Corrosion Resistance Of Layers Research Articles

Bio-inspired citrate-functionalized apatite thin films crystallized on Ti–6Al–4V implants pre-coated with corrosion resistant layers

In this paper the crystallization of a bioinspired citrate-functionalized apatite (cit-Ap) thin film (thickness about 2μm) on Ti–6Al–4V supports pre-coated with bioactive and corrosion resistant buffer layer of silicon nitride (Si3N4), silicon carbide (SiC) or titanium nitride (TiN) is reported. The apatitic coatings were produced by a new coating technique based on the induction heating of the implants immersed in a flowing calcium–citrate–phosphate solution at pH11. The influence of the buffer layers and the surface roughness of the substrate on the chemical–physical features and adhesion of the cit-Ap films were investigated. The best plasticity, compactness and adherence properties have been found in the Ap layer grown on Si3N4, followed by the Ap grown on SiC and TiN, respectively. The adhesion property was likely related to the roughness of the buffered substrates, whereas the compactness and plasticity were closely related to the operating conditions during the Ap crystallization (flow rate of the solution and increase of temperature) rather than to the nature of the buffer layer.

Bonding characteristics and corrosion resistance of silane–cerium-treated aluminum adherend

A silane–cerium treatment was applied on an aluminum adherend to simultaneously improve the bonding performance and corrosion resistance of the adhesively bonded aluminum joint in cryogenic applications, such as with liquefied natural gas containment tanks. The lap shear strengths and corrosion performances of the adhesively bonded joints composed of treated aluminum adherends were measured with respect to the silane–cerium treatment and the surface pretreatment on the aluminum adherend. The bonding characteristics of the aluminum adherend were investigated by measuring the water contact angle and conducting the potentiodynamic polarization test after the aluminum adherends with different surface treatments of silane–cerium were immersed in a 0.5 M NaCl solution. In addition, the surfaces were analyzed with scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to characterize the chemical compositions of the silane–cerium-treated aluminum adherend. The experimental results show that an appropriate silane–cerium treatment on the aluminum adherend produces an effective corrosion-resistant layer and that it has a highly reliable bonding characteristic for the adhesive joint at a cryogenic temperature of −150 °C.

The Effect of Ammonia Water on the Microstructure and Performance of Plasma Electrolytic Saturation Nitriding Layer of 38CrMoAl Steel

Abstract 38CrMoAl nitriding layer had been prepared by plasma electrolytic nitriding under different concentration of ammonia water. The layer structure, surface and phase composition had been analyzed by OM 、 SEM 、 XRD, respectively. Deeper analysis about element distribution in layer had been implemented by GDOES. The layer corrosion resistance had been measured by Parstat2273 Electrochemical workstation. microhardness and the wear properties of specimens were also evaluated. The experiment results show that: the nitriding layer consist mainly of Fe 2 N and Fe 3 N, the layer thickness is 85±5 to 165±15 μm and the cross-section microhardness of the layer is 650- 1023HV after treated 10 min at 220 V. When the concentration of ammonia water drops to 40%, FeO is observed in outer-layer. The intensity of the maximum diffraction peak changed with the varying of nitrogen concentration. With the increasing of ammonia water concentration, the thickness of uniform and compact the white layers increases, the diffusion layers consist of needle nitrides and small carbides first increases then decreases, the distance for the biggest microhardness position to the surface increases obviously. After treated at 60% ammonia water, the layer thickness would get 165 μm, the diffusion layer reach 114 μm, microhardness of the layer reach 1023HV while the substrate hardness remain 310HV. Compared with the treated sample, the untreated wearing weight increase 4.5 times. The corrosion potential had been improved greatly from -523.4 mV to -464.1 mV. The white layer reaches 52 μm while the ammonia water reaches 70. However the diffusion layer is thinner, so the layer thickness decrease gradually.

Chemical and Mechanical Properties of Cu Surface Reaction Layers in Cu-CMP to Improve Planarization

Chemical and mechanical properties of a surface reaction layer are essential to improve planarization in Cu-CMP. We compared the reaction layers on Cu surfaces formed by dipping in APS and H2O2 slurries and show that a thinner, mechanically stronger, and corrosion-resistant layer is preferable. It enables preferential polishing of the convex surfaces and consequently relaxes dishing after Cu-CMP. Controlling Cu oxidation reaction to form Cu2O in the slurry is essential for achieving further improvements of the planarization.

Improved Corrosion Resistance and Thinner Alpha-Case Layer on Titanium Casting Using Al<sub>2</sub>O<sub>3</sub>–5Ti as Investment Material

Improved Corrosion Resistance and Thinner Alpha-Case Layer on Titanium Casting Using Al<sub>2</sub>O<sub>3</sub>–5Ti as Investment Material

Pulse plated Zn transition layer in electroplating Zn–Ni coatings on magnesium alloys

A novel process with an environmentally friendly Zn transition layer was used in electroplating a Zn–Ni coating onto an AZ31 magnesium alloy, and direct current (dc) and pulse current (pc) electroplated Zn coatings were compared. The surface morphology, microstructure and macroresidual stress of the specimens were investigated using scanning electron microscope and X-ray diffraction spectrometry. The electrochemical method was adopted for corrosion resistance evaluation. The SEM images indicated that the Zn transition layer was necessary in electroplating a Zn–Ni coating. For the same electroplating time, the application of the pc plating mode was superior to the dc mode when producing a low residual stress, smooth, compact, nonporous and more corrosion resistant Zn transition layer. Moreover, the grain size of the pc plated Zn transition layers was finer than that of the dc plated layers. Most importantly, an electrodeposited Zn–Ni alloy coating on a magnesium alloy could be obtained successfully using a pc plated Zn transition layer.

Impact of heat treatment on microstructure of steel 30X padded with wire G18 8Mn

The practical purpose of padding is to increase mechanical properties, hardness and abrasion resistance of surface layers of structural elements while maintaining good plastic properties of the core, apply corrosion-resistant layers, regenerate and/or repair the surface etc. The article describes the results of macroscopic and microscopic metallographic examination of components made of 30X steel, which is an equivalent of 32HA steel produced in Poland, and surfaced with G18 8Mn filler wire using MAG method. One of components was not heat treated after surfacing while the other after surfacing was subjected to quenching and tempering. The examination was aimed at determining the effect of heat treatment on changes in the structure of surfaced components. The metallographic examination has been conducted using optical microscopy in the area of parent metal of 30X steel as well as in heat affected zone (HAZ) in steel under and in the surfacing weld. HAZ width under the surfacing weld has also been measured. On the basis of the results showed that heat treatment after padding is responsible for the presence of the structure of tempered martensite in the heat affected zone and is responsible for a greater width of the HAZ, if compared with the condition without heat treatment.

Corrosion protection of AA2024-T351 friction stir welds by laser surface melting with Excimer laser

The effect of an Excimer laser treatment on the corrosion resistance of friction stir welds in AA2024-T351 has been studied by means of electrochemical techniques and immersion tests. The results show a decrease in anodic and cathodic reactivity in the weld region after the laser treatment, achieved due to the formation of a 3–5 μm thick corrosion resistant layer. Immersion tests in 0·1M NaCl confirm that the presence of the treatment decreases the severity of corrosion attack. However they also show that, if the laser layer is damaged by a scratch, corrosion occurs preferentially in the scratch area. Delamination of the laser treated layer can also occur as a consequence of corrosion propagation during the exposure of laser treated samples.

Wear and corrosion resistance of pack chromised carbon steel

Pack chromising treatment is an environmentally friendly alternative to hard chromium to form wear and corrosion resistant surface layers. In this work, samples of AISI 1060 steel were pack chromised for 6 and 9 h at 1000 and 1050°C using different activator concentrations. Wear tests were performed in dry conditions and corrosion tests in natural sea water for the pack chromised samples and hard chromium. Pack chromising yielded the formation of layers with high chromium concentrations, high hardness and wear resistance. Increasing activator concentration causes no significant change on the morphology and thickness of the layers. The layers produced at 1050°C yielded only a (Cr,Fe)2N1−x phase, and those obtained at 1000°C are composed of a carbide mixture with (Cr,Fe)2N1−x. The sample treated at 1050°C for 9 h resulted in an optimum condition by means of better wear resistance and corrosion properties, which were close to that exhibited by the hard chrome, indicating that pack chromising is a promising alternative.

Chromium recovery from exhausted baths generated in plating processes and its reuse in the tanning industry

Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO3) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution.

Formation of High Corrosion Resistant Nanotubular Layers on Titanium Alloy Ti13Nb13Zr

This paper presents results of oxidation tests and corrosion investigations of titanium alloy Ti13Nb13Zr performed at different conditions. The oxide layers have been formed by electrochemical method in 2M H3PO4 + 0.3% HF solution for 30 min. and 1 h at 20 V constant voltage. The corrosion tests have been made by potentiodynamic method in Ringer`s solution at pH ranged between 3 and 7. It has been shown that the nanooxide films, which improve corrosion resistance of titanium alloy Ti13Nb13Zr even if acidic environment, have appeared.

Elimination of Start/Stop defects in laser cladding

Laser cladding represents an advanced hard facing technology for the deposition of hard, corrosion and wear resistant layers of controlled thickness onto a selected area of metallic substrate. When a circular geometry is required, the beginning and the end of the laser track coincide in the same area. When no special attention is paid the formation of irregular microstructural features results in non-homogeneous properties and even to cracking. This paper reports a few specially designed strategies that are tested to solve this problem. Laser cladding experiments were performed using 3.3 kW IPG Fiber laser, SS304 steel substrate bar 40 mm in diameter and two coating powders: Iron and Cobalt based. Standard metallographic methods, Scanning Electron Microscopy equipped with Energy Dispersive Spectroscopy and microhardness measurements were used to study the microstructure and properties inside the laser track overlapping areas created by different cladding strategies. These strategies were ranked according to a particular set of criteria. Correlations between the hardness variations and ‘local dilution’ inside the Start/Stop zone were identified for both materials.

Surface Oxygen Diffusion Hardened Titanium Material TC4

In this study, surface oxygen diffusion-hardened treatment for TC4 titanium alloy was carried out to enhance the wear and corrosion resistance. The surface oxygen diffusion-hardened treatment was performed in an electrical resistance furnace under atmosphere. Characterization of modified surface layers was made by means of microscopic examinations, microhardness measurements and X-ray diffraction (XRD) analysis. The wear resistance of both treated and untreated samples was evaluated. The accelerated corrosion tests in HCl solution was used to determine the corrosion resistance. The corrosion and wear resistant surface layers were obtained after treatment. The surface layers mainly consisted of rutile TiO2. A significant increment in surface hardness was achieved due to the formation of an oxygen diffusion zone. Corrosion and wear resistant surface on TC4 were obtained after the formation of diffusion zone.

Achieving a chromium rich surface upon steels via FBR-CVD chromising treatments

Surface alloying via fluidised bed reactor (FBR) chemical vapour deposition (CVD) can be used to produce adherent and highly corrosion resistant surface layers. In this work, 304, 316, and 409 stainless steels and 1020 steel were chromised, producing distinct surface layers tens of micrometres thick. The composition and surface of these layers was characterised using microscopy, GDOES, and XPS. Surfaces were highly enriched in Cr and displayed improved corrosion resistance as determined by electrochemical evaluations. This work demonstrates that it is possible to form continuous, functional and corrosion resistant Cr-rich surface layers via FBR-CVD on a variety of steels.

Oxygen ion irradiation effect on corrosion behavior of titanium in nitric acid medium

Abstract The corrosion assessment and surface layer properties after O 5+ ion irradiation of commercially pure titanium (CP-Ti) has been studied in 11.5 N HNO 3 . CP-Ti specimen was irradiated at different fluences of 1 × 10 13 , 1 × 10 14 and 1 × 10 15 ions/cm 2 below 313 K, using 116 MeV O 5+ ions source. The corrosion resistance and surface layer were evaluated by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and glancing-angle X-ray diffraction (GXRD) methods. The potentiodynamic anodic polarization results of CP-Ti revealed that increased in ion fluence (1 × 10 13 –1 × 10 15 ions/cm 2 ) resulted in increased passive current density due to higher anodic dissolution. SEM micrographs and GXRD analysis corroborated these results showing irradiation damage after corrosion test and modified oxide layer by O 5+ ion irradiation was observed. The EIS studies revealed that the stability and passive film resistance varied depending on the fluence of ion irradiation. The GXRD patterns of O 5+ ion irradiated CP-Ti revealed the oxides formed are mostly TiO 2 , Ti 2 O 3 and TiO. In this paper, the effects of O 5+ ion irradiation on material integrity and corrosion behavior of CP-Ti in nitric acid are described.

ChemInform Abstract: Plasma-Sprayed-Yttria Layers for Corrosion Resistance.

Crucible corrosion in the growth of YBa2Cu3O7-x (YBCO) superconducting single crystals is one of the major obstacles in obtaining high-quality crystals. Both metallic and ceramic crucibles have shown significant corrosion that affects the size and properties of YBCO crystals. Plasma spraying has been successfully used to produce yttria coatings on alumina substrates. Yttria coatings with thicknesses between 30 and 100 μm have shown corrosion rates of 3 to 4 μm/h; these rates are 5 to 10 times lower than that of the alumina substrate.

Mechanical characteristics and surface elemental composition of a Yasargil titanium aneurysm clip after long-term implantation

The mechanical properties of titanium-alloy aneurysm clips after long-term implantation in the human cranium are unclear. The characteristics of a Yasargil titanium aneurysm clip were evaluated after long-term implantation for 12 years in a patient with a cerebral aneurysm. The closing forces of the retrieved clip before and after implantation were approximately equal. The bending test showed no differences between the retrieved and control clips. Titanium oxide and calcium were identified on the surface of the retrieved clip, which indicated the formation of corrosion-resistant layers. Titanium-alloy clips retain their mechanical properties in the human cranium for a long time.

Exploring Electrosorption at Iron Electrode with in Situ Surface-Enhanced Infrared Absorption Spectroscopy

Surface-enhanced infrared absorption spectroscopy (SEIRAS) in attenuated total reflection (ATR) configuration has been extended to the Fe electrode/electrolyte interface in neutral and weakly acidic solutions for the first time. The SEIRA-active Fe film electrode was obtained through a potentiostatic electrodeposition of a virtually pinhole-free 40 nm-thick Fe overfilm onto a 60 nm-thick Au underfilm chemically predeposited on the reflecting plane of an ATR Si prism. The infrared absorption for CO adlayer at the Fe film electrode measured with ATR-SEIRAS was enhanced by a factor of larger than 34, as compared to that at a Fe bulk electrode with external infrared absorption spectroscopy in the literature. More importantly, the unipolar band shape enabled the reliable determination of the Stark tuning rates of CO adlayer at Fe electrode. In situ ATR-SEIRAS was also applied to study the electrosorption of a typical corrosion inhibitor benzotriazole (BTAH) on Fe electrode as a function of potential, providing additional spectral information at positive potentials in support of the formation of a polymer-like surface complex Fe(II)(m)(BTA)(n) as the corrosion-resistant layer.

Depth profile analysis: coatings and thin layers

Coatings and thin films are present in an amazing number of applications in our daily lives although in many cases we are not conscious of them. The field extends from protective layers for mechanical and corrosion resistance to multilayered materials for electronic, optoelectronic, or magnetic applications, coated glasses for buildings, biomaterials, photovoltaic devices, catalysts, sensors, imitation jewellery, and decorative coatings. Moreover, polymeric coatings are now also used for various technological applications, ranging from poly-LED displays or organic photovoltaic systems to food packaging. The ability to carry out the in-depth profile analysis of a given material, i.e., to determine the changes in the composition of major and trace components from the surface down to the bulk homogeneous solid, provides information about the composition and thickness of the layers, the distribution of doping constituents, possible diffusion processes, and the presence of impurities. The depth-resolved analytical data allow us to better understand the processes occurring at nanometer-length dimensions and to improve the materials, with the aim of achieving the optimum final performance. The rapid progress in materials science constantly poses new challenges for analytical chemistry and prompts the development of improved techniques and methods. The influence is particularly strong for coated materials and thin films, for which applications and demands are increasing at a rapid pace, with thinner films and more complex surface modifications continually being developed both to fit common market needs and also for high-tech applications. This special issue contains 15 papers (four reviews and 11 original research papers) from universities, institutes, and research laboratories working with direct solid analytical techniques such as X-ray photoelectron spectroscopy, grazing incidence X-ray fluorescence, confocal Raman spectroscopy, glow discharges coupled with optical emission or mass spectrometry, and atomic force microscopy. The contributions show the potential for improved analytical techniques and methods to adapt their performance to the new challenges brought by materials science, for example, expanding their capabilities from just elemental to also molecular information, allowing the analysis of thin films of a few nanometers instead of just micrometer-thick coatings, assisting the development of advanced materials of proper quality, allowing for nondestructive depth profile analysis, and providing not just qualitative but also quantitative depth profile information. We specially thank the authors for their contributions and wish them all the best in their professional lives. We are also very thankful to the reviewers for the thorough and ontime reviews of the papers, and, last but not least, to the editorial team of Analytical and Bioanalytical Chemistry for the invitation for us to act as guest editors of this issue and for their support. B. Fernandez :R. Pereiro (*) Department of Physical and Analytical Chemistry, University of Oviedo, 33006 Oviedo, Spain e-mail: mrpereiro@uniovi.es

The characterization of corrosion resistance in the Ti-6Al-4V alloy fusion zone using a gas tungsten arc welding process

The Ti-6Al-4V sheet alloys were welded by using a common gas tungsten arc welding process. In this work, we study the correlation of corrosion resistance and oxide layer structure produced after commonly used industrial heat treatments. We also study the oxide scales that were formed as a result of the heat-related treatment/aging process. The results indicate that better corrosion resistance of the Ti-6Al-4V alloy weldment can be obtained and significantly improved by a solution treatment plus an artificial aging (ST+AA) treatment, owing to the enhanced intensity of TiO2, V2O5, and Al2O3 oxides that compacted and grew on the surface of fusion zone. The newly found γ-TiAl and α2-Ti3Al particles that nucleated in the fusion zone due to different heat treatments do affect the composition of the oxide layer. The possible mechanism for this oxide layer formation in the fusion zone is discussed.