Effect Of Anodic Oxidation Research Articles

Effect of Anodic Oxidation on Antibacterial Properties and Biocompatibility of Ti‐13Nb‐13Zr‐3Cu for Biomedical Application

Ti‐13Nb‐13Zr (TNZ), a representative of β‐type titanium alloys, has garnered significant interest in biomedical implant materials recently because of its high strength, and closer elastic modulus to human bone. However, TNZ alloy does not have antibacterial properties and has the potential to cause implant‐related infection, even implantation failure. Herein, TNZ alloy is alloyed by Cu element and the surface is modified by anodic oxidation (AO) to enhance the biocompatibility and antimicrobial qualities. The corrosion resistance, antimicrobial properties, and cytotoxicity of the TNZ‐3Cu alloy before and after anodization are studied by X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, electrochemical test, mechanical property test, and cell test. The experimental results show that the primary constituents of the TNZ‐3Cu alloy are α″ martensite and β phase after solid solution treatment. The elastic modulus of TNZ‐3Cu alloy is (65 ± 1.33) GPa, 9 GPa lower than that of TNZ alloy. The AO treatment significantly improves the hydrophilicity and antibacterial properties as well as the corrosion resistance by the formation of a dense oxides composites coating. The cell test results show that the coating improves the initial adhesion of cells by the high hydrophilic surface and promotes the proliferation of cells by the release of copper ions.

Effect of anodic oxidation on the corrosion resistance and antibacterial properties of Ti-15Mo-9Ag for biomedical application

Ti-15Mo-9Ag (TM-9Ag) alloy was designed and prepared in order to produce a titanium alloy with low elastic modulus and excellent antibacterial properties. Anodic oxidation was used to surface modify and improve the surface bioactivity of TM-9Ag and the effect on the microstructure, corrosion resistance, antimicrobial properties and biocompatibility was investigated in an oxidation voltage range of 10–80 V. The results showed that TiO2, MoO2 and Ag2O were formed in the oxidized layer on TM-9Ag surface after the anodic oxidation. The antibacterial properties were evaluated by the plate counting method, and it was found that the antibacterial properties of the alloy were significantly improved, and the corrosion resistance was also enhanced. Cellular experiments showed that the anodic oxidized TM-9Ag alloys exhibited good cytocompatibility.

Effect of anodized titanium abutment collars on peri-implant soft tissue: A split-mouth clinical study

Statement of problemAnodic oxidation of titanium implant abutment collars has been used to mask their unesthetic grayish color. However, the effect of anodic oxidation on the health and appearance of peri-implant soft tissues is unclear. PurposeThe purpose of this split-mouth clinical study was to investigate the effect of anodized titanium on the health and esthetics of peri-implant soft tissues. Material and methodsA total of 60 osseointegrated implants placed in 30 participants were included in the present study. Each participant received 2 randomly allocated abutments, one with a pink anodized collar and the other with an unanodized one to form 2 groups: unanodized group (control group) and anodized group (experimental group). All implants were restored with lithium disilicate restorations. Evaluations of the peri-implant soft tissues were performed at the time of definitive restoration insertion (baseline) and after 3, 6, 12, and 18 months: peri-implant probing depth, soft tissue recession, modified sulcus bleeding index, modified plaque index, and modified gingival index. The esthetics of peri-implant soft tissues were evaluated by using the modified pink esthetic score. The paired t test or Wilcoxon signed-rank test was used for comparing the 2 study groups at each point of time depending on the normality of the variables (α=.05). To compare each variable at different time points within each group separately, repeated measures ANOVA or Friedman tests were used according to the normality of the variables, followed by post hoc pairwise comparisons by using the Bonferroni adjusted significance (α=.05). ResultsFive peri-implant soft tissue indices were followed up throughout the study. No statistically significant differences were found among the mean values of the tested indices in the anodized and unanodized groups throughout the evaluation periods (P>.05). The collective mean values of the modified pink esthetic score also showed no statistically significant differences between the groups (P>.05). ConclusionsBased on this split-mouth clinical study, pink anodized titanium abutment collars do not produce a clinically significant effect on the health or esthetics of peri-implant soft tissues.

Electrodeposits of nickel with reduced graphene oxide (Ni/rGO) and their enhanced electroactivity towards hydrogen evolution in water electrolysis

Catalytic performance of nickel cathodes for hydrogen production by water splitting can be improved by carbon nanomaterials, in particular graphene and reduced graphene oxide (rGO). In this work, electrodeposits Ni/rGO were examined in 0.1 M Na2SO4 with emphasis on hydrogen evolution reaction (HER) and effect of anodic oxidation. Ni and Ni/rGO were electrodeposited by galvanic square wave method with sonication. In contrast to smooth deposits of Ni, deposits of Ni/rGO had the cumulus/cauliflower type morphology with developed surface. Their increased surface area was confirmed by measurements of double layer capacitance. HER and anodic polarization currents were for Ni/rGO significantly higher than those for Ni. Voltammetric cycling or potentiostatic polarization to and above potentials of stability of Ni oxides (Ni3O4, Ni2O3 or NiO2) caused a rise in HER for both materials, but especially strongly for Ni/rGO. Enhanced HER on Ni/rGO was explained by greater surface area and the formation of larger amounts of electrocatalytic Ni oxides/hydroxides, as a result of the increased anodic reactivity of rGO-containing Ni. Incorporated rGO might also contribute by increasing electronic conductivity.

Effects of anodic oxidation for combustion chamber on heat transfer of the piston in an aero-engine

The effects of an anodic oxidation coating on piston temperature distribution and thermal stress are investigated by establishing an inverse heat conduction problem in the form of an optimization problem in an aero-engine. A thermal analysis is carried out for both coated and uncoated pistons at 2100 rpm under 50 and 100% of full load. Specially manufactured metal plugs (templugs) were installed in both kinds of pistons to measure the temperature of every survey station. The effect of the secondary motion of the piston and piston ring on the lubrication oil film was taken into consideration in determining the heat transfer coefficient. There was reasonable agreement between the numerical method and experimental measurement, shown with an error analysis using a third-order polynomial fit technique. Research results showed that the maximum temperature of the anodic oxidation coated piston head increased to 298.5°C and 309.6°C under 50 and 100% of full load, respectively. In addition, there was a temperature reduction in the skirt for the coated piston in contrast to the temperature for the uncoated pistons under 50 and 100% of full load. The temperature distribution and thermal stress in the pin boss were then analyzed. The results indicated an increase of maximum temperature; however, the maximum thermal stress decreased for the anodic oxidation coated piston in the pin boss. Furthermore, a 200-h durability test was performed, proving the thermal load of the piston with anodic oxidation coating would not damage the piston. Also, the effect of the anodic oxidation coating technique on aero-engine emissions was investigated. The anodic oxidation coating for the aero-engine combustion chamber slightly improved CO and HC under 50 and 100% of full load.

Effect of Current Density on Anodised Titanium in Sulphuric Acid for Biomedical Application

Bioinert titanium (Ti) can be modified to bioactive by performing various techniques including anodic oxidation. Where, this method encompasses electrode reactions in combination with electric field driven metal and oxygen ion diffusion to the formation of an oxide film on anode surface. The objective of this study is to evaluate the effect of current density of anodic oxidation upon the characteristic of titanium in sulphuric acid (H2SO4) under various conditions. The modified titanium was prepared using anodic oxidation method in 0.3 M of sulphuric acid as electrolyte. The applied voltage and current density of the anodic oxidation parameters were varied from 50 – 200 V and 25 – 75 mA.cm-2 respectively for 10 min of oxidation process at room temperature. The effects of anodic oxidation on the titanium were characterised using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that by increasing the current density of the anodic oxidation, different mineralogy, surface morphology, and surface profile were produced. At low current density (25 mA.cm-2), high voltage is needed to produce high crystalline of anatase formed on the titanium surface and only able to produced very low of rutile titanium with 200 V of applied voltage compared to high current density (75 mA.cm-2) with same applied voltage, very high rutile crystal with mixture of low anatase was observed on the titanium. This modified oxide of titanium has potentially to be applied in biomedical as implant.

Effects of anodic oxidation on corrosion properties of Al coating by arc spraying in seawater

A layer of Al coatings was prepared on the S355 steel by arc spraying, which was conducted by anodic oxidation treatment; the morphologies, chemical element compositions and phases of Al coating, and anodic oxide layer were analyzed with field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS) and X‐ray diffraction (XRD), respectively. The corrosion protections of Al coating before and after anodic oxidation were discussed with a seawater immersion test; the corrosion resistance mechanisms of Al coating and anodic oxide layer in the seawater were also investigated. The results show that the thickness of Al coating is about 300 µm by arc spraying, the sample surfaces become loose after seawater immersion corrosion and Cl− and O2− penetrate into the substrate from the cracks, destroying the binding properties of coating–substrate, and the coating fails. After anodic oxidation, the oxide layer is formed in the surface of Al coating with the thickness of about 30 µm; the corrosion products are mainly composed of Al(OH)3, which barraged the holes caused by seawater corrosion. The corrosion cracks are formed during the corrosion, while the number and depth of cracks decrease obviously after anodic oxidation treatment. The corrosion of Al coating becomes the local corrosion after anodic oxidation treatment, and the grains are smaller, which are easily nucleated to form a new corrosion resistance layer. Copyright © 2015 John Wiley & Sons, Ltd.

Anodic Oxidation of Titanium for Biomedical Application

Anodic oxidation (AO) is a chemical method which used to produce a bioactive layer (oxide) of titanium (Ti). The aim of this study is to evaluate the effect of anodic oxidation upon Ti foil in acetic acid (C2H4O2). The anodic oxidation was performed by varying the applied voltage (10 – 200 V) and concentration of the electrolyte (0.5, 1.5 and 3.0 M of C2H4O2). After anodic oxidation, the Ti specimens were soaked in simulated body fluid (SBF) to observe the precipitation of hydroxyapatite (HAP). The Ti sample was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) after anodic oxidation and SBF. The precipitation of apatite after soaked in SBF was observed using SEM. From this study, the applied voltage range from 100 to 200 V at low and high concentration of acetic acid resulting in the porous surface of anatase. The arcing process occurred during the oxidation process which lead to the formation of anatase and sites for HAP growth (nucleation site). The SBF result shows that the anodised Ti is suitable to be applied in biomedical especially as implant.

Effects of Anodic Oxidation in Ethylene Glycol Based Electrolyte on the Corrosion Resistance and Biocompatibility of NiTi Shape Memory Alloy

Nickel titanium (NiTi) is the most attractive shape memory alloy in industrial and in medical application but suffer from corrosion attack by body fluids. Nowadays, Electrochemical anodization has become a popular surface modification method for biomaterials. In this study we prepared TiO2 coating with nanoporous surface morphology on NiTi shape memory alloy by using electrochemical anodization in ethylene glycol based electrolyte followed by annealing in 600 °C and explored its appropriateness for biomedical applications. Morphology and crystal structure of the film was characterized by Field emission scanning electron microscopiy (FE-SEM) and X-ray diffraction (XRD) tests. The corrosion resistance of the treated NiTi alloy was investigated by potentiodynamic polarization test and The findings showed that the anodization in ethylene glycol solution extremely increased the corrosion resistance and hence biocompatibility.

Effect of anodic oxidation on the corrosion behavior of Ti-based materials in simulated physiological solution

Anodic oxidation in acetic acid was investigated as a means of improving the corrosion resistance, in simulated physiologic solution, of titanium and two titanium-based alloys, Ti–6Al–7Nb and Nitinol. The composition and the thickness of the surface layers formed by anodization were analyzed using X-ray photoelectron spectroscopy. The electrochemical characteristics were investigated by linear polarization, cyclic polarization, and electrochemical impedance spectroscopy at the open circuit potential. Anodization of all these three metals resulted in the formation of TiO2 as the main oxide. These layers improved the corrosion behavior in simulated physiological solution, as evidenced by significant increase in polarization resistance and decrease in corrosion current density. Electrochemical impedance results were interpreted based on the two-layer structure of the passive film. Anodization has thus been shown to provide a simple and effective means of improving the corrosion behavior of titanium-based alloys in simulated physiological solution.

Effect of Anodization on the corrosion behavior of Aluminium Alloy in HCl acid and NaOH

<b> </b>The effect of anodic oxidation on the corrosion behaviour of Aluminium alloy ‘7075’ in two different media was investigated. The weight loss technique was used to determine the corrosion rate in 1.0M HCl and 1.0M NaOH solutions. These specimens were allowed to stay in the solutions for 504 hours with an interval of 72 hours weight loss measurement. The results shows that in both media, the normal corrosion rate profile of an initial steep rise in corrosion followed by subsequent fall was observed for both anodized and unanodized specimens but with severe attack on those specimens in 1.0M HCl. The anodized Al-Alloys in both solutions have lesser corrosion rate as compared to the unanodized Alloys. It was concluded that, Aluminium Alloy ‘7075’ corrodes faster in 1.0M HCl than in 1.0M NaOH solution and that anodizing helps to reduce the corrosion rate of Al- Alloy in both media.

Effects of anodic oxidation and hydrothermal treatment on surface characteristics and biocompatibility of Ti–30Nb–1Fe–1Hf alloy

Anodic oxidation followed by hydrothermal treatment has been widely applied for surface modification of titanium alloys to precipitate a crystalline hydroxyapatite (HA) layer in order to achieve improved osteoconduction. A majority of the studies in the literature imposed relatively high powers to enhance Ca and P in the anodic oxide film (AOF). However, high powers have been found to cause deterioration of the adhesive strength in one of the author's previous study. In this study, a new electrolyte comprising calcium acetate monohydrate (CA), β-glycerophosphate disodium pentahydrate (β-GP) and HA powder was developed, and the Ti–30Nb–1Fe–1Hf alloy was anodized in this HA-containing electrolyte to a relatively low voltage. Results show that the AOF anodized in the HA-containing electrolyte exhibits a better HA forming ability during hydrothermal treatment, attributing to the presence of HA powder in the electrolyte that effectively enhances both the Ca content and Ca/P ratio in the AOF. On the other hand, the adhesive strength was little affected due to the decrease in size of the craters residing in the AOF. With respect to the biological responses, not much difference in biocompatibility of the treated and untreated Ti–Nb surfaces was obtained. However, the anodized and hydrothermally treated surface promotes the attachment of cells.

Electrochemical corrosion of liquid phase sintered silicon carbide ceramics

Liquid-phase sintered silicon carbide (LPS-SiC) is silicon carbide ceramic which contains sintering additives forming a liquid phase during sintering. These additives segregate in the grain boundary phase during cooling. The usually used Al2O3 dissolves partially in the SiC-grains and therefore changing the conductivity of the SiC (core rim structure). This study is focused on the electrochemical properties of LPS-SiC with yttria and alumina as sintering additives. Electrochemical corrosion behaviour of LPS-SiC has been determined by linear and cyclic voltammetry in acidic and alkaline solution. The effect of anodic oxidation on the material has been monitored by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX) as well as by atomic force microscopy (AFM). The core-rim structure of the investigated materials plays a decisive role in the vulnerability towards corrosion. If oxidative attack was found to occur under anodic polarization, it happened preferentially in the rim region of the SiC-grains, while the core of the SiC-grains remained basically unaffected.

Effect of anodic oxidation on the properties of Ni-coated carbon fibers produced by electrodeposition

PAN-based carbon fibers were continuously treated by anodic oxidation followed by electrodeposition of Ni on their surface.The influence of anodic oxidation on mechanical properties,surface morphology,amount of surface acidic groups and growth mode of the Ni coating were studied by SEM,XRD,TG and conductometric titration.Results showed that the total amount of surface acidic groups on the oxidized carbon fibers is about 10times as large as that of the untreated ones and the tensile strength of carbon fibers decreased slowly at first and then quickly with increasing depth of oxidation.The growth mode of the Ni coating changed from a Volmer-Weber mode to a Frank-van der Merwe mode and the grain size of the Ni coating decreased from 14.5 to 11.2nm for the untreated and treated carbon fibers respectively.The oxidation resistance of the carbon fibers was improved by the Ni coating.The initial oxidation temperature of the Ni-coated treated-carbon fibers with anodic oxidation is about 50℃ higher than that of the Ni-coated carbon fibers without the oxidation.Appropriate oxidation could improve the adhesion between the Ni coating and the carbon fibers.

Effect of anodic oxidation on fatigue performance of 7075-T6 alloy

Abstract Effect of anodic oxidation on fatigue performance of 7075-T6 alloy for pre-corroded and non-corroded specimens has been investigated by conducting a series of rotary bending fatigue tests at 95 Hz. The anodized specimens with different coating thickness (6, 12 and 23 μm) were exposed to 3.5 wt.% NaCl solution for 6, 48, 96 and 240 h. The results indicate that oxidation has a tendency to decrease the fatigue performance. Fatigue strength was reduced with increasing coating thickness; approximately 40% reduction for a 23 μm thick coating was obtained. It was observed that oxidation mitigated pitting corrosion. Superior corrosion resistance was obtained for the thickest coating layer. Fatigue tests with pre-corroded specimens showed that fatigue life of coated specimens was significantly affected by pre-corrosion, except for the specimen with the thickest coating layer. When the pre-corroded bare and coated specimens were compared, the coating improved the fatigue performance in high cycle fatigue (> 10 5 ) only and it degraded the fatigue performance in low cycle regime.

Effects of anodic oxidation in H 2SO 4 electrolyte on the biocompatibility of NiTi shape memory alloy

Effects of anodic oxidation in H 2SO 4 electrolyte on the biocompatibility of NiTi shape memory alloy (SMA) were investigated by characterizing surface structure, blood compatibility, wettability, release of harmful Ni ions of anodized NiTi SMA. Although titania film resulting from anodic oxidation in H 2SO 4 electrolyte has a porous structure, it can effectively block out-diffusion of Ni from NiTi SMA to simulated body fluid (SBF). Comparing with chemical polishing, anodic oxidation in H 2SO 4 electrolyte can also improve the wettability, blood compatibility, thromboresistance of NiTi SMA.

Effect of Anodic Oxidation on the Characteristics of Lattice-Matched AlInN/GaN Heterostructures

The effect of anodic oxidation on the electronic characteristics of lattice-matched AlInN/GaN heterostructures was investigated using field-effect transistor (FET) structures with the gate areas in direct contact with the electrolytes. The gate surface of the FETs was subjected to anodic oxidation in 0.1 M KOH. The oxidized heterostructures were analyzed by electrochemical impedance spectroscopy and by modeling the characteristics of the electrolyte-gate FETs and the energy-band diagram of the heterostructures. This analysis suggested that the anodic treatment induced a bulk oxidation of the AlInN barrier. The Fermi level at the oxidized AlInN surface was shifted deep into the bandgap. The oxidation led to a reduction of the carrier mobility and to partial depletion of the channel.

Effect of Fiber–Polymer Interactions on Fracture Toughness Behavior of Carbon Fiber-Reinforced Epoxy Matrix Composites

The effect of anodic oxidation on high-strength polyacrylonitrile-based carbon fibers has been studied in terms of fiber surface energetics and fracture toughness of the composites. According to contact angle measurements based on the wicking rate of a test liquid, anodic oxidation leads to an increase in surface free energy, mainly due to the increase of its specific (or polar) component. For the carbon-fiber-reinforced epoxy resin matrix system, a direct linear relationship is shown between the specific component and the critical stress intensity factor measured by the single edge notched beam fracture toughness test. From a surface-energetic point of view, the anodic treatment may be suitable for carbon fibers incorporated in a polar organic matrix, resulting in an increased specific component of the surface free energy. Good wetting plays an important role in improving the degree of adhesion at interfaces between fibers and matrices of the resulting composites.

Anodic oxidation of porous silicon bilayers

This paper focuses on the study of the effect of anodic oxidation in porous silicon bilayers composed of two porous layers of different porosities. The order of the two types of layers has been alternated, and the thicknesses and refractive indices have been optically characterized by Fourier transform infrared spectroscopy. The results show that the refractive index of anodic oxidized porous silicon is reduced significantly with respect to just formed porous silicon. It is also observed that the quality of the oxidation is related to the porosity of the inner porous layer of the silicon bilayer structure. This effect is interpreted in terms of quantum size effects.

Effects of anodic oxidation on the surface structure of highly oriented pyrolytic graphite revealed by in situ electrochemical scanning tunnelling microscopy in H 2SO 4 solution

Effects of the potential of anodic oxidation and of potential cycling on the surface structure of a highly oriented pyrolytic graphite (HOPG) electrode were observed by in situ electrochemical scanning tunnelling microscopy (ECSTM) in dilute H 2SO 4 solution with atomic resolution. With potential cycling between −0.1 V and 1.8 V vs. Ag/AgCl (sat. KC1), some atoms on the top layer of HOPG protrude out of the base plane, and the graphite lattice of these protrusions is still intact but is strained and expanded. With further potential cycling, some protrusions coalesced and some grew larger, and an anomalous superperiodic feature was observed (spacing 90 Å with a rotation 30 ° relative to atomic corrugations) which superimposed on the atomic corrugation of HOPG. On the topmost of these protrusions, some atoms form oxides and others are still resolved by the ECSTM image. With potential cycling between −0.1 V and +2.0 V vs. Ag/AgCl (sat. KC1), damage to freshly cleaved HOPG surface is more serious and fast, some ridges are observed, the atomic structure of the HOPG surface is partially and then completely damaged due to the formation of oxide. We also found that anodic oxidation occurred nonuniformly on the surface of HOPG near defects during potential cycling.