Review of nano-based smart coatings for corrosion mitigation: mechanisms, performance, and future prospects.

In response to environmental concerns about toxic corrosion inhibitors, nanomaterials have gained attention for their enhanced corrosion inhibition properties due to their high surface-to-volume ratio. This paper summarizes advancements in utilizing nanomaterials to control corrosion, exploring various preparation methods and effectiveness as inhibitors. Nano-based intelligent coatings have emerged as promising solutions, with this review examining their corrosion inhibition mechanisms, performance attributes, and future prospects. By combining nanomaterials with traditional inhibitors, synergistic effects can be achieved. Performance assessment extends to real-world scenarios, considering factors like adhesion, durability, and practical implementation across industries. Future trends include integrating real-time monitoring abilities and using environmentally conscious nanomaterials for sustainable corrosion control.

Dental Implant Abutment Screw Loss: Presentation of 10 Cases.

Re-tightening the loosened dental implant abutment screw is an accepted procedure, however the evidence that such screw will hold sufficiently is weak. The purpose of this study was material analysis of lost dental implant abutment screws made of the TiAlV alloy from various manufacturers, which became lost due to unscrewing or damaged when checking if unscrewed; undamaged screws could be safely re-tightened. Among 13 failed screws retrieved from 10 cases, 10 screws were removed due to untightening and 3 were broken but without mechanical damage at the threads. Advanced corrosion was found on nine screws after 2 years of working time on all surfaces, also not mechanically loaded. Sediments observed especially in the thread area did not affect the corrosion process because of no pit densification around sediments. Pitting corrosion visible in all long-used screws raises the question of whether the screws should be replaced after a certain period during service, even if they are well-tightened. This requires further research on the influence of the degree of corrosion on the loss of the load-bearing ability of the screw.

Performance of Austenitic High-Nitrogen Steels under Gross Slip Fretting Corrosion in Bovine Serum.

Modular artificial hip joints are a clinical standard today. However, the release of wear products from the head-taper interface, which includes wear particles in the nm size range, as well as metal ions, have raised concerns. Depending on the loading of such taper joints, a wide variety of different mechanisms have been found by retrieval analyses. From these, this paper concentrates on analyzing the contribution of gross slip fretting corrosion at ultra-mild wear rates using a bovine calf serum solution (BCS) as the lubricant. The parameters were chosen based on biomechanical considerations, producing wear rates of some ng/m wear path. In parallel, the evolution of tribomaterial (third bodies) was analyzed as to its constituents and generation rates. It has already been shown earlier that, by an advantageous combination of wear mechanisms and submechanisms, certain constituents of the tribomaterial remain inside the contact area and act like extreme-pressure lubricant additives. For the known wear and corrosion resistance of austenitic high-nitrogen steels (AHNSs), which outperform CoCrMo alloys even under inflammatory conditions, we hypothesized that such steels will generate ultra-mild wear rates under gross slip fretting. While testing AHNSs against commercially available biomedical-grade materials of CoCrMo and TiAlV alloys, as well as zirconia-toughened alumina (ZTA) and against itself, it was found that AHNSs in combination with a Ti6Al4V alloy generated the smallest wear rate under gross slip fretting corrosion. This paper then discusses the wear behavior on the basis of ex situ analyses of the worn surfaces as to the acting wear mechanisms and submechanisms, as well as to the tribological reaction products.

Medium-Entropy Monosilicates Deliver High Corrosion Resistance to Calcium-Magnesium Aluminosilicate Molten Salt.

For decreasing the global cost of corrosion, it is essential to understand the intricate mechanisms of corrosion and enhance the corrosion resistance of materials. However, the ambiguity surrounding the dominant mechanism of calcium-magnesium aluminosilicate (CMAS) molten salt corrosion in extreme environments hinders the mix-and-matching of the key rare earth elements for increasing the resistance of monosilicates against corrosion of CMAS. Herein, an approach based on correlated electron microscopy techniques combined with density functional theory calculations is presented to elucidate the complex interplay of competing mechanisms that control the corrosion of CMAS of monosilicates. These findings reveal a competition between thermodynamics and kinetics that relies on the temperatures and corrosion processes. Innovative medium-entropy monosilicates with exceptional corrosion resistance even at 1500 °C are developed. This is achieved by precisely modulating the radii of rare earth ions in monosilicates to strike a delicate balance between the competition in thermodynamics and kinetics. After 50 and 100 h of corrosion, the thinnest reactive layers are measured to be only 28.8 and 35.4 µm, respectively.

Zwitterion modified chitosan as a high-performance corrosion inhibitor for mild steel in hydrochloric acid solution.

Herein, a novel chitosan Schiff base (CS-FGA) as a sustainable corrosion inhibitor has been successfully synthesized via a simple amidation reaction by using an imidazolium zwitterion and chitosan (CS). The corrosion inhibition property of CS-FGA for mild steel (MS) in a 1.0 M HCl solution was studied by various electrochemical tests and physical characterization methods. The findings indicate that the maximum inhibition efficiency of CS-FGA as a mixed-type inhibitor for MS in 1.0 M HCl solution with 400 mg L-1 reaches 97.6 %, much much higher than the CS and the recently reported chitosan-based inhibitors. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and water contact angle (WCA) results reveal that the CS-FGA molecules firmly adsorb on the MS surface to form a protective layer. The adsorption of CS-FGA on the MS surface belongs to the Langmuir adsorption isotherm containing both the physisorption and chemisorption. According to the X-ray photoelectron spectroscopy (XPS) and UV-vis spectrum, FeN bonds presented on the MS surface further prove the chemisorption between CS-FGA and Fe to generate the stable protective layer. Additionally, theoretical calculations from quantum chemical calculation (DFT) and molecular simulations (MD) were performed to reveal the inhibition mechanism of CS-FGA.

Ultrathin Al2O3 film modification on waterborne epoxy coatings by atomic layer deposition for augmenting the corrosion resistance.

The polar channels formed by the curing of waterborne anticorrosive coatings compromise their water resistance, leading to coating degradation and metal corrosion. To enhance the anticorrosive performance of waterborne coatings, this study proposed a novel method of depositing ultrathin Al2O3 films on the surface of waterborne epoxy coatings by atomic layer deposition (ALD), a technique that can modify the surface properties of polymer materials by depositing functional films. The Al2O3-modified coatings exhibited improved sealing and barrier properties by closing the polar channels and surface defects and cracks. The surface structure and morphology of the modified coatings were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The hydrophilicity and corrosion resistance of the modified coatings were evaluated by water contact angle measurement, Tafel polarization curve, and electrochemical impedance spectroscopy. The results indicated that the water contact angle of the Al2O3-modified coating increased by 48° compared to the unmodified coating, and the protection efficiency of the modified coating reached 99.81%. The Al2O3-modified coating demonstrated high anticorrosive efficiency and potential applications for metal anticorrosion in harsh marine environments. .

Fretting and Tribocorrosion of Modular Dual Mobility Liners: Role of Design, Microstructure, and Malseating.

BACKGROUND: Modular dual mobility (DM) bearings have a junction between a cobalt chrome alloy (CoCrMo) liner and titanium shell, and the risk of tribocorrosion at this interface remains a concern. The purpose of this study was to determine whether liner malseating and liner designs are associated with taper tribocorrosion. METHODS: We evaluated 28 retrieved modular DM implants with a mean in situ duration of 14.6 months (range, 1 to 83). There were two manufacturers included (12 and 16 liners, respectively). Liners were considered malseated if a distinct divergence between the liner and shell was present on postoperative radiographs. Tribocorrosion was analyzed qualitatively with the modified Goldberg Score (mGS) and quantitatively with an optical coordinate-measuring machine. An acetabular shell per manufacturer was sectioned for metallographic analysis. RESULTS: There were six implants (22%) that had severe grade 4 corrosion, six (22%) had moderate grade 3, 11 (41%) had mild grade 2, and five (18.5%) had grade 1 or no visible corrosion. The average volumetric material loss at the taper was 0.086 ± 0.19 mm3. There were seven liners (25%) that had radiographic evidence of malseating, and all were of a single design (P = 0.01). The two liner designs were fundamentally different from one another with respect to the CoCrMo alloy type, taper surface finish, and shape deviations. Malseating was an independent risk factor for increased volumetric material loss (P = 0.017). CONCLUSION: Dual mobility tribocorrosion with quantifiable material loss occurred more commonly in malseated liners. Specific design characteristics may make liners more prone to malseating, and the interplay between seating mechanics, liner characteristics, and patient factors likely contributes to the shell/liner tribocorrosion environment.

The impact of urban rain on the changes of bare and artificially patinated bronze during 9-year exposure.

Atmospheric pollutants in the air form acid rain which interacts with bronze surfaces exposed in urban outdoor environment. In this study, different types of patinas on bronze were investigated during and after 9 years of exposure to urban environment in moderately polluted continental city. Natural bronze patina and artificial brown sulphide, green chloride, and green-blue nitrate patinas were investigated. Visual assessment was carried out at defined periods. After 9 years of exposure, an electrochemical study was performed to investigate the electrochemical activity of the patinas in artificial urban rain. Additionally, the patinas were characterised using a variety of techniques, including metallographic examination, scanning electron microscopy/energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffraction analysis, X-ray-photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry to analyse the surface morphology, chemical composition, and stratigraphic features of the patinas. Evolution of the patinas was shown to be a result of both, the composition of the acid rain and the hydrophobicity of the patinated surfaces.

Study on mechanism underlying the acceleration of pitting corrosion of B30 copper-nickel alloy by sulfate-reducing bacteria in seawater.

In this paper, the relationship between the pitting corrosion formation of B30 copper-nickel (CuNi) alloy and the metabolism of sulfate-reducing bacteria (SRB) was investigated. Combined with the influence of temperature during the actual operation of the cooling systems, the evolution law of the alloy passivation film was analyzed, and the mechanism of SRB promoting the accelerated development of B30 CuNi alloy pitting corrosion was revealed. The results show that SRB significantly promoted the pitting formation and development of B30 CuNi alloy. The maximum pitting depth was 3.9 µm in the sterile system and 15.3 µm with SRB, which was 3.9 times higher than that of sterile system. The loose porous Cu2S film formed by SRB metabolites and copper matrix was easily penetrated by corrosive anions, which promoted copper dissolution and led to pit nucleation. The sulfide adsorbed on the surface prevented or delayed the passivation of B30 CuNi alloy by blocking the adsorption site of O atom, and the corrosion nuclei continued to grow. The non-uniformity caused by the film peeling accelerated the longitudinal development of pitting corrosion, and the expansion and coalescence of adjacent pits caused the transverse development of pitting corrosion. Temperature had a certain influence on the SRB and the formation of B30 CuNi alloy passivation film. The passivation film was formed rapidly at 50 °C with poor quality and the passivation property of Cu2O film was weakened. With the increase of temperature, the pitting potential of sterile system negative shifted from 0.447 to 0.360 V (vs. SCE), while SRB system from 0.340 to 0.198 V (vs. SCE), and the pitting resistance decreased. The passivation film with defects and the Cu2S reduced the barrier efficiency of the film and accelerated the pitting corrosion of B30 CuNi alloy.

Corrosion and Biological Behaviors of Biomedical Ti-24Nb-4Zr-8Sn Alloy under an Oxidative Stress Microenvironment.

Biomaterials can induce an inflammatory response in surrounding tissues after implantation, generating and releasing reactive oxygen species (ROS), such as hydrogen peroxide (H2O2). The excessive accumulation of ROS may create a microenvironment with high levels of oxidative stress (OS), which subsequently accelerates the degradation of the passive film on the surface of titanium (Ti) alloys and affects their biological activity. The immunomodulatory role of macrophages in biomaterial osteogenesis under OS is unknown. This study aimed to explore the corrosion behavior and bone formation of Ti implants under an OS microenvironment. In this study, the corrosion resistance and osteoinduction capabilities in normal and OS conditions of the Ti-24Nb-4Zr-8Sn (wt %, Ti2448) were assessed. Electrochemical impedance spectroscopy analysis indicated that the Ti2448 alloy exhibited superior corrosion resistance on exposure to excessive ROS compared to the Ti-6Al-4V (TC4) alloy. This can be attributed to the formation of the TiO2 and Nb2O5 passive films, which mitigated the adverse effects of OS. In vitro MC3T3-E1 cell experiments revealed that the Ti2448 alloy exhibited good biocompatibility in the OS microenvironment, whereas the osteogenic differentiation level was comparable to that of the TC4 alloy. The Ti2448 alloy significantly alleviates intercellular ROS levels, inducing a higher proportion of M2 phenotypes (52.7%) under OS. Ti2448 alloy significantly promoted the expression of the anti-inflammatory cytokine, interleukin 10 (IL-10), and osteoblast-related cytokines, bone morphogenetic protein 2 (BMP-2), which relatively increased by 26.9 and 31.4%, respectively, compared to TC4 alloy. The Ti2448 alloy provides a favorable osteoimmune environment and significantly promotes the proliferation and differentiation of osteoblasts in vitro compared to the TC4 alloy. Ultimately, the Ti2448 alloy demonstrated excellent corrosion resistance and immunomodulatory properties in an OS microenvironment, providing valuable insights into potential clinical applications as implants to repair bone tissue defects.

Data analysis of the influence of microstructure, composition, and loading conditions on stress corrosion cracking behavior of Mg alloys.

Stress corrosion cracking (SCC) can be a crucial problem in applying rare earth (RE) Magnesium alloys in environments where mechanical loads and electrochemical driven degradation processes interact. It has been proven already that the SCC behavior is associated with microstructural features, compositions, loading conditions, and corrosive media, especially in-vivo. However, it is still unclear when and how mechanisms acting on multiple scales and respective system descriptors predictable contribute to SCC for the wide set of existing Mg alloys. In the present work, suitable literature data along SCC of Mg alloys has been analyzed to enable the development of a reliable SCC model for MgGd binary alloys. Pearson correlation coefficient and linear fitting are utilized to describe the contribution of selected parameters to corrosion and mechanical properties. Based on our data analysis, a parameter ranking is obtained, providing information on the SCC impact with regard to ultimate tensile strength (UTS) and fracture elongation of respective materials. According to the analyzed data, SCC susceptibility can be grouped and mapped onto Ashby type diagrams for UTS and elongation of respective base materials tested in air and in corrosive media. The analysis reveals the effect of secondary phase content as a crucial materials descriptor for our analyzed materials and enables better understanding towards SCC model development for Mg-5Gd alloy based implant.

Microstructural characterization and corrosion-resistance behavior of friction stir-welded A390/10 wt% SiC composites-AA2024 Al alloy joints.

This study examined the effect of traverse speed on the mechanical properties, corrosion-resistance behavior, and microstructure of friction stir-welded A390/10 wt% SiC composites-AA2024 Al alloy joints. The laminar flow of both materials was found to diminish in the stir zone (SZ) when the traverse speed of the tool increased from 40 to 80 mm/min, lowering their mixing rate. Large aspect ratio Si particles are broken by the tool pin-induced applied plastic strain, which turns them into refined equiaxed particles. Their aspect ratio remains unchanged in the SZ, despite their decreasing size. SiC and Si particles progressively come into view when moving from the AA2024 alloy's SZ to the composite workpieces. These changes happen abruptly as traverse speed increases due to the lack of an interfacial layer structure. The advancing side (AS)'s SZ grain size drops from 4.2 ± 0.3 µm to 1.2 ± 0.2 µm as the traverse speed drops from 80 to 40 mm/min. Increased traverse speed from 40 to 80 mm/min will result in a 5.8% decrease in elongation percentage (EP) and 8.4%, 36%, and 10.3% increases in the ultimate tensile strength (UTS), corrosion resistance, and yield strength, respectively.

Tracing the impact of CO2 on the electrochemical and charge-discharge behavior for Al-Mg alloy in KOH and LiOH electrolytes for battery applications.

For the first time, it has been found that the electrochemical performance of the Al-Mg alloy as an anode in alkaline batteries has been markedly enhanced in the presence of CO2 and LiOH as an electrolyte. This work compares the electrochemical performance of an Al-Mg alloy used as an anode in Al-air batteries in KOH and LiOH solutions, both with and without CO2. Potentiodynamic polarization (Tafel), charging-discharging (galvanostatic) experiments, and electrochemical impedance spectroscopy (EIS) are used. X-ray diffraction spectroscopy (XRD) and a scanning electron microscope (SEM) outfitted with an energetic-dispersive X-ray spectroscope (EDX) were utilized for the investigation of the products on the corroded surface of the electrode. Findings revealed that the examined electrode's density of corrosion current (icorr.) density in pure LiOH is significantly lower than in pure KOH (1 M). Nevertheless, in the two CO2-containing solutions investigated, icorr. significantly decreased. The corrosion rate of the examined alloy in the two studied basic solutions with and without CO2 drops in the following order: KOH > LiOH > KOH + CO2 > LiOH + CO2. The obtained results from galvanostatic charge-discharge measurements showed excellent performance of the battery in both LiOH and KOH containing CO2. The electrochemical findings and the XRD, SEM, and EDX results illustrations are in good accordance.

Evaluation of Corrosive Properties of Hafnium Nitride Coating Over Titanium Screws: An In Vitro Study.

Background Varied surface coatings have been studied time and again in medical sciences. Whether general or dental, studying the performance of coatings aims to assess their potential to improve the durability and longevity of titanium implants, thereby advancing implant technology for enhanced patient outcomes. Various analytical techniques are utilized to assess the performance of the coating, providing insights into its effectiveness in preventing corrosion. The findings of this evaluation will contribute to our understanding of corrosion mitigation strategies for titanium implants and pave the way for the development of more durable implant materials. This article aims to evaluate the corrosion resistance of an innovative metal compound coating applied over titanium implants.  Materials and methods In this study, a total of 20 medical-grade, commercially pure titanium screws were collected. The dimensions of the titanium screws were 2mm x 7mm. Around 10 of these commercially pure titanium screw samples were used as the control group. Hafnium nitride (HfN) (0.1 M) was mixed with 100% ethanol and stirred using a glass rod for about 48 hours. Then 10 of the implant screw samples were immersed in the prepared sol and sintered at 400o C for two hours. The HfN-coated samples were then used as the test group. The corrosion resistance of both groups was tested using electrochemical impedance spectroscopy and potentiodynamic polarization studies. The Nyquist, Bode impedance, and Bode phase angle plots were obtained and studied.  Results Using the Stern-Geary equation, the corrosion current density was calculated. On analysis, these values indicated that the higher impedance in HfN-coated titanium screws showed higher mean corrosion potential (Ecorr = -0.452 V) and corrosion current density ( icorr = 0.0354 µA/cm2) than the uncoated titanium screws.  Conclusion It was concluded that the corrosion properties of HfN-coated titanium screws had higher impedance and consequently the highest corrosion resistance. This thereby provides a promising scope for further research of this novel metal coating for use in the biomedical sectors, specifically for dental implants.

Preparation of corrosion inhibitor from natural plant for mild stil immersed in an acidic environmental: experimental and theoretical study.

In the present study, the inhibition performance of some medicinal plants (i.e. Yarrow, Wormwood, Maurorum, Marjoram, and Ribes rubrum) was theoretically and experimentally investigated for mild steel immersed in 1M HCl. In this way, the obtained extracts characterized by Fourier transform infrared spectroscopy (FT-IR) and the electrochemical and theoretical techniques were used to study the inhibition mechanisms of the extracts for the immersed electrode in the acidic solution. In addition, the microstructure of the electrode surface immersed in the blank and inhibitor-containing solutions characterized by field emission scanning electron microscopy (FE-SEM), and Violet-visible (UV-Vis) spectroscopy was used to confirm the adsorption of the compounds on the electrode surface. The obtained electrochemical results revealed that the inhibition performance of the green inhibitors increased by increasing their dosage in the electrolyte. In addition, it was proved that Marjoram plant extract possessed the most inhibition efficiency (up to 92%) among the under-studied herbal extracts. Marjoram extract behaved as a mixed-type inhibitor in the hydrochloric acid solution, and the adsorption process of the extract on the steel surface followed the Langmuir adsorption model. Adsorption of the compounds on the steel surface was also studied using density functional theory (DFT), and it was found that the protonated organic compounds in the extract have a high affinity for adsorption on the electrode surface in the acidic solution.

Green hydrogen generation in alkaline solution using electrodeposited Ni-Co-nano-graphene thin film cathode.

Green hydrogen generation technologies are currently the most pressing worldwide issues, offering promising alternatives to existing fossil fuels that endanger the globe with growing global warming. The current research focuses on the creation of green hydrogen in alkaline electrolytes utilizing a Ni-Co-nano-graphene thin film cathode with a low overvoltage. The recommended conditions for creating the target cathode were studied by electrodepositing a thin Ni-Co-nano-graphene film in a glycinate bath over an iron surface coated with a thin copper interlayer. Using a scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) mapping analysis, the obtained electrode is physically and chemically characterized. These tests confirm that Ni, Co, and nano-graphene are homogeneously dispersed, resulting in a lower electrolysis voltage in green hydrogen generation. Tafel plots obtained to analyze electrode stability revealed that the Ni-Co-nano-graphene cathode was directed to the noble direction, with the lowest corrosion rate. The Ni-Co-nano-graphene generated was used to generate green hydrogen in a 25% KOH solution. For the production of 1 kg of green hydrogen utilizing Ni-Co-nano-graphene electrode, the electrolysis efficiency was 95.6% with a power consumption of 52 kwt h-1, whereas it was 56.212. kwt h-1 for pure nickel thin film cathode and 54. kwt h-1 for nickel cobalt thin film cathode, respectively.

In vitro calibration and in vivo validation of phenomenological corrosion models for resorbable magnesium-based orthopaedic implants.

Metallic bioresorbable orthopaedic implants based on magnesium, iron and zinc-based alloys that provide rigid internal fixation without foreign-body complications associated with permanent implants have great potential as next-generation orthopaedic devices. Magnesium (Mg) based alloys exhibit excellent biocompatibility. However, the mechanical performance of such implants for orthopaedic applications is contingent on limiting the rate of corrosion in vivo throughout the bone healing process. Additionally, the surgical procedure for the implantation of internal bone fixation devices may impart plastic deformation to the device, potentially altering the corrosion rate of the device. The primary objective of this study was to develop a computer-based model for predicting the in vivo corrosion behaviour of implants manufactured from a Mg-1Zn-0.25Ca ternary alloy (ZX10). The proposed corrosion model was calibrated with an extensive range of mechanical and in vitro corrosion testing. Finally, the model was validated by comparing the in vivo corrosion performance of the implants during preliminary animal testing with the corrosion performance predicted by the model. The proposed model accurately predicts the in vitro corrosion rate, while overestimating the in vivo corrosion rate of ZX10 implants. Overall, the model provides a "first-line of design" for the development of new bioresorbable Mg-based orthopaedic devices. STATEMENT OF SIGNIFICANCE: Biodegradable metallic orthopaedic implant devices have emerged as a potential alternative to permanent implants, although successful adoption is contingent on achieving an acceptable degradation profile. A reliable computational method for accurately estimating the rate of biodegradation in vivo would greatly accelerate the development of resorbable orthopaedic implants by highlighting the potential risk of premature implant failure at an early stage of the device development. Phenomenological corrosion modelling approach is a promising computational tool for predicting the biodegradation of implants. However, the validity of the models for predicting the in vivo biodegradation of Mg alloys is yet to be determined. Present study investigates the validity of the phenomenological modelling approach for simulating the biodegradation of resorbable metallic orthopaedic implants by using a porcine model that targets craniofacial applications.

Evaluating the QileX-RhE skin corrosion test for chemical subcategorization in accordance with OECD TG 431.

Skin corrosion testing is integral to evaluating the potential harm posed by chemicals, impacting regulatory decisions on safety, transportation, and labeling. Traditional animal testing methods are giving way to in vitro alternatives, such as reconstructed human epidermis (RhE) models, aligning with evolving ethical standards. This study evaluates the QileX-RhE test system's performance for chemical subcategorization within the OECD TG 431 framework. Results demonstrate its ability to differentiate subcategories, accurately predicting 83% of UN GHS Category 1A and 73% of UN GHS Category 1B/1C chemicals with 100% sensitivity in corrosive prediction. Additionally, this study provides a comprehensive assessment of the test method's performance by employing nuanced parameters such as positive predictive value (PPV), negative predictive value (NPV), post-test odds and likelihood rations, offering valuable insights into the applicability and effectiveness of the QileX-RhE test method.

Understanding corrosion behavior of aluminum current collector in LiFSI electrolyte.

Cycling aging is the one of the main reasons affecting the lifetime of lithium-ion batteries and the contribution of aluminum current collector corrosion to the ageing is not fully recognized. In general, aluminum is corrosion resistant to electrolyte since a non-permeable surface film of alumina is naturally formed. However, corrosion of aluminum current collector can still occur under certain conditions such as lithium bis(fluorosulfonyl)imide (LiFSI)-based electrolyte or high voltage. Herein, we investigates the corrosion of aluminum current collector in the electrolyte of 1.2M LiFSI in ethylene carbonate (EC) and ethyl methyl carbonate (EMC) mixed solvents. The electrochemical results shows that the corrosion current of aluminum is enhanced by cycling time and potential, which is correlated with the surface species and morphology. The formation of AlF3, which is induced by deep penetration of F- anions through surface passivation film, leads to internal volume change and the surface crack in the end. Our work will be inspiring for future development of high-energy-density and high-power-density lithium-ion batteries in which the LiFSI salt will be intensively used.

In vitro and in vivo degradation, biocompatibility and bone repair performance of strontium-doped montmorillonite coating on Mg-Ca alloy.

Poor bone growth remains a challenge for degradable bone implants. Montmorillonite and strontium were selected as the carrier and bone growth promoting elements to prepare strontium-doped montmorillonite coating on Mg-Ca alloy. The surface morphology and composition were characterized by SEM, EDS, XPS, FT-IR and XRD. The hydrogen evolution experiment and electrochemical test results showed that the Mg-Ca alloy coated with Sr-MMT coating possessed optimal corrosion resistance performance. Furthermore, in vitro studies on cell activity, ALP activity, and cell morphology confirmed that Sr-MMT coating had satisfactory biocompatibility, which can significantly avail the proliferation, differentiation, and adhesion of osteoblasts. Moreover, the results of the 90-day implantation experiment in rats indicated that, the preparation of Sr-MMT coating effectively advanced the biocompatibility and bone repair performance of Mg-Ca alloy. In addition, The Osteogenic ability of Sr-MMT coating may be due to the combined effect of the precipitation of Si4+ and Sr2+ in Sr-MMT coating and the dissolution of Mg2+ and Ca2+ during the degradation of Mg-Ca alloy. By using coating technology, this study provides a late-model strategy for biodegradable Mg alloys with good corrosion resistance, biocompatibility. This new material will bring more possibilities in bone repair.