Outstanding Corrosion Resistance Research Articles

Partial Sulfidation Strategy to NiFe‐LDH@FeNi2S4 Heterostructure Enable High‐Performance Water/Seawater Oxidation

AbstractThe development of a high‐performance electrocatalyst for oxygen evolution reaction (OER) is imperative but challenging. Here, a partial sulfidation route to construct Ni2Fe‐LDH/FeNi2S4 heterostructure on nickel foam (Ni2Fe‐LDH/FeNi2S4/NF) by adjusting the hydrothermal duration is reported. The heterostructures afford abundant hydroxide/sulfide interfaces that offer plentiful active sites, rapid charge and mass transfer, favorable adsorption energy to oxygenated species (OH− and OOH) evidenced by the density functional theory calculations, which synergistically boost the alkaline water oxidation. In the 1.0 m KOH solution, Ni2Fe‐LDH/FeNi2S4/NF exhibits an excellent OER catalytic activity with a much smaller overpotential (240 mV) to reach the current density of 100 mA cm−2 than single‐phase Ni2Fe‐LDH/NF (279 mV) or FeNi2S4/NF (271 mV). More impressively, 2000 cycles of cyclic voltammetry scan for water oxidation results in the formation of a sulfate layer over the catalyst. The corresponding post‐catalyst demonstrates better OER activity and durability than the initial one in the alkaline simulated seawater electrolyte. The post‐Ni2Fe‐LDH/FeNi2S4/NF delivers smaller overpotential (250 mV) at 100 mA cm−2 and longer stability time than the original form (260 mV). The post‐formed sulfate passivating layer is responsible for the outstanding corrosion resistance of the salty‐water oxidation anode since it can effectively repel chloride.

Zirconium based neutron absorption material with outstanding corrosion resistance and mechanical properties

Zirconium hafnium (ZrHf) alloy with potential performance in spent nuclear fuel reprocessing was designed and investigated. Results showed that ZrHf alloy exhibited better mechanical and corrosion properties, compared with that of Zr702. Furthermore, the oxide film of ZrHf alloy was stable and compact owing to higher thermodynamic stability and highest Rct value (e.g. corrosion rates < 0.007 mm/y and Rct was 32.53 KΩ·cm2 of ZrHf alloy). Monte Carlo calculations showed the thickness of the ZrHf alloy was only 12 cm for completely absorbing neutrons with the energy of 100 keV, whereas the thickness of the Zr702 was 24 cm.

An additively manufactured magnesium-aluminium alloy withstands seawater corrosion

Magnesium, the lightest structural metal, has inherently poor corrosion resistance. In this study, we developed a magnesium-aluminium Mg-10.6Al-0.6Zn-0.3Mn alloy, additively manufactured by laser powder bed fusion. We reveal that this alloy has a record low degradation rate amongst all magnesium alloys in practically relevant corrosive solutions, and it even withstands seawater corrosion. As tested by a number of methods, the alloy shows even more enhanced passivation with longer immersion periods. The alloy surface following immersion maintained a nearly corrosion-free appearance and was determined to have a thin aluminium-containing surface film, due to surface enrichment of aluminium from the supersaturated matrix. Aluminium enrichment near the sample surface was also observed when the sample is immersed in phosphoric acid or exposed to atmosphere at room temperature. This study demonstrates the prospects for additively manufactured ultra-lightweight magnesium structure with outstanding corrosion resistance.

Microstructures and properties of nickel-titanium carbide composites fabricated by laser cladding

In this work, Ni/TiC composites were synthesized by the laser cladding technique (LCT). A scanning electron microscope (SEM), X-ray diffractometer (XRD), microhardness meter, electrochemical workstation, and friction and wear tester examined the microstructure, surface morphology, phase structure, microhardness, wear, and corrosion resistances of the Ni/TiC composites. These results indicated the Ni/40TiC composite contained finer equiaxed crystals than the Ni and Ni/20TiC composites. In addition, numerous TiC particles in the Ni/40TiC composite impeded growth of the nickel crystals, which resulted in the fine microstructure of the Ni/40TiC composite. The Ni, Ni/20TiC, and Ni/40TiC composites exhibited face-centered cubic (f c c) lattices. The average microhardness values of the Ni/20TiC and Ni/40TiC composites were approximately 748 HV and 851 HV, respectively. The Ni/40TiC composite had the lowest friction coefficient (0.43) among all three coatings, and only some shallow scratches appeared on the surface of the Ni/40TiC composite. The corrosion potential (E) of Ni/40TiC exceeded the Ni/20TiC composite, and both were larger than the Ni composite, which indicated the Ni/40TiC composite had outstanding corrosion resistance and the Ni composite had poor corrosion resistance. The corrosion current densities (i) of Ni, Ni/20TiC, and Ni/40TiC composites were 5.912, 4.405, and 3.248 μA/cm2, respectively.

Fabrication of superhydrophobic bio-based polybenzoxazine/hexagonal boron nitride composite coating for corrosion protection

Superhydrophobic coatings have attracted much attention in the field of anti-corrosion due to their excellent water repellency. In this work, a superhydrophobic bio-based polybenzoxazine/hexagonal boron nitride composite coating was fabricated for the corrosion resistance of mild steel (MS). Hexagonal boron nitride (h-BN) particles were introduced into cardanol/stearylamine-based benzoxazine (C-s) to construct a rough surface and enhance the stability of the coating. Gallic acid (GA), a natural polyphenol, was used as a curing agent to catalyze the ring-opening polymerization of benzoxazine. The differential scanning calorimetry results showed that GA could reduce the curing peak temperature of C-s from 260 °C to 173 °C. The as-prepared superhydrophobic coating (PC-s/GA/BN), of which the static water contact angle was 158.2 ± 2.4°, could withstand temperature treatments of −20 °C to 250 °C or acid/alkali immersion of pH values from 1 to 11 for 1 h. Furthermore, the PC-s/GA/BN coating could still maintain outstanding corrosion resistance after being immersed in 3.5 wt% NaCl aqueous solution for 30 days. This kind of stable superhydrophobic benzoxazine-based coating has great potential in the field of anti-corrosion.

High-efficiency oil-water separation and passive radiant cooling performance of nano-ZnO- embedded dust-free paper

Developing a flexible nano-composite material which is not only impermeable to low-polar oil, but also has the ability of daytime radiation cooling, remains a huge challenge for both academia and industry. By modifying the fiber network of the dust-free paper using nano-ZnO particles (ZnO-DF), we strategically designed and demonstrated dual capabilities of superhydrophilicity/superoleophobicity and daytime radiant cooling for the flexible cellulose nano-composite simultaneously. A superior surface with superhydrophilic/superoleophobic (oil contact angle up to 159° and water contact angle down to 0°) was attained by regulation of surface energy components and roughness. Furthermore, the materials revealed outstanding corrosion and mechanical damage resistance, 152,788 L m−2 h−1 high permeation flux and >99.2% continuous and efficient oil-water separation performance. In addition, a cooling effect of about 5.6 °C of ZnO-DF paper could be achieved by cooperative function of both radiative cooling and sweat evaporation. It is expected that the ZnO-DF paper is promising for the thermal management of wearable products integrated with passive radiant cooling, phase change cooling (e.g., sweat evaporation) and large-scale industrial oil-water separation.

Wire + Arc Additive Manufacturing and Heat Treatment of Super Martensitic Stainless Steel with a Refined Microstructure and Excellent Mechanical Properties.

Due to the advantages of relatively low cost, increased energy efficiency, increased deposition rate, and the capacity to create medium to large scale components, wire + arc additive manufacturing (WAAM) has gained growing interest. Super martensitic stainless steel (SMSS) combines outstanding strength, ductility, and corrosion resistance, making it a great option for WAAM. In the present work, an SMSS component was successfully produced by WAAM. Additionally, the influence of post-manufactured heat treatment on the microstructural characteristics and mechanical properties of SMSS components was systematically examined. A microstructural analysis of the as-printed and heat-treated samples revealed the formation of typical martensite and a small amount of retained austenite. However, the sample heat-treated by solutionizing at 1050 °C for 1 h followed by aging at 400 °C for 2 h exhibited a finer martensitic structure with an effective grain size of 5.6 μm compared to as-printed sample, leading to an increase in ultimate tensile strength from 1054 ± 6 MPa to 1141 ± 3 MPa with a concomitant increase in elongation from 7.8 ± 0.4% to 12.6 ± 0.2%. Additionally, the fracture morphology of the solution + aging sample demonstrated a more uniform distribution and greater mean size of dimples, indicating better ductility.

Synthetic polyaniline-boron nitride-aqueous epoxy resin composite coating for improving the corrosion resistance of hot-dip galvanized steel plates

Polyaniline (PANI) was covalently linked with hexagonal boron nitride (BN) using p-aminobenzoic acid (ABA) to obtain a PANI-BN powder. The PANI-BN/EP coating was applied on hot-dip galvanized steel, which exhibited remarkable corrosion resistance. Electrochemical test results showed that the impedance modulus in the low-frequency region of PANI-BN/EP was maximum after soaking in NaCl solution (3.5 wt.%) for 72 h compared with other coatings. The outstanding corrosion resistance of the PANI-BN/EP coating was primarily attributed to the synergistic effect of BN and PANI.

Simultaneous incorporation of gallium oxide and tantalum microparticles into micro-arc oxidation coating of titanium possessing antibacterial effect and stimulating cellular response.

Orthopedic implants with both osteogenesis and antibacterial functions are particularly promising for bone repair and substitutes. In this study, a micro-arc oxidation (MAO) coating containing titanium dioxide (TiO2), gallium oxide (Ga2O3) and tantalum oxide (Ta2O5) on the titanium surface (MGT) was fabricated by dispersing Ga2O3 and Ta microparticles in the electrolyte. The results showed that the simultaneous incorporation of Ga2O3 and Ta microparticles into the MAO coating resulted in optimized surface performance (e.g., micro-topography, roughness, wettability, surface energy, and protein absorption) of MGT compared with pure titanium (pTi). In addition, MGT exhibited outstanding corrosion resistance owing to the presence of both Ga2O3 and Ta microparticles, which exhibit excellent corrosion resistance and their microparticles were incorporated into the micropores of the coating. Moreover, MGT with good cytocompatibility and optimized surface resulted in improved cellular responses (e.g., proliferation and osteogenic differentiation) of rat bone mesenchymal stem cells, which was attributed to Ta microparticles with outstanding osteogenic bioactivity. Furthermore, the excellent antibacterial effect of MGT was attributed to the slow release of Ga3+ from the coating. Thus, the simultaneous incorporation of Ga2O3 and Ta microparticles into the MAO coating of MGT exhibited excellent cytocompatibility, osteogenic bioactivity, antibacterial functions, and corrosion resistance, suggesting that MGT possesses great potential for bone repair applications.

Mechanical, Corrosion Resistance Properties and Various Applications of Titanium and Its Alloys: A Review

Titanium (Ti) alloys have been employed for several structural purposes due to high strength, lightweight, temperature toughness, outstanding corrosion resistance and extreme temperature tolerance ability. However, their application for aircraft, military equipment and spacecraft etc. is limited by the exorbitant cost of raw materials and processing. Although, commercially unadulterated titanium exhibits satisfactory mechanical characteristics and has been used for some engineering applications. For many applications, titanium is combined or alloyed with little percentages of alloying elements such as vanadium and aluminium by weight. The combination possesses solid solubility which differs with temperature, enabling it to experience precipitation strengthening. This strengthening effect and effect of heat treatment does not only affect the mechanical and structural properties but alters the tribological and corrosion resistance (CR) properties of the alloys. The CR property of alloys is vital in any structural application and this affects other properties directly or indirectly. Therefore, this review paper examines the properties, classification and applications of Ti and its alloys.

Functionalization of h-BN by the exfoliation and modification of carbon dots for enhancing corrosion resistance of waterborne epoxy coating

The amino-functionalized carbon dots (FCDs) were used as intercalators to exfoliate and modify the boron nitride for obtaining the FCDs/boron nitride nanosheets (BNNS) nanocomposite. The FCDs, BNNS and FCDs/BNNS were respectively dispersed into the waterborne epoxy (WEP) matrix to prepare the corresponding modified WEP coatings on the copper substrate through the spray coating method. Their micro/macro-morphologies, compositions, surface roughness, self-healing and corrosion resistance behaviors were comparatively researched. Electrochemical results and surface morphology observation show that WEP FCDs/BNNS coating possesses the optimal corrosion protection performance after 40 d immersion in 3.5 wt% NaCl solution. And the impedance value (4.97 × 105 Ω cm2) of WEP FCDs/BNNS coating is still about an order of magnitude higher than that of pure WEP coating (3.36 × 104 Ω cm2). In the WEP FCDs/BNNS coating system, BNNS as physical barrier extend the diffusion path of corrosive species and block inherent defects of the coating, thus slowing down the corrosion rate; FCDs as intercalators strip BNNS enhancing its physical barrier effect. Besides, FCDs can also act as the effective corrosion inhibitors, which could adsorb on the exposed or corroded copper surface and hinder the further corrosion. Their synergistic effects of physical barrier performance from BNNS and self-healing capability from FCDs endow the WEP composite coating with outstanding corrosion resistance.

A Co-free Cr-Fe-Ni-Al-Si high entropy alloy with outstanding corrosion resistance and high hardness fabricated by laser surface melting

In this paper, a CrFeNiAl0.2Si0.2 high entropy alloy (HEA) was fabricated via laser-surface melting (LSM). The result shows that, this HEA could form fully BCC structure under such rapid-solidification condition. Moreover, it exhibits excellent corrosion resistance in 3.5 wt% NaCl solution with two-stage passivation, and could maintain good protectiveness until 1.06 V vs SCE during electrochemical polarization, which is much higher than stainless steel. In addition, this rapid-solidified HEA shows high hardness of ∼667 Hv. Such excellent corrosion resistance and unique passivation process are possibly caused by the diversity in compositional constitution of the passive films under different electrochemical corrosion conditions. This work provides a novel route for designing low-cost corrosion-resistant HEAs with high hardness for coating applications.

Microstructure and properties of cold sprayed aluminum bronze coating on MBLS10A-200 magnesium-lithium alloy

Aluminum bronze coatings were prepared on MBLS10A-200 magnesium-lithium alloy substrate by cold spraying technology to improve the surface properties of Mg–Li alloys. The microstructure, phase composition, microhardness, tribological properties and corrosion resistance of the coatings were systematically analyzed. The results show that aluminum bronze coatings are mainly composed of α phase. β phase in the original aluminum bronze powder disappeared in the coating due to the eutectoid transition of β→α + γ2 during the cold spraying. Compared with the Mg–Li alloy substrate, the aluminum bronze coating exhibits the higher microhardness (222.88 HV0.3) and wear resistance (friction coefficients, wear track widths and wear mass losses are 0.37, 0.79 mm and 2.47 mg, respectively). The dominant wear mechanism of the coatings was abrasive wear. In the electrochemical test, the corrosion current density of the aluminum bronze coating (3.07 × 10−5 A/cm2) was an order of magnitude lower than that of Mg–Li alloy substrate (6.15 × 10−4 A/cm2), indicating that the coating had superior corrosion resistance. The above analysis confirms that preparing a cold sprayed aluminum bronze coating has outstanding tribological and corrosion resistance properties.

Microstructured surface generation and cutting force prediction of pure titanium TA2

Titanium and its alloys have widespread applications in aerospace and medical fields due to their outstanding mechanical properties and corrosion resistance. However, very limited attention has been focused on machining the microstructure on their surface and the cutting force prediction during machining. Motivated by this, this study used the ultraprecision diamond surface texturing (UDST) process to generate microstructure on the commercially pure titanium TA2 and established a cutting force prediction model. Firstly, the two special characteristics of UDST are systematically investigated by the finite element simulation and the vibration trajectory analysis. And as a core component of the UDST process, a two-degree-of-freedom vibration generator is presented. Considering the periodical vibration motion, tool geometry, and material properties, a practicable cutting force model is next developed for predicting the dynamic cutting force. Finally, two types of unique microstructures are successfully fabricated on the TA2 surface. Experimental results show that the proposed cutting force model agrees well with the measured results, validating its effectiveness.

The limit of hot isostatic pressing for healing cracks present in an additively manufactured nickel superalloy

Inconel 738LC (IN738LC) is a nickel-based superalloy specially used in the hot section components of turbine engines due to its outstanding hot corrosion resistance and mechanical properties under high temperatures. However, one of the main drawbacks of this superalloy is its susceptibility to cracking when it is manufactured by Laser Powder Bed Fusion (LPBF). This paper describes the effect of 400 W laser power and 90° rotation strategy on the formation of cracks and the capability of Hot Isostatic Pressing (HIP) post-treatment to substantially reduce them in the LPBF manufactured IN738LC samples. Based on the characterization of the cracks, the most important finding from this research work was the identification of the limit of crack width at 6 μm, beyond which the HIP treatment is unable to effect crack healing. Furthermore, this research shows that the HIP treatment leads to microstructural changes in the IN738LC samples with a massive precipitation of γ´ phase. Indeed, the formation of precipitates implied an increase in the microhardness of up to 23 %, which demonstrates that the HIP treatment also affects the mechanical properties of the IN738LC superalloy. It was therefore shown that the HIP treatment could be a crucial process to substantially reduce the defects of the additively manufactured parts.

Introducing cyano-functionalized multiwalled carbon nanotubes to improve corrosion resistance and mechanical performance of poly(arylene ether nitrile) coating

Seeking high-performance coating with long service life to protect metallic substrates under complex corrosion environment has attracted abundant attention in modern industry. In this work, poly(arylene ether nitrile) (PEN) was applied as protective coating on metallic substrates for the first time, and the cyano- functionalized multiwalled carbon nanotubes (MWCNTs-CN) was introduced to further enhance the corrosion resistance and mechanical performance of the PEN coating. Electrochemical results demonstrated that the MWCNTs-CN incorporated composite coating possessed outstanding corrosion resistance that the |Z| 0.01Hz remained 196.9 MΩ cm 2 after 100 days' immersion process in 3.5 wt% NaCl solution, which was 2 orders of magnitude higher than the pure PEN coating. Besides, an evident improvement was investigated from the tensile strength of MWCNTs-CN/PEN coatings, which showed an increment about 20.1% of tensile strength was gained when 1 wt% of MWCNTs-CN was introduced. Benefiting from these advantages, this work is expected to provide a novel insight in high-performance protective coating. The well-dispersed MWCNT-CN fillers are successfully fabricated through the decomposition of AIBN, which significantly enhances the corrosion resistance and mechanical performance of PEN coating. • PEN was applied as protective coating on metallic substrate for the first time. • Dispersion of MWCNTs in PEN is notably enhanced via the cyanogen modification. • The corrosion resistance of MWCNTs-CN/PEN composite coating enhanced sharply. • The mechanical properties of MWCNTs-CN/PEN composite coating increased obviously.

A novel waterborne epoxy coating with anti-corrosion performance under harsh oxygen environment

• The graphene modified by eco-friendly N-CQDs could stably disperse in water for more than 90 days. • A facile spin coating method was designed to fabricate orientated graphene-based waterborne epoxy coating. • The coating exhibited excellent corrosion resistance under harsh oxygen environment. • N-CQDs reinforced interface bonding force and induced the formation of protective film on steel plate surface. • The orientation of graphene maximized the barrier effect of graphene and prevented the formation of conductive network. Waterborne coating is eco-friendly, but exhibits limited anti-corrosion performance. Graphene is an ultrahigh anti-corrosion material for its perfect impermeability. Unfortunately, graphene tends to aggregate and randomly align in waterborne resin to form conductive network to accelerate corrosion. Herein, N-doped carbon quantum dots (N-CQDs) modified graphene (N-CQDs@Gr) was prepared via π-π interactions between N-CQDs and graphene, stably dispersing in water over 90 days and showing good dispersibility and compatibility in waterborne resin. Meanwhile, we designed a spin coating method and successfully fabricated orientated N-CQDs@Gr/waterborne epoxy (N-CQDs@Gr/WEP) coating, which exhibited long-term anti-corrosion performance. The impedance modulus of N-CQDs@Gr/WEP coating was about 200 times higher than that of waterborne epoxy (WEP) coating after 90 days of immersion in 3.5 wt% NaCl solution and still remained above 10 9 ohm cm 2 after 260 days of immersion. The coating also exhibited outstanding corrosion resistance under harsh oxygen environment. After 10 days of immersion in harsh oxygen environment, the coating still protected the metal well, and the impedance modulus of the coating was still maintained above 10 10 ohm cm 2 which was about three orders of magnitude higher than that of WEP coating. The excellent anti-corrosion performance of N-CQDs@Gr/WEP coating was interpreted as the reinforced interface bonding force, the orientation of graphene and the protective film covering metal surface. The orientation of graphene maximized the barrier effect of graphene and avoided the formation of graphene conductive network. The protective film formed in normal environment was mainly N-CQD@Fe 3+ complex film, whereas in harsh oxygen environment was mainly passive film.

Multifunctional Slippery Polydimethylsiloxane/Carbon Nanotube Composite Strain Sensor with Excellent Liquid Repellence and Anti-Icing/Deicing Performance.

In this paper, a multifunctional slippery polydimethylsiloxane/carbon nanotube composite strain sensor (SPCCSS) is prepared using a facile template method. Benefitting from the slippery surface, the SPCCSS shows excellent liquid repellence properties, which can repel various liquids such as oil, cola, yogurt, hot water and some organic solvents. Meanwhile, the SPCCSS has a large strain sensing range (up to 100%), good sensitivity (GF = 3.3) and stable response with 500 cyclic stretches under 20% strain. Moreover, it is also demonstrated that the SPCCSS displays outstanding corrosion resistance (from pH = 1 to pH = 14) and anti-icing (8 min at −20 °C)/photothermal deicing (104 s with NIR power density of 1 W/cm2) properties, broadening its application in extreme acid, alkali and low-temperature conditions. Therefore, the multifunctional SPCCSS with the liquid repellence, anti-corrosion, and anti-icing/deicing properties has potential applications in wearable human motion monitoring tools under complex harsh environments.

Interpenetrating network polymer (IPN) composite coating containing fluorinated polyacrylic complex latex particles toward high wear and corrosion resistance

Interpenetrating network polymers (IPN) have broad development prospects because of achieving the expected performance characteristics via the selection of functional groups and the ratio of components. In this work, the as-prepared waterborne fluorinated polyacrylate (F-PA) complex latex particles using emulsion polymerization were introduced into waterborne epoxy resin (EP) coatings for improving its hydrophobicity, toughness and compactness. The structure and physicochemical properties of prepared samples were characterized by TEM, SEM, XPS, FTIR and DMA techniques. The results indicate that EP/F-PA with a dense IPN structure successfully solves poor compatibility between F-PA and EP, which leads to excellent mechanical and damping properties. Both increased by 33.2% and 26.8% respectively. The friction test shown that the negative volume was reduced by 50.6%, the composite coating displayed excellent wear resistance. In addition, the fluorinated components and IPN structure increase the diffusion path of the corrosive medium, which has been demonstrated by molecular dynamics simulations, providing outstanding corrosion resistance for coatings. The |Z|0.01 Hz of composite coating had increased by 3.4 times. Novel composite coating with an IPN structure can offer a feasible strategy for the development and real-world application of multifunctional coatings.

Bioinspired antifouling Fe-based amorphous coating via killing-resisting dual surface modifications

Fe-based amorphous coatings with outstanding corrosion resistance are promise for marine applications. However, these coatings encounter a great challenge of biofouling in marine environments. Inspired by the unique micro-nano hierarchical structure of shark skin with excellent antifouling properties, in this paper, we construct a bioinspired Fe-based amorphous coating with killing-resisting dual-effect via proper surface modifications, i.e., the modification with micro-patterned nanostructured Cu2O fibers (killing effect), followed by the modification with superhydrophobic surface (resisting effect). As a result, the modified amorphous coating exhibits impressive antifouling properties, achieving 98.6% resistance to Nitzschia closterium f. minutissima, 87% resistance to Bovine serum albumin protein and 99.8% resistance to Pseudomonas aeruginosa, respectively. The remarkable antifouling performance is attributed to a synergistic antifouling mechanism from both resisting effect and killing effect, wherein the superhydrophobic surface provides a barrier to resist protein adsorption, while the patterned nanostructured Cu2O fibers supply Cu+ ions to kill bacterial cells. In addition, the modified amorphous coating also exhibits excellent mechanical robustness, which ensures the durability of the Fe-based amorphous coating in practical services. This work may promote the development of new durable metal-based coatings integrated with anti-fouling and anti-corrosion properties.