Superior Corrosion Resistance Research Articles

Boosting corrosion resistance of Mg-Li alloy: Implanting bioinspired superhydrophobic surfaces into MAO matrix for enhanced protection

The corrosion problem has significantly impeded the practical application of Mg-Li alloys. In this report, a method that combines micro-arc oxidation (MAO) with electrochemical deposition is developed to create a superhydrophobic matrix on Mg-Li substrate. The combination approach harnesses the superiority of both coverages, including MAO as the dense, firmly bonded ceramic oxide layer on the metal substrate and the superhydrophobic surface (SHS) implanted into MAO matrix. The MAO-SHS coating exhibits high mechanical stability, maintaining the superhydrophobicity due to the “implanting effect” even after a long distance of friction effect. For corrosion inhibition, compared to the bare Mg-Li with icorr of 9.26 × 10−5 A/cm2, the icorr for MAO and MAO-SHS is 7.83 × 10−6 A/cm2 and 7.50 × 10−9 A/cm2, respectively, representing the reduction of approximately one and four orders of magnitude. Focusing the atmospheric corrosion inhibition, MAO-SHS proves to manipulate the dynamic evolution of saline solution evaporation and salt particle deliquation. The salt particle crystalized from saline solution on MAO-SHS is found to have significantly smaller contact area than that of the bare Mg-Li and MAO. By employing atomic force microscopy, the adhesion force of salt particle is revealed as ca. 45 nN, 13 nN, and 2 nN for salt particle on Mg-Li, MAO, and MAO-SHS, respectively. This suggests that the salt can be more easily removed from the MAO-SHS surface, thereby reducing the susceptibility to corrosion. The in situ deliquation is conducted to understand the formation of the droplet on different surfaces. The air in the SHS layer hinders chloride ingress and the SHS layer seals the pores in MAO layer, proving the synergistic effect afforded by MAO-SHS to achieve superior corrosion resistance.

Corrosion Behavior and Biological Properties of ZK60/HA Composites Prepared by Laser Powder Bed Fusion.

Magnesium alloy ZK60 shows great promise as a medical metal material, but its corrosion resistance in the body is inadequate. Hydroxyapatite (HA), the primary inorganic component of human and animal bones, can form chemical bonds with body tissues at the interface, promoting the deposition of phosphorus products and creating a dense calcium and phosphorus layer. To enhance the properties of ZK60, HA was added to create HA/ZK60 composite materials. These composites, fabricated using the advanced technique of LPBF, demonstrated superior corrosion resistance and enhanced bone inductive capabilities compared to pristine ZK60. Notably, the incorporation of 3 wt% led to a significant reduction in bulk porosity, achieving a value of 0.8%. The Ecorr value increased from -1.38 V to -1.32 V, while the minimum Icorr value recorded at 33.9 μA·cm-2. Nano-HA achieved the lowest volumetric porosity and optimal corrosion resistance. Additionally, these composites significantly promoted osteogenic differentiation in bone marrow stromal cells (BMSCs), as evidenced by increased alkaline phosphatase (ALP) activity and robust calcium nodule formation, highlighting their excellent biocompatibility and osteo-inductive potential. However, when increasing the HA content to 6 wt%, the bulk porosity rose significantly to 3.3%. The Ecorr value was -1.3 V, with the Icorr value being approximately 50 μA·cm-2. This increase in porosity and weaker interfacial bonding, ultimately accelerated electrochemical corrosion. Therefore, a carefully balanced amount of HA significantly enhances the performance of the ZK60 magnesium alloy, while excessive amounts can be detrimental.

Enhanced steam thermal cycle resistance of Yb2Si2O7 environmental barrier coatings via Al modification

SiC-based ceramic matrix composites are susceptible to performance losses in steam environments, necessitating the use of environmental barrier coatings for their protection. The high Si activity of Yb2Si2O7 material may induce the emergence of Si(OH)4 in steam environments, resulting in the development of a pore structure within Yb2Si2O7. This pore structure weakens the service life of the coating, highlighting the importance of enhancing the steam corrosion resistance of environmental barrier coatings as a key factor in improving their overall longevity. In the present study, we employed Al modification technique to improve the steam corrosion resistance of Yb2Si2O7 coatings. The results indicated that Al-modified Yb2Si2O7 coatings exhibited superior steam thermal cycle corrosion resistance compared to the non-modified Yb2Si2O7 coatings after testing performed at 1523 K for 1000 h (10 h per cycle). This improvement was attributed to the presence of Yb3Al5O12 and Al2O3 composite phases within the Al-modified Yb2Si2O7 coatings, which exhibited low steam activity and effective steam corrosion resistance. Moreover, Al-modified Yb2Si2O7 coatings obtained the dual excellent performance of improving the steam corrosion resistance of Yb2Si2O7 coating and not weakening the thermal cycle ability, providing a guarantee for the longer life of Yb2Si2O7 coating.

Enhanced Corrosion Protection of Printed Circuit Board Electronics using Cold Atmospheric Plasma-Assisted SiOx Coatings.

The miniaturization and widespread deployment of electronic devices across diverse environments have heightened their vulnerability to corrosion, particularly affecting copper traces within printed circuit boards (PCBs). Conventional protective methods, such as conformal coatings, face challenges including the necessity for a critical thickness to ensure effective barrier properties and the requirement for multiple steps of drying and curing to eliminate solvent entrapment within polymer coatings. This study investigates cold atmospheric plasma (CAP) as an innovative technique for directly depositing ultrathin silicon oxide (SiOx) coatings onto copper surfaces to enhance corrosion protection in PCBs. A systematic investigation was undertaken to examine how the scanning speed of the CAP deposition head impacts the film quality and corrosion resistance. The research aims to determine the optimal scanning speed of the CAP deposition head that achieves complete surface coverage while promoting effective cross-linking and minimizing unreacted precursor entrapment, resulting in superior electrical barrier and mechanical properties. The CAP coating process demonstrated the capability of depositing SiOx onto copper surfaces at various thicknesses ranging from 70 to 1110 nm through a single deposition process by simply adjusting the scanning speed of the plasma head (5-75 mm/s). Evaluation of material corrosion barrier characteristics revealed that scanning speeds of 45 mm/s of the plasma deposition head provided an effective coating thickness of 140 nm, exhibiting superior corrosion resistance (30-fold) compared to that of uncoated copper. As a proof of concept, the efficacy of CAP-deposited SiOx coatings was demonstrated by protecting an LED circuit in saltwater and by coating printed circuits for potential agricultural sensor applications. These CAP-deposited coatings offer performance comparable to or superior to traditional conformal polymeric coatings. This research presents CAP-deposited SiOx coatings as a promising approach for effective and scalable corrosion protection in miniaturized electronics.

Zr-based conversion film fabricated on cold rolled steel by separately providing zirconium and fluorine ions: Performance and mechanism study

Controlling the concentrations of Zr4+ and F− in traditional Zirconium (Zr)-based film-formation solution is challenging due to their dependence on the hydrolytic equilibrium of H2ZrF6. In this study, Zr-based films were prepared on cold rolled steel surface through the film-formation solution prepared by mixing Zr(NO3)4 and different amount of HF. The electrochemical results demonstrated that the Zr-based film prepared by Zr(NO3)4 and HF exhibited superior corrosion resistance compared to H2ZrF6. Under optimal film formation conditions, the protective efficiency of the prepared film reached 74.4 % which was higher than that of film fabricated in H2ZrF6. The electrochemical results concurrently demonstrated the self-reinforcing anti-corrosion performance of the prepared films. Scanning electron microscopy revealed that the Zr film, prepared in Zr(NO3)4 and HF, exhibited excellent corrosion resistance attributed to its high film density. The X-ray photoelectron spectroscopy and energy dispersive spectroscopic results indicated the presence of a fluoride layer on the surface of the Zr film. The F− ions can chelate with the corrosion products and selectively deposit onto the damaged areas of the film, thereby effectively contributing to the repair of the film layer. The results of density functional theory calculations demonstrated that Zr4+ readily forms Zr(OH)4 rather than ZrF62−. The present study offers an enhanced approach for regulating the properties of films prepared via H2ZrF6 by separately providing zirconium and fluorine ions.

Characterization of Nano-kaolin and its enhancement of the mechanical and corrosion resistance of epoxy coatings

This study compares the effects of varying concentrations of nano-kaolin and titanium dioxide on the mechanical and corrosion resistance of epoxy coatings. Characterization techniques such as TEM, XRD, Raman, FTIR, XPS, and AFM revealed surface features of nano-kaolin: the particle size reached the nanoscale, the XRD diffraction peak at 2θ = 25.3° disappeared, Raman peaks broadened with decreased intensity, and a blue shift occurred in the FTIR spectra for various functional groups. Compared to pure epoxy coatings, the composite epoxy coating with 10 wt% nano-kaolin showed an 83.87 % increase in adhesion, an 81.82 % improvement in impact resistance, and a 61.42 % reduction in friction coefficient; while a 20 wt% titanium dioxide composite coating showed a 74.19 % increase in adhesion, a 75.76 % improvement in impact resistance, and a 46.9 % reduction in friction coefficient. Electrochemical tests indicated that a composite coating with 10 wt% nano-kaolin, after soaking in 3.5 wt% NaCl solution for 960 hours, achieved a corrosion efficiency of 98.87 % and an impedance modulus of 108.8Ω.cm2, which was three orders of magnitude higher than that of pure epoxy resin, increasing corrosion resistance by 57.14 %; whereas a 20 wt% titanium dioxide composite coating reached a corrosion efficiency of 89.29 % and an impedance modulus of 106.6Ω.cm2 after the same conditions, increasing corrosion resistance by 17.86 % compared to the pure epoxy resin. The composite coating with 10 wt% nano-kaolin exhibited superior mechanical and corrosion resistance, outperforming the 20 wt% titanium dioxide coating. Mechanical and corrosion mechanisms suggest that the uniformly dispersed nano-kaolin inhibits interactions between epoxy resin molecules and carries the external load, thereby enhancing intermolecular cohesion. Improved adhesion and impact resistance indirectly extend the coating's lifespan by prolonging the path of corrosion media through the coating to the substrate. The novel coating modification method proposed in this study effectively replaces titanium dioxide and enhances the coating's mechanical and corrosion resistance, offering a new solution for corrosion prevention in metal materials.

Research on the Microstructures and Properties of AA5052 Laser-Welded Joints with the ER4043 Filler Wire

Researches were conducted on the laser welding of 3 mm sheet-thickness lap joints of AA5052 with ER4043 filler wires. The effects of laser power on the joint morphology, microstructure, mechanical properties, and corrosion resistance were investigated. The results indicate that both increased heat input and the addition of filler wires make the molten pool more instable, which results in more process pores. Circular pores are observed in the upper part of the weld, while chain-like pores are distributed in the middle of the weld. The highest tensile strength of the weld joint is 192.61 MPa with an elongation of 10.1% at a laser power of 3.5 kW. The microhardness at the center of the weld is approximately 25% higher than the base material, which is probably because the addition of ER4043 filler wires brings more Si element to the weld. Moreover, the weld joints display superior corrosion resistance compared to the base material. These outcomes enhance the understanding of AA5052 laser welding with fillers wire and provide valuable in-sights for engineering applications.

Fabrication of a Hydrophilic Al2O3/AlN EP Coating with Self‐Cleaning and High‐Efficiency Anti‐Corrosion Properties

AbstractCurrently, with the gradual development of anticorrosive coatings, the pursuit of simple preparation methods and the improvement of anticorrosive coatings’ properties have become the major research trends. This study successfully prepared a hydrophilic super anticorrosive coating through a simple mixing method. The coating has a contact Angle of 67.8° and a rolling Angle greater than 20°. This coating can withstand 180 days of salt spray test with no bubble or rust formation when placed on a Q 235 substrate in a 3.5 wt % NaCl solution, demonstrating the excellent corrosion resistance of the AO0.4AN0.6EP coating. Furthermore, after being immersed in a 3.5 wt % NaCl solution for 3 days, the AO0.4AN0.6EP coating exhibited the largest impedance diameter (2.07×108 Ω⋅cm2), almost three times larger than other coatings, and possessed the highest Bode modulus value, one order of magnitude higher than other coatings. After immersion in a 3.5 wt % NaCl solution for 7 days, the AO0.4AN0.6EP coating had the largest Ecorr and the smallest icorr, indicating its superior corrosion resistance. In addition to corrosion resistance, the AO0.4AN0.6EP coating showed no signs of cracking, discoloration, or decomposition after being exposed to ultraviolet aging lights for 30 days, demonstrating its excellent UV resistance. Moreover, neither dry soil particles nor muddy water could adhere to the coating surface, proving its good self‐cleaning ability. Therefore, this coating holds promising applications in the field of super corrosion‐resistant coatings.

Laser powder bed fusion of Mg–Zn–Zr alloy: Formability, microstructure evolution and biodegradation behavior

Laser powder bed fusion (LPBF) was used to fabricate Mg–Zn–Zr (ZK60) parts, with a thorough investigation of processability by varying laser power and scanning rate. The combined effect of these parameters, which determines laser energy density, significantly impacted the forming quality of LPBF ZK60. Dense parts (over 99%) free of visible defects such as pores and cracks were achieved at a laser energy density of 74.1 J/mm2. The formation mechanisms of pores and cracks were extensively analyzed concerning the characteristics of the molten pool and subsequent cooling behavior. The LPBF ZK60 parts exhibited extremely fine grains, with an average grain size of 3.2 μm. Both equiaxed and columnar grains were observed, with a central equiaxed zone in the melt pool and a perpendicular lamellar zone along its boundary. Additionally, the Mg7Zn3 eutectic phase precipitated within the α-Mg matrix of ZK60. Immersion and electrochemical tests indicated that the XZ plane displayed superior corrosion resistance, attributed to fewer deformation regions and lower dislocation density. Furthermore, in vitro cell experiments confirmed that the ZK60 alloy possesses good biocompatibility.

A Study on Microstructural Evolution and Corrosion Behavior of Ti36-Al16-V16-Fe16-Cr16 High-Entropy Alloy Fabricated via Spark Plasma Sintering Technology

This study focused on the synthesis of Ti36-Al16-V16-Fe16-Cr16 high-entropy alloys (HEAs) through spark plasma sintering to ascertain their corrosion resistance performance. Varied sintering temperatures, ranging from 700 to 1100 °C were employed to discern their impact on the alloy's characteristics. The fabricated HEAs underwent characterization using scanning electron microscopy and X-ray diffraction. A potentiodynamic polarization measurement was employed to compare the electrochemical properties of HEAs sintered at different temperatures in sulfuric and chloride aggressive media. The study outcomes indicate that the HEA sintered at 1000 °C exhibited superior corrosion resistance compared to other HEAs at other temperatures. This study contributes valuable insights into the nuanced relationship between sintering temperature, microstructure, and corrosion resistance of Ti36-Al16-V16-Fe16-Cr16 HEAs.

A review on AI-driven environmental-assisted stress corrosion cracking properties of conventional and advanced manufactured alloys

Stress corrosion cracking (SCC) poses a significant challenge to the integrity and longevity of both conventional and advanced manufactured alloys, impacting critical industries such as aerospace, marine, and nuclear energy. This review explores the use of artificial intelligence (AI) to analyse and predict SCC properties. Traditional alloys such as steel, aluminium, and titanium, as well as advanced materials such as additive-manufactured and high-entropy alloys, exhibit unique SCC behaviours influenced by corrosive environments, mechanical stress, and temperature variations. AI techniques, including machine learning models, offer transformative approaches to understanding and mitigating SCC. Leveraging extensive datasets from experiments and field studies, AI can identify patterns and correlations that traditional methods might miss. Predictive modelling through supervised learning forecasts SCC initiation and propagation, aiding in material design and maintenance. Unsupervised and reinforcement learning enhances alloy composition and processing parameter optimisation for better SCC resistance. In conventional alloys, AI identifies specific SCC conditions, leading to improved protective measures. For advanced alloys, AI-driven insights tailor additive manufacturing processes and design high-entropy alloys with superior corrosion resistance. This review includes case studies demonstrating AI's effectiveness in predicting SCC across various alloy–environment combinations, highlighting successes and challenges. Despite hurdles such as data quality and integration, AI holds immense potential to revolutionise SCC research, enhancing understanding of SCC mechanisms and fostering innovations in alloy design and preventative maintenance.

Predicting shear strength of fiber-reinforced concrete beams reinforced with longitudinal FRP bars with machine learning techniques

ABSTRACT This study investigates the shear strength prediction of Fibre-Reinforced Concrete (FRC) beams reinforced with Fibre-Reinforced Polymer (FRP) bars and without stirrups through the application of Machine Learning (ML) techniques. The utilisation of FRP bars, particularly Glass Fibre-Reinforced Polymer (GFRP) and Basalt Fibre-Reinforced Polymer (BFRP) bars, has emerged as a promising alternative to traditional steel reinforcement due to their superior mechanical properties and corrosion resistance. Moreover, the incorporation of macro- and micro-discrete fibres into concrete compositions enhances both shear and flexural behaviour while reducing crack propagation induced by tensile stresses. The primary objective of this research is to develop accurate predictive models for the shear capacity of FRP-reinforced concrete beams, considering various influential parameters. Six different ML techniques, namely Multiple Linear Regression (MLR), Gaussian Process Regression (GPR), k-Nearest Neighbors (KNN), Support Vector Machines (SVMs), Artificial Neural Networks (ANNs) and Random Forest Regression (RFR), are employed to analyse the complex interactions between input variables, such as fibre type, bar diameter, concrete compressive strength, beam dimensions and the resulting shear strength. By leveraging these computational approaches, we aim to overcome the limitations of conventional analytical methods and provide robust predictions for structural design and optimisation.

Controlled Compositions in Zn–Ni Coatings by Anode Material Selection for Replacing Cadmium

Cadmium-based coatings have long been used to protect high-strength steel in aerospace, but due to cadmium’s toxic and carcinogenic nature, its use is increasingly restricted. Zinc–nickel coatings, containing 10–14 wt% Ni, offer superior corrosion resistance compared to pure zinc, making them a promising alternative. However, Zn–Ni coatings are prone to cracking, which can compromise their protection. This study investigates how different anode materials influence crack formation and coating properties during electrodeposition. Zinc and nickel anodes produced coatings with consistent thicknesses of 13–15 µm, while 1020 steel and stainless steel resulted in thicker coatings of up to 33 µm. Notably, coatings deposited with nickel anodes demonstrated strong adhesion and consistent interface quality. Zinc anodes achieved a high Ni content of about 13.5 wt%, whereas 1020 steel and stainless steel produced lower Ni content, around 7 wt%. Additionally, zinc and nickel anodes led to fewer defects and minimal porosity, in contrast to the higher porosity observed with 1020 steel and stainless steel anodes. Furthermore, zinc anodes maintained stable voltages (~0.5 V), contributing to more uniform coatings. In terms of corrosion resistance, zinc anodes exhibited a lower corrosion rate of 0.44 mm/year compared to 1.54 mm/year for nickel anodes. This study highlights the importance of anode selection in reducing cracking and optimizing Zn–Ni coatings, presenting them as a safer and more effective alternative to cadmium-based coatings.

A comparative study of TiO2, Ta2O5 and Nb2O5 coated Ti6Al4V titanium alloy for biomedical applications

Refractory metal oxides such as titanium dioxide (TiO2), tantalum oxide (Ta2O5), and niobium oxide (Nb2O5) coated-titanium and its alloys for medical applications have recently gained significant attention due to their remarkable properties, including high hardness, strong chemical inertness, and excellent biocompatibility. However, comparative studies among them remain scarce. In this study, thin films of Ta2O5, Nb2O5, and TiO2 were deposited on Ti6Al4V titanium alloy using radio frequency sputtering technology. Their properties were comparably evaluated through a series of tests, including scratching, nanoindentation, friction and wear, potentiodynamic polarization, and cell cultivation experiments. The results revealed that all three coatings, with a thickness of approximately 2.6–2.8 μm, exhibited an amorphous columnar growth pattern with dense surfaces resembling cauliflower. The bonding force of the TiO2 coating exceeds 50 N, which is 26.2 times and 14.5 times greater than that of Ta2O5 and Nb2O5, respectively. Furthermore, all coated samples demonstrate superior wear resistance, corrosion resistance, and biocompatibility compared to bare Ti6Al4V. Among the coatings, TiO2 showed the best performance, followed by Ta2O5, while Nb2O5 exhibited the least favorable performance. These findings revealed the performance differences among the three ceramic coatings on Ti6Al4V samples and offer valuable insights for further research and the selection of coatings to enhance the properties of Ti6Al4V titanium alloy for biomedical applications.

Influence of friction stir processing (FSP) on arc directed energy deposited 316L stainless steel: a corrosion science study

Friction stir processing (FSP) was employed as a post-printing surface modification technique to enhance surface properties of arc-directed energy deposited 316L austenitic stainless-steel parts. Corrosion properties and passivity of stir zone and base metal were investigated in 3.5 wt.% NaCl solution. Results reveal a gradual improvement in corrosion protection ability of formed passive film on the alloy's surface over time. Specifically, FSPed region exhibited superior passive behavior and uniform corrosion resistance compared to base metal. This improvement was attributed to a more homogeneous microstructure of stir zone, which hindered micro-galvanic coupling effect. However, it was observed that FSP-treatment did not effectively impede the propagation of pitting corrosion.

Effect of Laser Energy Density on the Properties of CoCrFeMnNi High-Entropy Alloy Coatings on Steel by Laser Cladding

High-entropy alloys (HEAs) have emerged as a novel class of materials with exceptional mechanical and corrosion properties, offering promising applications in various engineering fields. However, optimizing their performance through advanced manufacturing techniques, like laser cladding, remains an area of active research. This study investigated the effects of laser energy density on the mechanical and electrochemical properties of CoCrFeMnNi HEA coatings applied to Q235 substrates. Utilizing X-ray diffraction (XRD), this study confirmed the formation of a single-phase face-centered cubic (FCC) structure in all coatings. The hardness of the coatings peaked at 210 HV with a laser energy density of 50 J/mm2. Friction and wear tests highlighted that a coating applied at 60 J/mm2 exhibited the lowest wear rate, primarily due to adhesive and oxidative wear mechanisms, while the 55 J/mm2 coating showed increased hardness but higher abrasive wear. Electrochemical testing revealed superior corrosion resistance for the 60 J/mm2 coating, with a slow corrosion rate and minimal passivation tendency in contrast to the 55 J/mm2 coating. The comprehensive evaluation indicates that the HEA coating with an energy density of 60 J/mm2 exhibits exceptional wear and corrosion resistance.

Effect of Ni on the mechanical and corrosion properties of TiC-reinforced steel matrix composites

Particle-reinforced steel matrix composites typically lead to a decrease in corrosion resistance while enhancing mechanical properties. However, steel matrix composites for marine applications require superior mechanical properties and corrosion resistance. In this study, 8 vol% TiC/Fe–C composites were prepared using the master alloy method. The effects of Ni contents (0, 1.2 wt%, 1.6 wt%, 2.0 wt%, and 2.4 wt%) on the mechanical and corrosion properties of the composites were evaluated. Results indicated that the tensile strength, elongation, and corrosion resistance of the composites initially increased and then decreased with increasing Ni content. The σUTS and εf of Ni2.0 composites increased from 536 MPa and 4.1 % for Ni0 to 1100 MPa and 9.0 %, respectively. The icorr and corrosion rate of the Ni2.0 composite were 0.440 μA/cm2 and 0.0057 mm/year, respectively. The mechanical properties and corrosion resistance of TiC particle-reinforced steel matrix composites were simultaneously enhanced by the addition of 2.0 wt% Ni. The increase in strength is mainly attributed to changes in thermal mismatch resulting from Ni addition, solid solution strengthening of the Fe–Ni solid solution, and improved interface compatibility between the TiC particles and the matrix, thus enhancing load transfer efficiency. The increase in plasticity can be attributed to the significant improvement in interface deformation compatibility with Ni addition. The increase in corrosion resistance primarily results from the steel matrix alloying, uniform distribution of TiC particles, and strong interface bonding between the particles and the matrix.

Pulsed laser surface texturing enhancing corrosion resistance of rare-earth WE43 magnesium alloys in simulated body fluid environment

The addition of rare earth (RE) elements in Magnesium (Mg) alloys could optimize alloy microstructures and improve the mechanical property. The corrosion resistance however is a tough issue that limits its application as biomedical materials in human bodies. In this work, a green, fast and economical method of pulsed laser surface texturing (PLST) was employed to modify the RE WE43 Mg alloys and the corresponding corrosion resistance after the PLST treatment in simulated body fluid (SBF) was further examined. The microstructural results show that the surface exhibits petal-like microstructures and an oxide film composed of various oxides with remelting particles are also generated on laser-processed areas after PLST treatment. The electrochemical results reveal that the WE43 sample treated by PLST exhibits a superior corrosion resistance in SBF compared with the as-cast one. As for the PLST treated sample with 24 W, the corrosion potential (Ecorr) positively shifts from −1.788 V to −1.556 V after being immersed in SBF for 7 days, which is also nobler than that of the as-cast one, −1.915 V. While the corrosion current density (icorr) drops to the value of 8.3 μA/cm2, considerably lower than that of the as-cast sample, 1380 μA/cm2. The enhancement of corrosion resistance in the early stage is mainly due to the protective oxide film induced by PLST. Furthermore, long-term immersion in SBF further accelerates the formation of deposited hydroxyapatite (HA) products layer on petal-like microstructures, which would further contribute to its enhancement in corrosion resistance in the long-term service in human bodies.

Effect of Mn content on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Zr–Mn alloys processed via spark plasma sintering

Herein, β-type Ti–Nb–Zr–Mn alloys were prepared by ball milling and spark plasma sintering. The effects of Mn addition and quenching treatment on the microstructure, mechanical properties, and corrosion behavior of the alloy were investigated. The Ti–Nb–Zr–Mn alloys are predominantly constituted of equiaxed β Ti grains with a small proportion of ω phase. An increase in Mn content inhibits the precipitation of the ω phase while promoting a more homogeneous solid solution. The tensile strength of the as-prepared alloys decreases and then increases, whereas the plasticity demonstrates the opposite trend. The Elastic modulus and hardness roughly show a trend of decreasing and then increasing. Additionally, the Ti–24Nb–4Zr–2Mn alloy, after undergoing a solid solution treatment at a temperature of 950 °C and subsequent water quenching (referred to as M2-950), demonstrates exceptional comprehensive performance, showing a yield strength of 956 ± 4 MPa, an ultimate strength of 995 ± 13 MPa, an elongation of 16.4 ± 1.6 %, a hardness of 312 ± 11 H V, and an Elastic modulus of 72.6 GPa. Moreover, the corrosion behavior in Ringer's solution was extensively investigated, and the M2-950 alloy has superior corrosion resistance.

Structural, mechanical, corrosion, and early biological assessment of tantalum nitride coatings deposited by reactive HiTUS

This study examined microstructure, mechanical, corrosion properties and initial biological evaluation of the tantalum nitride (Ta-xN, where x – nitrogen flow rate during deposition) coatings prepared by reactive High Utilization Sputtering (HiTUS) at various nitrogen flow rates (x = 0, 2, 4, 6, and 8 sccm). Coatings were deposited on a novel Mg alloy (Mgbal.-Zn0.9-Y2.05-Al0.25 at. %) containing long-period stacking ordered (LPSO) phases. The coatings' structure was analyzed using a combination of SEM/FIB/TEM techniques, while XRD determined the phase composition. The mechanical parameters investigated included hardness, indentation modulus, and scratch behavior. The corrosion resistance of the coatings with respect to the bare substrate was evaluated in chloride-containing solutions. The wettability and early biological assessment of the coatings were also examined. The phase evolution strongly influenced the hardness and indentation modulus. The Ta-xN coatings made at x = 2 sccm nitrogen corresponding to HCP-Ta2N exhibited the highest hardness and indentation modulus. An increase in nitrogen flow rates resulted in the formation of FCC structure with slightly reduced hardness and indentation modulus. In addition, Ta-xN coatings (x ≥ 4sccm) showed superior corrosion resistance compared to BCC structured α-Ta, enhancing the corrosion performance of the Mg-LPSO bulk substrate. Finally, at the early incubation stage (24 h), L929 fibroblasts exhibited better cell attachment to the Ta-6N coating than to the bare Mg-LPSO substrate.