Low Corrosion Resistance Research Articles

CARACTERIZAÇÃO E COMPARAÇÃO DE PROPRIEDADES MECÂNICAS E RESISTÊNCIA DE CORROSÃO DA TI-10MO-20NB, TI-6AL-4V E TI-CP PARA APLICAÇÕES BIOMÉDICAS

One of the main biomedical material for implants, the Ti-6Al-4V alloy, over time generates oxides of V and Al that accumulate in the body and cause cytotoxic effects. Researches have been making an effort for developing an alternative β metastable Ti alloy that combines corrosion resistance, biocompatibility and good mechanical properties. In view of this scenario, the present work aims to characterize a Ti-10Mo-20Nb alloy and compare the results obtained with a commercial purity Ti alloy and Ti-6Al-4V alloy. Ti-10Mo-20Nb samples were subjected to heat treatment at 1000°C, after that they were water quenched. A hot swagging process at 900°C was applied resulting on a cross section reduction of 80%. The alloy was characterized by optical microscopy, scanning electron microscopy (SEM), Vickers microhardness and the linear polarization technique. For the Ti-10Mo-20Nb alloy the ratio between the hardness and the elastic modulus was of 3.22, the hardness value of 238 HV and the elastic modulus of 74 GPa. The Ti-10Mo-20Nb alloy showed a better mechanical as well as biological compatibility due to the non-cytotoxic of its alloy elements, Mo and NB, in spite of the lower corrosion resistance value when compared to other alloys, it is still possessing reasonable resistance to corrosion and develops a remarkable passivation layer. As such Ti-10Mo-20Nb is a promising alternative for biomedical applications due to its superior mechanical properties and better biocompatibility with human bone.

Research Progress of Cryogenic Materials for Storage and Transportation of Liquid Hydrogen

Liquid hydrogen is the main fuel of large-scale low-temperature heavy-duty rockets, and has become the key direction of energy development in China in recent years. As an important application carrier in the large-scale storage and transportation of liquid hydrogen, liquid hydrogen cryogenic storage and transportation containers are the key equipment related to the national defense security of China’s aerospace and energy fields. Due to the low temperature of liquid hydrogen (20 K), special requirements have been put forward for the selection of materials for storage and transportation containers including the adaptability of materials in a liquid hydrogen environment, hydrogen embrittlement characteristics, mechanical properties, and thermophysical properties of liquid hydrogen temperature, which can all affect the safe and reliable design of storage and transportation containers. Therefore, it is of great practical significance to systematically master the types and properties of cryogenic materials for the development of liquid hydrogen storage and transportation containers. With the wide application of liquid hydrogen in different occasions, the requirements for storage and transportation container materials are not the same. In this paper, the types and applications of cryogenic materials commonly used in liquid hydrogen storage and transportation containers are reviewed. The effects of low-temperature on the mechanical properties of different materials are introduced. The research progress of cryogenic materials and low-temperature performance data of materials is introduced. The shortcomings in the research and application of cryogenic materials for liquid hydrogen storage and transportation containers are summarized to provide guidance for the future development of container materials. Among them, stainless steel is the most widely used cryogenic material for liquid hydrogen storage and transportation vessel, but different grades of stainless steel also have different applications, which usually need to be comprehensively considered in combination with its low temperature performance, corrosion resistance, welding performance, and other aspects. However, with the increasing demand for space liquid hydrogen storage and transportation, the research on high specific strength cryogenic materials such as aluminum alloy, titanium alloy, or composite materials is also developing. Aluminum alloy liquid hydrogen storage and transportation containers are widely used in the space field, while composite materials have significant advantages in being lightweight. Hydrogen permeation is the key bottleneck of composite storage and transportation containers. At present, there are still many technical problems that have not been solved.

Texture and grain boundary engineering in electrodeposited SnCu coatings and its effect on coating corrosion behaviour

ABSTRACT SnCu coatings (Cu between 0–33.0 at.%) were electrodeposited over mild steel. Corrosion analysis was performed over mirror polished SnCu coatings to remove surface morphology effect. Highest corrosion resistance was observed for the SnCu coating with ∼21.2 at.% Cu and lowest corrosion resistance was observed for the SnCu coating with ∼9.9 at.% Cu. Sn-rich phase and Cu6Sn5 intermetallic were present in all the coatings. For lower Cu content (∼6.0 at.% Cu), a significant fraction of Cu was found to be incorporated into the Sn rich solid solution phase, thus increasing strain within the grains. As the Cu content increased, the Cu6Sn5 phase formed predominantly at the Sn-rich phase grain boundaries. For the Sn rich phase, a preferred crystallographic orientation along the (001) was observed in SnCu coating with lower Cu content (Cu < 10 at.%). On the other hand, at high Cu content (Cu > 20 at.%), the low surface energy (100) texture was dominant. Addition of Cu decreased the Sn-rich phase grain size. The SnCu coating with ∼21.2 at.% Cu exhibited highest fraction of low angle grain boundaries (LAGBs) and low energy twin boundaries. It was established that the presence of low surface free energy (100) atomic planes exposed to corrosive medium, a high fraction of LAGBs, and low energy twin boundaries yields high corrosion resistance for SnCu coating with 21.2 at.% Cu, while a strong (001) texture and high strain within the grains, increased the corrosion susceptibility of the SnCu coating with ∼9.9 at.% Cu.

Effects of eucommia gum filler on the dielectric properties and chemical resistances of addition-cure liquid silicone rubber

It is of great interest and remains a challenge to simultaneously improve the low dielectric properties and chemical resistances of addition-cure liquid silicone rubber (ALSR). In this work, we proposed an efficient approach to address this issue by filling silicone-modified Eucommia ulmoides gum nanofiller (SEUG) into ALSR. By adding 5 wt% SEUG, the dielectric constant of the SEUG/ALSR composite rubber was significantly lower than that of neat ALSR both at 102 Hz, 103 Hz, and 104 Hz. Simultaneously, the SEUG/ALSR composite rubber exhibited better mechanical and insulation properties than the neat ALSR after HCl, NaCl, and oil resistance tests. Our findings demonstrated the great potential for fabricating silicone rubber with low dielectric properties and erosion resistance by the utilization of natural biomass rubber material, endowing it with excellent mechanical performance and degradability.

Enhanced Degradability of Mg-2Gd Alloy by Alloying Cu

To obtain alloys with both high degradability and plasticity used in the petroleum industry, 0.25, 0.5, 0.75 and 1.0 wt.% Cu were added into Mg-2Gd alloy. With Cu addition, finer grain size, precipitation of Mg2Cu, and variations of crystal orientation were observed. Regardless of the good mechanical properties gained by alloying Cu, the degradation rate was obviously increased in this study. The corrosion rate and I corr of Mg-2Gd were 13.0 ± 0.1 mm·y−1 and 1.04 × 10−4 A·cm−2, respectively, while those value of Mg-2Gd-1Cu increased to 226.4 ± 6.1 mm·y−1 and 3.42 × 10−4 A·cm−2, respectively. We confirmed by scanning Kelvin probe force microscopy and scanning electron microscope with electron backscatter diffraction detector that profuse second phases (mainly Mg2Cu), refinement of grain size, and weakened rare earth texture contributed to the lower corrosion resistance.

Effect of calcium oxide particle size on microstructure and properties of AZ91 Mg alloy

The effects of calcium oxide (CaO) particle size on the microstructure and properties of AZ91 alloy were investigated using commercial AZ91 (Mg-9Al-1Zn, wt%) alloy and CaO nano (50 nm), sub-micro (200 nm, 500 nm) and micro (1000 nm) particles as grain refiners. The results showed that the grain size of AZ91 alloy decreased non-linearly with the increase of CaO particle size from nano to micro. When the particle size was sub-micro (500 nm), the grain size decreased from 167.8 µm to the lowest value of 33.7 µm. Due to the in-situ replacement reaction between CaO and Mg matrix, a newly formed Al2Ca phase distributed uniformly, consuming elemental Al, which greatly reduced the content of the β-Mg17Al12 phase. As a result, AZ91-CaO500 nm alloy has relatively high mechanical properties and corrosion resistance. In addition, the research revealed that nano-CaO particles were too small to melt into AZ91 alloy completely and undissolved CaO particles residual in the form of a mixed aggregate, resulting in lower mechanical properties and corrosion resistance of AZ91-CaO50 nm alloy compared with AZ91-CaO500 nm alloy, and even lower than other alloys in this study.

The role of bedrock and climate for the Late Quaternary erosive-depositional behavior of an intraplate tropical river: The Tietê River case, southeastern Brazil

The evolution of fluvial systems has been related to tectonics and climate controls across various spatiotemporal scales. Despite the growing efforts to investigate the effects of those controls in the fluvial dynamics, there is a lack of studies in intraplate tropical regions. Here, we applied geomorphological, sedimentological, and optically stimulated luminescence dating (OSL) techniques to investigate the effects of climate and tectonic factors on the evolution of the Upper and Middle Tietê River during the late Quaternary, especially concerning alluvial aggradation and terraces formation. The Tietê River is one of the most important rivers of southeast Brazil, flowing from crystalline steep to sedimentary low-relief intraplate terrains, in an area with evidence of Cenozoic tectonics and under tropical monsoon climate. We recognized one fluvial terrace level in the Upper Tietê valley and a sequence of seven terraces, from 2 to 105 m above the channel level, in the Middle Tietê. These terraces are formed by thin deposits (<10 m), composed of sandy and gravelly sediments. The terraces of the Upper Tietê and the high and intermediate terrace levels of the Middle Tietê River are strath, while the low terraces of the middle reach are cut-and-fill. Lithological shifts and structural features of the watershed terrain play a strong control in the occurrence and distribution of these terrace levels. The Serra de Paranapiacaba, a regional knickzone, hinders the lowering of the base level and the river incision to upstream, limiting the formation and preservation of terraces in high topographic levels in the Upper Tietê. The formation of seven terrace levels in the Middle Tietê River was controlled by the combination of low erosion resistance of the lithological substrate and high stream power and coarse bedload that increased the erosion efficiency of the channels. Thus, the influence of intraplate tectonics on the fluvial landscape is restricted to passive controls by exhumated basement structures from older tectonic events. OSL dating of sedimentary deposits in different terrace levels indicate five periods of aggradation in the Middle Tietê valley since 18 ka: 17.7 ± 1.7 ka; 9.8 ± 1.0 to 8.6 ± 0.8 ka; 7.1 ± 0.7 to 5.8 ± 0.5 ka; 4.2 ± 0.4 to 3.1 ± 0.3 ka; and 0.6 ± 0.06 ka. The results indicate that changes in the activity of the South American Monsoon System induced changes in vegetation cover and water discharge in the river valleys of southeastern Brazil over the past 18 ka. The aggradation periods are correlated with drier environmental conditions and sparser vegetation. In contrast, valley incision occurred under transitions to wetter environmental conditions and was potencialized by vegetation recovery. Therefore, climate-induced changes in the water discharge were the main allogenic control on the late Quaternary landscape evolution.

Evolution of gradient structured layer on AZ91D magnesium alloy and its corrosion behaviour

This article investigates the microstructure evolution and corrosion response of surface mechanical attrition treated (SMAT) AZ91D magnesium alloy. In-depth transmission electron microscopy and combined isothermal calorimetry and pressure measurement technique, a novel and powerful tool for in situ monitoring of the magnesium corrosion process, are explored in the present study. A gradient structured layer of ~ 500 µm thickness with improved (~2.5 times) surface hardness is successfully obtained on the AZ91D alloy surface. SMAT introduces compressive residual stress in the treated layer. TEM results confirmed nanoscale grains of ~125 nm in topmost region and multiple deformation twin-modes, including 101¯2〈101¯1〉 dense twins and 101¯1 – 101¯2 double twinning in SMATed layer. Twining of secondary twins is established in the TEM analysis. Moreover, a twin density gradient is evident within the treated layer, where it decreases with an increase in depth. After 24 h of immersion in 0.9% NaCl solution, the average corrosion rate of SMATed and non-SMATed specimens is ~11.0 and ~3.8 mm/year, respectively. The corrosion product on non-SMATed specimens has densely packed nano-flakes morphology; however, the SMATed surface shows two different morphologies: sparse nanowires and porous honeycomb-like structure. The SMATed specimen's lower corrosion resistance is attributed to the combined effect of the high density of defects, rougher surface, and smaller volume fraction of β phase at the surface.

Controllable preparation of Ti/TiO2-NTs/PbO2–CNTs–MnO2 layered composite materials with excellent electrocatalytic activity for the OER in acidic media

High oxygen evolution overpotential and low corrosion resistance are the main challenges for oxygen evolution materials in acidic media. In this study, a novel composite material, Ti/TiO2-NTs/PbO2–CNTs–MnO2, with high oxygen evolution electrocatalytic activity was successfully prepared. First, TiO2 nanotubes (TiO2-NTs) were synthesized in situ on a Ti sheet via anodization and used as an intermediate layer. Subsequently, the adhesion and conductivity of the TiO2-NTs layer were increased through additional anodization, annealing, and electrochemical reduction. Finally, PbO2 was electrodeposited with a constant current in a lead acetate medium and doped with carbon nanotubes (CNTs) and MnO2. The surface morphology, phase composition, and electrochemical performance of the composite materials were investigated. Notably, in an acidic electrolyte (150 g/L H2SO4), Ti/TiO2-NTs/PbO2–CNTs–MnO2 exhibited good stability (30 h) and a low oxygen evolution overpotential of 410 mV at 50 mA/cm2, which is almost equivalent to that of precious metals (RuO2 and IrO2) and 499 mV lower than that of the industrial Pb–0.76 wt% Ag alloy. The outstanding performance is mainly attributed to the high aspect ratio of the TiO2-NT structure, synergistic effects of the active particles, and inherently good electrochemical properties of the active particles. Therefore, this study provides a new synthetic route for oxygen evolution materials in acidic media.

Synthesis and Assessment of Two Malonyl Dihydrazide Derivatives as Corrosion Inhibitors for Carbon Steel in Acidic Media: Experimental and Theoretical Studies.

Despite the extensive use of carbon steel in all industrial sectors, particularly in the petroleum industry, its low corrosion resistance is an ongoing problem for these industries. In the current work, two malonyl dihydrazide derivatives, namely 2,2’-malonylbis (N-phenylhydrazine-1-carbothiamide (MBC) and N’1, N’3-bis(-2-hydroxybenzylidene) malonohydrazide (HBM), were examined as inhibitors for the carbon steel corrosion in 1.0 M HCl. Both MBC and HBM were characterised using thin-layer chromatography, elemental analysis, infrared spectroscopy, and nuclear magnetic resonance techniques. The corrosion tests were performed using mass loss measurements, polarisation curves, and electrochemical impedance spectroscopy. It is obtained from the mass loss studies that the optimal concentration for both inhibitors is 2.0 × 10−5 mol/L, and the inhibition efficiencies reached up to 90.7% and 84.5% for MBC and HBM, respectively. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) indicate an increased impedance in the presence of both MBC and HBM and mixed-type inhibitors, respectively. Both inhibitors can mitigate corrosion in the range of 298–328 K. Values of free energy changes obtained from the Langmuir model suggest that the inhibitors suppress the corrosion process principally by chemisorption. The computational investigations were conducted to identify the factors connected with the anti-corrosive properties of the examined inhibitors.

A novel TiZrNb medium entropy alloy (MEA) with appropriate elastic modulus for biocompatible materials

A simple equiatomic TiZrNb medium entropy alloy (MEA) for biocompatible materials was designed by mismatch-parameter-related strengthening and prepared by arc melting. Then the alloy was cold rolled with different single pass reductions and finally annealed. All samples including as-cast, cold-rolled and annealed TiZrNb MEAs possessed BCC structure, exhibiting elastic modulus of 72 ± 3 GPa under tensile, closer to that of human bone than Ti6Al4V. The samples treated by different rolling processes had yield strength of 910 ± 25 MPa and 1060 ± 21 MPa respectively, higher than 830 ± 21 MPa of as-cast sample. Their strength decreased and the elongation increased after annealed, and an obvious work hardening caused by fine-grain strengthening appeared in tensile deformation. Furthermore, electrochemical behavior exhibited that corrosion resistance of samples were equivalent to that of Ti6Al4V in PBS. In a summary, the new TiZrNb MEAs with great mechanical properties, lower elastic modulus and good corrosion resistance has great potential in biomedical field.

Precipitation-dependent corrosion analysis of heat treatable aluminum alloys via friction stir welding, a review

Although the various advantages of novel Friction stir welding (FSW) process; the weld surfaces are subjected to various serious problems such as lower corrosion resistance, high susceptibility to stress corrosion cracking and poor joint fatigue strength due to complex material flow and severe plastic deformation during the welding process. Corrosion behaviour of friction stir welded (FSWed) precipitate strengthening Al alloys have significant impact on metallurgical and electrochemical properties of structures. In FSW of precipitate strengthening Al alloys the localized heat input and severe plastic deformation creating appreciable changes in microstructure and modifies the microchemistry and metallurgical characteristics of precipitates. The heterogeneous distribution of precipitates and precipitate free zones (PFZs) along the grain boundaries leads to variation in electrochemical behaviour across the weld zones and hence increasing the susceptibility of weld surface to various corrosion attacks such as intergranular corrosion, pitting corrosion, exfoliation corrosion, stress corrosion cracking and galvanic corrosion. However, the corrosion resistance of FSWed joints can be improved either by reducing the size or redissolve the coarsened precipitates within the joint or modifying the microchemistry by controlling the size, location and distribution of precipitates which largely determine the corrosion rate of the weld surfaces. Consequently, it is imperative to address the influence of material modifications during FSW on corrosion behaviour of weld surface. This review paper addresses the precipitate dependent corrosion behaviour of FSWed joints of heat treatable/precipitate strengthening Al alloys and the various effective methods either to reduce or eliminate the effect of corrosion attack in FSWed joints of heat treatable Al alloys.

In vitro corrosion-fatigue behavior of biodegradable Mg/HA composite in simulated body fluid

Magnesium and its composites as biodegradable materials offer especial capabilities to be used as bio-absorbable implants. However, their poor corrosion and fatigue properties in the physiological environment can restrict their applications. In this study, corrosion-fatigue tests have been performed on the extruded magnesium and magnesium/hydroxyapatite (Mg/HA) composites in a high cycle regime. To produce the composites, pure magnesium was reinforced by 2.5 wt.% and 5 wt.% of hydroxyapatite submicron particles using an electromagnetic-mechanical stirring method and hot extrusion process. The experimental density measurement exhibits that the porosity increases in the extruded samples with more hydroxyapatite particles. To investigate the corrosion and corrosion-fatigue behavior of the specimens, simulated body fluid (SBF) was used during in vitro tests. The results of the potentiodynamic polarization corrosion test show that the composite with 2.5 wt.% of hydroxyapatite (Mg/2.5 wt.% HA) and the pure magnesium specimen exhibit the highest and the lowest corrosion resistance, respectively. Regarding the elemental mapping analysis of the corroded samples, this behavior could be due to the formation of strong phosphorus-calcium based layers on the composite surface. The results obtained from the mechanical tests indicate that Mg/5 wt.% HA offered the highest tensile and compressive yield strengths, as well as the most promising high cycle fatigue behavior. During the corrosion-fatigue test, the simultaneous effects of fatigue and corrosion damages led to a similar corrosion-fatigue behavior in both composites. The fracture surfaces of the corrosion-fatigue samples suggest that the cracks are initiated in the corroded regions of the samples surface, which reduces the crack initiation step and subsequently decreases the fatigue life. In comparison with the pure magnesium, both composites exhibit more promising corrosion and corrosion-fatigue behaviors with a significant fatigue life improvement in the physiological environment.

Effects of laser shock peening on the hot corrosion behaviour of the selective laser melted Ti6Al4V titanium alloy

The effects of laser shock peening (LSP) on the hot corrosion behaviour of the selective laser melted (SLMed) Ti6Al4V titanium alloy were investigated. The results indicated that the SLMed specimen exhibited a significantly lower hot corrosion resistance in comparison to the SLM-LSPed specimen. In addition, high-density dislocations and a large number of nano-twins were generated after LSP treatment, which contributed to the grain boundary effect in the surface layer. The coupling effect of LSP-induced grain boundary effect and plastic deformation effectively improved the hot corrosion resistance of the SLMed Ti6Al4V.

Improvement on flame retarding performance: preparation and characterization of water-based indoor paints with addition of boric acid

The design of a fire-protection of the construction materials for buildings has become necessary to reduce the risk of a serious fire with the increasing population and increasing urbanization. During a fire, to extend the time of interfering with a building, water-based indoor paints have received attention; however, the performance and flame retardant property of these paints need to be improved. In this study, boric acid, which is the product of boron, was chosen as an additive for a flame retardant to develop this performance of the prepared paints due to its advantages such as a low toxicity, odorless, colorless, and corrosion resistance. In order to investigate the effect of different weight ratios of boric acid, water-based indoor paints have been prepared with the addition of 5%, 10%, and 20% (w/w) of boric acid. In addition, the synergistic effect of boric acid and melamine on the flame retarding performance of the prepared paints was also investigated. The physicochemical properties, flammability characteristics and thermal properties were analyzed by Fourier transform infrared spectroscopy (FTIR), limiting oxygen index (LOI), and thermogravimetric analysis (TGA), respectively. The results demonstrated that the characteristic peaks of boric acid were observed in the prepared paints. The prepared sample (P6) including 20% (w/w) of boric acid showed a more significant enhancement in flammability behavior from 24% to over 55% than that of containing melamine and boric acid. Moreover, the results of the thermogravimetric analysis demonstrated that increasing the amount of boric acid showed more effectiveness on the property of flame retardancy among the prepared paints due to the result of the mass-loss rate. In conclusion, the prepared indoor paint, P6, has served as a suitable option to halogen-based paints for the enhancement of the flame retardancy of the water-based indoor paints.

Selective electrochemical H2O2 generation on the graphene aerogel for efficient electro-Fenton degradation of ciprofloxacin

• Graphene aerogel was prepared by the ethylenediamine reduced self-assembly. • Graphene aerogel had high selectivity for two-electron oxygen reduction reaction. • The ciprofloxacin was efficiently mineralized in Electro-Fenton system. • The graphene aerogel as cathode showed good stability and reusability. A novel cathode of macroporous graphene aerogel (GA) with high specific surface area was proposed for the electro-Fenton (E-Fenton) system. The GA was prepared by reduction self-assembly method. The physicochemical properties were characterized in details. The GA displayed a low electrochemical resistance and exhibited an excellent electrocatalytic activity. Comparing with the traditional carbon fiber and graphite felt cathodes, the GA cathode showed more positive oxygen reduction potential of 0.07 V (versus saturated calomel electrode). In E-Fenton system, H 2 O 2 could be in situ electro-generated efficiently and continuously via a two-electron oxygen reduction reaction on the GA cathode. The electron transfer number n was calculated to be 1.0–2.0 for GA. The production of H 2 O 2 of 107.6 mg L −1 was obtained for GA in 90 min. Good performance was exhibited to degrade antibiotic ciprofloxacin. Results showed that nearly 100% ciprofloxacin degradation ratio and 91% TOC removal were achieved in 90 min and 120 min, respectively, which were much higher than control groups. The mineralization current efficiency was 12.75% in 30 min. It was attributed to the plenty of macro-pores of GA acted as reaction trap to accelerate electro-generated H 2 O 2 decomposing by Fe 2+ to form ·OH efficiently, which was verified by probe molecule trapping experiments and electron paramagnetic resonance analysis. Simultaneously, the strong charge transfer ability of GA was beneficial to the conversion of Fe 3+ /Fe 2+ . The GA also presented distinguished reusability and stability. Therefore, GA is a promising candidate material for E-Fenton cathode due to low cost, high efficient and corrosion resistance.

Ultra-thin pine tree-like MoS2 nanosheets with maximally exposed active edges terminated at side surfaces on stainless steel fiber felt for hydrogen evolution reaction

High active edge sites guarantee MoS2 as a promising electrocatalyst alternative for the costly Pt based materials. However, the inherent high surface energy nature of the layer edges thermodynamically blocks the large scale synthesis, and meanwhile poses instability problems. In this work, vertically grown ultra-thin MoS2 nanosheets with a large proportion of exposed edges on commercially available 316L stainless steel fiber felts (SSF) via a simple one-step kinetically controlled hydrothermal process is reported aiming for electrocatalytic H2 production. Notably, the synthesized MoS2 nanosheet presents a three dimensional pine tree-like structure featured by the maximally exposed active edges toward side surfaces. Abundant gaps between the MoS2 nanosheets together with impressive super-hydrophilic property assure the large density of effective edge sites that accessible to electrochemical reaction and the rapid desorption of H2 products, and thus high intrinsic hydrogen evolution reaction (HER) activity. In addition to those electrochemically desired properties, the reliable contact of the MoS2 sheet on the SSF substrate together with the low price, porosity, high conductivity and high chemical corrosion resistance properties of the SSF substrate guarantee the MoS2/SSF electrode as an efficient and durable HER electrode in both strong acidic and alkaline medium for potential commercial applications.

Morphologic and synergistic effects of GNP/NS binary-filler-based multifunctional coatings with robust anti-corrosion and hydrophobic properties

Traditional protective coatings used for metallic structures, such as oil/gas metallic pipelines and bridges, often suffered from premature damage due to either low corrosion resistance or weak mechanical performance. Thus, this study proposed a new nanocomposite coating that reinforced by binary nanofillers with graphene nanoplatelets (GNP) and nano-silica (NS) with multiple functionalities, striving for superior corrosion resistance and hydrophobic properties, as well as promising mechanical damage tolerances. A comprehensive experiment was conducted to characterize their mechanical, electrical, and tribological properties of the new developed nanocomposite coatings. The corrosion protection performance of the coatings was evaluated by electrochemical impedance spectroscopy (EIS) and long-term accelerated salt spray test. Tribological properties were evaluated using abrasion test. Test result demonstrated that the new composite with the combination of GNP with NS exhibited significantly improved corrosion protection performance, mechanical strength, and abrasion resistance. The GNP/NS hybrid filler nanocomposites remarkably enhanced the barrier and corrosion protection properties against environmental attack. Enhanced mechanical properties and wear resistance of the composite coatings allows high damage tolerance for engineering applications.

A systematic review of pure metals reinforced plastic composites

In conjunction with the pressing and rising needs to develop improved materials for modern tastes and demands, developing metal-reinforced plastic composites is equally a key aspect of solid waste management. In this study, the literature on pure metal-reinforced plastic composites was systematically reviewed to catalogue key findings, observe trends in results, evaluate the progress of the research area and predict future perspectives. The major metals used as fillers in plastic composites are aluminium, copper and iron and the most used polymer is epoxy. Aluminium is the most popular metal used due to its low cost, corrosion resistance, availability and excellent thermal and electrical properties. Studies preferred manual mixing, hand layup and casting for the composite production. Parametric studies have delved into the factor-response relationships for filler content against morphological, physical, electrical, thermal and mechanical properties of the composites. The nature of the base plastic resin had a greater influence on the electrical properties of the plastics and the conductivities of the composites in terms of their base resin was in the order PS > EP > PVC. Tribological investigations revealed that wear rate increased with increasing test load and speed and that increase in metal fillers was led to greater wear resistance. From the review, the need to gain further knowledge on the corrosion characteristics, flame retardation ability and effect of other process factors were noted. Metal reinforced plastic composites can be served as semiconductors, dielectric materials, ballistic protections, building panels and aircraft materials. Investigations and breakthroughs in this research area would be invaluable to many of other areas in science and technology.

Accelerated curing of adhesively bonded G-FRP tube connections — Part I: Experiments

In the wake of the industry-wide trend towards lightweight construction, fibre-reinforced polymers (FRP) gradually established as an alternative to traditional materials. They are used in particular when low weight, high strength or high corrosion resistance is required. For joining FRP components, adhesive bonding is increasingly preferred to mechanical fasteners as poorer transfer of loads resulting from interrupted fibres represents problematic. Despite all the technical advantages, adhesive bonding remains a comparatively slow joining process that is usually bound to limited manufacturing temperatures. This article shows, by means of experimental investigations performed on bonded FRP tubes, that curing by inductive heating of the adhesive bond can compensate for both disadvantages. For that, particles susceptible to electromagnetic fields (EMF) were added to two adhesives, a two component epoxy (2 K-EPX) and polyurethane (2 K-PUR), and the effect thereof on the adhesive was assessed. The particles consisted of Curie material (Curie particles, CP), which relieved all requirements regarding temperature control during the induction process. Subsequently, G-FRP single lap tubular joints (SLTJ) were assembled, cured following different protocols, and subjected to tensile tests. During the process, curing temperatures were monitored using appropriate measuring techniques. Mechanical testing showed that inductively cured SLTJ achieved equal or higher shear strengths, if compared to reference sets cured following the instructions given by the adhesive manufacturers. The results showed that adhesive type as well as curing conditions, in most cases had no significant influence on joint strength, which was verified by means of an analysis of variance. Summing up, inductive heating using CP proved effective in controlling temperatures without any external control, and yielded very high joint strengths with a reduction in curing time by the factor of 100 for the epoxy and 1400 for the polyurethane.