Coatings

In this study, liquid polysulfide rubber was modified by silane coupling agent. New kinds of anti-corrosion coatings with salt spray resistance and strong adhesion to the steel substrate were obtained using the modified liquid polysulfide rubber, bimetallic filler, carbon nanotubes, and epoxy resin. Infrared and nuclear magnetic resonance confirmed the preparation of new modified liquid polysulfide rubber through coupling reaction between the epoxy group of silane compound and the sulfide group of the liquid polysulfide rubber. A 1440 h neutral salt spray test showed the coating to be completely free of rust and blisters. The corrosion diffusion width of the scribed area was only 1.7 mm. In addition, in a 3.5% by weight NaCl solution, the coating shows no blistering and no corrosion phenomena compared with zinc-rich epoxy paints (the added zinc content was only 28.6%). These tests confirmed that the new coating had a dense microstructure, strong adhesion to the steel substrate, good corrosion resistance, and anti-blister performance. The performance indicates that the coatings have potential for use in the atmosphere and underwater, which provides a better choice for long-term protection of marine projects such as ships, wharves, offshore platforms, and wind power structures. Full article

The silt in the Yellow River alluvial plain typically features low strength and poor water stability, and, thus, alluvial silt treatment needs an amount of cement to improve soil performance. The development of an alternative to reduce or replace the use of cement in soil stabilization has been a hot topic research for a long time. This paper develops an industrial-solid-waste (ISW) curing agent using a response surface methodology, which is a novel composite material made of steel slag, mineral slag, and two desulfurization products; its feasibility on improved silt is expected to be studied systematically. The comparative tests of ISW- and cement-improved silt were conducted to analyze performance and action mechanism. Variance and multiple regression analysis were used to study the effect of factors on responses statistically, and check the significance and correlation of the suggested models. Finally, the in-service performance of ISW-improved silt was evaluated through in-situ tests. Results show that ISW-improved silt can present good mechanical properties and durability, but is much weaker than cement-improved silt in the early curing stage. The strength enhancement amplitude of ISW-improved silt between curing ages of 7 days to 28 days is larger than that of cement-improved silt. The correlation between factors and responses is established with good agreement. Synergisms in the ISW curing agent are stimulated in the alkaline environment, and are conductive to connect the silt particles. The in-service performance of ISW-improved silt showed little difference to that of cement-improved silt; both of them meet the requirements from the perspective of in-situ application. Moreover, the unit cost of an ISW curing agent is less than 1/5 of that of cement. ISW-improved silt has advantages of cost saving, resource recycling and environmental protection. Full article

In this work, the plasma generated by the cascaded SinplexPro^TM plasma spray gun was studied by means of numerical simulation. Special attention is given to the laminarity of the plasma flow. The simulation part is divided into two parts: arcing simulation inside the spray gun and plasma jet simulation outside the spray gun. A laminar as well as a turbulent model is used in each case. The results show that, under the investigated conditions, the internal flow of the plasma torch can be considered as laminar with low turbulence and can, hence, be regarded as quasi-laminar flow. If carrier gas is injected into the plasma jet, the ideal laminar plasma jet is often greatly affected. However, the turbulent plasma jet with low turbulence intensity generated by the cascaded SinplexPro^TM plasma spray gun is less affected and can remain stable, which is beneficial to the plasma-spraying process. Full article

The effects of expansion deformation on the mechanical properties and corrosion resistance of an AISI 304 stainless steel (SS) tube with dimensions of ϕ 108 mm × 6 mm were studied with a full-scale test, a mechanical property test, microstructural analysis and a corrosion property test in order to explore the feasibility of using AISI 304 SS tubes as solid expandable tubes in repairing damaged well casings. The results showed that the AISI 304 SS tube had good expansion performance, suitable strength after expansion and excellent corrosion resistance, and it met the technical requirements for repairing the casings of common oil wells. After ~11% radial expansion, the internal pressure strength and collapsing strength of the tube were 71 and 32 MPa, respectively. The increase in dislocations, and in the formation of strain-induced martensite and twinning stimulated by plastic deformation, led to the yield strength of the AISI 304 SS tube increasing from 249 to 539 MPa; however, the corrosion resistance of the AISI 304 SS tube was somewhat worsened because of the increase in dislocations and strain-induced martensite caused by expansion deformation. However, the corrosion resistance of the AISI 304 SS tube was still much better than that of conventional casings. Full article

Superhydrophobic surfaces were prepared using a two-step method that involved the etching of AZ31 and AZ91 magnesium alloys and then modifying the etched alloys with stearic acid. Magnesium alloys etched with ZnCl₂ and SnCl₂ exhibited surfaces roughened with micro- and nanoscale hierarchical structures consisting of two chemically distinct regions (Zn/Zn(OH)₂ or Sn/SnO₂ and Mg(OH)₂). An optimum etching time of ten minutes was chosen for both etchants. Superhydrophobic surfaces with the highest contact angle were prepared when stearic acid reacted with the etched alloys at 50 °C for 4 h. Stearic acid was bound as zinc stearate and magnesium stearate on Mg alloys etched with ZnCl₂ and SnCl₂ solutions, respectively. The superhydrophobic process on AZ31 alloys etched with ZnCl₂ and SnCl₂ improved the corrosion resistance in phosphate buffered saline (PBS) solution compared to bare AZ31 alloy, with the use of ZnCl₂ etchant leading to better results. An improvement in the corrosion resistance of AZ91 alloy was observed when the stearic-acid-modified AZ91 alloy was etched with SnCl₂. In contrast, the use of ZnCl₂ etchant to pretreat AZ91 alloy resulted in a significant deterioration in corrosion properties compared to bare AZ91 alloy. The microstructure of the Mg alloy had an impact on the etching and modification process. On the basis of the findings, a characterization of the chemistry of etching magnesium alloys and the formation of superhydrophobic surfaces was proposed. Magnesium alloys were prepared with superhydrophobic surfaces, incorporating antibacterial metals, features which may increase their potential for use in medical applications. Full article

In recycled asphalt mixtures, the RAP binder often becomes stiff and brittle due to aging, making it difficult to achieve a complete integration with the added virgin binder, which could provide a negative impact on the long-term performance of the recycled asphalt mixtures. In an attempt to identify the influence of the integration degree on the adhesion characteristics of virgin-aged composite binder and the corresponding binder-aggregate system, a series of experiments, including the modified boiling test and pull-off test and corresponding formation methods for the binder samples with various interfusion states, were designed and carried out in the present study. The two-layered composite binder (CB), consisting of a layer of virgin binder and a layer of aged binder was fabricated for the experiments, and the testing results were analyzed and compared with those of the virgin binder (VB), the aged binder (AB), and the blended binder (BB). The thermostatic treatments with various durations were subjected to the binder samples to attribute them with various integrations, and the wetting conditioning was also imposed on them to introduce the impact of moisture erosions. The rheological properties, creep recovery capacity, and fatigue resistance of the binders were first investigated based on a dynamic shear rheometer. The adhesion characteristics and failure behaviors of the binder-aggregate system were furthermore explored with the modified boiling test and pull-off test, and the percentage of residual binder (%_residual binder), pull-off test strength (POTS), and moisture damage index (MDI) were adopted to assess or quantify their adhesion characteristics and moisture susceptibility. The results found that the rheological properties and creep recovery capacity of the CB were similar to those of the VB, and its fatigue life exhibited an increasing trend with the extension of the thermostatic-treatment duration. In contrast to the modified boiling test, the pull-off test was more effective at evaluating the integration and distinguishing the failure behaviors of the binder-aggregate system. As the thermostatic-treatment duration prolonged, the interfusion between the virgin and the aged binder was facilitated, the cohesion within the binder and the adhesion between the binder and the aggregate was also enhanced, and thus the adhesion performance and moisture-damage resistance of the system were improved. Full article

Being inspired by nature, a series of experiments was carried out to deposit a calcium oxalate layer on the surface of the stone by the reaction between carbonate rock and oxalate salt. To increase the anti-dissolution properties of the calcium oxalate layer, the use of mixed oxalate solution has been proposed in the literature by two main routes: (1) adding acid agent to ammonium oxalate, which has the advantage of changing the particle structure and reducing layer porosity, and (2) using neutral methyl oxalate solution, which has the advantage of surface coverage due to slowly hydrolysis. In this study, we investigated the sequential application of ammonium oxalate, methyl oxalate, neutral mixed, and calcium acetate acid mixed solution. With this method, calcium carbonate and calcium oxalate solution can react inside the stone to reinforce it. The protective film’s coverage area can then be increased using dimethyl oxalate neutral mixed solution, and the crystal morphology can be modified with calcium oxalate acid mixed solution. The anti-dissolution properties of the coating were investigated using both a custom-designed apparatus and a selective outdoor environment. The coating displayed good acid resistance properties at pH 2–4. After one year of exposure, the coating is firmly bonded with the stone. Full article

SiO₂ is one of the most widely used dielectric materials in optical and electronic devices. The Josephson voltage standard (JVS) chip fabrication process has rigorous requirements for the deposition temperature and step-coverage profiles of the SiO₂ insulation layer. In this study, we deposited high-quality SiO₂ insulation films at 60 °C using inductively coupled plasma-chemical vapor deposition (ICP-CVD) to fulfill these requirements and fabricate JVS chips simultaneously. SiO₂ films have a high density, low compressive stress, and a sloped sidewall profile over the vertical junction steps. The sidewall profiles over the vertical junction steps can be adjusted by changing the radio frequency (RF) power, ICP power, and chamber pressure. The effects of sputtering etch and sloped step coverage were enhanced when the RF power was increased. The anisotropy ratio of the deposition rate between the sidewall and the bottom of the film was lower, and the sloped step coverage effect was enhanced when the ICP power was increased, or the deposition pressure was decreased. The effects of the RF power on the stress, density, roughness, and breakdown voltage of the SiO₂ films were also investigated. Despite increased compressive stress with increasing RF power, the film stress was still low and within acceptable limits in the device. The films deposited under optimized conditions exhibited improved densities in the Fourier transform infrared spectra, buffered oxide etch rate, and breakdown voltage measurements compared with the films deposited without RF power. The roughness of the film also decreased. The step-coverage profile of the insulation layer prepared under optimized conditions was enhanced in the junction and bottom electrode regions; additionally, the performance of the device was optimized. This study holds immense significance for increasing the number of junctions in future devices. Full article

The use of rubber in dynamic contacts often results in severe degradation and wear of the rubber surface, which is why dynamic rubber seal contacts are usually oil lubricated to ensure their functionality. However, the increasing demand for more convenient and environmentally friendly sealing solutions has prompted the development of dry low-friction rubber coatings. In this work, and for the first time, Ni-P and polytetrafluoroethylene (PTFE) particles were co-deposited by electroless plating on Nitrile Butadiene Rubber (NBR), as a low-cost solution to improve the NBR tribological behavior. A cationic surfactant, cetyltrimethylammonium bromide (CTAB), was added to the plating bath to ensure a homogeneous and efficient incorporation of PTFE into the Ni-P. The optimized PTFE incorporation reached 6.8%, and the composite coating adhesion to NBR was 20% higher than that of nickel-phosphorous (Ni-P) films. The tribological properties of the coatings evaluated by pin-on-disk tests showed a marginal decrease in the coefficient of friction (CoF) (10%, 1 N load), compared to that of Ni-P. However, the tested PTFE-based coatings displayed significantly smoother surfaces with less debris and cracks, clearly demonstrating the benefits of the PTFE in terms of wear resistance for loads up to 5 N. Full article

This article described the protective properties of Cr coatings with a barrier layer composed of ZrO₂/Cr multilayers deposited onto E110 zirconium alloy. The coatings with a ZrO₂/Cr multilayer thickness of 100, 250, and 750 nm and single-layer (1.5 µm) ZrO₂ barrier were obtained by multi-cathode magnetron sputtering in Ar + O₂ atmosphere. Then, cracking resistance and oxidation behavior were studied under conditions of thermal cycling (1000 °C) in air and high-temperature oxidation at 1200–1400 °C in a water steam. The role of the ZrO₂/Cr multilayers and multilayer thickness on cracking resistance of the experimental coatings and oxidation resistance of the coated E110 alloy was discussed. It was shown that the coatings with more quantity of the ZrO₂/Cr multilayers have higher cracking resistance, but such types of samples have a large amount of coating spallation under thermal cycling. The high-temperature steam oxidation (1200–1400 °C) demonstrated that interfaces of the ZrO₂/Cr multilayers can act as a source of cavities formed by the Kirkendall mechanism that results in accelerating Cr–Zr interdiffusion for Cr-coated E110 alloy. Full article

In this research, Cr₃C₂-NiCr and WC-Co-Cr cermet coatings were developed on A356 aluminum-based alloy substrate by the high-velocity oxy-fuel (HVOF) technique for use in wear and corrosion applications. The substrate and coatings were characterized using a field emission scanning electron microscope (FESEM) equipped with the energy dispersive spectroscope (EDS), microhardness, wear, and corrosion test instruments. Microstructural observations revealed that the coatings with an average thickness of about 250 μm were well bonded with the substrate. The microhardness of the Cr₃C₂-NiCr (~930 HV) and WC-Co-Cr (~1300 HV) coatings were about eleven and sixteen times higher than that of the A356 substrate (~80 HV), respectively. Cermet coatings showed significantly lower mass losses, wear rates, and friction coefficients in comparison with the A356 substrate. WC-Co-Cr coating illustrated higher tribological performance in comparison with Cr₃C₂-NiCr coating. The mass loss and friction coefficient of the WC-Co-Cr coating under an applied load of 10 N was about 0.2 mg and 0.13 (about 99.5% and 79.7% lower than that of the A356 substrate, e.g., 41.5 mg and 0.64), respectively. Rising applied load increased the wear characteristics of the A356 substrate with the more pronounced degrees. FESEM observations on wear test specimens illustrated the different wear mechanisms on the surfaces. The results illustrated significant improvements in the corrosion performances of the coated samples. Full article

ZnFe₂O₄ microspheres were prepared by solvothermal method, and a novel ZnFe₂O₄@TiO₂ core-shell composite photocatalyst was prepared by ultrasonic (denoted as ZT-x) and mechanical stirring (denoted as ZTM-1.2). The morphology, structure, magnetic, and optoelectronic properties of the catalyst were investigated comprehensively, and the degradation performance of the catalyst was explored through the photocatalytic degradation of Rhodamine B (RhB) under UV light. The concentration of RhB was 10 mg/L, and the catalyst concentration was 0.3 g/L. ZT-1.2 showed the best photocatalytic degradation activity, and the degradation rate of RhB reached 97.3% within 60 min. The degradation ability of the catalyst was further evaluated by Methylene blue (MB), Methyl orange (MO), Phenol, and Ofloxacin (OFX). ZT-1.2 also exhibited excellent stability. The improved catalyst degradation performance was attributed to constructing a Z-type heterojunction. Moreover, the low-efficiency degradation of ZTM-1.2 was caused by catalyst agglomeration and low TiO₂ loading, confirming the superiority of the ultrasonic method and providing a new method for the preparation of magnetically recoverable TiO₂-based core-shell photocatalyst. Full article

In the study, a conductive polypyrrole (PPy) is deposited on the lamellar sericite powder (SCP) surfaces by an in situ oxidization growth method and the prepared PPy/SCP conductive additive is successfully applied on the zinc-rich primer (ZRP) coating. The equal mass substitution and the equal volume substitution methods of the conductive additives to zinc dusts are discussed, as well as the optimal replacing ratio to achieve the best corrosion protection effect of the ZRP coatings. The results indicate that the equal volume substitution method is in favor of corrosion resistance of coating film. The salt spray test and the electrochemical impedance spectroscopy (EIS) and polarization curves show that the prepared ZRP coating with a 66% zinc content and replacing ratio of 1:3 possesses the best corrosion-resistant performance and an optimal adhesion strength. The replacement of PPy/SCP particles to zinc dusts using the equal volume substitution method is feasible to achieve the improvement in anticorrosion ability through a synergic function of the cathodic protection effect and barrier effect. Full article

[email protected] nanospheres were fabricated by in situ polymerizing and high-temperature carbonizing processes. This unique synthesis method does not require any template or reducing gas. The synthesized multicore-shell structure has a shell of about 500 nm and multiple nuclei of several tens of nanometers. Subsequently, extensive experiments were conducted to adjust the material composition of the nanospheres by adjusting the amount of resorcinol and formaldehyde. The results showed that the obtained material performed best when resorcinol and formaldehyde were added to 0.2 g MnCo₂O₄ at 0.3 g and 0.42 mL, respectively. The efficient absorption bandwidth (EAB) value reaches 3.3 GHz when the absorber thickness is 3 mm. The reflection loss (RL) is up to −23.8 dB when the frequency is at 8.6 GHz. The unique yolk core-shell structure gives the material a heterogeneous interface, and the enhanced interfacial polarization loss causes the enhanced dielectric loss. The carbon layer with microporosity also causes conduction loss and multiple reflections. The composite structure formed by metallic Co, MnO, and carbon has better impedance matching and improved microwave absorption capability. Full article

AISI 430 ferritic stainless steel with different initial microstructures was low-temperature plasma nitrided to improve its hardness and wear resistance in the present investigation. The microstructure and properties of the low-temperature nitrided layers on stainless steel with different initial microstructures were studied by an optical microscope, X-ray diffractometer, scanning electron microscope, microhardness tester, pin-on-disk tribometer, and electrochemical workstation. The results show that the low-temperature nitrided layer characteristics of ferritic stainless steel are highly initial-microstructure dependent. For the ferritic stainless steel with a solid solution and annealing treatment, it had the best performance after low-temperature plasma nitriding when compared with the stainless steel with other initial microstructures. The nitrided layer thickness reached 34 μm after nitriding at 450 °C for 8 h. The phase composition of the low-temperature-nitrided layer consisted mainly of a nitrogen “expanded” α phase (α_N) and iron nitrides (Fe₄N and Fe_2–3N). The hardness of the nitrided layer could reach up to 1832 HV_0.1. Moreover, the wear and corrosion resistance of the nitrided layer on the solution and annealing treated ferritic stainless steel could be improved at the same time. Full article

The fabrication of bio-composite-derived bovine amniotic membrane (BAM) with hydroxyapatite (HAp) is an approach to combining organic and inorganic bio-material to improve the properties of both materials. This research aims to combine, fabricate and characterise the bio-composite of BAM–HA. The combination of bio-composite is made from BAM and HAp in a ratio of 30:70, 35:65, and 40:60. Dried BAM is immersed in saline and then blended until it forms an amniotic slurry with a jelly-like consistency. At this stage, HAp is added so that it can bind to BAM. After the mixture is homogeneous, the freeze-drying process is carried out. After fabrication, all the bio-composites were characterised using Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and porosity analysis, and biological activity was conducted using fibroblasts. The bio-composite has functional groups of amides I, II, III, A, B, OH, CO₃²⁻ and PO₄³⁻ according to the results of the FTIR. The XRD analysis showed the presence of HAP crystals. This functional group and the crystal HAP indicate that these two materials are bound. An SEM examination revealed a variety of porous patterns on the surface area. The bio-composite with BAM and HAp at a ratio of 35:65 has a higher mean pore size of 155.625 µm with mean porosity of 89.23% and can maintain the fibroblast viability of 95.14%. In conclusion, the study successfully combined both bio-materials BAM and HAp, which have potential synergistic effects on soft and hard tissue regeneration. The ratio of 35:65 showed good characteristics and was non-toxic. Full article

The purpose of this paper is to reveal the corrosion behavior of J55 and N80 carbon steels in formation water under oil wells at different partial pressures, explore the formation process of corrosion product films under supercritical CO₂ conditions, and analyze the reasons why the microstructure of carbon steel affects the corrosion behavior. The results show that the corrosion rate gradually increases with the increase in CO₂ partial pressure. When the pressure exceeds 10 MPa, the corrosion rate of J55 increases slightly, and that of N80 decreases slightly. Under different partial pressures, the surface composition of the corrosion product film of J55 steel is FeCO₃, and that of N80 steel is FeCO₃ with a small amount of Fe₃C. The analysis shows that the corrosion product films of two kinds of carbon steels can be divided into three layers under the condition of supercritical CO₂. There are holes in the middle layer, which are formed first, and then the inner layer and the outer layer are formed at the same time. It is believed that the difference in the morphology and distribution of Fe₃C is the reason why the corrosion rate of J55 steel is lower than that of N80 steel. Fe₃C in J55 steel is lamellar, which can anchor FeCO₃, promote the formation of corrosion product films, and improve the compactness of corrosion product films. However, the Fe₃C in N80 is granular and dispersed in the ferrite matrix, which makes it easy to fall off the surface, form pits, and destroy the integrity of the corrosion product film. Full article

Polyaniline/Au nanocomposites were synthesized by a novel method. Aniline monomers were loaded in the hydrophobic cavities of beta-cyclodextrin, and a polymerization reaction occurred at the interface of the beta-cyclodextrin cavities and the liquid phase of chloroauric acid. UV-vis absorbance indicated that the nanocomposite covered the range of visible light and NIR (near infrared). The photo-excitation experiment was carried out with typical wavelengths in the visible light (405 nm, 532 nm, and 650 nm) and NIR (780 nm, 808 nm, 980 nm, and 1064 nm) regions (10–200 mW) based on Au inter-digital electrodes on flexible polymer substrates casting a thick film. The nanocomposites exhibited photo-current switching behavior in visible light and NIR. The ratio of on/off was enormously dependent on the power and wavelength of incident light. The robust interface coupling between Au and PANi of the nanocomposite promoted the separation and transfer of electron/hole. The mechanism of carrier generation, separation, and transfer at interfaces of Au/conjugated polymer/non-conjugated small organic molecules by light inducement was discussed at the electron level. The results illustrate that the nanocomposites quickly produced free electrons and holes by low-power incident light, could prevent the recombination of electron/hole pairs to a certain extent, and could overcome the interface barriers between metal, conjugated polymer, and small organic molecules for transfer. This provides a simple and practical approach for developing multi-functional nanocomposites that have the potential act as intelligent nano-carriers, photo-current switches, NIR detectors, and for information storage. Full article

In this study, we aimed to improve our understanding of the response mechanisms associated with the formation of CdS thin films. CdS thin film remains the most valuable option for many researchers, since it has shown to be an effective buffer material for film-based polycrystalline solar cells (CdTe, CIGSe, CZTS). We performed experimental and numerical simulations to investigate the effect of different thiourea concentrations on the characteristics of the CdS buffer layer. The experimental results reveal that an increase in thiourea concentrations had a direct effect on the optical results, with bandgap values ranging from (2.32 to 2.43) eV. XRD analysis confirmed that all deposited films were polycrystalline, except for [1/0.75], where there is no CdS formation. Electrical studies indicated that CdS with a molar ratio of [Cd]/[S] of 1 had the maximum carrier concentration (3.21 × 10¹⁴ cm⁻³) and lowest resistivity (1843.9 Ω·cm). Based on the proposed mechanism, three kinds of mechanisms are involved in the formation of CdS layers. Among them, the ion-by-ion mechanism has a significant effect on the formation of CdS films. Besides, modelling studies reveal that the optic-electrical properties of the buffer layer play a crucial role in influencing the performance of a CIGS solar cell. Full article