion.

(Bio)degradable Biochar Composites of PLA/P(3HB-co-4HB) Commercial Blend for Sustainable Future-Study on Degradation and Electrostatic Properties.

Interesting alternatives to expensive biodegradable polymers are their composites with natural fillers. The addition of biochar to a blend of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) was studied, and the resulting materials were evaluated for their properties and changes during degradation. Introducing biochar as a filler brought a noticeable improvement in electrostatic properties. Surface resistivity decreased from 3.80 × 1012 for the sample without biochar to 1.32 × 1012 for the sample with 30% filler content. Degradation tests revealed distinct differences in the degradation profile for composites due to the presence of filler. Composites with a lower biochar content displayed curling crack edges during hydrolytic degradation, and when the filler content reached 20 wt%, PLA loss accelerated. This study suggests that biochar-based composites have potential to be used as sustainable materials with improved properties.

Synthesis of Zn2+:LaMnO3 perovskites nanoparticles by facile co-precipitation approach: Physicochemical characteristics and supercapacitor application

This work has examined the impact of Zn2+ on the crystal architecture and electrochemical functionality of LaMnO3 perovskite nanoparticles. Crystalline parameters of the as-prepared samples were analyzed by X-ray Diffraction studies (XRD). Fourier transform infrared (FT-IR) measurements are utilized to detect the functional groups present in the sample. Raman spectroscopy technique was used to analyze the nature of the chemical bonds in the prepared material. The shape and elemental content of the produced nanomaterials were determined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX). Brunauer-Emmett-Teller (BET) technique is used to study the porosity and surface area of the material. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) is employed to study the surface resistivity, oxidation–reduction potential and super capacitance efficiency of the prepared electrode material.

Beneficial role of manganese dioxide for reducing surface resistivity to increase surface flashover voltage of vacuum insulating ceramics

Electric vacuum insulated devices generate surface flashover and breakdown under instantaneous high voltage. Flashover voltage can be increased through coating without changing the structure of the ceramic device. Herein, multiphase coatings with different manganese dioxide contents are prepared on α-Al2O3 insulating ceramic surface by screen printing and solid-state sintering methods to yield an average film thickness of about 12.38 μm with good bonding strength. X-ray diffraction shows that the crystal phases of the coating are (Al0.9Cr0.1)2O3 and MnAl2O4. Scanning electron micrographs and atomic force microscopy reveal that greater surface height difference and deeper surface depth are more conducive to increasing the surface roughness and the formation of "pores", and decreasing the surface potential decay rate. When MnO2 content is 0.0069 mol, the deep trap center energy level on the material surface reaches its maximum, increasing from 1.506 eV to 1.550 eV, and the surface resistivity of ceramics decreases from 1016 Ω to 1013 Ω. The formation of deep trap centers on the surface makes it difficult for surface charges to detach, which reduces the charge mobility and surface potential decay rate, and leads to decrease in surface resistivity and increase in surface flashover voltage.

Feasibility of Sprayable Engineered Cementitious Composites Using Natural Sand and Low Fiber Content: Effect of Hybrid Fiber System, Silica Fume, and Air-Entraining and Shrinkage-Reducing Admixtures

Deterioration of corrugated steel culverts (CSCs) is a significant problem for the Virginia Department of Transportation and other U.S. transportation agencies. Spray-on lining using shotcrete engineered cementitious composites (ECCs) is a promising structural repair strategy for deteriorated CSCs. This study evaluates the feasibility of practical sprayable ECCs using natural silica sand and low fiber content, while forgoing the use of commonly utilized calcium sulfoaluminate cement to allow for delivery of the materials via ready-mixed concrete trucks. Aspects of the compositional space evaluated include the effect of a hybrid polyvinyl alcohol/polyethylene fiber system, silica fume (SF), shrinkage reducing admixture (SRA), and air-entraining admixture (AEA) on the properties of the composites. Experimental results suggested that the development of the proposed materials is feasible, because flow characteristics associated with shotcrete ECCs and ECC-like tensile ductility were achieved in the fresh and hardened state, respectively. Notwithstanding, further mixture optimization may be required for satisfactory field performance, which should be assessed through field testing. Generally, the use of the hybrid fiber system tended to improve the strength and ductility of the composites, especially when coupled with the use of SF. Furthermore, SF was effective at mitigating the strength loss associated with the incorporation of AEA and SRA, and meaningfully improved surface resistivity. SF also tended to reduce the mixture’s flow, whereas the contrary occurred with the use of SRA and AEA. SRA contributed to the reduction in drying shrinkage at early ages. However, the effect of SRA in reducing shrinkage was negligible at later ages.

Electroless Copper Plating on a Cotton Surface: Effect of Metal Ion Ligand Stability Constant on Reduction Deposition.

Electroless plating facilitates the metallization of nonconductive substrate surfaces, and of note, the precise control of the bath stability constant influences the deposition process of metal particles. In this paper, trisodium citrate, potassium sodium tartrate, nitrogen triacetic acid, thiourea, and ethylenediamine tetraacetic acid disodium were selected as coordination agents, and the effect of the metal ion ligand stability constant on the reduction deposition was studied. Coordination bonds can be established between the Cu2+ and O/N/S particles in the ligand because paired electrons in O/N/S hybrid orbitals tend to occupy empty Cu2+ hybrid orbitals and establish coordination bonds. More importantly, the copper-potassium sodium tartrate ligand exhibits the lowest stability constant and lowest reduction barrier. As an exception, a consecutive Cu-plated coating with an excellent crystallinity property was deposited on the cotton surface when potassium sodium tartrate was used as the coordination agent in the plating solution. The deposition amounts are 55.2% and 74.1% after 1 and 4 h of electroless copper plating, respectively. The surface resistivity of Cu-plated cotton is 0.38 Ω/cm2, and additionally, the surface resistivity ratio before and after 1000 cycles fluctuated between 0.9 and 1.1, indicating that the Cu-plated cotton exhibits outstanding flexibility. In this paper, the deposition rate can be optimized by adjusting the copper particle ligand stability constant in the plating solution, aiming to achieve optimal results.

A comparative study of comprehensive performances for transparent plasticized polyvinyl chloride films with different plasticizers

AbstractFor flexible polyvinyl chloride (PVC) films with excellent mechanical performances and high transparency, the demand for antistatic properties is becoming increasingly urgent in textile and electronic fields. This study compares the effects of 60 phr bis (2‐(2‐butoxyethoxy) ethyl) adipate (DBEEA) with other five equal amounts of plasticizers on the conductivity, electrical stability, transparency, and mechanical properties of plasticized PVC. The infrared spectra of plasticizers indicate that there are unique ether groups exist in DBEEA. Then the calculated solubility parameters suggest the good compatibility between DBEEA and PVC. For conductivity, the volume resistivity and surface resistivity of the PVC sample with DBEEA (PVC/DBEEA) are 107 Ω· m and 1010 Ω, respectively, which are both lower by 3–4 orders of magnitude than that of other plasticized PVC. For electrical stability, the results indicate that PVC/DBEEA placed in air still maintains lowest resistivities. Under 10, 23, and 30°C, PVC/DBEEA keeps high and stable electrical properties. The similar refractive indices of DBEEA and PVC resin prepared by suspension method indicate good transparency for PVC/DBEEA. Moreover, PVC/DBEEA still has good mechanical property.

Optimization of Ti2O3 thin films by magnetron sputtering and study of their photoelectric performance

AbstractAbstractIn this study, Ti2O3 thin films were successfully produced using magnetron sputtering. Through orthogonal gradient experiments, the impact of substrate temperature, sputtering vacuum, RF power, and sputtering duration on surface morphology, roughness, physical structure, and resistivity was investigated. Various analytical techniques were employed, including AFM and SEM for surface morphology observation, XRD and Raman for qualitative physical structure analysis, XPS for elemental valence examination, and the four‐probe method for resistivity measurements. The study identified optimal growth conditions for Ti2O3 films, demonstrating a low resistivity of 2.66 × 10−3 Ω cm under the following conditions: RF power of 200 W, sputtering vacuum of .6 Pa, substrate temperature of 600°C, and sputtering duration of 60 min. Additionally, the sensor arrays were efficiently fabricated using the Lift‐off method to evaluate the photoelectric performance of the films. A light responsiveness of approximately 6 µA/W was observed in the device when illuminated with 950 nm light for 10 s. This finding carries important implications for the use of Ti2O3 thin films in future photoelectric devices.

Feasibility of using calcined clays and reclaimed coal ashes in binary and ternary cementitious systems

This study evaluates the feasibility of using three different calcined clays (CCs) to partially replace ordinary Portland cement (OPC) in concretes. Furthermore, the best performing CC was investigated in conjunction with the addition of reclaimed fly ash (RFA) or reclaimed ground bottom ash (GBA) to partially replace OPC. OPC replacement levels by mass considered in the present study for both binary (i.e., OPC + CCs) and ternary (i.e., OPC + CC + GBA or RFA) cementitious systems were 10, 20, and 30 %. It was shown that, relative to the control mixture (CO), the utilization of CCs can significantly improve properties of the hardened concrete, at the cost of significantly reducing the workability of fresh concrete mixtures. Conversely, the incorporation of coal ashes to form ternary system produced concretes with superior hardened properties (relative to CO) while partially mitigating workability loss. Overall, both binary and ternary systems can produce concretes with significantly higher strength and surface resistivity. Additionally, characteristics of CCs that could be used as rapid indicators to predict their performance as supplementary cementitious materials (SCMs) in concrete were identified by coupling materials characterization techniques and concrete test results.