Voltage Time Response Research Articles

Growth pattern of soft-spark micro-arc oxide coating on titanium alloy in silicon anion electrolyte

Soft-spark micro-arc oxidation (MAO) is considered a potential solution for eliminating the porosity on the surface coating of titanium alloys during the MAO process. However, the mechanisms behind soft-sparking and the growth of coatings on Ti alloys are not yet fully understood. This study aimed to investigate the growth pattern of soft-spark MAO coating on titanium alloys by using sodium silicate as the electrolyte and manipulating the soft-sparking duration. The research focused on analyzing the positive and negative pulse voltage-time response curves, surface micromorphology, surface composition, cross-sectional structure, phase composition, dynamic potential polarization curve, microhardness, and thickness growth curve during the soft-spark process. The research findings revealed that soft spark discharges occurred in the plasma atmosphere near the surface of the external porous layer. The sparks penetrated the weak points of the amorphous interface layer (existing between the MAO coating and the substrate), forming filamentary discharges within the coating. This phenomenon led to the formation of a significant amount of rutile phases and bubble pores within the soft-spark coating, promoting the expansion of soft-sparks into the coating and facilitating the growth of the soft-spark coating. While the inner hardness of the soft-spark MAO film reached 1146 HV, the plasma atmosphere discharge also led to the formation of numerous filamentary channels and gas pores within the coating. Consequently, the coating's corrosion resistance did not show any improvement.

Photoactive TiO2-V2O5-WO3 film composites immobilized in titanium phosphate matrix by plasma electrolytic oxidation

V-, W-containing oxide-phosphate layers on titanium were obtained by plasma electrolytic oxidation (PEO) for 5 min at anode current density i = 0.08 A/cm2 in electrolytes containing 0.05 mol/L Na6P6O18 and 0.1 mol/L (Na2WO4 + NaVO3). The effect of replacing vanadate with tungstate (NaVO3:Na2WO4 = 0:1, 1:3, 1:1, 3:1, and 1:0) was studied on voltage–time responses, PEO coatings surface morphology, composition, optical and photocatalytic properties. The coatings were investigated by X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray microanalysis, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. Under experimental conditions, amorphous coatings with a thickness of 18–27 μm and a surface porosity of 1.5–3.6% were formed. Results show that vanadium (up to 10.5 at. %) and tungsten (up to 5.2 at. %) are incorporated into surface layers in proportion to their concentrations in electrolyte. The main mechanism for the incorporation of V and W into coatings is assumed to be thermolysis of vanadungstophosphate heteropolyoxoanions, while high concentrations of polyphosphate species contribute to the amorphization of coatings and the formation of a titanium phosphate matrix. The band gap of V-containing composites decreases from 2.22 to 1.97 eV as tungsten replaces vanadium. For W-containing composites (V-free ones), the band gap is 3.19 eV. All formed coatings exhibit photocatalytic activity in the degradation of methyl orange (10 mg/LMO, 10 mmol/L H2O2) in a neutral medium (pH 6.8) under visible and UV irradiation. The gradual substitution of vanadium for tungsten in the coatings leads to a decrease in MO degradation (from 87 to 50% and from 32 to 9% under 3-h UV and visible irradiation) with a simultaneous increase in their durability due to a decrease in vanadium leaching. An electrolyte with Na2WO4:NaVO3 = 1:3 is optimal for the formation of photoactive and stable composites. When using composites obtained in this electrolyte, MO conversions are 83 and 31% under UV and visible irradiation, respectively. The mechanism of the photocatalytic action of WO3-V2O5-TiO2 composites is considered, and the role of hydrogen peroxide is discussed.

Comparative Analysis of Boost and Hybrid Boost Converters

Context: In power electronics applications, it is important to make comparisons between converters to choose the device that best suits a particular application. This paper compares the Boost converter and the hybrid Boost converter. The operating models of both converters under study are developed and explained in detail to allow for a proper comparison and analysis. Method: Using the passive sign law, the differential equations that govern the behavior of each converter are determined upon the basis of their switching states. Then, circuit simulations are performed by using the OpenModelica software to analyze the output signals of both converters with the same input parameters. Results: Comparisons of voltage and current gains, current and voltage time response, and ripple were obtained. Additionally, the efficiency was analyzed by adding resistive losses in each passive element of both converters. Conclusions: For high duties, the hybrid Boost converter has a greater capacity to increase the output voltage than the Boost converter. It was also found that the hybrid Boost converter has a low overshoot and a low ripple in the time response of its output signals. However, this converter is less efficient.

Growth methods of PEO coatings on 7075 aluminum alloy at two cathodic current densities

Plasma electrolytic oxidation (PEO) coatings were prepared on 7075 aluminum alloy at a constant anodic current density of 150 mA·cm−2. The cathodic current densities (75 and 300 mA·cm−2) i.e., Rpn (ratio of positive to negative charge quantities during one period in the process) = 2 and 0.5 was adjusted to elucidate the effect of the cathodic pulse over time on the coating formation. To better observe the microstructure, the coating was detached from the substrate using an electrochemical method. Voltage-time response curves were obtained using a power supply equipped with a signal-collection system. The phase composition of the coating was determined by X-ray diffraction analysis. The surface, cross-section, and substrate/coating interface of the coating were observed by using scanning electron microscopy with energy-dispersive X-ray spectrometry. The results show that all the coating phases consisted of γ-Al2O3 at different cathodic current densities. The application of a cathodic current density of 300 mA·cm−2 did not affect the process at the initial stage but led to a voltage rise in stage III (from 273 to 682 s). The surface structure and thickness results suggest that the application of a cathodic current density of 300 mA·cm−2 reduces the proportion of nodular structures, promotes an increase in thickness, and results in coatings, which have fewer defects and better compactness. The cavity structure of the coating is related to the generation of a hill-like structure at the interface. In the “soft” regime, the thickening of the coating was dominated by inward growth, and there was no obvious hill-like structure at the coating/substrate interface. A coating growth model with different cathodic current densities is proposed.

Silicate and Hydroxide Concentration Influencing the Properties of Composite Al2O3-TiO2 PEO Coatings on AA7075 Alloy

This work evaluates the effect of sodium meta-silicate pentahydrate (SMS) and potassium hydroxide concentrations on properties of Al2O3-TiO2 coatings produced through plasma electrolytic oxidation in a solution containing 3 g L−1 potassium titanyl oxalate, (PTO), using a unipolar waveform with constant current density. The surface and cross-section characteristics of PEO coatings including morphology, elemental distribution, and phase composition were evaluated using FESEM, EDS, and XRD techniques. Voltage-time response indicated the concentration of SMS and KOH had a significant effect on the duration of each stage of the PEO process. More cracks and pores were formed at the higher concentrated solutions that resulted in the incorporation of solution components especially Si into the coating inner parts. Ti is distributed throughout the coatings, but it had a dominant distribution in the Si-rich areas. The coating prepared in the electrolyte containing no silicate consisted of non-stoichiometric γ-Al2O3 and/or amorphous Al2O3 phase. Adding silicate into the coating electrolyte resulted in the appearance of α-Al2O3 besides the dominant phase of γ-Al2O3. The corrosion behaviour of the coatings was investigated using the EIS technique. It was found that the coating prepared in the presence of 3 g L−1 SMS and 2 g L−1 KOH, possessed the highest barrier resistance (~10 MΩ cm2), owing to a more compact outer layer, thicker inner layer along with appropriate dielectric property because this layer lacks the Si element. It was discovered that the incorporation of Ti4+ and especially Si4+ in the coating makes the dielectric loss in the coating.

INCORPORATION OF MULTI-WALLED CARBON NANOTUBES INTO OXIDE LAYER FORMED ON AL ALLOY BY PLASMA ELECTROLYTIC OXIDATION

Plasma electrolytic oxidation (PEO) is an electrochemical-based surface modification technique that produces oxide layers on valve metals. The PEO process is performed in an electrolyte solution, which offers the possibility of particles’ incorporation into the growing oxide layer. In this study, we employed a PEO technique on a commercial Al alloy in an aqueous suspension of carbon nanotubes (CNTs) to fabricate CNT-incorporated oxide layer. The voltage–time response was recorded during the process. The surface of the resulting oxide layer was characterized by means of a scanning electron microscope (SEM), an energy-dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD). It was found from the SEM observation that the CNTs were successfully incorporated into the oxide layer. The PEO with the addition of CNTs led to a delay in time to breakdown (50[Formula: see text][Formula: see text][Formula: see text]s) and a decrease in breakdown voltage (442[Formula: see text][Formula: see text][Formula: see text]V) in the voltage–time curve. The microstructural feature was clearly distinguishable between the oxide layers produced with and without CNTs: a pancake-like structure for PEO without CNTs, and a doughnut-like structure for PEO with CNTs. However, neither the results of the structure analysis nor the elemental analysis provides a clear indication of carbon, even though the presence of CNTs in the oxide layer is evident, suggesting that further optimization of CNT concentration is required.

Effects of graphene nanosheets on the ceramic coatings formed on Ti6Al4V alloy drill pipe by plasma electrolytic oxidation

Ceramic coatings were formed on the surface of Ti6Al4V alloy drill pipe by plasma electrolytic oxidation (PEO) technology in the silicate electrolyte with and without graphene nanosheets. Voltage-time responses were recorded. The microstructure, elements distribution and phase composition were investigated by SEM, TEM, EDS and XRD. The basic physical properties and wear resistance were studied. The morphology of wear tracks was observed by SEM and three-dimensional microscope. Results indicated graphene nanosheets successfully incorporated in the ceramic coating. The main elemental components were Ti, Si and O. They were crystallized and composed of anatase and rutile. The coating with graphene nanosheets showing the morphology and structure of flatter and less pores was superior to the coating without graphene nanosheets exhibiting rugged and more pores, and the microhardness of the coating with graphene nanosheets was 1250 HV which was noteworthy improved in contrast with the coating without graphene nanosheets of 870 HV. Wear test results showed the coating with graphene nanosheets displayed extremely significant wear resistance due to the physical barrier of graphene nanosheets. In summary, the application of graphene nanosheets to improve the wear resistance of titanium alloy drill pipe is a promising and promotional research.

Al2O3-ZrO2 nanocomposites coating on aluminum alloy by plasma electrolytic-electrophoretic hybrid process

Alumina-zirconia nanostructured layers were coated on an aluminum alloy (AA7075) by the plasma electrolytic (PE) technique in a direct current galvanostatic mode at 0.1–0.4 A/cm2 current density. The coatings were formed in an electrolyte containing monoclinic nano-ZrO2 powder as a zirconia source. The microstructure of the produced coatings was studied by transmission electron microscopy (TEM), scanning electron microscopy and X-ray diffraction to develop an understanding of the growth mechanism. The investigation of the coating process was complemented with voltage-time response measurements and in-situ optical spectroscopy observations. The results showed formation of various alumina-zirconia composite microstructures as a function of the current density during processing. At the higher current density, the composite layer consists of high temperature phases (tetragonal zirconia and α-alumina) in addition to monoclinic zirconia. High current density introduced larger amounts of zirconia to the coated layer due to the high energy applied to the nanoparticles in the electrolyte. TEM analysis showed formation of four sub-layers across the coating. The coating-substrate interface (sub-layer 1) contained higher amounts of alumina (both α and γ) while the amount of zirconia nanoparticles increased by moving toward the outer surface. In sub-layer 2, formation of tetragonal zirconia was observed resulting from a phase transformation of monoclinic to tetragonal zirconia. In sub-layer 3, the existence of untransformed monoclinic zirconia hints to inadequate energy for the phase transformation due to lower temperatures. At the top region of the coating, sub-layer 4, a shallow amorphous layer was formed due to quenching from the direct contact with the electrolyte. The PE process was found to be responsible for the monoclinic to tetragonal zirconia transformation, while the electrophoretic process facilitated the deposition of the original monoclinic zirconia from the electrolyte. The results showed that the coating mechanism involves a hybrid PE-electrophoretic process.

An investigation about the evolution of microstructure and composition difference between two interfaces of plasma electrolytic oxidation coatings on Al

The plasma electrolytic oxidation (PEO) coatings were fabricated on AA1060 aluminum alloy at a constant current density of 4.4 A/dm2. The images of discharge sparks and voltage-time response were recorded during the PEO process. The characteristics of the two interfaces of coatings were investigated as a function of PEO processing time by using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS). Hundreds of coatings were detached from the substrate by an electrochemical method and ground into homogeneous powders to carry out differential scanning calorimeter (DSC) and further XRD qualitative test. In addition, matrix-flushing method was employed to quantitatively measure the content evolution of phase compositions of Al-based detached PEO coatings. The distribution rule of amorphous phases in the PEO coatings was investigated by thickness-reduction method for the first time. Based on the experiments above, gaining an insight into the formation, distribution and evolution of the amorphous and crystalline phases in the PEO process.

Influence of process parameters on growth behaviour and properties of coatings obtained by plasma electrolytic oxidation (PEO) on AA 6061

Plasma electrolytic oxidation coating is obtained on AA6061 alloy using positive uni-polar pulsed DC in a sodium silicate-based electrolyte. The effect of process parameters such as solution concentration, process time, average current density, pulse frequency and positive on-time is investigated systematically and the corresponding voltage–time response is correlated with the coating growth rate. Surface morphology of the coatings is studied using scanning electron microscopy and the elemental distribution on the coating is investigated using energy dispersive X-ray spectroscopy. The concentration of sodium silicate in the solution is found to play a key role in determining the morphology and composition of the coating. X-ray diffraction studies indicate a transition from crystalline to amorphous nature of the coating with increase in silicate content of the electrolyte. Effect of pulse frequency on the voltage–time response and the corresponding coating growth rate is highly dependent on the solution concentration.

Effects of oxygen evolution on the voltage and film morphology during galvanostatic anodizing of AA 2024-T3 aluminium alloy in sulphuric acid at −2 and 24 °C

The effects of oxygen evolution on the voltage-time response and film morphology during galvanostatic anodizing of AA 2024-T3 alloy at 50 mA cm−2 in sulphuric acid have been investigated at −2 and 24 °C. The study employed interrupted anodizing experiments and real-time gravimetric measurements of the oxygen generated. The results showed that similar amounts of oxygen were evolved at the two temperatures, but with significantly different film morphologies and voltage responses. At −2 °C, a relatively large voltage increment accompanied the formation of linear cells in a relatively compact arrangement. The increment was mainly due to increase in the barrier layer thickness. In contrast, at 24 °C, the voltage increase was comparatively negligible and a sponge-like film morphology was generated that contained significant inter-cell porosity. It is proposed that the anodizing voltage and film morphology are dependent on the transport paths for oxygen gas escaping the film, in particular the relative proportions of gas escaping from the film via intra-cell and inter-cell porosity.

Influence of cathodic duty cycle on the properties of tungsten containing Al2O3/TiO2 PEO nano-composite coatings

Current waveforms with different cathodic duty cycles of 0, 20 and 40% were applied to coat 7075 aluminum alloy in a silicate based electrolyte containing titania nano-particles. Using a constant current mode, the recorded voltage-time response showed that the required voltage for PEO coating process is lower in the presence of sodium tungstate as additive. By increasing the cathodic duty cycle, pancake surface morphology was converted to crater-like. Phase and chemical composition of the coatings were investigated by using grazing angle XRD and SEM/EDS. The tungsten concentration decreased linearly with the increase of cathodic duty cycle, which is dissimilar to the titania content. It was proposed that physical entrapping has been associated with electrophoretic incorporation of titania nano-particles, while the adsorption mechanism of tungstate anions is purely electrophoretic. Corrosion performance of the coatings was evaluated by potentiodynamic polarization and EIS measurements. Addition of sodium tungstate was detrimental for corrosion performance of the coating in the case of unipolar waveform while the corrosion resistance was improved when bipolar waveforms were used. Long-term corrosion behavior of the coatings was investigated by EIS up to 16 weeks. The results showed remarkable difference between corrosion performance of the coatings produced by unipolar and bipolar waveforms, but the difference was negligible for the coatings produced by the bipolar waveforms with different cathodic duty ratios.

Role of Si in the Anodizing Behavior of Al-Si Alloys: Additive Manufactured and Cast Al-Si10-Mg

In this work, the role of the Si phase microstructure in the anodizing behavior of Al-Si alloys is studied. Experiments were conducted using an additive manufactured (AM) Al-Si10-Mg specimen and a cast alloy of approximately the same chemical composition. A systematic characterization of the anodic oxide film was conducted using a variety of surface analysis techniques. Clear evidence is provided through X-ray photoelectron spectroscopy analysis for the almost entire oxidation of Si during the anodizing of the additive manufactured specimens, which can explain the lower anodizing efficiency observed in the AM material compared to the cast alloy. Additionally, a more detailed characterization of the oxide layer revealed that a slightly thinner anodic oxide film is formed at the borders of the characteristic melting tracks resulting from the metal additive manufacturing process. Furthermore, the features observed in the voltage–time response during the anodizing of the AM specimens seem to be closely associated with the dimensions of the Al/Si cells present in the plane parallel to the direction of the oxide front growth.

Ceramic oxide coating formed on beryllium by micro-arc oxidation

Beryllium was oxidized at a current density of 10mAcm−2 in a 0.5M Na2CO3 (pH=11.2) electrolyte to understand the micro-arc oxidation (MAO) process. Different oxidation stages were investigated by analysing the voltage–time responses and coating morphology. ‘Electric breakdown’ accompanied by sparks travelling across the metal/electrolyte interface occurs when the voltage rises above a certain point (∼202V), leading to the formation of an off-white ‘ceramic-like’ BeO coating. The MAO coating consists of two layers—an inner barrier layer and an outer porous layer—and shows improved corrosion resistance and insulation properties. XPS and XRD indicate that the coating has a chemical composition of BeO and is crystalline. Further, corrosion resistance and insulation properties of the coating were estimated by EIS analysis.

Delay in micro-discharges appearance during PEO of Al: Evidence of a mechanism of charge accumulation at the electrolyte/oxide interface

PEO was conducted on Al by applying a pulsed bipolar current. The role of the cathodic polarization on the appearance of micro-discharges (MDs) and on the subsequent formation of the PEO oxide layers is investigated. Various ratios of the charge quantity RCQ=Qp/Qn (defined as the anodic Qp to cathodic Qn charge quantity ratio over one current pulse period) in the range [0.5; 6.0] were selected by changing the waveform parameters of the cathodic current while keeping the waveform of the anodic current unchanged. Results show that the appearance of MDs is delayed with respect to the rising edge of the anodic current; this delay strongly depends on both the processing time and the applied cathodic charge quantity. It is also evidenced that shorter delays promoted by high RCQ values (RCQ>1) are associated with stronger MDs (large size and long life) that have detrimental effects on the formed PEO oxide layers. Thicker and the more compact oxide layer morphology is achieved with the intermediate RCQ value (RCQ=0.9) for which the delay of the MDs appearance is high and the MDs softer. Low RCQ (RCQ<0.9) results in an earlier extinction of the MDs as the process goes on, which leads to poorly oxidized metal. A mechanism of charge accumulation taking place at the oxide/electrolyte interface and arising before the occurrence of dielectric breakdown is proposed to explain the ignition of MDs during pulsed bipolar PEO of aluminium. A close examination of the voltage-time response which can be adequately simulated with an equivalent RC circuit evidences the capacitive behaviour of the oxide layer and therefore confirms this proposed mechanism of charge accumulation.

Statistical analysis of the voltage-time response produced during PEO coating of AZ31B magnesium alloy

Plasma-electrolytic oxidation (PEO) is a corrosion prevention technique which produces a protective oxide layer on a metal surface by high-voltage oxidation to increase its corrosion resistance. Traditionally, PEO processing on a magnesium alloy surface has been investigated via the voltage-time response measured during the treatment. Thus far, the information extractable from voltage-time measurements has been limited due to the sporadic nature of coating evolution. The current study presents a new approach to examine the mechanisms governing PEO coating formation and the subsequent influence of process parameters. The instantaneous voltage-time response has been recorded and analyzed using a statistical approach. Combining the voltage-time measurements with structural analysis (XRD/SEM/EDX), a multi-step coating formation mechanism has been proposed. The first stage of the treatment process was similar to traditional anodization. When the voltage was sufficiently high to induce dielectric breakdown of the existing oxide material, plasma discharging occurred and a silica containing layer was formed. Two predominant types of discharge governed the oxidation process; discharge through deep pores, and discharge through micro-voids. Increasing the current density proportionally accelerated the rate of oxide development. Increasing the temperature of the electrolyte resulted in thinner coatings due to an increased oxide dissolution rate. From an application point of view, the PEO coating process can be accelerated by choosing a high current density, but the problem of localized heating by the discharges must be addressed to avoid severe dissolution of coating.

High Temperature Monolithic Biochar Supercapacitor Using Ionic Liquid Electrolyte

A supercapacitor comprising of two binder-free biochar monolith electrodes and 1-butyl-3-methylimidazolium tetrafluoroborate based ionic liquid electrolyte was studied at room temperature and 140°C by cyclic voltammetry, constant-current charge-discharge, and electrochemical impedance spectroscopy. The supercapacitor exhibits an operating voltage window of approximately 6 V. It is found that increasing temperature from room temperature to 140°C considerably increases its specific mass capacity and its charge-discharge rate by a factor of approximately 10. The specific capacity of the supercapacitor calculated from the voltammetric measurements depended on scan rates. At 140°C, a capacity of 21 F g−1 was obtained at 5 mV s−1 and this value decreases to around 10 F g−1 at 100 mV s−1; the constant-current charge-discharge profiles exhibit pseudo-linear voltage-time responses during the discharges. The supercapacitor shows good stability characteristics of no obvious performance decay after 1000 cycles within a voltage window of 6 V. Electrochemical impedance spectra of the supercapacitor display a wide linear region corresponding to diffusion control. The energy densities of the supercapacitor that are normalized to the total active electrode materials are higher than 20 Wh kg−1 when its power density is lower than 2000 W kg−1. These facts suggest that the high-temperature biochar supercapacitor would be a promising energy-storage device with high energy and power density.

Effects of silicate ion concentration on the formation of ceramic oxide layers produced by plasma electrolytic oxidation on Al alloy

Plasma electrolytic oxidation (PEO) coatings were fabricated on 5083 Al alloy in KOH electrolyte solution with adding various concentrations of Na2SiO3. Changes in voltage–time response and micro-discharge evolution were analyzed, and the surface and cross-section of the resulting coating layer were further characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results showed that discharge characteristics were evidently changed with different Na2SiO3 concentrations, particularly higher Na2SiO3 concentrations leading to lower dielectric breakdown voltages. It was found that porous surface structure became prevalent with increasing Na2SiO3 concentration. The EDS analysis confirmed the incorporation of Si element in the PEO coatings. The result of XRD analysis revealed that metastable phases such as γ- and η-alumina were produced as a result of PEO, while amorphous phases appeared with excessive Na2SiO3 concentrations (10 and 14 g/L). The coating thickness was significantly increased about 2–8 times with increasing Na2SiO3, almost depending on Na2SiO3 concentration.

Characterization of Ceramic Oxide Layer Produced on Commercial Al Alloy by Plasma Electrolytic Oxidation in Various KOH Concentrations

Plasma electrolytic oxidation (PEO) is a promising coating process to produce ceramic oxide on valve metals such as Al, Mg and Ti. The PEO coating is carried out with a dilute alkaline electrolyte solution using a similar technique to conventional anodizing. The coating process involves multiple process parameters which can influence the surface properties of the resultant coating, including power mode, electrolyte solution, substrate, and process time. In this study, ceramic oxide coatings were prepared on commercial Al alloy in electrolytes with different KOH concentrations (0.5 ~ 4 g/L) by plasma electrolytic oxidation. Microstructural and electrochemical characterization were conducted to investigate the effects of electrolyte concentration on the microstructure and electrochemical characteristics of PEO coating. It was revealed that KOH concentration exert a great influence not only on voltage-time responses during PEO process but also on surface morphology of the coating. In the voltage-time response, the dielectric breakdown voltage tended to decrease with increasing KOH concentration, possibly due to difference in solution conductivity. The surface morphology was pancake-like with lower KOH concentration, while a mixed form of reticulate and pancake structures was observed for higher KOH concentration. The KOH concentration was found to have little effect on the electrochemical characteristics of coating, although PEO treatment improved the corrosion resistance of the substrate material significantly.

Effects of alumina nanoparticles concentration on microstructure and corrosion behavior of coatings formed on titanium substrate via PEO process

Plasma electrolytic oxidation (PEO) process was employed to create ceramic coatings on titanium substrate by using silicate-based electrolytes containing different concentrations of alumina nanoparticles (0, 3, 6, and 10g/lit). The effect of alumina nanoparticles concentration on the morphology, chemical and phase composition of the PEO coatings was investigated by scanning electron microscope, energy dispersive spectrometer, and X-ray diffractometer, respectively.The corrosion behavior of samples was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. SEM, EDS, and XRD analyses illustrated that alumina nanoparticles incorporated into the coatings and reduced the density and size of the pores. Furthermore, according to the voltage-time responses, presence of alumina nanoparticles in the electrolyte increased the starting time of sparking due to hindrance effect of these particles on the barrier layer formation. It was found that the corrosion resistance rose by increasing the concentration of alumina nanoparticles. The coating which was formed in electrolyte containing 10g/l alumina nanoparticles possessed the lowest porosity (11.2%) which boosted the corrosion resistance of the substrate from 2.33×104 to 1.26×106Ωcm2.