Anodic Oxidation Treatment Research Articles

Synthesis and mechanism of (101)-preferred orientation rutile titania via anodic spark oxidation

This work is aimed to investigate the mechanism and factors that affect (101) orientation of rutile titania layers by anodic spark oxidation (ASO) treatment. The formation of (101)-preferred orientation of the rutile layer is ascribed to the internal high thermal stress generated by the thermal effect of spark discharges. Under high thermal stress, (101) planes will change their orientations parallel to the layer surface to endure the thermal stress, the residual stresses of samples with different (101)-orientation degree have been calculated using a sin2ψ technique of X-ray diffraction (XRD) method. The results indicate that only the arc type discharges can effectively favor (101) orientation because they can generate the thermal stress large enough to cause (101) crystalline planes rotation while both the micro arc and luminescent spark cannot. The anodic mode and electrochemical parameters influence the energy, frequency, and duration time of the arc discharge stage, which lead to different orientation degree. The results also show that high applied voltage, optimal applied current density and H2SO4 electrolyte with medium concentration might be beneficial to obtain rutile layers with high (101) orientation.

Decolourization and degradation of C.I. Acid Red 73 by anodic oxidation and the synergy technology of anodic oxidation coupling nanofiltration

This work is conducted to study ability of anodic oxidation treatment azo dye C.I. Acid Red 73 (AR73) using the electrodes of Y doped Ti/SnO2–Sb electrodes prepared by thermal decomposition and Ti/SnO2–Sb electrodes prepared by electrodeposition. It has been shown that doping Y can enhances the electrochemical activity of the electrodes, but the accelerated service life was slightly reduced. Both the lifetime and electrochemical activity of Ti/SnO2–Sb electrodes prepared by electrodeposition in a new Sn–Sb electrodeposition bath outperform the Ti/SnO2–Sb electrodes prepared by thermal decomposition. Moreover, the effect of varying wastewater process indexes (initial pH (4–10), the addition of NaCl (0–9mM) and initial dye concentration (0.5–2.0gL−1)) on the performance of anodic oxidation using Ti/SnO2–Sb electrodes prepared by electrodeposition was investigated followed by the performance indicators analyses including color, chemical oxygen demand (COD), current efficiency and specific energy consumption. Finally, the synergy technology of anodic oxidation coupling nanofiltration was adopted to treat AR73 wastewater in order to overcome the low current efficiency of anodic oxidation. Preliminary results have shown that the synergy technology could cost-effectively treat AR73 wastewater.

Study on Corrosion Wear Behavior of 70 Aluminum Alloy Anodic Oxide Coating

In vitriolic electrolyte, DC power supply is used on 7075 aluminum alloy to have anodic oxidation treatment then let the oxidized samples have a treatment of electroless plating. Surface morphology of the coating and performance of corrosion wear are studied by means of scanning electron microscope (SEM) and friction and wear experimental machine. The results show that unsealed oxide coating have many holes and cracks, which are extremely badly-distributed; corrosion resistance of the oxide coatings which have the treatment of electroless plating have improved, having lower coefficient of friction and better performance of corrosion wear; besides; coefficient of friction of the samples in water is higher than that in salt water, its wear amount is less.

The Mechanical and Tribological Properties of Anodic Oxidation Treatment Carbon Fiber-Filled PU Composite

The interfacial adhesion of the carbon fiber (CF) reinforced polyurethane (PU) composite was improved by the means of anodic oxidation treatment. The mechanical and reciprocating sliding wear properties were studied and results showed that the anodic oxidation treatment have definitely improved the mechanical strength. And the wear and the friction coefficient of PU decreased with the addition of CF. The friction coefficients of anodic oxidation treated CF/PU composites are lower than those of PU and CF/PU composite. The interfacial adhesion between the CF and PU dominated the main wear mechanisms.

Surface Modification of Titanium Implant by Anodic Oxidation Treatment and Bisphosphate Immobilization

본 연구의 목적은 만성 뇌졸중 환자를 대상으로 전정자극훈련 프로그램이 정적 균형 및 동적 균형에 미치는 영향을 알아보는 것이다. 본 연구는 2014년 7월 15일부터 9월 6일까지 진행하였으며, 대상자는 뇌졸중 진단을 받은 환자 20명이 본 연구에 참여하였고, Group Ⅰ(일반운동치료, n=10)과 Group Ⅱ(전정자극훈련, n=10)로 나누었다. 두 군 모두 주 3회, 회당 40분씩 6주간 치료적 중재를 실시하였다. 균형 능력은 Good Balance System을 이용하여 정적 균형 및 동적 균형을 측정하였으며, 중재 전과 후를 비교하였다. 연구 결과, 전정자극 훈련군에서는 눈감고 선자세의 좌우 및 전후 균형, 눈뜨고 선자세의 좌우 및 전후 균형, 이동시간, 이동거리에서 통계학적으로 유의한 차이를 보였고, 일반운동 치료군에서는 눈뜨고 선자세의 좌우 균형을 제외한 모든 항목에서 통계학적으로 유의한 차이는 보이지 않았다. 결론적으로, 본 연구에서 전정자극 훈련은 만성 뇌졸중 환자의 정적 균형 능력과 동 적균형 능력 향상에 긍정적인 영향을 미쳤으며, 이러한 뇌졸중 환자의 균형 능력 향상을 위한 치료프로그램에 다양한 방법으로 활용될 수 있을 것이다.

Preparation and bioactivity of TiO2 nanotube arrays containing calcium and phosphorus

With NH4H2PO4 and NH4F glycerin/water mixed solvent as electrolyte, through the anodic oxidation and calcium hydroxide hydrothermal treatment, TiO2 nanotube arrays containing calcium and phosphorus were prepared. Moreover, the influence of the processing time, titania crystalline phase and pH value of the solution were investigated. And the bioactivity of the nanotube arrays were examined by soaking in simulated body fluid. The results showed that the TiO2 nanotube arrays prepared in the phosphate-containing glycerin system can contain a small amount of phosphorus. When the processing time <0.5h, the nanotube arrays maintained the original tubular structure, but the quantity of Ca element reduces. When the processing time was ≥2h, the original tubular structure of the anatase nanotube arrays was transferred into nano four pillars, and with extending the processing time, the sizes of nano four pillars were slightly increased. But the morphology of the as-prepared nanotube arrays changed very slightly. And a content of Ca element increased with the increase in the hydrothermal treatment time. The existence form of Ca element is calcium titanate. The samples after hydrothermal treatment in saturated Ca(OH)2 solution are clearly more efficient in promoting apatite formation than the as-prepared or anatase nanotube arrays.

Fabrication of TiO2 nanotubes on porous titanium scaffold and biocompatibility evaluation in vitro and in vivo

Porous titanium was modified by anodic oxidation and heat treatment method. Scanning electron microscopy and X-ray diffraction examinations revealed that the modified surface of porous titanium was covered by anatase nanotubes. In vitro, the bioactivity of specimens before and after modification was evaluated by immersing into the double-concentration simulated body fluid for 7 days. The porous titanium specimens were implanted into the femurs of dogs for 3 months. The osteointegration of the implants was investigated by push-out test and histological examination. The results showed that the porous titanium with anatase nanotubes has the superior ability of apatite formation and a higher push-out force when compared with the other implants. The histological analysis indicated that the implant with anatase nanotubes had excellent ability to facilitate the osteointegration in vivo.

Adsorption of bovine serum albumin onto titanium dioxide nanotube arrays

Abstract Titanium dioxide nanotube arrays on titanium were fabricated via anodic oxidation and heat treatment. The diameters of nanotubes ranged from 20 to 200 nm, and the lengths were 500 and 1000 nm. The adsorption behavior of bovine serum albumin onto the nanotube arrays was investigated. Surface characterization for samples was carried out using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Adsorbance of bovine serum albumin was detected with an ultraviolet spectrophotometer. The results showed that the nanotube arrays on titanium surfaces significantly enhanced bovine serum albumin adsorption. The nanotube arrays with larger diameter could adsorb more bovine serum albumin, but longer nanotubes showed less adsorbance than shorter nanotubes. In the present work, the nanotube arrays with 160–200 nm diameter, the largest diameter, showed the highest adsorption ability, and the maximum adsorption capacity q m was 31.40 mg · cm−2. In addition, the adsorbance of bovine serum albumin increased with increase of initial bovine serum albumin concentrations, and a saturation value was achieved at the initial bovine serum albumin concentration of 2.0 mg · ml−1.

The effect of surface microgrooves and anodic oxidation on the surface characteristics of titanium and the osteogenic activity of human periodontal ligament cells

ObjectiveThe purpose of this study was to investigate the effect of titanium (Ti) surface microgrooves and anodic oxidation on the surface characteristics of titanium and the osteogenic activity of human periodontal ligament cells (PLCs) cultured on theses surfaces. DesignMechanically ground Ti was used as the control substratum (NE0). Truncated V-shaped microgrooves, 60μm-wide and 10μm-deep in cross-sections, were created on the Ti substrata by photolithography (NE60/10). Anodically oxidized Ti (NE0AO) and anodically oxidized microgrooved Ti (NE60/10AO) were also prepared. Scanning electron microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were performed for surface characterization. Cell proliferation assay, osteoblast differentiation assay, and quantitative real-time PCR analysis were performed to compare the osteogenic activity of PLCs on NE0, NE60/10, NEAO, and NE60/10AO. ResultsA decrease in the microgroove-width of NE60/10AO compared to NE60/10 due to Ti oxide layer generation by anodic oxidation was detected with XRD and XPS. Cell proliferation, osteoblast differentiation, and osteo-related gene expression were enhanced on the NE60/10AO substrata compared with NE0, NE60/10, and NE0AO. ConclusionsThe combination of Ti surface microgrooves and subsequent anodic oxidation treatment synergistically upregulated osteo-related gene expression, despite showing limited ability to increase cell proliferation and osteoblast differentiation levels in PLCs.

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.

Strong-bonding calcium phosphate coatings on carbon/carbon composites by ultrasound-assisted anodic oxidation treatment and electrochemical deposition

The current work describes the ultrasound-assisted anodic oxidation treatment of carbon fiber-reinforced carbon (C/C) composites with H3PO4. The aim was to create chemical bonds between the surface-treated C/C composites and subsequently deposited calcium phosphate (CaP) coatings. The surface energy of C/C obviously increased after undergoing ultrasound-assisted anodic oxidation treatment at a current density of 50mA/cm2 in aqueous 0.5M H3PO4 solution (USAT–C/C-50). A large number of O-containing groups and some P-containing groups were found on the treated C/C substrate. The formation of O-containing groups may have been promoted by the energy input of the ultrasound and electric field. P-containing species could be bonded to C/C by CPO or COP bonding. Among the species formed, the formation of (H2PO4)− on C/C was promoted by ultrasound. When USAT–C/C-50 was used as the substrate for CaP coatings deposited by ultrasound-assisted electrochemical deposition (USECD), the surface of USAT–C/C-50 acquired strong CaP induction ability, and large amounts of CaP were deposited on it during the initial deposition process. After USECD, very strong-bonding CaP coatings formed on USAT–C/C-50. The average shear bond strength of the coatings obtained on the USAT–C/C-50 substrate [(12.14±1.30)MPa] was about twice that of the coatings obtained on untreated C/C [(6.78±1.06)MPa].

Research on Forming Process of Anodic Oxide Film of AZ91D Magnesium Alloy

The matrix of AZ91D Magnesium alloy can be covered with a coat of protective film through anodic oxidation treatment, it’s able to make certain that the optimal surface combination properties are generated especially on corrosion resistance. This thesis is devoted to the research on forming process of anodic oxide film of AZ91D magnesium alloy; the experiment shows the formation of anodic oxide film at constant pressure is accompanied by precipitation of gases and fluctuation of current, XRD indicates that anodic oxide film is composed of MgO、γ-Al2O3 and a small amount of Si.

Surface changes of anodic oxidized orthodontic titanium miniscrew

To evaluate the structural stability of anodic oxidation treatment of miniscrews during a self-drilling procedure and an initial loading period. Eight orthodontic miniscrews with a machined surface and an anodic oxidized surface were placed in the mandible of two beagle dogs. With all miniscrews, an orthodontic force was applied immediately after placement and was continued for 12 weeks. After beagle dogs were sacrificed, the miniscrews were carefully removed from decalcified bone fragments. Miniscrews were evaluated by comparing and quantitatively analyzing changes in surface roughness of unused and used miniscrews (machined surface vs anodic oxidized surface) utilizing both scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM revealed that only a thread edge close to the tip of the used anodic oxidized miniscrew became smooth by smearing, compared with the unused anodic oxidized miniscrew. No definite changes were observed in the thread valleys of the two groups after placement. AFM measurements demonstrated that all surface roughness parameters of thread edges of the used anodic oxidized miniscrews were significantly reduced compared with the unused anodic oxidized miniscrew (P < .05). A middle thread edge of the used anodic miniscrew surface was rougher than the unused and used machined surface miniscrews (P < .05). Anodic oxidized miniscrews had improved surface characteristics compared with machined surface miniscrews, even if the surface texture was changed by the self-drilling procedure and during the initial loading period.

Physicochemical state of the nanotopographic surface of commercially pure titanium following anodization-hydrothermal treatment reveals significantly improved hydrophilicity and surface energy profiles

A method of coating commercially pure titanium (cpTi) implants with a highly crystalline, thin hydroxyapatite (HA) layer using discharge anodic oxidation followed by hydrothermal treatment (Spark discharged Anodic oxidation treatment ; SA-treated cpTi) has been reported for use in clinical dentistry. We hypothesized that a thin HA layer with high crystallinity and nanostructured anodic titanium oxide film on such SA-treated cpTi implant surfaces might be a crucial function of their surface-specific potential energy. To test this, we analyzed anodic oxide (AO) cpTi and SA-treated cpTi disks by SEM and AFM. Contact angles and surface free energy of each disk surface was measured using FAMAS software. High-magnification SEM and AFM revealed the nanotopographic structure of the anodic titanium oxide film on SA-treated cpTi; however, this was not observed on the AO cpTi surface. The contact angle and surface free energy measurements were also significantly different between AO cpTi and SA-treated cpTi surfaces (Tukey's, P < 0.05). These data indicated that the change of physicochemical properties of an anodic titanium oxide film with HA crystals on an SA-treated cpTi surface may play a key role in the phenomenon of osteoconduction during the process of osseointegration.

Nanomechanical Properties of Bioactive Ti Surfaces Obtained by NaOH-Based Anodic Oxidation and Alkali Treatment

Titanium has been used in the production of dental implants and orthopedic prostheses due to the low tendency to corrosion and good biocompatibility. Meanwhile, the surface of titanium is not bioactive. Several surface treatments have been developed to make the surface of such metals bioactive. The aim of this work was to evaluate two of these modification processes in commercially pure titanium grade 2, both of them using NaOH solutions: the anodic oxidation and the alkali treatment. The surface morphology was evaluated by SEM/EDS, the crystal structure by XRD, and the mechanical properties and scratch resistance by instrumented indentation. The anodic oxidation (AO) was carried out using NaOH electrolyte 0.1 mol/L and constant current density of 150 mA/cm² for one minute. The alkaline treatment (AT) was performed by soaking the Ti sample in NaOH 5 mol/L solution at 60 °C for 24 hours; after this, the sample was heat treated at 600 °C for one hour in atmospheric air. The AO produced a TiO2 layer on Ti, whereas a thin sodium titanate layer was obtained by AT. Each surface modification resulted in a specific morphology, but both of them presented the increase in roughness as a common characteristic. The alkali treated Ti surfaces showed the lowest elastic modulus and hardness values. The largest increase in hardness between the treated surfaces was obtained for Ti after anodic oxidation. Scratch test indicates that the TiO2 film from AO has higher strength to tangential loading than the Ti substrate. In addition, for the Ti submitted to AT, the scratch test indicates that the modified surface layer has a poor adhesion with the substrate. Based on these results it is possible to conclude that, using NaOH solutions, Ti surfaces treated by anodic oxidation present improved mechanical properties than the alkali-treated ones.

Regulation on the biocompatibility of bioactive titanium metals by type I collagen

To study the regulation on the biocompatibility of titanium metal surface structure, the interaction between the collagen and the titanium surface structure were studied with titanium surfaces subjected to anodic oxidation and acid-alkali treatment. The cell response on the treated surfaces was studied in vitro experiments of MG63 osteoblasts. The effects of different collagen adsorption ability on the biomineralization were investigated with simulated body fluid (SBF) experiment and osteoblasts culture experiments in a mineralization culture medium. It was found that the collagen adsorption ability was controlled by the wettability. The acid-alkali treated titanium could adsorb much more collagen on its surface. The abilities of cell attachment and proliferation were improved after collagen soaking. The apatite formation ability was inhibited in SBF after collagen adsorption on the surfaces, but improved in cell-involved situation. The ALP and OCN activity of MG63 cells assay showed the collagen on the titanium surface could enhance the bioactivity of the cells, which could accelerate the biomineralization process in cell culture experiments. The result indicated that the different adsorption ability of type I collagen could regulate the biocompatibility of titanium metal surface. It is possible to optimize the biocompatibility of the titanium metals by using suitable surface modification method.

A hierarchically graded bioactive scaffold bonded to titanium substrates for attachment to bone

In this paper we report a Ti-based, hierarchical porous scaffold anchored to Ti substrates, prepared by synthesizing hydroxyapatite–calcium carbonate-Ti three–layer spheres and combining a modified plasma spraying process and an anodic oxidation treatment. The hierarchical porous scaffolds were composed of 100–350 μm interconnecting macropores, 0.2–90 μm pores and ∼100 nm nanopores with >70% porosity. At the same time, the scaffolds also had the graded structures constructed by bioactive TiOx in surface transforming to metallurgy-bondable Ti in bottom. Mechanical property tests demonstrated that the porous scaffolds had similar Young’s modulus with natural bone and strong bonding strength with the Ti substrates. The simulate body fluid immersion showed that bone-like apatite layer could form rapidly at scaffold surface. The in vitro cell incubation demonstrated that the porous scaffolds had good cellular compatibility and could correctly regulate cascade gene expression of primary osteoblasts. The intramuscular implantations indicated the porous scaffolds had high osteoinductivity and the bone implantations demonstrated that the scaffolds could facilitate new bone growth and have strong bonding strength with surrounding bone.

Effect of Bisphosphonates on Anodized and Heat‐Treated Titanium Surfaces: An Animal Experimental Study

Recent investigations reported that osseointegration of titanium implants can be significantly reinforced with a nanostructure treated with anodic oxidation and heat treatment. This experimental study investigates the effect of bisphosphonates on the nanotubular implant surface in rats. Thirty-six titanium implants were divided into three groups: 1) machine-turned (MT), 2) anodized and heat-treated (AH), and 3) anodized and heat- and bisphosphonate-treated (AHB) groups. The 36 implants were randomly placed in both tibias of 18 male Wistar rats. After 2 and 4 weeks, the levels of osseointegration of the implants were evaluated by a removal torque test and microcomputerized tomography (μCT). Peri-implant bone tissue on the extracted region was examined for the expression of type I collagen and osteocalcin. The AHB group showed the highest removal torque at 2 and 4 weeks (13.92 ± 1.51 Ncm and 18.10 ± 2.15 Ncm, respectively) followed, in order, by the AH group (11.63 ± 1.58 Ncm at 2 weeks and 14.80 ± 2.34 Ncm at 4 weeks) and MT group (4.30 ± 0.76 Ncm at 2 weeks and 6.20 ± 1.33 Ncm at 4 weeks) with statistically significant differences between the MT and other two groups at both time points. μCT images also revealed a denser appearance around implants in the AHB group than in the other groups. Levels of type I collagen and osteocalcin expression were similar between the MT and AH groups; however, the values were significantly higher in the AHB group compared to the other groups, which were 220.85% ± 71.09% and 363.04% ± 100.21%, respectively (P <0.05). Within the limits of this experiment, it was concluded that surface loading with bisphosphonates significantly improved the degree of osseointegration of titanium implants with a nanostructure.

A novel method for the growth of ZSM-5 zeolite membrane on the surface of stainless steel

Thin ordered micropore ZSM-5 zeolite membrane has formed on the stainless steel surface. The influence of three different pre-treatment methods for the growth of ZSM-5 zeolite membrane on the stainless steel was studied, including mechanical polishing, soaking in a 20 wt.% sulfuric acid aqueous solution and anodic oxidation treatment. It was found that the anodic oxidation technique was more favorable for the growth of ZSM-5 zeolite membrane on the stainless steel surface compared with the other two methods. By this appropriate pre-treatment process, ordered ZSM-5 zeolite membrane was immobilized on the stainless steel surface and it showed good interaction with the stainless steel. Energy-dispersive X-ray (EDX) spectroscopy result indicates that the ZSM-5 zeolite membrane has a Si/Al ratio of 37. X-ray diffraction (XRD), N 2 adsorption and scanning electron microscopy (SEM) were used to study the crystal structure, specific surface area and morphologies of the ZSM-5 zeolite membrane.

Anodic Oxidation and Silane Treatment for Corrosion Protection of AM60B Magnesium Alloy

Oxide films have been produced on AM60B magnesium alloy using micro-arc oxidation process in an environmentally friendly alkaline solution with and without addition of different oxides nanoparticles (TiO2, ZrO2 and Al2O3). In order to seal the oxides porosity generated in the sparking process, a silane-based top coat has been applied. The surface morphology of samples was analyzed by Scanning Electron Microscopy (SEM). Scratch tests were performed for evaluating the adhesion strength of the anodic oxides. The corrosion resistance of the oxide- silane- based topcoat composite coatings was evaluated in 3.5% NaCl solution using anodic polarization tests. The anodizing in oxides nanoparticles rich solutions (ZrO2 or Al2O3), followed by a silane top coat treatment performed using OSi as precursor, is an interesting way to synthesize adherent corrosion resistant coatings on magnesium alloy AM60B.