An Analysis of Trapping Effect on Hydrogen Diffusion in Cold Rolled Palladium

The applicability of the "two-energy-level" trap model for hydrogen diffusion proposed by one of the present authors to the experimental diffusivity data for cold rolled palladium was examined, together with the both models of Oriani and McLellan. The present model provided a better description of the experimental results. The trap interaction energy and trap density in cold rolled palladium was determined to be ⊿GtH,l=-8.4kJ mol-1 and ft=2.9×10-2 respectively

Preparation of Metal-Containing Diamond-Like Carbon Films by Magnetron Sputtering and Plasma Source Ion Implantation and Their Properties

Metal-containing diamond-like carbon (Me-DLC) films were prepared by a combination of plasma source ion implantation (PSII) and reactive magnetron sputtering. Two metals were used that differ in their tendency to form carbide and possess a different sputter yield, that is, Cu with a relatively high sputter yield and Ti with a comparatively low one. The DLC film preparation was based on the hydrocarbon gas ethylene (C2H4). The preparation technique is described and the parameters influencing the metal content within the film are discussed. Film properties that are changed by the metal addition, such as structure, electrical resistivity, and friction coefficient, were evaluated and compared with those of pure DLC films as well as with literature values for Me-DLC films prepared with a different hydrocarbon gas or containing other metals

Surface Structuring of Diamond-Like Carbon Films by Chemical Etching of Zinc Inclusions

A diamond-like carbon (DLC) film with a nanostructured surface can be produced in a two-step process. At first, a metal-containing DLC film is deposited. Here, the combination of plasma source ion implantation using a hydrocarbon gas and magnetron sputtering of a zinc target was used. Next, the metal particles within the surface are dissolved by an etchant (HNO₃:H₂O solution in this case). Since Zn particles in the surface of Zn-DLC films have a diameter of 100–200 nm, the resulting surface structures possess the same dimensions, thus covering a range that is accessible neither by mask deposition techniques nor by etching of other metal-containing DLC films, such as Cu-DLC. The surface morphology of the etched Zn-DLC films depends on the initial metal content of the film. With a low zinc concentration of about 10 at.%, separate holes are produced within the surface. Higher zinc concentrations (40 at.% or above) lead to a surface with an intrinsic roughness

Enhanced initial cell responses to chemically modified anodized titanium.

BACKGROUND: Previously, we reported that anodized porous titanium implants have photocatalytic hydrophilicity. However, this effect was not always sufficient for the significant improvement of bone apposition. PURPOSE: The purpose of this study was to improve the photocatalytic properties of porous titanium implants by the fluoride modification of the anodized titanium dioxide (TiO(2)), and to investigate the initial cell response to it. MATERIALS AND METHODS: The ideal concentration of ammonium hydrogen fluoride (NH(4)F-HF(2)) used in this study was determined by a static water contact angle assay. The ideal concentration of NH(4)F-HF(2) was 0.175%, and experimental disks were treated with this concentration. A pluripotent mesenchymal cell line, C2C12, was cultured on the disks in order to investigate cell attachment, morphology, and proliferation. RESULTS: Cell attachment after 30 minutes of culturing was significantly higher for the ultraviolet-irradiated, fluoride-modified anodized TiO(2) (p < .05), and the simultaneous scanning electron microscope observation showed a rather flattened and extended cell morphology. The proliferation rate after 24 hours was also significantly higher for the fluoride-modified anodized TiO(2). CONCLUSION: Fluoride chemical modification enhances the hydrophilic property of the anodized TiO(2) and improves the initial cell response to it

Modification, Synthesis, and Analysis of Advanced Materials Using Ion Beam Techniques

Energetic ion beams are employed for the synthesis, modification, and analysis of advanced, technologically important materials, and many novel applications have emerged over the past several decades. The evolution of the field over this period is recorded in a broad range of conferences that are dedicated to particular aspects of ion-beam modification or analysis of materials, including international conferences on ion beam modification of materials (IBMM), ion beam analysis (IBA), surface modification of materials by ion beams (SMMIB), and so forth. This special issue aims to present some of the latest results in the field

Platinum implantation into tantalum for protection against hydrogen embrittlement during corrosion

Platinum is well known for its catalytic activity, even in small quantities. Among others, it catalyzes the recombination of hydrogen atoms to molecules and the desorption of the molecules from a surface. This favourable feature can be used to protect metals from detrimental hydrogen incorporation. This may take place in the case of tantalum when it corrodes in strong acids. Tantalum is a highly inert metal which can be used for devices and vessels for acid handling. When it is exposed to concentrated sulphuric acid, its corrosion rate is acceptably low. However, a side reaction may become problematic. When the metal is being dissolved, hydrogen is being formed at the metal surface at the same time. Being the smallest chemical element, hydrogen can easily diffuse into the metal lattice. There, is reacts to the metal hydride and may even form bubbles. By the phase change it creates pressure. The hydride is very brittle, and the metal can easily fail mechanically. In order to prevent catastrophic hydrogen embrittlement, small amounts of platinum were implanted into the surface of metallic tantalum and of tantalum coated with a protective oxide film. Depth profiles by secondary ion mass spectrometry showed that the platinum was located close to the surface; the implantation zone of the oxidized tantalum was considerably thicker than the one of the bare tantalum. Upon exposure to hot mineral acids, the untreated tantalum failed in mechanical tests due to embrittlement after short time, while the platinum-implanted one achieved considerably enhanced life-times. No difference was found between the bare and the oxide-coated tantalum

Complete coating of metal rings by ion beam sputtering of a W-shaped concave target with a broad-beam ion source

Ion beam sputter coating with the substrate at ambient temperature or water-cooled is a well-known process for coating temperature-sensitive substrates with films of high quality, despite the low process temperature. However, ion beam based methods suffer from an intrinsic drawback, the so-called line-of-sight restriction. Since a directed beam of the material to be deposited is used, only that part of a sample that is “seen” by the particle source is properly treated. This renders coating of 3-dimensional objects with ion beam methods difficult. Particularly challenging is to completely coat such objects from all sides. A typical example are rings. When they are to be treated with ion beam techniques, sophisticated manipulation of substrate or ion beam or even both is required. Despite these problems, under certain circumstances it is nevertheless possible to apply ion beam techniques for treating/coating 3-D objects. When ion beam sputter coating is used, the sputter target, i.e. the source of the material to be deposited, is usually flat. With such a sputter target, a ring can hardly be coated uniformly. However, when the sputter target is formed according to the substrate shape, here as a concave/convex double-cone, a very effective coating can be achieved. This is demonstrated by coating rings for corrosion protection

DLC coating of interior surfaces of steel tubes by low energy plasma source ion implantation and deposition

The plasma source ion implantation (PSII) process can be used for the treatment of the interior surfaces of tubes. Typically, this is done with higher ion energies of 10 keV or more. The resulting film thickness and the properties of the DLC film usually show a dependence on position, i.e. the distance from the edge of the tube. In order to investigate whether this effect is also present with lower energies (and if so, to what extent), deposition was carried out at negative pulse voltages of -5 kV. A diamond-like carbon (DLC) film was deposited by using acetylene as the plasma gas. The substrate consisted of stainless steel tubes with an inner diameter of 20 mm and a length of 100 and 200 mm, respectively. The distribution of the thickness, film composition, structure, surface morphology and friction coefficient as a function of the position inside the tube were investigated. The results of this low energy treatment were compared with investigations which employed higher ion energies

Mechanical and electrical properties of diamond-like carbon films deposited by plasma source ion implantation

Diamond-like carbon (DLC) films were prepared by a plasma source ion implantation method with superposed negative pulse and negative DC voltage. Acetylene gas was used as working gas for plasma formation. A negative DC voltage and a negative pulse voltage were superposed and applied to the substrate holder. The DC voltage was changed in the range from 0 to −4.8 kV and the pulse voltage was changed from −18 to −13.2 kV. The films were annealed in the range of 200–450 °C for 1 h. The surface morphology of the films and the film thickness were observed by atomic force microscopy and scanning electron microscopy. The film structure was characterized by Raman spectroscopy. The hardness of DLC films was evaluated by an indentation method. Measurement of the electrical resistivity was performed using a four-point probe station. Furthermore, a ball-on-disc test with 2 N load was employed to obtain information about the friction properties and sliding wear resistance of the films. The surface of the DLC films was very smooth and featureless. The deposition rate was changed with the DC voltage and pulse conditions. Integrated intensity ratios ID/IG of Raman spectroscopy and electrical resistivity of the DLC films changed with DC voltage. The electrical resistivity decreased with increasing ID/IG ratio. The ID/IG ratio was increased and the electrical resistivity was decreased with annealing temperature owing to graphitization. Very low friction coefficients around 0.05 were obtained for as-deposited films