Ion Beam Surface Modification Research Articles

Effects of the microstructure of carbon materials under ion-beam surface modification

The effect of high-fluence (1018 cm–2) irradiation by helium and argon ions with energy of 30 keV on the structure and morphology of the surface of carbon materials with significantly different microstructure: highly oriented pyrolytic graphite, glassy carbon, carbon fibres from PAN and viscose has been studied experimentally.

Effects of the Microstructure of Carbon Materials under Ion-Beam Surface Modification

Effects of the Microstructure of Carbon Materials under Ion-Beam Surface Modification

Ion-Beam Surface Modification of Carbon Fibers

Carbon fibers are used in the production of automobiles, airplanes, sporting goods, energy, and biomedicine due to their unique properties such as high specific strength, high specific tensile strength, low coefficient of thermal expansion, and low density. The research and development of both the technology of carbon fibers production and their modification for a wide range of applications have been and remain relevant. The summary of the accumulated experience in the modification of carbon fibers shows that ion-beam treatment allows to obtain a variety of geometry of the developed surface topography, in particular, whisker-shaped and corrugated oriented across or along the fiber. Such processing compares favorably with ordinary fiber whiskering both by a variety of geometry of the composite interface, and by the absence of the problem of whisker-fiber adhesion. Ion-beam treatment also makes it possible to modify the surface layer structure from amorphized to ordered with different degrees of graphitization. Irradiation with chemically active ions leads to functionalization of carbon fiber due to formation, for example, of nitrides and carbon oxides. The choice of nitrogen ions for the technology of carbon-carbon and carbon-ceramic composites seems to be more preferable due to less stringent requirements for the temperature of the irradiated fiber. For ion-beam corrugation of polyacrylonitrile-based carbon fiber surface, only its heating above the temperature of dynamic annealing of radiation damage is required. The use of helium ions in technological plasma acceleration systems leads to a significant efficiency increase in ion-beam processing.

Ion-Beam Surface Modification of Carbon Fibers

Ion-Beam Surface Modification of Carbon Fibers

Surface wetting on micromilled and laser-etched aluminum with ion-beam postprocessing

In this work, micromilling and laser-etching microfabrication techniques are trialed for mimicking the super water repellence of the lotus leaf and the directional water droplet control of the Namib desert beetle. To further alter the surface wetting properties, subsequent ion-beam surface modification techniques are used. Ion-beam postprocessing is used to create an additional nanoroughness on a microstructure as well as a controllable Gibbs surface free energy change of the substrate material. The in-plane spreading for control (smooth) surfaces are compared to the micropatterned surfaces and combined micropatterned and ion-beam processed surfaces. Combined microscale surface engineering via milling or laser etching and ion-beam surface modification allows engineering both hydrophobic and mass-transport properties directly from a bulk material rather than involving a coating. Such surfaces have potential applications in advanced heat-exchanger technology (increasing the condensation heat transfer coefficient), wind turbine technologies (delaying or eliminating ice/frost formation under extreme weather conditions), as well as for atmospheric water harvesting and condensation control on industrial heat exchangers.

Некоторые особенности модификации поверхности ионными пучками очень большого размера

Ion beam surface modification is typically carried out in a laboratory environment where the processing rate is not a big concern. Nevertheless, it is interesting to consider the possibilities that might allow substantial increase (orders of magnitude) in the processing rate, possibly for industrial application. Here we consider two possible approaches to very large scale ion beam surface modification – the use of very broad beam vacuum arc ion sources and the use of ion sources that have been developed to provide intense neutral beams as part of the world controlled fusion research effort. These sources can provide beam intensities in the tens of amperes range, and quasi-dc operation has been demonstrated. A third possibility is scale-up of the Plasma Immersion Ion Implantation approach, and some relevant work has been done along these lines. These approaches to giant ion beam surface modification systems, and the implied parameters and features of such systems, as well as the highly related concern of the necessary accompanying electrical systems, are briefly considered here.

A Study on the Wettability of Ion-Implanted Stainless and Bearing Steels

To satisfy the harsh service demand of stainless steel and aviation bearing steel, the anticorrosion and wettability behaviors of 9Cr18 stainless steel and M50 bearing steel tailored by ion beam surface modification technology were experimentally investigated. By controlling the ion implantation (F+, N+, N+ + Ti+) or deposition processes, different surface-modified layers and ceramic layers or composite layers with both effects (ion implantation and deposition processes) were obtained on metal surfaces. The wettability was characterized by a contact angle instrument, and the thermodynamics stabilization of ion implantation-treated metals in corrosive solution was evaluated through an electrochemical technique. X-ray photoelectron spectroscopy (XPS) was employed for detecting the chemical bonding states of the implanted elements. The results indicated that ion implantation or deposition-induced surface-modified layers or coating layers could increase water contact angles, namely improving hydrophobicity as well as thermodynamic stabilization in corrosive medium. Meanwhile, wettability with lubricant oil was almost not changed. The implanted elements could induce the formation of new phases in the near-surface region of metals, and the wettability behaviors were closely related to the as-formed ceramic components and amorphous sublayer.

Alternative uses of a megavolt tandem accelerator for few-keV studies with ion-source SIMS monitoring.

We increase the versatility of a tandem electrostatic accelerator by implementing simple modifications to the standard operation procedure. While keeping its ability to deliver MeV ion beams, we show that the experimental setup can (i) provide good quality ion beams in the few-keV energy range and (ii) be used to study ion-beam surface modification with simultaneous secondary ion mass spectrometry. This latter task is accomplished without using any chamber connected to the accelerator exit. We perform mass spectrometry of the few-keV anions produced in the ion source by measuring their neutral counterparts at the accelerator exit with energies up to 1.7 MeV. With an additional modification, a high-current few-keV regime is obtained, using the ion source as an irradiation chamber and the accelerator itself only as a mass spectrometer. As an example of application, we prepare a sample for the study of ion-beam assisted dewetting of a thin Au film on a Si substrate.

Controlling cell morphology on ion beam textured polymeric surfaces

Objectives: Nano and micro sized textures on surfaces are generally useful biomaterials. Although the importance of roughness degree has been reported for cell morphology, texture morphology can be more determining for cell adhesion and proliferation. Biodegradable polymers are extensively used as scaffolds as well as implant materials in the human body. The aim of this study was to investigate the effect of ion beam bombardment on cell morphology. Methods: Gold and carbon ion implantation was made on biodegradable polymers polyglycolic acid, polycaprolactone and polylactic-co-glycolic-acid. Roughness data were obtained from atomic force microscopy. After surface modification with ion beam, B35 neural cells were evaluated on surfaces for cell compatibility. Morphology and cell surface interaction were analyzed with scanning electron microscopy. Results: We observed improved cell adhesion after ion beam surface modification. Cell adhesion was greater on gold implanted surfaces compared to the carbon implanted. Neural cells attached to lamellar wrinkles, spread by taking the shape of the pattern and exhibited high aspect ratios and axon extension. In contrast, cells that attached on the untreated surfaces remained rounded with low spreading. Conclusion: The findings of this study are important for development of ion beam modified cell cultures and scaffold systems to understand texture-based cell adhesion mechanisms. Keywords: cell culture; ion implantation; polylactic-co-glycolic acid; surface treatment; topography; wettability

Effect of ion-beam surface modification technology on the variation of surface texture

Ion-beam surface bombardment modification technology is successfully used to manufacture different kinds of nano-textures on the surface of silicon substrate. Relationship between the morphology and arrangement patterns of nano-textures and the bombarding parameters is studied. Results show that the ion-beam bombardment has a significant impact on surface morphology. Different kinds of textures on silicon substrate can be formed according to the variation of bombardment time. The nanodot array texture is observed on the surface of silicon substrate when the duration of argon ion-beam bombardment is 15 minutes. Simultaneously, the tetrahedral amorphous carbon film is deposited on the silicon substrates that have different kinds of nano-texture. The microstructure of ta-C film deposited on unprocessed and nano-textured silicon substrate is analyzed by X-ray photoelectron spectroscopy. Results indicate that the content of sp3 bonds decreases with increasing bombardment time, and thereafter keeps a steady value. The ta-C films deposited on the nanodot-textured substrate shows the lowest sp3 fraction. It is also observed by friction and wear test that the wear time is enhanced from 10 to 70 min. The tribological properties is highly improved when the coating is deposited on the nano-textured substrate.

Effect of Surface Alloying by Silicon on the Corrosion Resistance and Biocompatibility of the Binary NiTi

This paper presents the study on changes in element and phase compositions in the near-surface layer and on surface topography of the NiTi specimens after the silicon ion-beam treatment. The effect of these parameters of the near-surface layer on corrosion properties in biochemical solutions and biocompatibility with mesenchymal stem cells of rat marrow is studied. Ion-beam surface modification of the specimens was performed by a DIANA-3 implanter (Tomsk, Russia), using single-ion-beam pulses under oil-free pumping and high vacuum (10−4 Pa) conditions in a high-dose ion implantation regime. The fluence made 2 × 1017 cm−2, at an average accelerating voltage of 60 kV, and pulse repetition frequency of 50 Hz. The silicon ion-beam treatment of specimen surfaces is shown to bring about a nearly twofold improvement in the corrosion resistance of the material to attack by aqueous solutions of NaCl (artificial body fluid) and human plasma and a drastic decrease in the nickel concentration after immersion of the specimens into the solutions for ~3400 and ~6000 h, respectively (for the artificial plasma solution, a nearly 20-fold decrease in the Ni concentration is observed). It is shown that improvement of NiTi corrosion resistance after treatment by Si ions occurs mainly due to the formation of two-layer composite coating based on Ti oxides (outer layer) on the NiTi surface and adjacent inner layer of oxides, carbides, and silicides of the NiTi alloy components. Inner layer with high silicon concentration serves as a barrier layer preventing nickel penetration into biomedium. This, in our opinion, is the main reason why the NiTi alloy exhibits no cytotoxic properties after ion modification of its surface and leads to the biocompatibility improvement at the cellular level, respectively.

Ion Beam Surface Modification of GaN Films for High Efficient Light Emitting Diodes

Ion Beam Surface Modification of GaN Films for High Efficient Light Emitting Diodes

Effects of ion beam surface modification on water absorption characteristics of perfluorosulfonic acid membranes

The dynamic behavior of water within ion beam (10 keV Ar+, 1.0 × 1016–1.2 × 1017 ions/cm2) modified perfluorosulfonic acid (PFSA) membranes was investigated at room temperature by combining direct-current (DC) resistance with alternative-current (AC) impedance methods under a water-saturated air atmosphere. The bulk impedance in existing surface sulfonate groups (SO3−) decreased approximately one order of magnitude as a result of Ar+ ion irradiation compared to the unirradiated membrane. The enhancement in the proton conductivity results in an improvement of the water absorption characteristics at the Ar+ ion-modified surface which showed large superficies as well as hydrophilic radicals. These results can be explained in base of a relative increase in both the water content of the membrane and the change in the interactions of water molecules with sulfonate group at the interface on the proton-transfer process.

Introduction

Plasma and ion-beam surface treatments by energetic particle bombardment enable a high degree of freedom and control of surface material chemistry and microstructure. The development of plasma and ion-beam surface modification methods and tools has allowed the synthesis, modification and exploration of new technologically important materials. Plasma surface treatments together with low energy (< 5 keV) ion-beam processing of surfaces, thin films, and nanostructures result in new phases and metastable states that directly impact the chemical, physical, and morphological properties of the material. Thus, this field is highly relevant for new applications such as tribological, optical and biomedical coated surfaces.

Experimental Evaluation of a New Antithrombogenic Stent Using Ion Beam Surface Modification

A new antithrombogenic stent using ion beam surface modification nanotechnology was evaluated. The ion stent is being developed to inhibit acute and chronic stent-related thrombosis. Thirty self-expanding mesh stents were fabricated from Ti-Ni metal wires with a dimension of 4 mm (diameter) x 25 mm (length) x 0.15 mm (thickness). Twenty stents were coated with type I collagen and irradiated with a He(+) ion beam at an energy of 150 keV with fluences of 1 x 10(14) ions/cm(2) (ion stent group). Ten stents had no treatment (non-ion stent group). The self-expanding stents were implanted into the right and left peripheral femoral arteries of 15 beagle dogs (vessel diameter approximately 3 mm) via a 6Fr catheter under fluoroscopic guidance. Heparin (100 units/kg) was administered intravenously before implantation. Following stent implantation, no antiplatelet or anticoagulant drugs were administered. The 1-month patency rate for the non-ion stent group was 10% (1/10), and for the ion stent group it was 80% (16/20) with no anticoagulant or antiplatelet drugs given after stent implantation (P = 0.0004 by Fisher's exact test). Ten stents remain patent after 2 years in vivo with no anticoagulant or antiplatelet drugs. These results indicate that He(+) ion-implanted collagen-coated Ti-Ni self-expanding stents have excellent antithrombogenicity and biocompatibility. This ion stent is promising for coronary and cerebral stent applications.

Effect of Pulsed High Energy Ion Beam on Surface Modification of AZ91 Magnesium Alloy

This study is concerned with the effect of high energy ion beam irradiation on surface properties of AZ91 magnesium alloy. The study included a characterization of ion beam surface modification zone in terms of microstructure, and mechanical properties like nanohardness, wear, and corrosion resistance of the surface layer were studied in details. Nanohardness of the modification layer was improved about 2 times as that of the as-received AZ91. The corrosion resistance of the modified layer was significantly improved in NaCl solution because of refined grains. The wear resistance of the modification layer was also improved as compared to as-received AZ91.

Metal ion bombardment of onion skin cell wall

Ion bombardment of living cellular material is a novel subfield of ion beam surface modification that is receiving growing attention from the ion beam and biological communities. Although it has been demonstrated that the technique is sound, in that an adequate fraction of the living cells can survive both the vacuum environment and energetic ion bombardment, there remains much uncertainty about the process details. Here we report on our observations of onion skin cells that were subjected to ion implantation, and propose some possible physical models that tend to support the experimental results. The ion beams used were metallic (Mg, Ti, Fe, Ni, Cu), mean ion energy was typically 30keV, and the implantation fluence was in the range 1014–1016ions/cm2. The cells were viewed using Atomic Force Microscopy, revealing the formation of microcrater-like structures due to ion bombardment. The implantation depth profile was measured with Rutherford backscattering spectrometry and compared to the results of the TRIM, T-DYN and PROFILE computer codes.

Selective area growth of aligned carbon nanotubes by ion beam surface modification

O 2 + ion beams are used to modify the surface of 50 nm thick Fe catalyst films deposited on Si(100) substrates to demonstrate selective area growth of aligned multiwall carbon nanotubes (MWNT). Aligned MWNTs were grown on the modified Fe/Si substrate using the hot filament plasma enhanced chemical vapor deposition (HF-PECVD) method. A higher growth rate and density of MWNTs was observed on the ion-modified areas, facilitating selective area growth of aligned MWNTs at temperatures as low as 560 °C. Deposition of graphitic sheets at the initial growth process on the unmodified areas inhibits the deposition of MWNTs.

Mechanisms of argon ion-beam surface modification of polystyrene

The surface characteristics of polymers are important factors determining their interfacial properties and their technological performance. Changes in physical and chemical properties of a polymer film may be induced by subjecting the material to a variety of surface modification techniques, one of which is ion-beam modification. In order to understand the underlying mechanisms X-ray photoelectron spectroscopy (XPS) was used to study the alterations of the polystyrene (PS) surface after Ar-ion treatment under well controlled conditions with low ion doses from 10 12 to 10 16 cm −2. The ion bombardment leads to surface functionalization, loss of aromaticity, and free radical formation. Induced surface cross-linking and the formation of polar groups raised the surface glass transition temperature of PS film.

Characteristics of an ion beam modification system with a linear ion source

Characteristics of an ion beam surface modification system with a linear ion source are described in this article. The linear ion source is principally based on an anode layer thruster, which is generally referred to as “closed drift thruster.” The linear ion source has a slit type racetrack-shape extraction geometry. The spatial current distribution of the extracted ion beam has, therefore, a racetrack shape. Experiments were carried out for the discharge voltages ranging from 500 to 1500 V and ion doses ranging from 7.3×1013 to 8.2×1014 ions/cm2, using three kinds of ion species, namely, oxygen, nitrogen, and argon. Ion beam current density was uniform in the direction of the straight part of the extraction slit. Metalization of the surface modified polymers was also performed. To study the improvement of the adhesion of the metal films to the polymers, the peel-off tests were carried out on ion-irradiated polyimide-copper films. The results indicated that adhesion strength between polyimide and copper was improved as a result of the surface modification by the linear ion source.