Substrate Protection Research Articles

Amide-Based Naphthotubes as Biomimetic Receptors for Acetal Protection and Other Substrates in Water via Noncovalent Interactions.

Active compound protection can allow inherently unstable molecules to be stabilized and latent reactivity to be masked. Synthetic receptors are attractive in terms of providing such protection. Nevertheless, preserving the activity and functionality of organic molecules in water poses a challenge. Here, we show that biomimetic receptors, specifically amide naphthotubes and an amide anthryltube, allow the efficient preservation of functional organic molecules in water. In particular, the amide naphthotubes were found to extend the half-lives of acetal-containing substrates ("acetals") against acid-catalyzed hydrolysis by up to 3000 times. This kinetic protection effect was ascribed to hydrogen bond-based recognition of the organic guests. A substrate dependence was seen that was further exploited to achieve the kinetic resolution of acetal isomers. To the best of our knowledge, the present study constitutes one of the most effective acetal protection strategies reported to date. The recognition-based protection approach reported here appears generalizable as evidenced by the protection of eight different substrates against six distinct chemical reactions. Based on the present findings, we propose that it is possible to design receptors that provide for the protection of specific substrates under a variety of reaction conditions including those carried out in water.

Mussel-Inspired, Self-Healing, Highly Effective Fully Polymeric Fire-Retardant Coatings Enabled by Group Synergy.

Fire-retardant coatings represent a universal cost-effective approach to providing fire protection for various substrates without compromising substrates' bulk properties. However, it has been attractive yet highly challenging to create waterborne polymeric fire-retardant coatings combining high-efficiency, generally strong adhesion, and self-repairability due to a lack of rational design principles. Inspired by mussel's unique adhesive, self-healing, and char-forming mechanisms, herein, a "group synergy" design strategy is proposed to realize the combination of self-healing, strong adhesion, and high efficiency in a fully polymeric fire-retardant coating via multiple synergies between catechol, phosphonic, and hydroxyethyl groups. As-created fire-retardant coating exhibits a rapid room-temperature self-healing ability and strong adhesion to (non)polar substrates due to multiple dynamic non-covalent interactions enabled by these groups. Because these functional groups enable the formation of a robust structurally intact yet slightly expanded char layer upon exposure to flame, a 200µm-thick such coating can make extremely flammable polystyrene foam very difficult to ignite and self-extinguishing, which far outperforms previous strategies. Moreover, this coating can provide universal exceptional fire protection for a variety of substrates from polymer foams, and timber, to fabric and steel. This work presents a promising material design principle to create next-generation sustainable high-performance fire-retardant coatings for general fire protection.

Isothermal oxidation behavior of EB-PVD TBCs based on (Yb0.1Gd0.9)2Zr2O7 ceramic coat and Cr modified (Ni, Pt)Al bond coat

Rare earth oxide doping zirconate ceramics are a new kind of thermal barrier coatings (TBCs) materials that can be suitable for higher service temperature. Single layer (Yb0.1Gd0.9)2Zr2O7 ceramic coatings were fabricated onto both of (Ni, Pt)Al and Cr-modified (Ni, Pt)Al bond coat surfaces. The microstructure, interface elemental diffusion, residual stress as well as isothermal oxidation behavior of two TBCs specimens were evaluated. The compact and uniform Cr-modified layer can act as a diffusion barrier, effectively preventing Al element from diffusing to the bond coat surface. The thickness of pre-oxidation layer grown at the interface between Cr-modified (Ni, Pt)Al and (Yb0.1Gd0.9)2Zr2O7 is relatively thin, which is measured to be only ∼140 nm. With the prolonging of oxidation durations, the surface microcracks' width and sintering morphology of Cr-modified (Ni, Pt)Al TBCs are obviously less severe than that of (Ni, Pt)Al TBCs. The modification effect of Cr onto (Ni, Pt)Al surface is also reflected in the decrease of the thickening rate of thermally grown oxide (TGO) and the improvement durability of β phase within bond coat. Although the residual stress in TGO layer of Cr-modified (Ni, Pt)Al TBCs increases continuously during thermal exposure from 200 h to 700 h, no serious microcracks' propagation occurs on the surface of (Yb0.1Gd0.9)2Zr2O7 coating. The ceramic coat of (Ni, Pt)Al TBCs spalls extensively and further the TGO exhibits a double-layer structure when the isothermal oxidation is carried out up to 700 h. In that TGO morphology, the columnar crystals are observed near the bond coat, while the fine equiaxed grains are detected approach to the ceramic coat. In comparison, the bond coat of Cr-modified (Ni, Pt)Al with (Yb0.1Gd0.9)2Zr2O7 ceramic topcoat has better interlayer matching, and such TBCs shall have the potential to provide thermal protection for the superalloy substrate even after 700 h of isothermal oxidation.

DLHEnhancing tribological properties of involute gear teeth through discrete hardening treatment using a biased laser source with axis

Traditional methods for enhancing surface fatigue in gears are limited by their techniques and processes, making it increasingly challenging to achieve a balance between strength and toughness and meet the demands for fatigue-resistant manufacturing of high-energy-density gears. In this study, a novel tooth surface laser discrete strengthening method is proposed, focusing on validating the actual effects of laser discrete processing and strengthening on the involute gear tooth surface. Through comprehensive simulations and experiments, the consistency and feasibility of the process within a tilt angle range of 0 to 30° are demonstrated. To address laser interference between adjacent gear teeth, a processing technique is introduced that involves the offsetting of the laser beam from the gear axis and the tilting of the optical path relative to the normal of the tooth profile. By deriving the coordinates of evenly distributed points on the involute gear profile, a strategy for biased discrete hardening processing is formulated. Furthermore, remarkable benefits are revealed through friction experiments conducted on physical gears processed using this technique, including the reduction of friction power (9.36 % to 27.10 %), the stabilization of output torque, and the improvement of substrate protection, thus confirming the effectiveness of this technique in resisting contact fatigue damage. Valuable insights into advancing the field of fatigue-resistant gear manufacturing through the utilization of laser-based discrete hardening techniques are provided by this research.

Water-Enhancing Gels Exhibiting Heat-Activated Formation of Silica Aerogels for Protection of Critical Infrastructure During Catastrophic Wildfire.

A promising strategy to address the pressing challenges with wildfire, particularly in the wildland-urban interface (WUI), involves developing new approaches for preventing and controlling wildfire within wildlands. Among sprayable fire-retardant materials, water-enhancing gels have emerged as exceptionally effective for protecting civil infrastructure. They possess favorable wetting and viscoelastic properties that reduce the likelihood of ignition, maintaining strong adherence to a wide array of surfaces after application. Although current water-enhancing hydrogels effectively maintain surface wetness by creating a barricade, they rapidly desiccate and lose efficacy under high heat and wind typical of wildfire conditions. To address this limitation, unique biomimetic hydrogel materials from sustainable cellulosic polymers crosslinked by colloidal silica particles are developed that exhibit ideal viscoelastic properties and facile manufacturing. Under heat activation, the hydrogel transitions into a highly porous and thermally insulative silica aerogel coating in situ, providing a robust protective layer against ignition of substrates, even when the hydrogel fire suppressant becomes completely desiccated. By confirming the mechanical properties, substrate adherence, and enhanced substrate protection against fire, these heat-activatable biomimetic hydrogels emerge as promising candidates for next-generation water-enhancing fire suppressants. These advancements have the potential to dramatically improve the ability to protect homes and critical infrastructure during wildfire.

Current-carrying friction behavior of CrN coatings under the influence of DC electric current discharge

CrN coatings are renowned for their low friction coefficients, high chemical inertness, excellent corrosion resistance, and substantial hardness, making them ideal for the tribological demands of bearings and gears in electric vehicles. This study investigated the current-carrying friction behavior of CrN coatings when sliding against steel balls under both non-electrified and electrified conditions. The friction coefficient (CoF), wear volume, wear type, and mechanism of the coating were reported by adjusting the direct current (DC) intensity and lubrication status. The findings indicate that while the current significantly exacerbates substrate wear during dry friction, its impact on the CrN coating is minimal. Even at a maximum DC current of 1.5 A, the wear rate of CrN coating during dry friction is only 1.9 × 10−4 mm3·(N·m)−1, representing a reduction by 79.1 % compared to the steel substrate. This effect is further pronounced when lubricated with PAO oil. The wear of CrN coating shows minimal change even as the current increased, and surface wear remains very slight. At a current of 1.5 A, the wear rate of CrN coating decreases to as low as 9.7 × 10−6 mm3·(N·m)−1, indicating a reduction by 98.7 % compared to its substrate. It is observed that under electrified conditions, the oxidation and degradation of CrN coating are accelerated, thereby resulting in the formation of a loose and low-hardness Cr2O3 oxide layer on the surface. The oxide layer is primarily attributable to the deterioration in frictional properties of the CrN coating under electrified conditions. Finally, CrN coatings exhibit minimal changes in tribological behavior under electrified conditions, thereby offering effective protection for substrates against electrical damage. Therefore, CrN coatings are ideal for applications involving electrical contacts.

In Situ PANI Encapsulation of Zinc Powder Enhancing the Corrosion Resistance of Zinc-Rich Epoxy Coatings

An approach to encapsulate zinc powder by in situ polymerization of aniline (PANI@Zn) is developed for Zn-rich epoxy coatings (ZRCs). With the application of PANI@Zn composites in the ZRCs, the encapsulated zinc particles are not activated due to the corrosion inhibition of PANI at the early stage of immersion, and physical shielding being mainly responsible for the protection of the steel substrate. At the stage of cathodic protection, the consumption of zinc powder is relatively uniform from the outer layer to the inner layer of the coating PANI@Zn coating, and the utilization rate of zinc powder is higher than that in the coating incorporated by the raw zinc powder. The required amount of zinc powder for achieving the same protective effect as the case of the raw zinc powder is reduced by ca. 20% after the application of the PANI@Zn composites.

Spatially Resolved Assessment and Analysis of Al-Zn, Mg, and Mg/Al-Zn Metal-Rich Primers Applied to AA 7075-T651 in Full Immersion

The scanning vibrating electrode technique (SVET) was utilized to monitor localized corrosion and substrate protection of three metal-rich primers (MRP). The ability to suppress localized corrosion and provide widespread cathodic polarization to enable sacrificial anode-based cathodic protection of a AA 7075-T651 substrate with either an aluminum-rich primer (AlRP), magnesium-rich primer (MgRP), or a composite magnesium + aluminum-rich primer (MgAlRP) in a polyamide-based epoxy primer coatings fully immersed in 1 mM NaCl was investigated. Pigments did not activate uniformly in each MRP. The notion of throwing power polarizing the bare substrate and uniform current and potential distributions at scratch sites does not describe the behavior observed. In cases where activation occurred, protection was noticed in the form of suppression of local anodes on bare AA 7075-T651. Local corrosion was suppressed on heterogeneously corroding AA 7075-T651 with strong local anodes and cathodes. Widespread cathodic polarization was absent. The MgRP and MgAlRP were shown to provide superior local corrosion suppression associated with pitting on AA 7075-T651 compared to the AlRP.

Stability optimization of iron-based catalysts: Application of Cr-enriched alloy steel catalyst in ozonation pharmaceutical wastewater

Catalytic ozonation for advanced treatment of industrial wastewater has proved to be effective, and the stability of the catalyst is crucial for the long-term application of the ozonation process in practical engineering. In this study, the electrochemical characteristics of four iron (Fe) shavings: alloy steels (38CrMoAl and 40Cr) and carbon steels (A3 and 45#) were investigated, and a new citric acid-optimized H2O2 modification method was proposed. The low open circuit potential (OCP) of carbon steels indicated that they were more likely to be oxidized therefore required shorter modification times. The higher the OCP of alloy steels, the higher H2O2 concentration was required to enhance modification efficiency. By adding citric acid, the rapid modification of alloy steel was achieved, and the catalysts exhibited lower passivation current (Ip), indicating a lower rate of substrate loss and a longer lifetime of alloy steel catalysts. Furthermore, chromium (Cr) enrichment occurred in the oxide layer of alloy steel catalysts. The Cr/Fe (atomic ratio) in oxide layer for 38CrMoAl and 40Cr increased from 0.018 to 0.040 and from 0.010 to 0.037, respectively. The presence of CrOOH and Cr2O3 within the oxide layer reinforced the layer’s overall structural integrity and enhanced its protection for the internal substrate, making the catalysts more resistant to adapt to high-salinity wastewater. Through laboratory tests, it was found that among the four catalysts, 38CrMoAl showed the highest stability and good catalytic activity with low Fe loss concentration. Therefore, the pilot-scale application effect of 38CrMoAl catalyst was evaluated. In the advanced treatment of pharmaceutical wastewater, chemical oxygen demand (COD) and total organic carbon (TOC) removals were 56.3% and 32.4%, respectively. These results showed that the stability of catalyst can be improved by optimizing the selection of steel, and the introduction of citric acid achieved Cr enrichment effect and amplified the potential stability advantage of alloy steel. The research provides guidance on raw material selection for catalyst preparation to different industries' wastewater treatment, especially in high-salinity wastewater ozonation treatment, which can realize the long-term stable application of catalyst.

Performance Enhancement of Ti/IrO2-Ta2O5 Anode through Introduction of Tantalum-Titanium Interlayer via Double-Glow Plasma Surface Alloying Technology.

Ti/IrO2-Ta2O5 electrodes are extensively utilized in the electrochemical industries such as copper foil production, cathodic protection, and wastewater treatment. However, their performance degrades rapidly under high current densities and severe oxygen evolution conditions. To address this issue, we have developed a composite anode of Ti/Ta-Ti/IrO2-Ta2O5 with a Ta-Ti alloy interlayer deposited on a Ti substrate by double-glow plasma surface alloying, and the IrO2-Ta2O5 surface coating prepared by the traditional thermal decomposition method. This investigation indicates that the electrode with Ta-Ti alloy interlayer reduces the agglomerates of precipitated IrO2 nanoparticles and refines the grain size of IrO2, thereby increasing the number of active sites and enhancing the electrocatalytic activity. Accelerated lifetime tests demonstrate that the Ti/Ta-Ti/IrO2-Ta2O5 electrode exhibits a much higher stability than the Ti/IrO2-Ta2O5 electrode. The significant improvement in electrochemical stability is attributed to the Ta-Ti interlayer, which offers high corrosion resistance and effective protection for the titanium substrate.

Chromium Coatings Applied to Zr Alloy Claddings by Cathodic Arc Ion Plating: Effect of Nitrogen Inclusion on Limiting Columnar Defects

The effect of nitrogen on an anticorrosive Cr coating for the Zr alloy cladding of nuclear fuel rods is investigated. It is aimed to reduce the number of typical columnar defects generated in Cr‐based coatings when using the cathodic arc ion plating method through reactive nitrogen inclusion and improve the oxidation resistance. Under a working pressure of 5 Pa and an arc current of 60 A in a chrome target, Cr‐based coatings are fabricated under varying N2/Ar gas flow ratios and substrate biases. The growth structures, crystallography, and corrosion behavior of the coatings are characterized using scanning electron microscopy, X‐ray diffraction, and potentiodynamic polarization tests. The Cr coating exhibits a typical columnar structure with voids, pores, and columnar defects. In comparison, through nitrogen inclusion, when the nitrogen content of the Cr‐based coating is less than 15 at%, the Cr(N) coating shows a “featureless structure” similar to an amorphous structure, resulting in fewer voids and defects. Potentiodynamic polarization tests reveal that the Cr(N) coating, featuring a distorted body‐centered cubic‐Cr structure, exhibits a significantly low corrosion current in the passive region. The protection efficiency of the Cr(N) coating is calculated to be 96.9%, confirming its superior substrate protection capabilities compared with chromium nitride coatings.

Hydrothermal oxidation improves the corrosion resistance of titanium and initial cellular responses

Hydrothermal oxidation is the key reaction in the hydrothermal treatment for titanium-based biomedical materials. However, there is still a lack of detailed characterization and in-depth research on the bonding between the oxide film and the substrate, the protection for substrate and the early cellular responses. In this study, nanostructured oxide films were prepared on the titanium surface through hydrothermal oxidation in pure water. The interfacial structure was thoroughly analyzed, corrosion resistance was evaluated, and wetting properties, surface energy and protein adsorption capacity were measured; the interaction between cells and the oxide film was revealed through fluorescence staining and microscopic observations. The results showed that nanocrystalline anatase grew in situ on the titanium surface between 150–200 °C, forming a dense oxide film of approximately 40–50 nm. The oxide film significantly improved the corrosion resistance of the substrate, providing strong shielding protection even after immersion in a solution containing fluoride ions for 30 days. Furthermore, the oxide film endowed the titanium substrate with superhydrophilicity and high surface energy, enhancing protein adsorption, accelerating the polymerization of actin and the formation of stress fibers, and facilitating a tight bond between the cell matrix and the substrate surface; cell attachment and spreading were greatly improved.

The antibacterial, antioxidant, and insecticidal activities of essential oils from Thymus vulgaris L., Salvia officinalis L., and Ocimum basilicum L.

AbstractThe essential oils from Thymus vulgaris, Salvia officinalis, and Ocimum basilicum were extracted by hydrodistillation, characterized by gas chromatography/mass spectrometry, and quantified by gas chromatography/flame ionization detector. The principal constituents were thymol, ρ‐cymene and carvacrol (T. vulgaris); camphor, β‐pinene, and 1,8‐cineole (S. officinalis); and (E)‐anethole, linalool, and 1,8‐cineole (O. basilicum). The essential oil from T. vulgaris was the most effective, forming inhibition halos of 46.16 ± 0.16 and 26.38 ± 0.33 mm, respectively, for Salmonella choleraesuis and Listeria monocytogenes. This essential oil was also more effective against S. choleraesuis, with a minimum inhibitory concentration of 8.85 mg mL−1, and a minimum inhibitory concentration of 17.71 mg mL−1 for L. monocytogenes. No bactericidal activity against S. choleraesuis and L. monocytogenes was observed for the essential oils from S. officinalis, and O. basilicum. Scanning electron micrographs showed that the addition of essential oils left the bacterial cells damaged and deformed. Significant 2,2‐diphenyl‐1‐picrylhydrazyl free radical scavenging capacity and lipid substrate protection were observed in the β‐carotene bleaching assay for the essential oil from T. vulgaris, with IC50 of 231.13 ± 0.53 and 15.25 ± 0.38 μg mL−1, respectively. A dose‐dependent relationship between antioxidant activity and concentrations was observed in the tests. Toxicities of LC50 = 1.24, 3.51 and 1.19 mg mL−1 against Drosophila suzukii flies, respectively, were observed for the essential oils from T. vulgaris, S. officinalis, and O. basilicum. Results suggest that essential oils can be promising antioxidant agents, insecticides, and inhibitors of pathogenic bacteria.

Corrosion-Resistant Organic Superamphiphobic Coatings

In recent years, organic superhydrophobic coatings have emerged as a promising direction for the protection of metal substrates due to their excellent liquid-repelling properties. Nonetheless, these coatings face challenges such as poor mechanical robustness and short service lives, which have limited their development and garnered attention from numerous researchers. Over time, researchers have gained a deeper understanding of superhydrophobic coatings and have published many related articles. Nevertheless, the lack of logical organization and systematic summarization of research focus in this field hinders its advancement. Therefore, the main purpose of this review is to clarify the design principles and working mechanisms of organic superhydrophobic coatings, as well as to summarize and synthesize the latest research on different aspects of superhydrophobic coatings, including liquid-repellent performance, wear resistance, adhesion, antibacterial properties, and self-healing properties. By employing decoupling mechanisms to study each performance aspect separately, this review aims to provide references for extending the service life of organic superhydrophobic coatings.

Improvement of UV resistance and mechanism in polypropylene wax on wood surface through maleic anhydride and β-nucleating agent modification

In China, beeswax is commonly used to protect hardwood surfaces through hot waxing, and is widely utilized in wood furniture and buildings. However, beeswax, with its low melting point and high cost, is prone to being destroyed and falling off, and has a short-term protective effect on wood under ultraviolet (UV) light. Polypropylene wax (PPW), with its low cost and high melting point, holds potential for application in wood protection. The introduction of maleic anhydride enhanced the combination of PPW and wood, resulting in excellent surface properties. Additionally, the β-nucleating agent (WBG-II) induced PPW to form β crystal structure, further enhancing the UV barrier property of the wax coating. After UV irradiation, the surface properties of the hot-waxed wood using the modified polypropylene wax exhibited minimal changes, including color, adhesion, hydrophobicity, and surface roughness. The chemical structure, crystalline structure, and surface morphology were analyzed by FTIR, XRD, and SEM to reveal the photodegradation mechanism of the surface wax coating. The results demonstrated that the co-modification of polypropylene wax by maleic anhydride and WBG-II has a positive effect on the long-term protection of wood substrate, providing a reference for wood protection, particularly for dark and precious wood, and helping to reduce deforestation.

High heat flux ablation behaviors of Ir-Hf coatings in wind tunnel tests up to 6.6 MW/m²

The Ir-Hf coatings have good resistance to oxidative ablation, in order to investigate the ablation resistance limit and ablation failure mechanism of the Ir-Hf coatings, graphite/Re/Ir/Ir-Hf samples were prepared by an optimized pack cementation method. The Ir-Hf coating samples were tested for anti-ablation properties under stepwise and constant working conditions in a high-frequency plasma wind tunnel, respectively. The results showed that the Ir-Hf coating passed the high-frequency plasma wind tunnel test at a heat flux of 5.7 MW/m2 for 650 s without defects. And the heat flux limit of the Ir-Hf coating was about 6.6 MW/m2 in the plasma wind tunnel with a lifetime no less than 400 s and a surface temperature of about 2200℃, exceeding most of the reported heat flux limits for non-ablative materials, such as SiC, ZrB2 and HfC. The failure mechanism of the Ir-Hf coating is as follows: when the surface temperature reaches a certain level, the interface temperature between Ir and the oxide layer will exceed its low eutectic point and a liquid phase will appear, triggering failure. The Ir-Hf coatings have the advantages of high heat flux resistance, zero ablation, low thermal response and good protection of the graphite substrate, which makes them promising as the thermal protection coatings in ultra-high temperature (over 2000 °C) aerospace applications.

The Effect of Wet and Dry Cycles on the Strength and the Surface Characteristics of Coromandel Lacquer Coatings

Research on the degradation mechanism of coating materials is crucial for the preservation of cultural heritage. The purpose of this study was to evaluate the protective effect of Coromandel coatings on wooden substrates by analyzing their dimensions, weight, adhesion strength, hydrophobicity, and glossiness. The results indicate that after five cycles, the radial moisture expansion rate of the wood specimen is 0.332%, while that of the lacquer specimen is 0.079%, representing 23.8% of the radial moisture expansion rate of untreated wood specimens. This performance is superior to that of the ash and pigment specimens. Across different experimental conditions, the change in the mass of the Coromandel specimens aligns with the trend in their dimensional changes, indicating that moisture absorption and desorption are the primary reasons for dimensional changes. The influence of temperature on mass and dimensional stability is significant only in terms of dry shrinkage rate. After wet and dry cycles at 40 °C, the adhesion strength of the Coromandel specimens decreases the most, with the ash specimens decreasing by 7.2%, the lacquer specimens by 3.2%, and the pigment specimens by 4.5%. Following wet and dry cycles at three different temperatures, the contact angle of the lacquer layers changes by less than 5%, with their contact angle values exceeding 120°. These data indicate that among the Coromandel coatings, the lacquer layer provides the best protection for the wooden substrate, while the ash coating is the most fragile. The degradation rate of the Coromandel specimens increases with rising temperatures. These findings emphasize the critical roles of humidity and temperature in protecting wooden coatings and aim to provide theoretical insights and practical significance for the preservation of wooden artifacts and the assessment of coating performance.

Corrosion resistance and ion exchange properties of montmorillonite film on AZ31 in SBF solution

Montmorillonite (MMT) film was prepared on the surface of alkali-heat treated Mg alloys by one-step hydrothermal method. The structure and composition of MMT film were characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The corrosion resistance of MMT film in simulated body fluid (SBF) was investigated using electrochemical tests and immersion experiments. The experimental results showed that with the extension of hydrothermal time, the corrosion resistance of film increased and then decreased. With the increase of MMT powder mass fraction in precursor solution, the corrosion resistance of films also increased and then weakened. The best performance of MMT films was obtained at hydrothermal time of 12 h and MMT powder mass fraction of 2 wt%, with an impedance value of 9.77×106 Ω·cm2, which is an improvement of four orders of magnitude compared to substrate, and the efficiency of corrosion protection was up to 100%. The ion exchange properties, barrier effect and inertness characteristics of MMT provide excellent corrosion protection for magnesium substrates. This study provides a new coating strategy for the preparation of biodegradable magnesium alloys with excellent corrosion resistance and biocompatibility for use as biomedical materials.

Silica-Containing Phosphorus-Based Sol-Gel Finishing to Improve Flame Retardant Performance of Cotton Fabrics

In this paper, the sol-gel technique was used to design hybrid phosphorus-doped silica structures for improving the thermal stability and flame retardancy of cotton fabrics. To this aim, diethylphosphatoethyltriethoxysilane (DPTS) was employed as phosphate alkoxysilane in a multistep procedure that involved multiple layers (from 1 to 6) depositions. The multi-layer coatings were applied by padding using sols containing appropriate molar ratios of the precursor, anhydrous ethanol, catalyst, and hydrochloric acid. Moreover, the synergism P-N on flame retardancy of cotton was assessed by introducing 3-aminopropyltriethoxysilane (APTES) as an N-donor precursor in DPTS sols. The effects of the catalyst during the alkoxide reaction and the silica amount applied by sol-gel treatment on the thermo-oxidative behavior of the treated fabrics were deeply studied. The creation of the silica skeleton on the cotton surface and the interactions between the cellulosic fibres and the doped layer were investigated using FT-IR ATR spectroscopy. Moreover, thermal and thermo-oxidative stability, flammability properties, and combustion behavior of the sol-gel treated cotton fabrics were also studied, proving the effectiveness of the sol-gel coating in the fire protection of the cellulosic substrate.

The performance of a self‐adherent foil system for the corrosion protection of steel substrates for offshore wind tower structures

AbstractThe application of multilayer organic protective coating systems with conventional liquid spray methods is complex, time‐ and energy‐consuming, and it requires extensive technical equipment. An alternative to these methods is the application of thin, self‐adherent foil systems directly to the steel substrate. The corrosion protection performance of newly developed foil systems was tested for various combinations of foil materials and pressure‐sensitive adhesives (with and without corrosion inhibitors) and different surface preparation parameters by means of accelerated cyclic laboratory tests with simulated offshore conditions. The adhesion properties were determined by means of peel tests. The tests were designed, by means of statistical methods (design of experiments, analysis of variance). A foil system with the following factor combination was found to provide an optimum performance: Surface preparation grade: Sa 2½; roughness: Rz = 50–75 µm; abrasive material: high‐carbon steel grit; adhesive layer thickness: 200 g/m2; inhibitor material: calcium aluminum polyphosphate silicate hydrate; foil material: polyvinylchloride (160 µm) + poly(methyl methacrylate) (40 µm).