Nitrogen Partial Pressure Research Articles

Microstructure and thermal stability of Mo-(Ag)-N coatings with high nitrogen content

The interplay between the chemical composition and the microstructure of nitrogen-rich Mo-(Ag)-N coatings deposited by reactive magnetron sputtering was investigated using a combination of wavelength-dispersive X-ray spectroscopy, glancing-angle X-ray diffraction and transmission electron microscopy with high resolution. It was proven that the microstructure of the coatings, in particular the amount of hexagonal and cubic molybdenum nitrides, can be controlled by the nitrogen partial pressure in the deposition apparatus. In the as-deposited coatings, a metastable nitrogen-rich cubic phase of molybdenum nitride was detected, which decomposed into the thermodynamically stable cubic Mo2N and hexagonal MoN upon annealing at 600 °C. The mechanisms stabilizing the metastable cubic phase are discussed. Silver is only marginally soluble in the molybdenum nitrides, thus its addition leads mainly to the interruption of the growth of the Mo-N crystallites and to the grain refinement in the Mo-Ag-N coatings. The small amount of silver, which is incorporated into the crystal structure of the molybdenum nitrides, affects predominantly the thermal stability of the metastable cubic phase.

Reactive sputter deposition of CoCrCuFeNi in nitrogen/argon mixtures

Thin films of (CoCrCuFeNi)Nx were deposited by direct current reactive magnetron sputtering. Two different targets were used. Thin films deposited from a solid near-equimolar target showed a Cu excess with segregation of Cu in the film resulting in the formation of a nanocomposite film. It was also not possible to reach fully stoichiometric nitride thin films with this target. To overcome this problem, a powder target with adjusted composition was used in a second series of experiments. As derived from longitudinal and transversal sound velocity measurements, a transition from the metallic face-centred cubic lattice to the nitride B1 (NaCl) structure is observed. The observed transition corresponds with the process change from the metallic regime at low nitrogen partial pressure to the poisoned regime at high nitrogen partial pressure. TEM measurements show a typical zone T growth with a strong (100) texture in the nitride regime, and reveal a mixing of the constituent metals at the nanometer scale. This study demonstrates that the constituent metals do not form binary nitrides, but a complex nitride is formed.

Nitridated Ru/B4C multilayer mirrors with improved interface structure, zero stress, and enhanced hard X-ray reflectance.

Ru/B4C multilayer mirrors are used for hard X-ray monochromators with moderate spectral resolution and high integral flux. To overcome the problem of large compressive stress inherent in Ru/B4C multilayers, a reactive sputtering technique using a mixture working gas of argon and nitrogen with different partial pressures was tested, and the fabricated multilayers had a period of 3 nm. The intrinsic stress was essentially reduced after nitridation and relaxed to zero value at approximately 15% partial pressure of nitrogen in the working gas. Interface roughness was slightly increased which can be caused by the polycrystalline structure inside the nitridated samples. More importantly, the nitridated multilayers showed an enhanced reflectance (67% at 8.04 keV photon energy) as compared with the one fabricated with pure Ar (54%). The structure analysis with transmission electron microscopy and X-ray photoelectron spectroscopy demonstrated that nitrogen incorporated into a multilayer structure was mostly located in the B4C layers forming BN compounds, which suppressed the diffusion of boron, stabilized the interfaces and enhanced the reflectance.

Research on Nitrogen Solubility of Fe–Cr–Mn–V–N System Alloys in Liquid and Solid Phases

In this paper, the thermodynamic model of nitrogen solubility in vanadium nitrogen microalloyed high strength weathering steels of Fe–Cr–Mn–V–N system, according to Hillert’s model for Gibbs energy of its various phases, was established and validated. In the model, the effect of the nitrogen partial pressure on the activity coefficient and the lattice structure characteristics of the vanadium nitrogen precipitated phase were considered. It would be of guiding significance for the design and smelting of Fe–Cr–Mn–V–N system alloys. Based on the established model, the nitrogen contents in $$\delta$$ , $$\gamma$$ , $$\alpha$$ phase and liquid were calculated as a function of the temperature for Fe–Cr–Mn–V–N system alloys. The results show that: first, the maximum solubility of nitrogen in the solidification process is obviously affected by the phase transition when there is a sudden change in the solubility of nitrogen at the phase transition point. The maximum nitrogen solubility of the molten steel in the delta phase region determines whether nitrogen bubbles are formed during the solidification process. The nitrogen solubility is lowest in the solid–liquid region (about 1673 K). Secondly, the increase of Cr and Mn content is beneficial to improve nitrogen solubility in liquid and solid phases. However, the increase of V content mainly affects the nitrogen solubility in the solid phase because the nitrogen in this temperature range is precipitated in the form of vanadium nitride, as the second phase plays a role in strengthening. In addition, the alloying element Mn has a significant effect on nitrogen solubility since the Mn element is the promoting element of austenitic formation. During the solidification process, the delta ferrite region gradually reduces and may disappear with increasing Mn content. Therefore, increasing the Mn content of the alloy system in the design of alloy composition, can reduce the precipitation trend of the nitrogen during the solidification process, which can effectively avoid bubble formation in high nitrogen weathering steels. Lastly, with the increase in the nitrogen partial pressure, the solubility of nitrogen increases during the liquid and solid phases.

Neutralization processes of atomic/molecular deuterium ions assisted by ND3 in low density D2-N2 plasmas

The formation mechanisms of ND3+ and ND4+ are investigated in weakly ionized nitrogen-hydrogen plasmas with electron densities ne ∼ 1016 m−3 and electron temperatures Te ∼ 3 eV. The plasmas are created by an inductively coupled RF (13.56 MHz) discharge of 500 W at the total pressure of 10 mTorr in the nitrogen partial pressure ranging from 0.02 to 2.9 mTorr. The ion density fractions are measured by an electrostatic quadrupole plasma analyzer, which is a combination of ion energy analyzer and mass spectrometer, after calibration with neutral gases. A zero-dimensional rate equation model, sometimes called a global model, is used to understand the source and loss processes of each ion and neutral species in the plasma. The ion density fractions calculated by the model show qualitatively good agreement with the experimental results. Model calculations suggest that ND3+ and ND4+ generation is dominated by electron or D+ exchange reactions of deuterium atomic/molecular ions with ND3. These processes are thought to play an important role in the recombination process of D plasma with ammonia formed in the N2 seeded divertor region.

Oxygen exposures at NASA’s Neutral Buoyancy Lab: a 20-year experience

Astronauts training for extravehicular activity (EVA) operations can spend many hours submerged underwater in a pressurized suit, called an extravehicular mobility unit (EMU), exposed to pressures exceeding 2 atmospheres absolute (ATA). To minimize the risk of decompression sickness (DCS) a 46% nitrox mixture is used. This limits the nitrogen partial pressure, decreasing the risk of DCS. The trade-off with using a 46% nitrox mixture is the increased potential for oxygen toxicity, which can lead to severe neurologic symptoms including seizures. Suited runs, which typically expose astronauts of 0.9-1.1 ATA for longer than six hours, routinely exceed the recommendation for central nervous system oxygen toxicity limits (CNSOTL) published by the National Oceanic and Atmospheric Administration (NOAA). Fortunately, in over 50,000 hours of suited training dives spanning 20 years of EVA training operations at NASA's Neutral Buoyancy Laboratory (NBL) there has never been an occurrence of oxygen toxicity. This lends support to anecdotal sentiment among certain members of the hyperbaric community that the NOAA CNSOTL recommendations might be overly conservative, at least for the oxygen pressure and time regime in which NBL operates. The NOAA CNSOTL recommendations are the result of expert consensus with a focus on safety and do not necessarily reflect rigorous experimental evidence. The data from the NBL suited dive operations provide a foundation of evidence that can help inform the expert discussion on dive-related neurologic oxygen toxicity performance and overnight recovery in young, healthy males.

Surface phase diagrams of titanium in Oxygen, Nitrogen and Hydrogen environments: A first principles analysis

Density functional theory and ab initio thermodynamics studies are performed to investigate the interaction of oxygen, nitrogen and hydrogen molecules with hexagonal close packed Ti (0001) surfaces. The system is modeled as a slab where the concentration of the adsorbed atoms is systematically increased and the most favorable configuration is determined based on total energy comparisons. Varying tendencies are observed for the ground state structures of oxygen, nitrogen and hydrogen adsorption. Oxygen and hydrogen atoms are found to be adsorbed on the surface with increasing concentration and tend to migrate to interior layer only after surface saturation. However, nitrogen prefers to migrate into the interior layers. For all elements, the favorable position in the interior layers is the octahedral interstitial site. Taking into account the partial pressure of oxygen, nitrogen and hydrogen and the effect of temperature, we develop surface phase diagrams that display stable surface configurations. Our studies provide an atomic insight into the structure of the surface scale, passivation effects, and surface tension of Ti for advanced powder manufacturing processes and applications in catalysis.

Structure, phase evolution, and mechanical properties of DC, pulsed DC, and high power impulse magnetron sputtered Ta–N films

The microstructural development of reactively sputter-deposited tantalum nitride thin films is investigated as a function of the N2-to-total-pressure ratio (pN2/pT) and the operating mode of the metallic tantalum cathode; by direct current magnetron sputtering (DCMS), pulsed DCMS, and high power impulse magnetron sputtering (HiPIMS). For all sputtering modes investigated, the phase evolution of the Ta-N films strongly depends on the nitrogen partial pressure, pN2, used when keeping the total pressure, pT, constant at 0.3 or 0.6 Pa. The major crystalline phases identified, with increasing the pN2/pT-ratio, are α-Ta, orthorhombic o-Ta4N, hexagonal close packed (hcp) γ-Ta2N, face-centred cubic δ-TaN, and hcp ε-TaN. Their development is basically determined by the N2 partial pressure present. The deposition rate decreases slowest with increasing pN2 for the HiPIMS mode and fastest for the DCMS mode. The coatings with a dominating γ-Ta2N phase (which could be obtained for pN2 between 0.08 and 0.15 Pa) exhibit the highest hardness with 38.2 ± 4.6 GPa (HiPIMS), 38.0 ± 2.3 GPa (pulsed DCMS), and 40.0 ± 3.8 GPa (DCMS) among all samples studied. Higher pN2 lead to the formation of δ- and ε-TaN phases and a reduction in hardness. Especially, the ε-TaN rich coatings are comparably soft with only ~20 GPa.Based on our results we can conclude that coatings dominated by Ta-rich o-Ta4N or γ-Ta2N phases exhibit the most favourable mechanical properties, according to which the most important pN2-range is between 0.04 and 0.15 Pa, as for higher N2 partial pressures the films undergo a transformation from γ-Ta2N (plus o-Ta4N) into mixed δ- and ε-TaN.

Evolution of atmospheric xenon and other noble gases inferred from Archean to Paleoproterozoic rocks

We have analyzed ancient atmospheric gases trapped in fluid inclusions contained in minerals of Archean (3.3 Ga) to Paleozoic (404 Ma) rocks in an attempt to document the evolution of the elemental composition and isotopic signature of the atmosphere with time. Doing so, we aimed at understanding how physical and chemical processes acted over geological time to shape the modern atmosphere.Modern atmospheric xenon is enriched in heavy isotopes by 30–40‰ u−1 relative to Solar or Chondritic xenon. Previous studies demonstrated that, 3.3 Ga ago, atmospheric xenon was isotopically fractionated (enriched in the light isotopes) relative to the modern atmosphere, by 12.9 ± 1.2 (1σ) ‰ u−1, whereas krypton was isotopically identical to modern atmospheric Kr. Details about the specific and progressive isotopic fractionation of Xe during the Archean, originally proposed by Pujol et al. (2011), are now well established by this work. Xe isotope fractionation has evolved from 21‰ u−1 at 3.5 Ga to 12.9‰ u−1 at 3.3 Ga. The current dataset provides some evidence for stabilization of the Xe fractionation between 3.3 and 2.7 Ga. However, further studies will be needed to confirm this observation. After 2.7 Ga, the composition kept evolving and reach the modern-like atmospheric Xe composition at around 2.1 Ga ago.Xenon may be the second atmospheric element, after sulfur, to show a secular isotope evolution during the Archean that ended shortly after the Archean-Proterozoic transition. Fractionation of xenon indicates that xenon escaped from Earth, probably as an ion, and that Xe escape stopped when the atmosphere became oxygen-rich. We speculate that the Xe escape was enabled by a vigorous hydrogen escape on the early anoxic Earth. Organic hazes, scavenging isotopically heavy Xe, could also have played a role in the evolution of atmospheric Xe.For 3.3 Ga-old samples, Ar-N2 correlations are consistent with a partial pressure of nitrogen (pN2) in the Archean atmosphere similar to, or lower than, the modern one, thus requiring other processes than a high pN2 to keep the Earth's surface warm despite a fainter Sun. The nitrogen isotope composition of the atmosphere at 3.3 Ga was already modern-like, attesting to inefficient nitrogen escape to space since that time.

Effects of Nitrogen Partial Pressure Ratio and Anneal Temperature on the Properties of Al–N Co-Doped ZnO Thin Films

The authors report the conversion of conduction type from n-type to p-type in the Al–N co-doped ZnO thin films by using thermal annealing treatment under argon atmosphere. The samples were deposited on fused silica by radio frequency magnetron sputtering. X-ray diffraction measurements showed that ZnO thin films have (002)-preferred orientation and the lattice constant decreases with the increase of nitrogen partial pressure. The average optical transmittance of these films is over 80%. The hole density is around 1.58 × 1017 cm−3 with an annealing temperature of 700°C. After exposing the samples in air for 1 year, the conduction type remains p-type with only a slight decrease of hole density, which indicates that the p-type ZnO with Al–N co-dopants has good electrical stability.

Formation of Nitrogen Bubbles During Solidification of Duplex Stainless Steels

The nucleation and growth of nitrogen bubbles for duplex stainless steels are of great significance for the formation mechanism of bubbles during solidification. In the current study, numerical method and theoretical analysis of formula derivation were used to study the formation of nitrogen bubbles during solidification. The critical sizes of the bubble for homogeneous nucleation and heterogeneous nucleation at the solid–liquid interface during solidification were derived theoretically by the classical nucleation theory. The results show that the calculated values for the solubility of nitrogen in duplex stainless steel are in good agreement with the experimental values which are quoted by references: for example, when the temperature T = 1823 K and the nitrogen partial pressure $$ P_{{N_{2} }} = 40P^{\varTheta } , $$ the calculated value (0.8042 wt pct) for the solubility of Fe-12Cr alloy nitrogen in molten steel is close to the experimental value (0.780 wt pct). Moreover, the critical radii for homogeneous nucleation and heterogeneous nucleation are identical during solidification. On the one hand, with the increasing temperature or the melt depth, the critical nucleation radius of bubbles at the solid–liquid interface increases, but the bubble growth rate decreases. On the other hand, with the decreasing initial content of nitrogen or the cooling rate, the critical nucleation radius of bubbles at the solid–liquid interface increases, but the bubble growth rate decreases. Furthermore, when the melt depth is greater than the critical depth, which is determined by the technological conditions, the change in the Gibbs free energy for the nucleation is not conducive enough to form new bubbles.

Effect of Solidification Pressure on Thermodynamic and Kinetic Parameters of 19Cr14Mn4Mo0.9N High Nitrogen Steel

The influence of solidification pressure on the thermodynamic and kinetic parameters of 19Cr14Mn4Mo0.9N high nitrogen steel is clarified by Thermo‐Calc/DICTRA software, including phase diagram, solidification mode, liquidus/solidus temperature, nitrogen solubility, partition coefficient, diffusion coefficient, driving force for nucleation, and diffusion coefficient. On this basis, the effect of pressure on critical nucleation radius and nucleation rate is also revealed. In the calculated vertical sections of 19Cr14Mn4Mo‐xN alloy phase diagram, δ single‐phase region decreases, both γ single‐phase region and three‐phase region L + δ + γ increase with increasing pressure. Additionally, the reaction mode of solidification transition gradually turns from peritectic to eutectic reaction, and the solidification mode changes from FA to A mode. Increasing the partial pressure of nitrogen can suppress the formation of ferrite trap and increase nitrogen solubility. Meanwhile, the partition coefficients of C, N, Cr, and Si increase, that of Mn and Mo decreases, resulting in decrease of C, N, and Cr microsegregation and improvement of Si, Mn, and Mo microsegregation. Pressurization has a small impact on diffusion coefficients, but it obviously promote the driving force for produced phase (δ and γ) nucleation, this lead to the decrease of critical nucleation radius, improvement of nucleation rate, and grain refinement of 19Cr14Mn4Mo0.9N high nitrogen steel.

Effect of low temperature baking in nitrogen on the performance of a niobium superconducting radio frequency cavity

We report the rf performance of a single-cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of 120-160 {\deg}C with a nitrogen partial pressure of ~25 mTorr. This increase in quality factor as well as the Q-rise phenomenon (anti-Q-slope) is similar to those previously obtained with high temperature nitrogen doping as well as titanium doping. In this study, a cavity N2-treated at 120 {\deg}C and at140 {\deg}C, showed no degradation in accelerating gradient, however the accelerating gradient was degraded by 25 with a 160 {\deg}C N2 treatment. Sample coupons treated in the same conditions as the cavity were analyzed by scanning electron microscope, x-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a complex surface composition of Nb_2O5, NbO and NbN(1-x)Ox within the rf penetration depth. Furthermore, magnetization measurements showed no significant change on bulk superconducting properties.

Effect of laser power on oxygen and nitrogen concentration of commercially pure titanium manufactured by selective laser melting

This study analyzed the variation of mechanical properties and its causes with increasing the laser power in the fabrication of pure titanium by selective laser melting (SLM). SLM samples were fabricated using commercially pure titanium grade 1 powder when the scan speed was 1000 mm/s and the laser power as 120, 200, 280, 360, and 440 W, respectively. As the laser power increased, the hardness and strength of the samples increased gradually. During the SLM processing, the concentrations of oxygen and nitrogen in the SLM samples were increased, which resulted in the increase of hardness and strength. The SLM equipment used in this study removed oxygen in the chamber by flowing high purity argon gas and fabricates the sample while preserving the oxygen concentration in the atmosphere to 0.2%. Evaluating the possibility of oxidation and nitriding during the SLM process by thermodynamic analysis, it was found that the process occurred under conditions in which temperature and residual oxygen and nitrogen partial pressure led to oxidation and nitriding.

Nitrogen solubility in the deep mantle and the origin of Earth's primordial nitrogen budget

The solubility of nitrogen in the major minerals of the Earth's transition zone and lower mantle (wadsleyite, ringwoodite, bridgmanite, and Ca-silicate perovskite) coexisting with a reduced, nitrogen-rich fluid phase was measured. Experiments were carried out in multi-anvil presses at 14 to 24 GPa and 1100 to 1800 °C close to the Fe–FeO buffer. Starting materials were enriched in 15N and the nitrogen concentrations in run products were measured by secondary ion mass spectrometry. Observed nitrogen (15N) solubilities in wadsleyite and ringwoodite typically range from 10 to 250 μg/g and strongly increase with temperature. Nitrogen solubility in bridgmanite is about 20 μg/g, while Ca-silicate perovskite incorporates about 30 μg/g under comparable conditions. Partition coefficients of nitrogen derived from coexisting phases are DNwadsleyite/olivine = 5.1 ± 2.1, DNringwoodite/wadsleyite = 0.49 ± 0.29, and DNbridgmanite/ringwoodite = 0.24 (+0.30/−0.19). Nitrogen solubility in the solid, iron-rich metal phase coexisting with the silicates was also measured and reached a maximum of nearly 1 wt.% 15N at 23 GPa and 1400 °C. These data yield a partition coefficient of nitrogen between iron metal and bridgmanite of DNmetal/bridgmanite ∼ 98, implying that in a lower mantle containing about 1% of iron metal, about half of the nitrogen still resides in the silicates. The high nitrogen solubility in wadsleyite and ringwoodite may be responsible for the low nitrogen concentrations often observed in ultradeep diamonds from the transition zone. Overall, the solubility data suggest that the transition zone and the lower mantle have the capacity to store at least 33 times the mass of nitrogen presently residing in the atmosphere. By combining the nitrogen solubility data in minerals with data on nitrogen solubility in silicate melts, mineral/melt partition coefficients of nitrogen can be estimated, from which the behavior of nitrogen during magma ocean crystallization can be modeled. Such models show that if the magma ocean coexisted with a primordial atmosphere having a nitrogen partial pressure of just a few bars, several times the current atmospheric mass of nitrogen must have been trapped in the deep mantle. It is therefore plausible that the apparent depletion of nitrogen relative to other volatiles in the near-surface reservoirs reflects the storage of a larger reservoir of nitrogen in the solid Earth. Dynamic exchange between these reservoirs may have induced major fluctuations of bulk atmospheric pressure over Earth's history.

Influence of Nitrogen on Hydrogenated Amorphous Carbon Thin Films Deposited by Plasma Focus Device

To carry out our research, a plasma focus device is used to deposit thin films of nitrogen doped hydrogenated amorphous carbon (a-C:H:N) onto the stainless steel-AISI-304 substrates at room temperature. Thin films are deposited with the same numbers of focus shots, at the same distance from the anode tip and with different partial pressures of nitrogen in the mixtures of acetylene/nitrogen as working gas. The nitrogen contents of deposited films are studied using nuclear reaction analysis (NRA) techniques. The results prove that nitrogen contents of the samples do not increase significantly by increasing partial pressure of nitrogen of the working gas for both sets of the samples. Moreover, NRA results exhibit the limitation of nitrogen incorporated into the samples, when this experimental setup is used. G-peak position and peak intensity ratio of the D-band to G-band (ID/IG) are used to investigate the diamond characters. Also, they show that sp2 clustering is highly dependent on the nitrogen atomic contents and angular position of the samples. Scanning electron microscopy (SEM) shows the granular surface morphology of the films. Furthermore, it shows that angular position of the samples with respect to the anode axis plays an important role in the grain size of the surface of the samples. The thickness of the films decreases significantly by increasing angular position of the samples, while it decreases slightly by increasing partial pressure of nitrogen of the working gas. The Vickers surface hardness of the thin films exhibits significant dependency on the sp2 clustering.

Specific Features of the Microstructure and Properties of Multielement Nitride Coatings Based on TiZrNbAlYCr

Multicomponent nanostructured coatings based on (TiZrNbAlYCr)N with a hardness as high as 47 GPa were obtained by cathodic arc deposition. The effect of partial nitrogen pressure PN (with constant bias potential U b =–200 V applied to the substrate) on the phase-composition variation, the size of crystallites, and their relation to the microstructure and hardness was investigated. An increase in the nitrogen pressure resulted in the formation of two phases with characteristic BCC (the lattice period is 0.342 nm) and FCC lattices with averaged nanocrystallite sizes of 15 and 2 nm. At a high pressure of 0.5 Pa, crystallites in the FCC phase with a lattice period of 0.437 nm grew in size to ~7 nm. The hardness of deposited coatings with larger (3.5 nm) FCC-phase crystallites and smaller (7 nm) BCC-phase crystallites was enhanced considerably.

Influence of Nitrogen Partial Pressure on Microstructure and Tribological Properties of Mo-Cu-V-N Composite Coatings with High Cu Content

In this study, Mo-Cu-V-N composite coatings with high Cu content of ~18 at.% were deposited on 316L stainless steel and YT14 cemented carbide substrates by high power impulse magnetron sputtering in Ar–N2 gas mixtures. The influence of N2 partial pressure was investigated with respect to the microstructure and tribological properties of the coatings. The results indicated that the Mo-Cu-V-N composite coatings exhibited FCC B1-MoN phase with a strong (200) preferred orientation, and Cu phase was found to exist as metallic species. As the N2 partial pressure increased from 0.11 to 0.35 Pa, the peak intensity of (200) plane decreased gradually and simultaneous peak broadening was observed, which was typical for grain refinement. With increasing the N2 partial pressure, the columnar microstructure became much coarser, which led to the decrease of residual stress and hardness. The Mo-Cu-V-N composite coatings with high Cu content exhibited a relatively low wear rate of 10−8 mm3/N·m at 25 °C, which was believed to be attributed to the mixed lubricious oxides of MoO2, CuO and V2O5 formed during tribo-oxidation, which cannot be formed in the coatings with low Cu content. When the wear temperature was increased up to 400 °C, the wear rate increased sharply up to 10−6 mm3/N·m despite the formation of lubricious oxides of MoO3/CuMoO4 and V2O5. This could be due to the loss of nitrogen and pronounced oxidation at high temperatures, which led the wear mechanism to be transformed from mild oxidation wear to severe oxidation wear.

Preparation and characterization of CrN thin film by DC reactive magnetron sputtering

In this work, the DC reactive magnetron sputtering were used to deposit the chromium nitride (CrN) thin films on silicon (100) wafers and 304-type stainless steels in argon-nitrogen gas mixture at room temperature. The effect of nitrogen partial pressure ratios [%PN2 = PN2/(PN2+PAr)×100] on the microstructural were studied. The crystal structure of the prepared CrN films were analyst by X-ray diffraction. For the physical morphological analysis, atomic force microscopy and field-emission scanning electron microscopy were used. An element analysis of the CrN thin films were performed by energy dispersive X-ray spectroscopy (EDS). It was found that the deposition rate of the films increased with decreasing the nitrogen partial pressure ratio. The changes in crystal structures and morphological related with nitrogen partial pressure ratio were systematically investigated and discussed in this paper.

Особенности микроструктуры и свойств многоэлементных нитридных покрытий на основе TiZrNbAlYCr

AbstractMulticomponent nanostructured coatings based on (TiZrNbAlYCr)N with a hardness as high as 47 GPa were obtained by cathodic arc deposition. The effect of partial nitrogen pressure P _N (with constant bias potential U _ b =–200 V applied to the substrate) on the phase-composition variation, the size of crystallites, and their relation to the microstructure and hardness was investigated. An increase in the nitrogen pressure resulted in the formation of two phases with characteristic BCC (the lattice period is 0.342 nm) and FCC lattices with averaged nanocrystallite sizes of 15 and 2 nm. At a high pressure of 0.5 Pa, crystallites in the FCC phase with a lattice period of 0.437 nm grew in size to ~7 nm. The hardness of deposited coatings with larger (3.5 nm) FCC-phase crystallites and smaller (7 nm) BCC-phase crystallites was enhanced considerably.