Titanium nitride

One of the critical steps toward producing void-free and uniform bottom-up copper electroplating in high aspect-ratio (AR) through-silicon vias (TSVs) is the ability of the copper electrolyte to spontaneously flow through the entire depth of the via. This can be accomplished by reducing the concentration gradient of cupric ions from the via mouth to the via bottom by enhancing the wettability of the vias sidewalls. In this paper, we report on a new dry technique to enhance the hydrophilicity in high AR (∼15) TSVs as one of the key solutions to face the mass transport limitation. low pressure chemical vapor deposition silicon nitride and atomic layer deposition titanium nitride of composition SiN 0.95 and TiN 1.1 , respectively, are used as both barrier layers and wetting surfaces in these vias. Ammonia plasma immersion is used to treat silicon nitride. Xray photoelectron spectroscopy shows both a partial oxidation and grafting of hydrophilic components. Alternatively, a rapid flood ultraviolet exposure step in order to photocatalytically activate the surface and induce a partially oxidized titanium nitride is used to create a highly wettable interface with a

Surface coatings, like titanium nitride (TiN) and diamond-like carbon (DLC) coatings offer high wear resistance and low friction performance for a wide range of applications. By using new techniques like modelling and simulation, the coating performance under load can be estimated and thus provide valuable information for the coating design and for the use of coatings in different applications.

Reflection high-energy electron diffraction (RHEED) operated at high pressure has been used to monitor the initial growth of titanium nitride (TiN) thin films on single-crystal (100) MgO substrates by pulsed laser deposition (PLD). This is the first RHEED study where the growth of TiN films is produced by PLD directly from a TiN target. At the initial stage of the growth (average thickness ∼2.4 nm) the formation of islands is observed. During the continuous growth the islands merge into a smooth surface as indicated by the RHEED, atomic force microscopy and field emission scanning electron microscopy. These observations are in good agreement with the three-dimensional Volmer-Weber growth type, by which three-dimensional crystallites are formed and later cause a continuous surface roughening. This leads to an exponential decrease in the intensity of the specular spot in the RHEED pattern as well.

A study was undertaken to investigate the performance of P10 TiN coated carbide inserts in semi-finishing and finishing end milling of hardened AISI H13 tool steel (50 ± 3 HRC) at high cutting speed regime. The effects of cutting speed, feed rate, and depth of cut on the tool life were studied experimentally. For the tested range of milling conditions, the result shows that the tool life is highly affected by the feed rate and depth of cut. However, the tool life is not affected significantly by the cutting speed that is contrary to the findings of the previous researchers. This may be due to the fact that the main contributions to the tool failure were initiated by fracturing and cracking when high feed rate and depth of cut were used. Furthermore, in milling operation, the intermittent process produces fluctuated temperatures, and loading and unloading cutting forces lead to cracking and fracturing of cutting edges especially when higher cutting forces are produced. © 2004 Elsevier B.V. All rights reserved.

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Titanium nitride has excellent corrosion and wear resistance properties, and has been used as a hard coating material on titanium hip prostheses. Analysis of explants reveals that calcium phosphate phases grow spontaneously and stick strongly on TiN-coated hip prosthesis heads, indicating a degree of bioactivity of the implant surface which is absent in standard uncoated titanium implants. We investigate the mechanism of TiN oxidation using spectroscopic and first principles molecular dynamics techniques. We find that the deposition of Ca 2þ ions-which is the first step of calcium phosphate nucleation-is favoured by TiO x N y oxynitride surface phases. This is due to the presence of mixed-valence states of the surface Ti atoms which leads to localisation of negative charge on surface oxygens, promoting the adsorption of Ca 2þ ions. These results indicate that nitridation and controlled oxidation of titanium implant surfaces can promote the in vivo formation of bone-like material.

Titanium nitride (TiN) multilayer (7.5 Á/12 nm) structures with excellent conformity were produced by chemical vapor deposition from Ti[N(CH 3 ) 2 ] 4 (the so-called TDMAT) on a heated substrate with an additional N 2 /H 2 plasma treatment (PT) after deposition. They are well suited for deep submicron vias with aspect ratios of more than three. We apply time-of-flight secondary ion massspectroscopy, transmission electron microscopy, and Auger electron spectroscopy for a detailed characterization of morphology, structure and composition of the multilayers and analyze the barrier efficiency against Al diffusion. We demonstrate that low-energy primary beams and sample rotation applied during ion sputtering analysis significantly improves the depth resolution in elemental depth profiles and allows to characterize the effect of PTs more efficiently. The N 2 /H 2 PT introduces a strongly anisotropic layer modification including etching, densification, crystallization and compositional changes. The plasma is effective in removing process induced contamination of the TiN layers (O, C) up to a depth of up to 5 Á/8 nm, where the concentration is reduced by more than one order of magnitude. A minor influence is detected up to a depth of 10 nm, obviously mainly due to outdiffusion effects. The analysis of Al diffusion in TiN reveals a good diffusion resistance of the barrier up to 570 8C. #

Two experimental techniques including the bulge test and depth sensing nanoindentation measurements were used to describe mechanical properties of titanium nitride (TiNx) thin films in terms of their growth morphology. Thin layers of titanium nitride (t=400–700 nm) were deposited in a RF magnetron sputtering system on the Si(100) wafers containing a layer of low stress (LPCVD) silicon nitride. Variation of the Young’s modulus, hardness, and residual stresses of the TiNx films versus deposition parameters such as the substrate bias voltage and nitrogen partial pressure was investigated. It was found that, in particular, the tensile residual stress of the films first increases with the substrate bias to a maximum, then drops to zero and converts to the compressive stress, that grows again with the negative bias. At the same time, both modulus and hardness monotonously rise with the substrate bias without any abrupt changes. The nanoindentation data extracted from dynamically loading–unloading of TiN films converged to the bulge test measurements for compact coatings, but diverged from the bulge test data for porous coatings. The morphology of the films were observed using scanning electron microscopy and the relationships between microstructural evolution of columns and mechanical properties of coatings are discussed in terms of deposition parameters.

Reactive plasma spraying of titanium in a nitrogen-containing plasma gas allows the formation of hard titanium composite Ž . coatings reinforced by in situ formed titanium nitrides TiN and Ti N . In the present study, the formation of titanium nitrides 2 Ž . during the reactive spraying of titanium was studied by means of two different analysis techniques: X-ray diffraction XRD and Ž . X-ray photoelectron spectroscopy XPS . The diffusion and solidification sequence predicted by the Ti-N phase diagram was consistent with the experimental results. The nitrogen retained in the coating was found mainly as titanium nitrides and not as interstitial nitrogen in the titanium lattice. It is hypothesised that the formation and direct solidification of TiN occurs during the flight of the sprayed particles. The presence of solid TiN constrains the thermal contraction of titanium splats upon solidification. The observed cell distortion of the residual ␣-Ti is thus attributed to tensile stresses arising from the solidification process. ᮊ

Reactive plasma spraying of titanium in a nitrogen-containing plasma gas allows the formation of hard titanium composite Ž . coatings reinforced by in situ formed titanium nitrides TiN and Ti N . In the present study, the formation of titanium nitrides 2 Ž . during the reactive spraying of titanium was studied by means of two different analysis techniques: X-ray diffraction XRD and Ž . X-ray photoelectron spectroscopy XPS . The diffusion and solidification sequence predicted by the Ti-N phase diagram was consistent with the experimental results. The nitrogen retained in the coating was found mainly as titanium nitrides and not as interstitial nitrogen in the titanium lattice. It is hypothesised that the formation and direct solidification of TiN occurs during the flight of the sprayed particles. The presence of solid TiN constrains the thermal contraction of titanium splats upon solidification. The observed cell distortion of the residual ␣-Ti is thus attributed to tensile stresses arising from the solidification process. ᮊ

Di titanium nitride coatings were synthesized on commercial AISI 304 stainless steel using a Cathodic Arc Plasma Deposition (CAPD) technique. The effect of substrate bias voltage on the formation of coatings was studied keeping other parameters constant. The study revealed that 120 volts of substrate bias volt age is the most suitable for formation of Ti 2 N on the substrate. The thickness of the Ti 2 N coating was 0.70 to 0.80 μm for all the experiments. The hardness of the thin Ti 2 N coatings, determined by using Johnson and Hog mark relation was 2000 Hv. The structure of the coatings was studied by XRD. The surface roughness and tex ture was also studied which are important parameters for the given films. The case studies for high energy mag nets and fertilizer industry are also discussed to show the worthiness of the work for industrial applications.

This paper presents a plug-and-play module for wireless electroencephalogram (EEG) applications. The wireless module is composed by an electrode, processing electronics, a radio-frequency (RF) transceiver, and an associated antenna. The RF transceiver was fabricated in the UMC RF 0.18 m CMOS process, and operates in the 2.4-GHz ISM band. The receiver has a sensitivity of 60 dBm and a power consumption of 6.3 mW from a 1.8 V supply. The transmitter delivers an output power of 0 dBm with a power consumption of 11.2 mW, for a range of 10 m. It is also presented the electrical performance and comparison between different electrodes for EEG applications, namely sputtered titanium nitride (TiN) electrodes, standard sintered silver/silver chloride (Ag/AgCl) ring electrodes and sputtered iridium oxide (IrO 2 ) electrodes. The experimental results show a better performance of the sputtered IrO 2 electrodes compared with the standard sintered Ag/AgCl ring electrodes. These results promise a new opportunity for the application of a dry IrO 2 electrodes in wireless modules for using in a wearable EEG braincap. These wireless EEG modules will allow patients to wear a brain cap and maintain their mobility, while simultaneously having their electrical brain activity monitored.

Two kinds of reactively evaporated titanium nitilde films with columnar (/3o films) and fine-grained film structure (B+ films) have been examined as diffusion barriers, preventing the silicon diffusion in silicon devices. The silicon diffusion profiles have been investigated by 2 MeV 4He+ Rutherford backscattering spectrometry (RBS) after annealing at temperatures up to 900 ° C, in view of application of high-temperature processes. The diffusivity from 400 to 900 ° C: D (m 2 s -x) = 2.5 x 10 -18 exp[-31 kJ/mol/ (RT)] in B0 layers and D (m 2 s -1) = 3 x 10 -19 e x p [ -2 6 k J / mol/(RT) in B+ TiN layers. The diffusivities determined correspond to grain boundary diffusion, the difference being due to the different microstructure. The very low diffusivity of silicon in B+ TiN layer makes it an excellent high-temperature barrier preventing silicon diffusion.

Zn was electrochemically deposited onto square TiN electrodes with edge dimensions of 490μm and 40μm. These were fabricated by standard microfabrication techniques, which provide an extremely reproducible electrode for experimentation. Reliable constant-potential electrodeposition of Zn on the TiN was performed at −1.2V, just below the Zn/Zn2+ redox potential. At more negative potentials, the hydrogen evolution reaction on TiN interfered with

The mechanical properties of titanium nitride (TiN x ) thin films have been investigated using depth sensing nanoindentation tests. The effects of substrate temperature (T s ) and of substrate biasing (V b ) on the mechanical properties and the microstructure of the TiN x films were studied. T s and V b have strong effect on the film's microstructural characteristics such as density, grain size and orientation. It was found that deposition at high T s and V b promotes the growth of (002) oriented films with density close to the bulk density of stoichiometric TiN, indicating the absence of voids and the growth of stoichiometric TiN. The film hardness and elastic modulus were measured using the continuous stiffness measurements technique. It was found that there exists a direct correlation between the film's mechanical properties and microstructure. The films that exhibit the best mechanical performance are those grown along the (002) orientation and being denser and stoichiometric.

Graded layers and multilayers have been reported to improve surface properties of steel tools. Our study was aimed at defining the appropriate processing parameters for deposition of graded Al-AlN and AlN-TiN-TiAlN multilayers on silicon, glass, and M2 steel tools. The layers were deposited by r.f. reactive magnetron sputtering using dual cathode targets, Ti and Al. The ratio of nitrogen flow to nitrogen plus argon flow ( f N 2 /f (N 2 +Ar) ), r.f. power, and bias voltage (V B ) were used as the processing parameters. These parameters may be varied continuously, thus allowing the formation of a graded structure. The layers were characterized with regard to structure, composition, and mechanical properties using Fourier transform IR (FTIR) spectrometer, X-ray diffractometry, Auger electron spectroscopy microscope, Vickers microhardness tester, and scratch tester (testing adhesion). The reactive sputtered AlN layers displayed oriented (101 :1) or (0002) crystalline structure dependent on the gas pressure, while the graded Al-AlN layer had an oriented (0002) AlN structure and a randomly oriented Al structure with (0002) the highest peak. FTIR spectra of AlN thick layers showed sharp and intense absorbance bands at 1025 cm−1, 930 cm−1, and 544 cm−1. However, peaks related to thin films were seen to be broadened and shifted compared with those of thick films. The TiN and TiAlN layers displayed (111) oriented crystalline structures of d-TiN and high microhardness and adhesion characteristics. The relationship between the processing parameters and the structure of the layers formed is presented and discussed. may become dominant in multicomponent systems, e.g. 0257-8972/99/$ -see front matter

. The Astrid-2 mission has dual primary objectives. First, it is an orbiting instrument platform for studying auroral electrodynamics. Second, it is a technology demonstration of the feasibility of using micro-satellites for innovative space plasma physics research. The EMMA instrument, which we discuss in the present paper, is designed to provide simultaneous sampling of two electric and three magnetic field

In the present work, Ti and Ti-6Al-4V were PIRAC nitrided at the relatively low temperatures of 700-850°C. To obtain thicker TiN layers, 3 stage PIRAC based coating was applied: (1) PIRAC nitriding followed by (2) PIRAC titanizing followed by (3) additional PIRAC nitriding. The microstructure and phase composition of the obtained surface layers were characterized employing X-ray diffraction and scanning electron microscopy with chemical analysis (SEM/EDS). Bending test was employed to evaluate the coatings adhesion to the substrate. Lower PIRAC nitriding temperatures yielded smoother TiN coatings with a more gradual microhardness decrease from the surface to the bulk. All PIRAC TiN based coatings have excellent adhesion to substrate – no delamination of the coating in bending tests was observed. The best combination of microhardness and adhesion was obtained using 3 stage PIRAC process.

In this in vitro study, we investigated the influence of titanium nitride (TiN) treatments on the Staphylococcus aureus colonisation and biofilm formation on Ti6Al4V alloy at different times. The development of biofilm in static tests was carried out in a TSB culture medium at 37°C, for 12, 24, 48 and 72 h. Bacterial adhesion on nitrided titanium alloy was analysed by both epifluorescence microscopy and scanning electron microscopy. The results revealed that the number of attached bacteria, their viability, and distribution were different for nitrided alloys than for the control group (non-nitrided alloys).

The paper discusses microstructure, mechanical and physical testing with several examples of advanced coating systems. Another development for use with the plasma nitriding system is surface deposition after the nitriding treatment. This allows nitriding to be carried out in the plasma nitriding chamber followed by a surface deposition treatment, such as depositing titanium nitride. Samples were plasma nitrided at different thickness of plasma surface layers. TiN was deposited with classics BALZER PVD equipment. The other samples were produced with IBAD technology in DANFYSIK chamber. The properties and quality of ion beam-assisted deposition (IBAD) coatings depend on many process parameters, such as the ion energy, ion to atom arrival ratio, angle of ion incidence, pressure, temperature, etc. This is the reason why IBAD coatings must be planned very accurately. X-ray diffraction studies were undertaken in an attempt to determine the phases present, and perhaps an estimate of grain size from line broadening. The surface roughness was measured using stylus type (Talysurf Taylor Hobson) instruments. The coating morphology was evaluated (with SEM), using the well-known structure zone model of Thornton. The present coating method can produce dance structures, high hardness and the high-critical load values can be achieved. r

Monolithic TiN coatings deposited onto cemented carbide cutting tool inserts coated by chemical vapor deposition (CVD) or physical vapor deposition (PVD) methods, respectively, were subjected to pulsed intense electron beam treatments in the energy range 3 to 5 J·cm−2. The temperature profiles for this rapid thermal processing (RTP) covered the range between fusion of the cobalt binder in the carbide to surface fusion of the TiN coatings. The treatment caused extensive cracking in all coatings, removed the atomic level defects, vacancies and dislocations, and the residual stress in the PVD coatings, but caused little change in the CVD coatings. There was some nitorgen loss very close to the surface but no change in the stoichiometry of the bulk of the nitride. In contrast, no changes were found in the carbide substrate below the PVD coatings, but microscopic changes were found immediately below the surface in the carbide under the CVD coatings. Steel turning tests suggest that treatment of the PVD coatings at the lowest power used, 3 J·cm−2, reduced the flank wear by a factor of 2 but had no effect on any of the CVD coatings.

The attachment of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN) and modified hydroxyapatite (HA) films was studied. Direct current magnetron sputtering method was used to deposit various Ti and TiN films with similar smooth topography but different surface composition as investigated by using atomic force microscope and X-ray photoelectron spectroscope. Native oxidation was predominant in all the films, however, the nitrogen percentage varied from 2.6-14.1% and 3.1-19.3% in the surface of Ti and TiN films respectively. Fluorine and zinc modified HA films were prepared by solution gel method. Replacement of a percentage of OH − group by F and 3.2 at.% of Ca by Zn in hydroxyapatite was confirmed by Fourier transform infrared spectroscope and energy dispersive analysis using X-rays measurements respectively. All the film samples were sterilized by gamma radiation or pressurized steam prior to bacterial culture experiments. The bacterial culture was performed at anaerobic condition and the bacteria treated samples were examined by means of scanning electron microscope measurements. A few of the Ti films with typical surface stoichiometries of combinations of oxygen and nitrogen exhibited minimum bacterial attachment, and on the modified HA films relatively less attached bacteria were recorded. The TiN films did not show any inhibiting action against the attachment of the bacteria, where more number of bacteria were found attached on the TiN films independent of the surface chemical composition of the films.

Titanium nitride (TiN) thin films of different thickness were deposited by direct current (dc) magnetron sputtering under conditions of various N 2 concentrations (0.5-34%). The electrical, optical, structural, compositional and morphological properties of the films were studied and the results were discussed with respect to N 2 concentration and thickness of the films. At low N 2 concentration of 0.5% (of the total sputtering pressure 1.1 Pa), golden coloured stoichiometric TiN films were obtained and with increase in the N 2 concentration non-stoichiometric TiN x phases resulted. However, irrespective of the N 2 concentration, the TiN stoichiometry in the films increased with increase in the film thickness. In the surface of the films the presence of nitride (TiN), oxynitride (TiO x N y ) and oxide (TiO 2 ) phases were observed and the quantity of these phases varied with the N 2 concentration and thickness. The films of lower thickness were found to be amorphous and the crystallinity was observed in the films with increase in the thickness. The crystalline films showed reflections corresponding to the (1 1 1), (2 0 0) and (2 2 0) orientation of the cubic TiN and also features associated with TiN x phases. The transmission spectra of the films revealed the typical characteristics of the TiN films i.e. a narrow transmission band, however, the width varied with thickness, in the wavelength range of 300-600 nm and exhibited low transmission in the infrared region. The TiN films deposited at low N 2 concentration of 0.5% showed smooth and uniform morphology with densely packed crystallites. With increase in N 2 concentration various characteristics such as needle type crystallization, bubble precipitates and after bubble burst morphologies were observed in the films. However, at higher N 2 concentration conditions, uniformity developed in the films with increase in thickness.

Corrosion of solder pots and solder pot components in wave soldering equipment has been reduced with the introduction of corrosion resistant coatings and improved lead free solder alloys. The latest trends in protecting wave solder machine components from liquid metal corrosion by lead free solder alloys will be presented in order to provide guidelines for evaluating existing equipment as well as for purchasing new systems.

Titanium nitride films are prepared by Ti evaporation with simultaueous nitrogen ion beam irradiation on a martensitic stainless steel . In lids study, the influe , ices of the phase compositions, interplanar spacings of the lattice planes and crystal orientation on microhardness are investigated in relation to process parameters such as ion energy, ion current, substrate temperature, deposition rate and nitrogen pressure . It is recognized that the interplanar sp-irings of preferred lattice planes are related to the N/Ti ratios. The result, Show that the change in, r;icrt,hardness of titanium nitride films is dependent on the inerplanar spacings of these planes.

As an II-VI semiconductor, with wide bandgap and high exciton binding energy, zinc oxide has been favored for the new opto-electronic devices. One of the key issues for such applications is the integration of the zinc oxide onto silicon substrates. In this paper, we report a new integration methodology for depositing high quality zinc oxide thin films on silicon substrates. We have developed a novel epitaxial system for this purpose. An yttria stabilized zirconia (YSZ) buffer layer was used for depositing high quality, single crystalline zinc oxide films on Si (100) substrates. The heterostructure was developed with a pulsed laser deposition system. The results show that ZnO films grow epitaxially on YSZ buffered Si (100) substrates, with c-axis perpendicular to the substrate surface. High resolution image demonstrated that the interface between YSZ and ZnO is atomically smooth without any evidence of reaction. These zinc oxide films on Si (100), with YSZ buffer, showed excellent photoluminescence, evidenced with an extremely high exciton emission centered at 377 nm, at room temperature.

This paper presents a comparison of the performance characteristics of TiN (Titanium nitride) and ZrN (Zirconium nitride) coatings on split point drills. The objective of this work was to choose the better coating for machining tough materials like INCONEL. This leads to an increased productivity of drilling holes in certain components of environmental control systems and fuel control systems (in aerospace industry) made of tough materials like INCONEL. The comparison of the performance characteristics was based on the measurement of the mean values and dynamic fluctuations of the cutting force and the number of holes drilled under the same optimum machining conditions. The measurements were carried out using two specially designed piezoelectric dynamometers. The dynamometer was calibrated from static and dynamic outputs and techniques were employed for increasing the measuring accuracy and reducing the cross interference by obtaining the elements of the tranfer function. Power spectrum plots of the drift force, axial force and torque were obtained so that these plots may be used as a signature. Results show that the ZrN coating is better than the TiN coating because (a) the mean values of the axialforce, drift force and torque are smaller, thus improving the roundness, (b) the dynamic flutuations of the forces and torque about the mean are smaller thus improving the surface quality of the holes produced, (c) the number of holes before the failure of the drill is about three times more for a ZrN coated split point drill as compared to a TiN coated drill.

Titanium is a good material for dental and orthopaedic implants, but many authors reported that it releases ions into the surrounding tissues and into the serum. Titanium nitride has good mechanical properties and chemical inertless and may be employed as an implant coating material. In this experiment, pure titanium and SiO, coated with TiN implants were inserted in the tibia of rats. After thirty days, the bones were taken and examined by a proton microprobe. TiN-coated implants showed a lower ion release into the bone compared with pure titanium. This suggests that TiN may be a good coating for endosseous implants.

Titanium oxynitride compounds exhibit interesting properties for applications in fields ranging from protectiveydecorative coatings to solar panels. The properties of TiN O are related to the oxideynitride ratio and can be tailored playing with this ratio. x y In this work we studied the influence of substrate bias voltage and flow rate of reactive gases (a mixture of N and O ) on the 2 2

The thermal nitridation of titania powder (anatase and P25) by reaction with ammonia has been investigated by in-situ reaction studies and ex-situ characterizations using X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and X-ray ...

In the field of engineering materials, the study of titanium nitride (TIN) films has attracted great interest because of its unique combination of properties. This paper is concerned with the implantation of nitrogen or carbon ions into TiN films to evaluate and obtain the optimum conditions for increased tribological resistance. A commercially available titanium nitride coating produced by ion plating, of approximately 3.5 pm thickness, was treated by implantation of nitrogen or carbon ions at energies of 100 and 75 keV, respectively. The dose range was between 5 x 1016 and 1 x 10" ions cm-'.

The paper reports the synthesis of nano-crystalline ceramics like titanium dioxide and titanium nitride using a plasma chemical experimental reactor powered by a multi-segment (cascaded) arc plasma torch. The precursor-laden plasma beam emerging from the torch anode section expands supersonically through a converging nozzle to a low-pressure collection chamber. This results in a uniform and controlled gas dynamic quenching ensuring rapid synthesis of pure, un-coagulated free-flowing particles with a narrow size distribution. Simple Langmuir probes and calorimetric energy balance methods are used for plasma and reactor characterization, while X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman and X-ray photoelectron spectroscopy (XPS) techniques have been used for product analysis. It is shown that size distribution of both the product particles is comparatively narrower than that found in most thermal plasma assisted laboratory synthesis studies. The expansion process was observed to produce a non-equilibrium electron population, which could charge up the particles after nucleation and hence could curb unwanted coagulation.

Polycrystalline, smooth, and hard thin films of TiN are successfully deposited on AISI-304 substrates using a 1.5 kJ Mather-type dense plasma focus device charged at 18 kV. The purpose of this study is to investigate the structural and mechanical properties of the TiN thin films in terms of ion dose and substrate position to establish the optimum deposition conditions. The films are analyzed using XRD, SEM, electron microprobe and micro-hardness testing. XRD confirms the deposition of a polycrystalline TiN thin film together with the emergence of an iron chromium nickel phase. The surface hardness-in comparison to the unexposed substrate-is found to increase up to 250% when a film is deposited using 30 focus shots at an axial distance of 6 cm. SEM micrographs show that the quality of the film is improved with an increasing number of focus shots. The constituent elements of the film are also confirmed by electron microprobe.

We have shown that the magnetic properties of nanoparticles may be tuned from superparamagnetic to ferromagnetic by changing the substrate or thin film matrix in which they are embedded. Nickel nanoparticles were embedded into alumina, titanium nitride, and cerium oxide matrices on both silicon and sapphire substrates via pulsed laser deposition. The laser ablation time on the nickel target was kept constant. Only nickel nanoparticles in cerium oxide showed characteristics of ferromagnetism ͑room temperature coercivity and remanence͒. Ni nanoparticles, in either alumina or titanium nitride, possessed blocking temperatures below 200 K. Detailed scanning transmission electron microscopy analysis has been conducted on the samples embedded into cerium oxide on both substrates and related to the magnetic data.

Laser remelted tracks were produced on the surface of titanium nitride (TiN) coated titanium. In order to produce different microstructures, seven conditions were tested by varying laser power and speed. The remelted tracks were then evaluated from the surface mechanics point of view through microhardness and sliding friction tests. Samples produced in conditions where laser speed varied from 5 to 100 mm/s presented high TiN surface content and increased hardness. In the velocity range of 20-100 mm/s, the remelted tracks presented high resistance to wear. The dendrites tend to coalescence when the scanning velocity is below 2 mm/s. The low velocity experiments (1 and 2 mm/s) presented eutectoid decomposition of the TiN/Ti phases creating a Ti 2 N phase at boundaries, which decreased the hardness and the wear resistance at surface. The results indicated that the best condition in terms of surface properties is obtained when the scanning rate is 5 mm/s and the laser power is 500 W. D

We report the synthesis of titanium nitride coating on a titanium substrate by utilizing energetic nitrogen ions emitted from a 2.3 kJ dense plasma focus device for 30 focus shots. The number of nitrogen ions transferred to the sample by a single ion pulse of about 140 ns duration in the energy interval (40-600 keV) is about 1.09 Â 10 12 with a mean energy per ion of 58 keV. The corresponding energy flux delivered to the titanium surface is estimated to be 6.17 Â 10 14 keV cm À3 ns À1 leading to a transient temperature rise of the top layer of about 5400 K which helps layer growth. The coating is investigated on the basis of its morphological, compositional and hardness properties. X-ray diffraction analysis of the sample reveals the formation of a nanocrystalline titanium nitride coating having (1 1 1) and (2 0 0) plane reflections with an average crystallite size of 40 nm. The compressive residual stresses in the nitride coating have been evaluated to be 2.80 GPa and 6.81 GPa corresponding to (1 1 1) and (2 0 0) plane orientations. A complete restructuring of the manually polished titanium substrate has been observed with appearance of nanosized multidimensional granular surface morphologies. The thickness of the nitride coating is about 1 lm, whereas the coating has a nitrogen content of 35.35 at.% and 13.78 ± 3.57 wt.% and a surface hardness of 8.19 GPa.

In this work, an ultra-high vacuum reactive evaporation procedure has been tested and optimized for the growth of TiN thin films, throwing very good results both in composition of the TiN layers and secondary emission yield values and performance. Stoichiometry and composition are analyzed by means of X-ray photoemission spectroscopy which, together with the secondary electron emission measurements, allow us determine the appropriate growth parameters in order to obtain in a reproducible manner optimum results towards the multipactor effect suppression. After refining the growth on test layers, several waveguide pieces, specially designed and constructed for testing multipactor level (maximum RF power attainable without multipactor discharge), have been coated with TiN films following those optimized growth conditions. r

The production of biosurfactant by Bacillus subtilis LSFM-05 was carried out using raw glycerol, obtained from a vegetable oil biodiesel plant in Brazil, as the sole carbon source. Production of the biosurfactant was carried out in a 15-L bench-top fermentor and the surfactant was obtained from the foam produced. The crude surfactant was purified by silica gel column chromatography with a yield of 230 mg of the purified biosurfactant per liter of foam. TLC, IR spectroscopy, 1 H and 13 C NMR and Fourier transform ion cyclotron resonance mass spectrometry with electrospray ionization (ESI-FTMS) were used to characterize the purified surfactant. The isolated surfactant was identified as a surfactin lipopeptide. MS/MS data identified the amino acid sequence as GluOMe-Leu-Leu-Asp-Val-Leu-Leu and showed that the fatty acid moiety contained 14 carbons in iso, anteiso or normal configurations. The critical micelle concentration of the C 14 /Leu 7 surfactin was 70 M, with emulsification efficiency after 24 h (E 24 ) of 67.6% against crude oil. Raw glycerol represents an abundant and renewable carbon source and provides an opportunity for reducing the cost of biosurfactant production and may add value to biodiesel production by creating new commercial applications for this by-product.

New contact fill integration schemes were developed for high aspect ratio Gb DRAM contact metallization. Integration schemes for both tungsten-plug contacts and aluminum-plug contacts were studied. For tungsten-plug contacts, various types of titanium liners and Ž . titanium nitride barriers were investigated and evaluated. These included collimated PVD physical vapor deposition titanium, ion metal Ž . Ž . Ž . plasma IMP titanium, and CVD chemical vapor deposition titanium liners; plasma enhanced CVD PECVD titanium nitride and Ž . Ž . plasma enhanced MOCVD ECVD titanium nitride barriers. The electrical results of 0.3 mm, 5:1 aspect ratio AR contact structures processed with a TiCl -based CVD titanium liner and plasma enhanced CVD titanium nitride barrier show the lowest and the most tightly 4 distributed contact parametrics. This is attributed to the conformal nature of the CVD process. In addition, the high titanium-deposition temperature, which leads to a simultaneous titanium silicide formation during the CVD titanium deposition process, may also have attribution to the low contact resistance and diode leakage obtained. In the case of aluminum-plug contacts, two different types of Ž . titanium nitride barriers ECVD titanium nitride vs. silane-treated MOCVD titanium nitride were evaluated and both showed comparable contact parametrics. q 1998 Elsevier Science S.A. All rights reserved.

... The effect of thermal treatment on the structure, optical and electrical properties of amorphous titanium nitride thin films. Adam Tarniowy a , Ryszard Mania b and Mieczyslaw Rekas c , *. a R&D Centre of Rubber and Vinyl Plastics, Oswiecim 32-600, Poland. ...

Irradiation of 1 in 2,3-dimethyl-2-butene through Pyrex with a 450-W Hanovia medium-pressure mercury arc led to four products in 60% yield. Intramolecular insertion gave 4, which is the first compound reported that contains a two-carbon carbon-to-boron bridge.8 Addition to the double bond gives 5, and formal insertion into an allylic carbon-hydrogen bond produces 6. Most unusual is the formation of 1,2,3-trimethyl-o-carborane (7), a major product and the apparent result of a double abstraction by carbene 2.9 I \ 1 c 4, 8% 5, 25% hv 6, 3av0 7, 29% The substantial formation of 7 is unusual, and a likely origin is double abstraction of hydrogen by triplet 2. Compound 4 does not give 7 either photochemically or on heating at the temperature of the photolysis of 1 (ca. 35 "C). As 7 is formed in solution, there is no reason to suspect rearrangements of "hot" molecules. However, analysis of the products of reaction with cis-and trans-2-butene shows that the cycloaddition reaction is largely stereospecific. This indicates substantial singlet reactivity. In these reactions, 4 and products of carbon-hydrogen insertion are still formed, and compound 7 remains a major product.'0 The most economical explanation is that both spin states of carbene are present, with the singlet leading to most of the cyclopropanes and the triplet to most of the products of hydrogen abstraction as well as, presumably, the small amounts of cyclopropanes formed with loss of the stereochemistry present in the original olefins.

A strategy used to reduce wear of the ultra high molecular weight polyethylene (UHMWPE) component of orthopedic joint implants has been to coat the metallic part with a hard ceramic layer. The advantage of this procedure is to reduce both wear and ion release of the metal while keeping a high mechanical resistance. In the present study, the performance of three titanium nitride coatings: TiN, TiNbN, and TiCN for biomedical applications was assessed in terms of their surface properties and cytotoxicity. The morphology, chemical composition, and wettability were determined through atomic force microscopy (AFM) imaging, X-ray photoelectron spectroscopy (XPS) and contact angle measurement, respectively. The tribological behaviour of the coatings rubbing against UHMWPE in lubricated conditions was investigated using a pin-on-disk apparatus. Albumin adsorption on the three coatings was studied with a quartz crystal microbalance with dissipation (QCM-D) and AFM scratching. Cytotoxicity was determined both in direct or indirect contact of the cells with the coating materials. The results demonstrate that the three coatings have similar surface properties and are not cytotoxic. TiNbN seems to have the best tribological performance in the presence of albumin, although albumin adsorption is slightly higher on TiN.

The room temperature oxidation process of thin TiN x ®lms, grown by DC reactive magnetron sputtering, was studied by in-situ and real time spectroscopic ellipsometry, X-ray re¯ectivity, Auger electron spectroscopy, X-ray photoelectron spectroscopy and stress measurements. The ®lms were deposited at various negative bias voltages (V b) in order to vary the TiN x stoichiometry and then exposed to several gases and to air at room temperature. The oxidation rate was found to depend strongly on V b and thus on ®lm stoichiometry. Fast oxidation was observed in ®lms deposited at low uV b u, that contain nitrogen which is weakly bonded to Ti and can be easily replaced by oxygen. At high uV b u values (above 2 80 V) stoichiometric TiN ®lms were developed, that were stable and not prone to oxidation. The results showed that oxidation takes place in the bulk of the ®lm and can proceed up to about 10% transformation of titanium nitride into titanium oxide. The fastest step in the ®lm oxidation mechanism is diffusion of oxygen along the columnar grain boundary structure, followed by the reaction of oxygen with the weakly bonded TiN. The results suggest that the oxidation process proceeds with different stages involving formation of TiON, followed by a slow stage of TiO 2 formation. These microstructural changes are consistent with the evolution of compressive stresses in the ®lms and the increase in ®lm density and thickness and the decrease in surface roughness as determined by X-ray re¯ectivity.

This paper presents investigation results of the in¯uence of substrate type made from the W±Mo±V Si high-speed steels with addition of Nb or Ti, or else from the Mo±V±Co Si steel with the economically selected chemical composition, and from the sintered steels of the ASP 23 and ASP 30 types, on structure and properties of the hard, wear resistant, TiN, titanium nitride, and Ti(C,N), titanium carbonitride coatings, put down in the PVD process. It was demonstrated that the high-speed steels containing 9±11% of tungsten, 2% of molybdenum, 0.7% of silicon, in which vanadium was partially substituted by 0.5% of niobium or 0.3% of titanium, covered with the investigated coatings in the PVD process, demonstrate properties comparable to those obtained on the sintered high-speed steels of the ASP 23 and ASP 30 types. It was found out that the investigated TiN and Ti(C,N) coatings display the columnar structure with the clear axial texture {1 1 1}, with the solidi®ed titanium drops deposited directly onto the substrate or coating layers developed earlier, and also with pits developed by falling out by some of these drops. The TiN and Ti(C,N) coatings display a good adhesion to the substrates from the investigated high-speed steels, and it is not only the adhesion deciding this but also the diffusion or ion implantation connected mix of elements in the transition zone between the coating and its substrate. The Ti(C,N) coatings display double erosion resistance compared to the TiN ones. The erosion resistance grows along with increasing of the coating hardness, whereas neither the critical load value in the adhesion test, nor the chemical composition do not have any signi®cant effect. This makes it possible to exploit in practice high-speed steels with the relatively low concentration of the alloying elements instead of the high-alloy cobalt steels, provided the substrate's heat treatment is made so that it ensures its maximum secondary hardness. Moreover, a new methodology was developed for evaluation of the erosion resistance of materials coated in the PVD process, employing the computer image analysis on the scanning electron microscope.

Titanium nitride has long been used for its favourable mechanical and chemical properties and it has been demonstrated that monocrystallinity in thin films enhances these properties. While the synthesis of monocrystalline thin films is well documented, common synthesis processes for titanium nitride nanoparticles yield only polycrystalline, spherically shaped powders. The process presented here allows for the synthesis of monocrystalline, cube-shaped nanoparticles by means of a dual plasma process. Pulsed electric arc erosion of a Ti cathode in a N-rich atmosphere produced by a radio-frequency discharge is used for the synthesis of the TiN nanoparticles. Electron microscopy revealed the cubic morphology of the synthesized powders and electron diffraction patterning confirmed the crystalline structure of the TiN nanoparticles.