The studies and the experimental work for constructing an electron cyclotron resonance ion source... more The studies and the experimental work for constructing an electron cyclotron resonance ion source (ECRIS) for the new tritium linear accelerator (TRILAC) at the Institute of Atomic Physics are presented. The absence of consumable parts, the low neutral pressure, and the high ionization efficiency with light elements make ECRIS very attractive for this accelerator. Some special configurations for the microwave
ABSTRACT TiN biocompatible thin films were deposited on 316L stainless steel substrates by cathod... more ABSTRACT TiN biocompatible thin films were deposited on 316L stainless steel substrates by cathodic arc evaporation in nitrogen atmosphere under various deposition conditions. The corrosion behavior of TiN films in artificial physiological solution was investigated using an electrochemical test. Microchemical, microstructural and mechanical characteristics of the coatings were also analyzed.
The development of a positron annihilation spectroscopy laboratory at the HH‐NIPNE Bucharest‐to b... more The development of a positron annihilation spectroscopy laboratory at the HH‐NIPNE Bucharest‐to be used for material studies and applications was started in the last 10 years. In the framework of a national research project extended over the last 3 years, was ...
TiN and TiAlN coatings were deposited on CoCr alloy, 316L stainless steel, and Si substrates by c... more TiN and TiAlN coatings were deposited on CoCr alloy, 316L stainless steel, and Si substrates by cathodic arc method. Various ion bombardment conditions were obtained by different DC and pulsed bias voltages applied on the substrates. A comparative analysis of the coating characteristics for different substrate biasing conditions was performed.
The corrosion behavior of TiN coated 316L stainless steel in an artificial physiological solution... more The corrosion behavior of TiN coated 316L stainless steel in an artificial physiological solution was investigated by means of an electrochemical test. Two different PVD methods were used for film deposition: cathodic arc and reactive magnetron sputtering. The dependence of the corrosion resistance on the main deposition parameters (nitrogen pressure, substrate bias) was analyzed. For a better characterization of the investigated coatings, other characteristics, like elemental composition, phase composition, texture, microhardness, adhesion to the substrate were determined. The selection of biocompatible materials is based on their biocompatibility and their biofunctionality. The first characteristic refers to the implant effect on the surrounding tissue and the second one to its capability to assume the function of the replaced biologic system. In practice, both properties are closely interdependent and are connected to wear-corrosion resistance of the materials. If the implant rejection as a result of mechanical imperfections is relatively rare, most failures are caused by a lack of biocompatibility which is directly related to the corrosion resistance of the implant (1), (2). In order to find the most adequate materials to be used as implants in living tissue, many alloys have been developed, beginning with austenitic stainless steels (3). In general, the austenitic stainless steels 316 and 316L have good corrosion resistance and the additional alloying with molybdenum decreases their susceptibility to pitting corrosion. Nevertheless, in certain cases (in strongly stressed or nonoxigenated environments) stainless steels are affected by corrosion. Moreover, these types of steel have a low wear resistance. The performance of implants made of stainless steel could be improved if they were coated with thin films of materials offering protection against corrosion and wear. Among these coatings, TiN would be a suitable choice, due to its remarkable properties such as high microhardness, chemical inertness, high wear and abrasion resistance (4)-(6). The goal of this work was to investigate the corrosion behavior of TiN coated 316L stainless steel in artificial physiological solution. Two techniques were used for TiN deposition (cathodic arc method (c.a.m.) and reactive magnetron sputtering method (r.m.s.m.)), in order to select the most suitable system for preparation of anticorrosive coatings. For each method, the influence of the main deposition parameters (N2 pressure, substrate bias) on the corrosion resistance of the TiN films was examined. Additional information on the film characteristics was obtained by elastic recoil detection (ERD) and X-ray diffraction (XRD) analyses, microhardness and thickness measurements and adhesion tests.
TiOxNy coatings were investigated as possible candidates for ion diffusion barrier layers. The el... more TiOxNy coatings were investigated as possible candidates for ion diffusion barrier layers. The elemental and phase composition, texture, hardness, adhesion, and corrosion resistance of the coatings were analyzed. The ion release in Ringer solution for uncoated and coated samples were also determined. The film properties were found to significantly depend on the reactive gas composition (O2/N2 ratio). The coatings proved to enhance the corrosion protection and to reduce the ion release of the uncoated specimens.
Spectroscopic diagnostics, using intensified high speed CCD camera, was applied to study the arc ... more Spectroscopic diagnostics, using intensified high speed CCD camera, was applied to study the arc dynamics in low voltage circuit breakers, in vacuum and in air. Time-resolved emission spectroscopy of the vacuum arc plasma, generated during electrode separation, provided information about the interruption process. The investigations were focused on the partial unsuccessful interruption around current zero. Absorption spectroscopy, in a peculiar setup, was used in order to determine the metallic atoms densities in the interelectrode space of a low voltage circuit breaker, working in ambient air.
The thin titanium nitride films deposited on glass in a planar d.c. magnetron configuration have ... more The thin titanium nitride films deposited on glass in a planar d.c. magnetron configuration have been optically investigated. The influence of the nitrogen partial pressure, substrate bias and film thickness as deposition parameters on the transmission (Vis) and the reflectance (Vis, FIR) spectra of the samples was studied. The analysis of surface properties of TiN films was also made by spectroscopic ellipsometry for different deposition conditions. The data were compared with the similar spectrum of a gold evaporated film.
Nanocomposite Me–C–N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ... more Nanocomposite Me–C–N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ratios, were prepared by cathodic arc method using TiNb, TiZr and TiAl alloy cathodes in a CH4+N2 atmosphere. For comparison purposes, a-C–N:H films were also produced through evaporating a graphite cathode in a similar atmosphere. The films were characterized in terms of elemental and phase compositions, chemical
The studies and the experimental work for constructing an electron cyclotron resonance ion source... more The studies and the experimental work for constructing an electron cyclotron resonance ion source (ECRIS) for the new tritium linear accelerator (TRILAC) at the Institute of Atomic Physics are presented. The absence of consumable parts, the low neutral pressure, and the high ionization efficiency with light elements make ECRIS very attractive for this accelerator. Some special configurations for the microwave
ABSTRACT TiN biocompatible thin films were deposited on 316L stainless steel substrates by cathod... more ABSTRACT TiN biocompatible thin films were deposited on 316L stainless steel substrates by cathodic arc evaporation in nitrogen atmosphere under various deposition conditions. The corrosion behavior of TiN films in artificial physiological solution was investigated using an electrochemical test. Microchemical, microstructural and mechanical characteristics of the coatings were also analyzed.
The development of a positron annihilation spectroscopy laboratory at the HH‐NIPNE Bucharest‐to b... more The development of a positron annihilation spectroscopy laboratory at the HH‐NIPNE Bucharest‐to be used for material studies and applications was started in the last 10 years. In the framework of a national research project extended over the last 3 years, was ...
TiN and TiAlN coatings were deposited on CoCr alloy, 316L stainless steel, and Si substrates by c... more TiN and TiAlN coatings were deposited on CoCr alloy, 316L stainless steel, and Si substrates by cathodic arc method. Various ion bombardment conditions were obtained by different DC and pulsed bias voltages applied on the substrates. A comparative analysis of the coating characteristics for different substrate biasing conditions was performed.
The corrosion behavior of TiN coated 316L stainless steel in an artificial physiological solution... more The corrosion behavior of TiN coated 316L stainless steel in an artificial physiological solution was investigated by means of an electrochemical test. Two different PVD methods were used for film deposition: cathodic arc and reactive magnetron sputtering. The dependence of the corrosion resistance on the main deposition parameters (nitrogen pressure, substrate bias) was analyzed. For a better characterization of the investigated coatings, other characteristics, like elemental composition, phase composition, texture, microhardness, adhesion to the substrate were determined. The selection of biocompatible materials is based on their biocompatibility and their biofunctionality. The first characteristic refers to the implant effect on the surrounding tissue and the second one to its capability to assume the function of the replaced biologic system. In practice, both properties are closely interdependent and are connected to wear-corrosion resistance of the materials. If the implant rejection as a result of mechanical imperfections is relatively rare, most failures are caused by a lack of biocompatibility which is directly related to the corrosion resistance of the implant (1), (2). In order to find the most adequate materials to be used as implants in living tissue, many alloys have been developed, beginning with austenitic stainless steels (3). In general, the austenitic stainless steels 316 and 316L have good corrosion resistance and the additional alloying with molybdenum decreases their susceptibility to pitting corrosion. Nevertheless, in certain cases (in strongly stressed or nonoxigenated environments) stainless steels are affected by corrosion. Moreover, these types of steel have a low wear resistance. The performance of implants made of stainless steel could be improved if they were coated with thin films of materials offering protection against corrosion and wear. Among these coatings, TiN would be a suitable choice, due to its remarkable properties such as high microhardness, chemical inertness, high wear and abrasion resistance (4)-(6). The goal of this work was to investigate the corrosion behavior of TiN coated 316L stainless steel in artificial physiological solution. Two techniques were used for TiN deposition (cathodic arc method (c.a.m.) and reactive magnetron sputtering method (r.m.s.m.)), in order to select the most suitable system for preparation of anticorrosive coatings. For each method, the influence of the main deposition parameters (N2 pressure, substrate bias) on the corrosion resistance of the TiN films was examined. Additional information on the film characteristics was obtained by elastic recoil detection (ERD) and X-ray diffraction (XRD) analyses, microhardness and thickness measurements and adhesion tests.
TiOxNy coatings were investigated as possible candidates for ion diffusion barrier layers. The el... more TiOxNy coatings were investigated as possible candidates for ion diffusion barrier layers. The elemental and phase composition, texture, hardness, adhesion, and corrosion resistance of the coatings were analyzed. The ion release in Ringer solution for uncoated and coated samples were also determined. The film properties were found to significantly depend on the reactive gas composition (O2/N2 ratio). The coatings proved to enhance the corrosion protection and to reduce the ion release of the uncoated specimens.
Spectroscopic diagnostics, using intensified high speed CCD camera, was applied to study the arc ... more Spectroscopic diagnostics, using intensified high speed CCD camera, was applied to study the arc dynamics in low voltage circuit breakers, in vacuum and in air. Time-resolved emission spectroscopy of the vacuum arc plasma, generated during electrode separation, provided information about the interruption process. The investigations were focused on the partial unsuccessful interruption around current zero. Absorption spectroscopy, in a peculiar setup, was used in order to determine the metallic atoms densities in the interelectrode space of a low voltage circuit breaker, working in ambient air.
The thin titanium nitride films deposited on glass in a planar d.c. magnetron configuration have ... more The thin titanium nitride films deposited on glass in a planar d.c. magnetron configuration have been optically investigated. The influence of the nitrogen partial pressure, substrate bias and film thickness as deposition parameters on the transmission (Vis) and the reflectance (Vis, FIR) spectra of the samples was studied. The analysis of surface properties of TiN films was also made by spectroscopic ellipsometry for different deposition conditions. The data were compared with the similar spectrum of a gold evaporated film.
Nanocomposite Me–C–N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ... more Nanocomposite Me–C–N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ratios, were prepared by cathodic arc method using TiNb, TiZr and TiAl alloy cathodes in a CH4+N2 atmosphere. For comparison purposes, a-C–N:H films were also produced through evaporating a graphite cathode in a similar atmosphere. The films were characterized in terms of elemental and phase compositions, chemical
Uploads
Papers by Viorel Braic