Anti-corrosion Layer Research Articles

Anticorrosion Coated Stainless Steel as Durable Support for C-N-TiO2 Photo Catalyst Layer

The development of durable photocatalytic supports resistant in harsh environment has become challenging in advanced oxidation processes (AOPs) focusing on water and wastewater remediation. In this study, stainless steel (SS), SS/Ti (N,O) and SS/Cr-N/Cr (N,O) anticorrosion layers on SS meshes were dip-coated with sol gel synthesised C-N-TiO2 photo catalysts pyrolysed at 350 °C for 105 min, using a heating rate of 50 °C/min under N2 gas. The supported C-N-TiO2 films were characterised by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy. The results showed that C-N-TiO2 was successfully deposited on anticorrosion coated SS supports and had different morphologies. The amorphous C and TiO2 were predominant in C-N-TiO2 over anatase and rutile phases on the surface of SS and anticorrosion supports. The C-N-TiO2 coated films showed enhanced photocatalytic activity for the decolouration of O.II dye under both solar and UV radiations. The fabricated C-N-TiO2 films showed significant antibacterial activities in the dark as well as in visible light. Herein, we demonstrate that SS/Ti(N,O) and SS/Cr-N/Cr(N,O) anticorrosion coatings are adequate photocatalytic and corrosion resistant supports. The C-N-TiO2 photo catalytic coatings can be used for water and wastewater decontamination of pollutants and microbes.

Dual Antifouling Mechanisms Induced by Cupric Ions and Needle-Like Alumina in Arc-Sprayed Composite Coatings

Aluminium-polymethyl methacrylate-copper (Al-PMMA-Cu) composite coatings were developed using cored wire arc spraying. The bacteria Bacillus sp. was used to evaluate the antifouling performances of the coatings. The microstructures and antifouling mechanisms of the coatings were investigated and discussed. The results show that the composite coatings presented improved antifouling performances, and two antifouling mechanisms were explored. On the one hand, the Cu nano-particles were released to seawater due to corrosion of the Al components, converted to cupric ions, and killed the bacteria. Meanwhile, oxidation of Al was accelerated due to Cu-Al galvanic reaction, and the needle-like corrosion products were formed, which pierced the cell membranes and killed the bacteria. The effects of the PMMA on the electrochemical properties of the coatings were also evaluated. The results show that the sealing function of the PMMA components enhanced the corrosion resistance of the Al-PMMA-Cu coatings. This investigation shed light on one-step construction of antifouling and anticorrosion layers for marine applications.

Microwave measurement and imaging for multiple corrosion cracks in planar metals

Metal structures (such as buried pipelines, steel bridges) are subjected to long-term corrosion in the harsh environment, once the anticorrosion layer coated on the metals peeled off, corrosion cracks will occur and result in pipeline leaks, bridge fractures and other fatal effects that endanger human life and property safety. Therefore, an approach to characterize the location, size and boundary of the corrosion cracks is essential to guarantee the structures' health. In this paper, a microwave measurement and imaging approach is proposed to characterize the multiple corrosion cracks in planar metal. Firstly, a numerical model based on finite integral technique (FIT) and an experimental platform is established, respectively. Secondly, for the typical corrosion cracks, the relationships between the location as well as the size of the cracks, and the phase of the reflection coefficient are investigated. Then, an approach to characterization the location and size of the corrosion cracks is proposed. Finally, the boundary of the corrosion cracks is imaged by an improved canny algorithm. The microwave measurement and imaging approach proposed can quantitatively characterize the number, location, size and boundary of the cracks, while the cracks can be visually recognized by imaging

Review of the Application of Graphene-Based Coatings as Anticorrosion Layers

Due to the excellent properties of graphene, including flexibility that allows it to adjust to the curvature of the substrate surface, chemical inertness, and impermeability, graphene is used as an anticorrosion layer. In this review, we present the current state-of-the-art in the application of graphene in the field of protective coatings. This review provides detailed discussions about the protective properties of graphene coatings deposited by different methods, graphene-based organic coatings, the modification of graphene-based coatings, and the effects of graphene functionalization on the corrosion resistance of protective coatings.

Study on cutting PV polysilicon with a new type of diamond abrasives-helix-distribution saw wire based on controlling the subsurface microcrack damage depth

There are large brittle fracture pits on the surface of photovoltaic polysilicon wafer cut by diamond wire saw, because of the problems such as poor flow of cutting fluid and difficulty in chip discharge. At the same time, the anti-corrosion amorphous layer on the wafer surface can obviously block the subsequent acid etching and texturing reaction. In order to solve these problems, a new type of diamond abrasives-helix-distribution saw wire is used as the sawing tool to obtain the surface characteristics of photovoltaic polysilicon wafer suitable for acid texturing, then research on wire sawing photovoltaic polysilicon based on controlling subsurface microcrack damage depth control is carried out. The concept of high-quality cutting abrasives (HQCA) is defined, and the cutting process of polycrystalline silicon is numerically calculated based on the established new type diamond wire model, the influence of the process parameters and the structural parameters of the saw wire on the cutting characteristics is analyzed, and the reasonable matching between the process parameters and the saw wire parameters is discussed. The study results show that the number and proportion of HQCA in all abrasive grains involved in sawing can be increased by increasing the workpiece feed speed or reducing the moving speed of saw wire, properly reducing the abrasive concentration on the saw wire surface or increasing the abrasives size, or setting the ratio of axial distance between the abrasive area on wire surface and the bare wire area as 1:1. In this case, the formation of the wafer surface tends to be removed in the way of material microbrittleness, and the subsurface crack depths are in the optimal etching depth range. The number and proportion of HQCA remain basically unchanged when the workpiece feed speed changes in constant proportion to the wire speed, and the screw pitch of the abrasive groups on the surface of the saw wire has little effect on it.

Biocompatibility and bone regeneration of PEO/Mg-Al LDH-coated pure Mg: an in vitro and in vivo study

Forming a stable anti-corrosion surface layer on magnesium (Mg) and its alloys has become a major challenge in developing a desirable degradable medical implant in bone. In this study, a porous MgO layer was first formed on Mg by plasma electrolytic oxidation (PEO), and then a Mg-Al layered double hydroxide (LDH) layer was prepared to seal the porous structure of the PEO layer (LDH-2h and LDH-12h) via hydrothermal treatment. The bilayer structure composite coating, which can effectively resist the penetration of surrounding media, is similar to plain Chinese tiles. The in vitro results revealed that compared with other coatings, the LDH-12h composite coating can reduce the release of Mg ions and induce a milder change in pH when immersed in phosphate-buffered saline (PBS). In vitro rat bone marrow stem cell (rBMSC) culture suggested that the LDH-12h composite coating is favorable for cell activity, proliferation and could improve the osteogenic activity of rBMSCs. A subcutaneous implantation test revealed that the as-prepared sample showed enhanced corrosion resistance and histocompatibility in vivo, especially in the LDH-12h group. Moreover, LDH-12h had the lowest rate of degradation and the closest combination with the new bone after being inserted into a rat femur for 12 weeks with no major organ dysfunction. In summary, the asprepared PEO/Mg-Al LDH composite coating is able to improve the corrosion resistance and biocompatibility of Mg and to enhance osteogenic activity in vivo, suggesting its promising prospects for orthopedic applications.

Formation of Aluminum Composite Passive Film on Magnesium Alloy by Integrating Sputtering and Anodic Aluminum Oxidation Processes

Anodic aluminum oxidation (AAO) process on sputtered-Al film to form an oxide coating as an anticorrosion layer on AZ91D magnesium alloy was performed. The cross-sectional scanning electron microscope images showed an increase on the thickness of anodized oxide layer with increasing oxidation duration. By X-ray photoelectron spectroscopy and X-ray diffraction analyses, the anodized alumina layer had an amorphous structure, where the chemical composition is mainly composed of aluminum oxide. From the results of anticorrosion test, the higher charge transfer resistance of oxide layer was obtained for all AAO specimens by electrochemical impedance spectroscopy, as compared to the raw AZ91D substrate. In addition, the potentiodynamic polarization measurement showed that the specimen with 15 min anodizing treatment had the lower corrosion current density (0.29 μA/cm2), and the higher protection efficiency (99.64 %). These results proved that Al oxide/Al bi-layer composite passive film on AZ91D alloys is significantly improved the corrosion resistance behaviors and the optimal parameter for AAO process is 15 min.

Anti-Corrosion Layer Embedded Top Cathode for Semi-Transparent Perovskite Solar Cells

Power conversion efficiency (PCE) of perovskite solar cells (PSCs) has exceeded 25%, which is comparable to that of silicon solar cells and makes PSCs promising candidates for the next generation photovoltaics. However, their commercialization is still seriously hindered by the low device stability. Besides the well-known thermal and chemical factors, another major cause of the instability is the interaction of top metal electrodes with the Iodine-containing compounds decomposed from perovskite absorber layers. Both these volatile compounds and metal atoms can diffuse towards each other through hole transport layers and consequently lead to the degradation of device performance. In order to resolve this problem, an anti-corrosion layer against undesired mass transport is required to be inserted between the metal electrode and the perovskite absorber layer. Molybdenum is intrinsically resistant to the corrosive reaction of Mo to MoI3 because of its higher Metal-Metal bonding energy (435.5 kJ/mol) than Metal-Iodine bonding energy (266.9 kJ/mol). Besides, it has also been proven that Mo is stable against metal atom diffusion into perovskite by theory analysis. In this work, Mo was chosen to act as the anti-corrosion layer embedded in Oxide/Metal/Oxide (OMO) transparent cathodes for inverted semi-transparent PSCs. Bottom indium zinc tin oxide (IZTO) layers with a thickness of 30nm were fabricated via facing target sputtering using a low power before the deposition of magnetron sputtered Mo to protect organic layers from sputter damage. The electrical and optical characteristics of IZTO/Mo/IZTO (IMI) transparent electrodes were analyzed with dependence on Mo thickness and top IZTO thickness. Inverted semi-transparent PSCs integrated with the optimized IMI top cathode were assembled, in which the diffusion of iodine ions and metal atoms were more efficiently blocked compared to the reference device without a Mo anti-corrosion layer.

Electric Arc Deposition of an Anticorrosive Layer with Two Strip Electrodes

A two-strip electrodes surfacing with controlled transfer of electrode metal is proposed for applying an anti-corrosion layer to the surface of the base metal with a variable angle to the horizon. To prevent the formation of defects in the formation of the deposited layer, it is proposed to adjust the parameters of the surfacing mode in places where the angle of inclination of the surface changes.

Performance of different layers of graphene as protective coating for copper wire

Graphene can be used as an anti-oxidation and anti-corrosion layer due to its impermeability to oxygen or etchant and its atomically thin thickness. In this study, monolayer, bi-layer, and multilayer graphene were grown on copper (Cu) wire samples using a low-pressure chemical vapor deposition (LPCVD) process, and their performances for copper wire protection were characterized experimentally. The results show that multilayer graphene provided anti-oxidation protection up to 350 °C under continuous heating of 30 min. The etching time of copper wire with multilayer-graphene protection doubled comparing to their bare Cu wire counterparts. Furthermore, multilayer graphene protection significantly reduced the contact resistance between twisted-pair copper wires.

FORECASTING OF STRUCTURAL TRANSFORMATIONS IN HEAT AFFECTED ZONE STEEL OF 15Kh2NMFA AT ANTI-CORROSION CLADDING

Using mathematical modeling based on existing parametric regression equations the prediction of microstructure-phase transformations in heat affected zone( HAZ) metal of base material (steel 15Kh2NMFA) of WWER-1000 reactor vessel in arc cladding of protective anti-corrosion layer was carried out as well as performed comparative analysis of modeling results with obtained experimental data of dilatometric and metallographic analysis. The comparison of results ensures formation of bainite-martensite structure in HAZ metal of WWER-1000 reactor vessel, however a value of content of martensite in calculation and experimental determination is different on ~ 40…50%. To clarify the calculated results, a thermokinetic diagram of the decomposition of supercooled austenite was constructed for characteristic cooling rates (3; 4, and 5 °C/s) during the welding/surfacing thermal cycle. As a result, adequate parameters of the microstructure-phase composition in the HAZ of steel 15Kh2NMFA at corrosion-resistant cladding were obtained.

Al2O3–TiO2 composite coatings with enhanced anticorrosion properties for 316L stainless steel

Abstract316L stainless steel is used as an important structural material in various industries. However, its service life is limited in the presence of chloride ions due to severe chemical corrosion. Herein, a facile radiofrequency magnetron sputtering process is reported for the synthesis of various Al2O3–TiO2 composite coatings as an anticorrosion layer for 316L stainless steel substrates. The enhanced chemical stability of Al2O3–TiO2 composite coatings was investigated by X‐ray photoelectron spectroscopy, electron paramagnetic resonance, and X‐ray diffraction measurements. Moreover, the high specific surface area of Al2O3–TiO2 composite coatings displayed better hydrophobic property which can be confirmed by scanning electron microscopy and contact angle measurements. Finally, the direct characterization of anticorrosion properties was carried out using electrochemical tests. All of the above results exhibited the enhanced anticorrosion properties of Al2O3 coating after the incorporation of TiO2. Significantly, the Al2O3–TiO2 composite coatings with 15.56% Ti content provided the best corrosion resistance for 316L stainless steel.

Mechanical and corrosion protection properties of polymer–clay nanocomposite coatings for mild steel in marine environment

Polymer–clay nanocomposites (PCNs) are potentially interesting as anti-corrosion surface pretreatment layers because of their outstanding barrier characteristics. Corrosion behavior of steel coated with epoxy–indole-modified clay nanocomposite films was studied. The electrochemical behavior of films containing polymer–clay nanocomposites was analyzed by potentiodynamic polarization techniques, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM) measurements in 3.5% NaCl solution. Microstructural characterization and surface analysis of substrates and coatings were performed by FE-SEM/EDX techniques. Results from electrochemical measurements reveal good long-term corrosion protection of steel provided by polymer–indole-modified clay coating. This polymer–clay coating yields a highly ordered multilayered brick and mortar structure, where polymer provides a physical barrier for the diffusion of corrosive agents/corrosion products within the coating. The results of the study show that the incorporation of nanoclay has a significant effect on the mechanical behavior of composites. Mechanical properties of the coatings were found to be improved in the presence of modified nanoparticle. The adhesion strength was found to have increased (8.10 MPa) up to 2 wt.% and decreased in its value to 7.56 MPa for 3 wt.% of nanoclay reinforcement, which made the composite to become more brittle. The optimum loading of clay in the epoxy–fclay composites was attained at 2 wt.%, where the improvement in hardness and properties was seen.

Cadmium and its inorganic compounds - expressed as Cd - inhalable fraction. Documentation of proposed values of occupational exposure limits (OELs)

Cadmium (Cd) is a white metal with a bluish tint. It forms a number of compounds occurring in them on the degree of oxidation 2+. Cadmium compounds are water-soluble to varying degrees. The highest risk groups include employees involved in the production of nickel-cadmium batteries, alloys, cadmium pigments as well as employees of non-ferrous metal smelters and cutting welders of metals covered with a cadmium anti-corrosion layer. According to the Central Register of Data on Exposure to Substances , Preparations, Factors or Technological Processes on Carcinogenic or Mutagenic Action, 4276 workers in Poland were exposed to cadmium and its compounds. Cadmium is absorbed into the body through inhalation and digestive systems. In humans, the absorption is 2–50% and 4–6%, respectively. Elimination of cadmium from the body is a slow process. The estimated half-life of cadmium is from 5 to 30 years. Results of studies conducted in subjects exposed to cadmium in the work environment showed that the threshold concentration of cadmium in urine, at which increased excretion of low molecular weight proteins in urine was found, is 5–10 µg/g creatinine. In 1993, IARC identified cadmium and its compounds as a human carcinogen (group 1). The results of experimental studies in rats provided evidence of cadmium carcinogenicity as a result of inhalation exposure. Cadmium is recognized by SCOEL as a category C carcinogen, i.e. as a genotoxic carcinogen for which a threshold of action (concentration) can be determined, also called a practical threshold. The critical organs for the toxic effects of cadmium and its inorganic compounds in humans, depending on the route of exposure, are kidneys, lungs and possibly bones. The critical effect of cadmium on kidneys is increased excretion of low molecular weight proteins in urine, while the critical effect on lungs is the carcinogenic effect. Inhalation studies in rats exposed to cadmium at concentrations of 30 µgCd/m3, 13.4 µgCd/m3 and 10 µgCd/m3 for 18 months were used as the basis to propose TLV-TWA. The concentration of 10 µg Cd/m3 was taken as the NOAEL value. After applying the formula and taking into account the uncertainty factors with a total value of 10, the concentration of 0.001 mg/m3 (1 µgCd/m3) was determined as the TLV-TWA value for the inhaled fraction. Biological monitoring is the best indicator of cadmium exposure. The excretion of cadmium in urine enables the assessment of cumulative cadmium in the body and takes into account all sources of cadmium exposure, including contaminated food and smoking, while the blood cadmium concentration is a measure of current exposure. Previous BEI values in blood and urine were 5 μgCd/l and 5 μgCd/g creatinine, respectively. After discussion at the 91st meeting of the Interministerial Committee for TLVs and PELs, these values were maintained as mandatory. This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

A novel multiwalled LiF@GO@SiO2 microcapsule with high phase change temperature

High temperature phase change materials (PCMs)-encapsulated microcapsules with large heat exchange area for addressing specific energy storage have increasing application potentials in many fields. Herein, a novel hybrid multiwalled microcapsule LiF@GO@SiO2 with high phase change temperature was designed and fabricated, which could overcome strong corrosion and volume expansion of lithium fluoride (LiF) during heat storage process. The multiwalled structure of microcapsule contained three layers, consisting of volume expansion buffer layer polydopamine (PDA), anti-corrosion leakage-proof layer (GO) and heat-resist strength layer (SiO2), respectively. Volume expansion buffer layer would be vanished during thermal cycling, and GO as well as SiO2 layers played important roles in protecting molten LiF from leakage. A series of tests including SEM, SEM-EDS, FTIR, XPS, XRD and TGA revealed that three-layer shells were sequentially coated on the surface of core material LiF successfully. Besides, DSC results via quantitatively analyzing, indicated that LiF@GO@SiO2 microcapsules had high phase change temperature of 848 °C, encapsulation ratio of 82.0% and latent melting heat of 894.5 J/g. In addition, encapsulation ratio of the microcapsule had a minor deflection within 5% after 10 times loops by calculating and comparing corresponding enthalpies, which displayed prepared microcapsule could be used repeatedly in high temperature energy storage. Overall, our results opened new avenues for the utilization of high temperature PCMs and their packaging technique.

In Vitro Osteocompatibility and Enhanced Biocorrosion Resistance of Diammonium Hydrogen Phosphate-Pretreated/Poly(ether imide) Coatings on Magnesium for Orthopedic Application.

Magnesium, as a biodegradable metal, is a promising candidate for biomedical applications. To modify the degradation behavior of magnesium and improve its osteocompatibility, chemical conversion and spin coating methods were combined to develop a diammonium hydrogen phosphate-pretreated/poly(ether imide) (DAHP/PEI) co-coating system. The diammonium hydrogen phosphate pretreatment was employed to enhance the attachment between PEI coatings and the magnesium substrate; meanwhile, it could serve as another bioactive and anticorrosion layer when PEI coatings break down. Surface characterization, electrochemical tests, and short-term immersion tests in DMEM were performed to evaluate DAHP/PEI coatings. Electrochemical measurements showed that DAHP/PEI coatings significantly improved the corrosion resistance of pure magnesium. No obvious changes of the chemical compositions of DAHP/PEI coatings occurred after 72 h of immersion in DMEM. An in vitro cytocompatibility study confirmed that viability and LDH activity of human osteoblast-like cells on DAHP/PEI coatings showed higher values than those on the DAHP-pretreated layer and pure magnesium. The DAHP-pretreated layer could still enhance the ALP activity of MG-63 cells after the degradation of PEI in DAHP/PEI coatings. Besides that, the in vitro cellular response to the treated magnesium was investigated to gain knowledge on the differentiation and proliferation of human adipose-derived stem cells (hADSCs). Cell distribution and morphology were observed by fluorescence and SEM images, which demonstrated that DAHP/PEI coatings facilitated cell differentiation and proliferation. The high level of C-terminals of collagen type I production of hADSCs on DAHP/PEI coatings indicated the potential of the coating for promoting osteogenic differentiation. Positive results from long-term cytocompatibility and proliferation tests indicate that DAHP/PEI coatings can offer an excellent surface for hADSCs.

Influence of ZrO2 Incorporation into Coating on Electrochemical Response of Low-Carbon Steel Processed By Plasma Electrolytic Oxidation

The carbon steel is one of the most widely used metals material in engineering with good properties, such as high strength, high toughness, good mechanical properties and low cost. The surface treatment of the steel is essential, however, before use it in industry due to the low corrosion resistivity of steel substrate, which is a problem to use in high humid environment. Meantime it is important to improve the wear resistance and the interfacial adhesion of the coating. Since the thick alumina coating is one of most effective anti-corrosion layer which has high corrosion resistance relatively with the metals, the alumina coating on the steel substrate is good way to improve corrosion resistance. Among the ceramic coating technique for fabrication the alumina layer, such as chemical vapor deposition, magnetron sputter and ionization-assisted beam, plasma electrolytic oxidation (PEO) has been investigation as a new electrochemical surface treatment.PEO process is a unique process that utilized electrochemical reactions to form an oxide layer on a metal surface. The PEO process has been reported to attractive combination of wear resistance and corrosion resistance as well as enhancing thermal property of coating layer. However this advanced coating technique has been performed only if material was valve metals, such as Mg, Al, Ti, Nb and etc. and only a few papers of PEO processed steel have been published. Although several researchers performed PEO process on the steel substrate, the specimen was pretreated by plasma spray, laser re-melting or chemical vapor deposition, therefore it was not convenience to widely use in engineering due to the very high cost and thermal shock to the substrate.The structure and morphology of coating layer formed by PEO process, on the other hand, is influenced on experiment conditions which are composition and concentration of electrolyte, current density and condition of substrate, in particular, composition of electrolyte effect on forming oxide layer. Recently, the incorporation of second oxide nanoparticles into the oxide layer generated by the PEO process in order to improve functionality has received considerable attention. Our previous work has demonstrated that incorporated ZrO2 nanoparticles into oxide layer may enhance the resistance against pitting corrosion.In this study, we conducted PEO process on A36 carbon steel without any pretreatment and successfully formed an incorporated alumina layer with 200-400 nm size of ZrO2 nanoparticles on the carbon steel and prepared comparison specimen which is unincorporated alumina coating with any others during PEO process. The microstructure and phase of coating layers were investigated and corrosion behavior was evaluated by electrochemical impedance spectroscopy.

Ultra Low Power Sensor for 3-Phase Water-Cut Applications

Precise measurement of the water fraction in oil is of critical importance in the oil industry. Currently, cost-effective, reliable, and compact downhole measurement technologies capable of full-range three-phase measurements are not available. This article presents an ultra low power, low cost, wireless, and noncorrosive resonance sensor based on magnetoelastic technology that has been implemented by an amorphous ribbon and electromagnetic interrogation. The proposed technology enables distinguishing all three gas, water, and oil phases with amplitude changes of 75% and 99% and resonant frequency shifts of 0.46% and 3.88%, respectively, compared to the gas phase. The response of the sensor enables characterizing the water-cut range from 10% to 90%. The addition of a Teflon anticorrosion layer enables sensor deployment for extended periods of time in harsh environments.

Microstructure evolution and electrochemical properties of TiO2/Ti-35Nb-2Ta-3Zr micro/nano-composites fabricated by friction stir processing

Forming stable anti-corrosion surface layer and homogenized microstructure on the surface of material has become a major challenge in developing biomedical β titanium alloy. In the study, TiO2/Ti-35Nb-2Ta-3Zr anti-corrosion micro/nano-composites with different amount of TiO2 particles were successfully fabricated by one-pass friction stir processing (FSP). The composition, microstructure and electrochemical properties of the material are characterized systematically. In particular, compact passive oxide films formed on surface of the material after electrochemical corrosion are elaborated from constituent, thickness and structural characteristics. Furthermore, the relationship between various FSP parameters, microstructure presented and corresponding corrosion resistance has been discussed in detail. The results show that TiO2/Ti-35Nb-2Ta-3Zr micro/nano-composite layers possess massive uniform β grains with homogeneous dispersive oxygen on the surface. Nanocrystallines surrounded by amorphous phases and α″ martensite accompanied with dislocations are discovered. TiO2/Ti-35Nb-2Ta-3Zr micro/nano-composite layers present outstanding corrosion resistance. More TiO2 added and higher rotation speed promotes the optimization in corrosion resistance forming more compact passive films. The study displays the potential of a new micro/nano-composite with outstanding surface microstructure and corrosion resistance that serves better as a biomedical implant.

Plasma Electrolytic Oxidation Treatment of Zr-2.5%Nb Alloy for Corrosion Resistance Enhancement

Anticorrosion layers were prepared on commercial Zr-2.5%Nb alloy by employing plasma electrolytic oxidation (PEO) process in aqueous electrolyte solutions. Microstructure and electrochemical behavior were evaluated using X-ray diffraction (XRD), optical metallography and potentiodynamic polarization measurements. The obtained coatings are uneven, presenting a dominant monoclinic crystallographic phase of ZrO2. Enhanced corrosion resistance was attributed to the PEO-treated samples compared to the commercial black oxide coating.