Papers by Keyword: Anodic Oxidation

Abstract: The mechanical properties of anodic oxide films of Nb, Ta and Zr were studied by the nanoindentation method. Anomalously high elastic recovery after deformation was observed for oxides with thickness of 20 nm. An analogue of this behavior can be elastic membrane fixed on soft base that does not prevent the membrane from bending. Increase of the oxide thickness to 300 nm reduced the effect associated with the high elasticity of oxide and easy deformation of the soft metal substrate, and was accompanied by an increase in the plastic component of deformation, which is similar to the behavior of ceramic materials with low elastic and significant residual plastic deformation.

Abstract: Full functioning of wells in oil and gas fields is impossible without the use of tubing. Main function of tubing is transportation of gases and liquids produced in productive zone to well surface. In addition, tubing acts as a kind of insulator that protects the gas and liquid transported through them from the walls of the well, and also prevents the occurrence and development of corrosion, deposits of paraffin and asphaltene on casing pipes. The tubing pipe placed in the well is also necessary in order to ensure the carrying out of downhill and repair work, which is regularly necessary. Standard tubin g (tubing) as a result of technological difficulties does not undergo a strengthening operation. When manufacturing tubing and locks to them from alloyed steels, the main attention is paid to improving mechanical properties, which is achieved by thermal and chemical-thermal treatment. However, the practice of operating tubing shows that the introduction of these measures does not solve the issue of reliability, since threaded connections for the coupling and nipple remain vulnerable sections of tubing. Tubing (tubing) during its operation experiences significant loads and is in constant contact with aggressive media, which leads to serious requirements for their quality. The possibility of replacing its production from alloyed steels with aluminum alloys, for example, AlCuMg₂ will facilitate the design by 2.5 times, prevent the tendency to stress corrosion cracking (SCC) in a hydrogen sulfide-containing medium and eliminate inhibitory protection. The main disadvantage of aluminum alloys is the tendency to pitting corrosion. It is possible to improve the protective properties of the passive film on aluminum alloys by anodizing.

Abstract: The paper deals with the complaint between the manufacturer and the customer. The object of the dispute is a damaged stroller construction made by welding Al-Mg-Si aluminum alloy profiles with the final surface layer produced by anodic oxidation. The aim of the analysis is to identify clearly the causes of breaking the aluminum structure using fractographic and metallographic techniques.

Abstract: The ceramic surface treatment of aluminum alloy is an important means to improve the mechanical properties and corrosion resistance of aluminum alloy.This paper focuses on the process and research status of aluminum alloy anodic oxidation technology and aluminum alloy micro-arc oxidation technology and analyzes the future development direction.

Abstract: In this paper, a kind of novel TiO₂ nanotube arrays (TNTs) hybrid structure was presented to improve the performance of hydrogen sensors. In this novel structure, palladium functionalized TNTs hybrid nanostructure supported on titanium wire. TNTs arrays was prepared by anodizing Ti wire using a standard electrochemical procedure. Pd nanomaterials were deposited on TNTs. Optimized experiments showed the hydrogen sensor supported on titanium wire showed a good response time of 8 s and high sensitivity of 94.8% at 1.9 vol% H₂ at room temperature (25 °C). The research work revealed potential good hydrogen sensitivity of this kind of hybrid nanostructure.

Abstract: Anodic oxidation of Mg-Li-Al alloys using phosphoric acid-based bath were processed to obtain the corrosion-proof surface coating. The specimen oxidized at low voltage anodically dissolved without the formation of oxidized film. Anodic oxidation film could be formed at higher voltage due to thin layer preferentially formed on tthe active surface, this layer develops to stable thick film. There were no significant differences in film thickness between LA141 and LA143 alloys.

Abstract: We investigate the effects of static and dynamic anodic oxidation treatment on the surface chemical composition and functionality of carbon fibers. During static treatment, the electrolytic surface oxidation process is performed on a spatially fixed carbon fiber bundle, while in the dynamic process a moving, continuous carbon fiber tow is oxidized. In both treatment modes electrolytic current density and treatment time were varied. Surface chemical composition and functionality of the resulting carbon fibers were analyzed by x-ray photoelectron spectroscopy. A good agreement between the chemical composition and the functionality of fibers from static and dynamic anodic oxidation treatment is found. This suggests that results from static fiber treatment in a variable, easy to handle laboratory setup can be applied to dynamic anodic oxidation process conditions on a large scale.

Abstract: Highly ordered TiO₂ nanotube arrays are very attractive to the dental implant due to microstructural advantage for drug loading. We have fabricated the highly ordered TiO₂ nanotube arrays on the surface of the dental implant. The surface of TiO₂ nanotube arrays grown by normal anodic oxidation was not clean and the window of TiO₂ nanotube was closed. These closed nanotubes decrease the surface area to load the drug and also decrease the osseointegration performances. To obtain the clean surface of TiO₂ nanotube arrays, two-step anodic oxidation was used. The microstructures of TiO₂ nanotube arrays from two-step anodic oxidation were compared with those from normal anodic oxidation. The length and diameter of TiO₂ nanotube arrays with anodizing time were measured. TiO₂ nanotube arrays grown by two-step anodic oxidation had the clean surface and the diameter of TiO₂ nanotubes was ~100 nm at anodizing conditions of 60V and 20 min. It was applied to the surface of dental implant to improve the osseointegration. The improved osseointegration was observed by micro CT analysis. TiO₂ nanotube arrays had a promising microstructure to load some drugs such as BMP-2 and anti-inflammatory.

Abstract: TiO₂ nanotube arrays fabricated by anodic oxidation had a large surface area and high refraction index. These microstructural properties are very attractive as interferometric biosensing materials. Label free interferometric biosensor usually used nanoporous Si materials. TiO₂ nanotube arrays had more stability for wide pH range solutions. The interferometric spectrum from nanoporous layer was treated by Fast Fourier Transform and optical thickness was measured. The optical thickness was changed with the materials in nanoporous layer. To fabricate the TiO₂ nanotube arrays, anodizing time, voltage and electrolyte were optimized. The diameter and length of TiO₂ nanotube arrays were ~100 nm and ~4 µm, respectively. To observe the loading and elution of the chlorhexidine in TiO₂ nanotube in real time, the optical thickness was measured with flow cell system. In 10 wt% chlorhexidine, optical thickness change of ~125 nm was observed.

Abstract: Carbon and Nitrogen-doped TNTA were synthesized by in-situ anodic oxidation of Ti using glycerol containing NH₄F followed by annealing with 20% H₂/Argon at 500 °C. Variation water content in the electrolyte solution (25 and 37.5 v%) and time of anodic oxidation (1, 2, 4 and 6 h) that influence the morphology of TNTA and H₂ produced was examined. At water content 37.5 v% in the electrolyte solution, FESEM results indicated that the disorder with not vertically oriented of the tube were observed. For water content 25 v%, TNTA with average inner diameters of 81 to 105 nm, wall thicknesses from 15 to 27 nm and lengths from 882 to 1705 nm were synthesized for 1-6 h anodization. Morphology of TNTA such as well developed, vertically oriented, ordered and long could influence photon absorption and, therefore, influence the accumulative H₂ production. The result indicated that the average inner diameter of the tubes increase as anodic oxidation time increased up to 6 h, on the other hand, the tube length reached the maximum at 4 h anodic oxidation. TNTA that anodized for 2 h, water content in the electrolyte solution 25 v% with average tube length 1570 nm showed the highest accumulative H₂ production (47 mmol/m²photocatalyst).