Use Of Nitride Research Articles

Titanium Nitride Coated Implant Abutments: From Technical Aspects And Soft tissue Biocompatibility to Clinical Applications. A Literature Review.

To review the most up to date scientific evidence concerning the technical implications, soft tissue biocompatibility, and clinical applications derived from the use of titanium nitride hard thin film coatings on titanium alloy implant abutments. A review was performed to answer the following focused question: "What is the clinical reliability of nitride coated titanium alloy abutments?". A MEDLINE search between 1980 and 2021 was performed for investigations pertaining to the clinical use of nitride coated titanium alloy implant abutments (TiN) in case reports, case series, and short- and long-term non/randomized controlled clinical trials. Literature analysis led to addition evaluation of research related to the technical and biological aspects, as well as the physicochemical characteristics of TiN hard thin film coatings and their impact on titanium abutment biocompatibility, mechanical properties, macroscopic surface topography, and optical properties. Therefore, preclinical data from biomechanical and in vitro investigations were also considered as inclusion criteria. The limited number of clinical investigations published made a systematic review and meta-analysis not possible, therefore a narrative review was conducted. TiN coatings have been applied to dental materials and instruments to improve their clinical longevity. Implant abutments are coated with titanium nitride to mask the titanium oxide surface and enhance its surface characteristics providing the TiN abutment surface with a low friction coefficient and a very high chemical inertness. TiN coating is suggested to reduce early bacterial colonization and biofilm formation and enhance fibroblast cell proliferation, attachment and adhesion when compared to Ti controls. Additionally, studies indicate that hard thin film coatings enhance the mechanical properties (hardness and wear resistance) of titanium alloy and appears as a yellow color when deposited on the titanium alloy substrate. To date, clinical investigations show that nitride coated titanium abutments provide promising short-term clinical outcomes. Published research on nitride-coated abutments is still limited, however, the available biomedical research, mechanical engineering tests, in vitro investigations, and short-term clinical trials have, to date, reported promising mechanical, biological, and esthetic outcomes.

60‐5: Invited Paper: Display Technology Responds to COVID‐19 Challenges

We demonstrate the use of Nitride semiconductors as the light emitting layer in a series of devices, from Visible emitting LEDs, to far‐UVC LEDs and novel light emitting devices.

Results of steel 20Kh13 samples with combined hardened-structured surface erosion tests

The work presents the results of erosion tests and metallographic studies of samples from blade steel 20Kh13 with diffusion coating obtained by ion nitriding and samples from nitrided steel 20Kh13 with a relief previously formed on the surface. Studies of the samples resistance to high-speed water droplet erosion were carried out using the unique hydraulic impact rig «Erosion-M» of the NRU «MPEI». It was established that the use of nitriding and nitriding with preliminary surface structuring allows increasing the relative erosion resistance in the area with a maximum wear rate of at least 2 times, and in the area with a steady wear rate of at least 3 times. It was also found that structuring the surface layer before the nitriding process allows reducing the wear rate in the area with a maximum erosion rate compared to the nitrided surface by at least 10%.

Silicon Nitride as a Reinforcement for Aluminium Metal Matrix Composites to Enhance Microstructural, Mechanical and Tribological Behavior

In recent years, aluminium and its hybrid composites receiving more attention due to its excellent property combinations like improved mechanical properties, better wear and high corrosion resistance, ease to process and probably reduced production cost etc.. Composite is made of two phases one is matrix and another one is reinforcement. The performance of composite highly depends on some key factors that decide overall performance and they are properties of constituent phases, reinforcement size, reinforcement distribution in the matrix and their interfacial interaction. Particle reinforced metal matrix composites (particulate metal matrix composites- PMMCs) are becoming more popular due to their low cost, easy to process and compatible to conventional processing techniques. Also they give isotropic properties. The most commonly used reinforcements are carbides, oxides and nitrides. A lot of research has taken place including carbide and oxide as a reinforcement particles for aluminum matrix composites (AMCs) and hybrid aluminium matrix composites (HAMCs) while there is a bit research lag in use of nitride as a reinforcement for development of AMCs and HAMCs. Recent competitive market demands the material having better combination of properties, cost effectiveness and eco-friendly nature. Present article focused on to study the microstructural features, physical properties, mechanical and tribological behavior of aluminium matrix composites when reinforced with silicon nitride particles (Si3N4). Potential area of applications has also been suggested on the basis of literature data. In this review a comprehensive study has done for current scientific development carried out in Al based Si3N4 composites as well as its future scope has also been discussed.

Recent Progress in the Design and Synthesis of Nitrides for Mesoscopic and Perovskite Solar Cells

With growing concerns about global warming and the energy crisis, a variety of photovoltaic devices have attracted worldwide attention as alternative energy sources. Among them, organic-inorganic hybrid photovoltaics, typically mesoscopic and perovskite solar cells, are promising, owing to their potential for low-cost energy production, which mainly comes from unlimited combinations of materials optimized for each step of solar energy conversion. However, the commercialization of organic-inorganic hybrid solar cells is hampered by costly electrocatalysts or hole-transport materials. Currently, state-of-the-art dye- or quantum-dot-sensitized solar cells and perovskite solar cells necessitate noble metals and high-price polymeric materials. In an attempt to resolve this issue, various kinds of metal compounds have been investigated, and nitrides have been actively reported to possess a number of favorable properties for the aforementioned purpose, such as excellent electrical conductivity and superb electrocatalytic performance. Herein, the use of nitrides as cost-effective electrocatalysts or hole-transport materials in organic-inorganic hybrid solar cells is reviewed. Nitrides with a variety of morphologies and scales are discussed, together with the synergistic effect in the case of diverse composites. In addition, prospects and challenges for applying nitride materials are briefly suggested.

Pressure-induced stable BeN4 as a high-energy density material

Polynitrogens are the ideal rocket fuels or propellants. Due to strong triple N≡N bond in N2, the direct polymerization of nitrogen is rather difficult (i.e. extreme high temperature and high pressure). However, the use of nitrides as precursors or the reaction of N2 with other elements has been proved to be an effective way to obtain polynitrogens. Here, with assistance of the advanced first-principles swarm-intelligence structure searches, we found that P1¯-BeN4, containing infinite zigzag-like polymeric nitrogen chains, can be synthesized by compressing the mixture of Be3N2 and N2 at 25.4 GPa, which is greatly lower than 110 GPa for synthesizing cubic gauche nitrogen and other polynitrogen compounds (e.g. bulk CNO at 52 GPa and SN4 at 49 GPa). Its structural stability can be attributed to the coexistence of ionic Be-N and covalent N-N bonds. Intriguingly, this phase has high kinetic stability and remains metastable at ambient pressure. The exceptional properties, including high energy density (3.60 kJ g−1), high nitrogen content (86.1%), high dynamical stability, and low polymerization pressure, make P1¯-structured BeN4 a promising high energy material. Infinite nitrogen chains in P1¯-BeN4 transform to N10 rings network in P21/c phase at 115.1 GPa. P1¯-BeN4 is metallic, while P21/c-BeN4 is an insulator.

Environmental Aspects of a Pilot Power Complex in Project Breakthrough

The particularities of the formation of the potential biological danger of actinides and fission products in time and the influence of the migration factor on it are examined. The calculation of the dose characteristics of long-lived radionuclides took account of the effect of internal and external irradiation on humans. The internal irradiation dose was calculated taking account of the transfer of radionuclides from soil into food products. It was found that the actinides, 90Sr and 137C, make the main contribution to the biological danger for 500 years, and are followed by americium and 99Tc from the fission products. The separation of 99% of the americium and technetium (which can be transmuted) from the irradiated fuel is optimal for satisfying the principle of radiation equivalence. The use of nitride fuel in fast reactors requires special attention to isolation of 14C from the environment. It was shown that taking account of the presence of agricultural lands in the action zone of enterprises in the pilot demonstration power complex softens the requirements of admissible carbon emission in the gas phase with absolute satisfaction of the safety requirements for the effect on the general public.

Viability of uranium nitride fueled high-conversion PWR

Light water breeder reactors have been examined periodically for decades, and considerable research into the neutronics and thermal hydraulics of several designs has been performed. Currently, there is an interest in reduced moderation boiling water reactors in Japan and in the United States, where Department of Energy (DOE)-sponsored university research programs are examining proposed breeding BWRs.This study assesses the thermal hydraulic and neutronic feasibility of a nitride fueled pressurized water reactor (PWR) breeder design. Because of the higher fuel density, the use of nitride fuel would be preferable to the traditional oxide fuel for a high conversion PWR design. To illustrate the advantage, a design that uses large hexagonal assemblies was considered. The design has 14 inner seed pin rows and 4 outer blanket pin rows, leading to 505 inner seed pins and 366 outer blanket pins per assembly. Each assembly contains 6 thimble locations for control rods. The same assembly type can be used at all locations in the core. For this study a fuel pin diameter of 1.2 cm was used with a gap of 1 mm between pins. The seed regions had 12.75% percent of the heavy metal as fissile plutonium (Pu-239 and Pu-241), hosted in depleted uranium (0.25% U-235). The plutonium vector for the seed region was 2.7% Pu-238, 47.9% Pu-239, 30.3% Pu-240, 9.6% Pu-241, 8.5% Pu-242 and 1.0% Am-241. The Blanket regions contained only depleted uranium with 0.25% U-235.This assembly was modeled with the Monte Carlo depletion code Serpent to determine the initial to final fissile inventory ratio (FIR). The as-specified assembly model did not achieve an FIR value above 1.0, so the water in the thimble regions was changed to void, to lower the H/HM ratio. This led to FIR values above 1.0 for the oxide, the 85% theoretical density nitride (N85) and the 95% theoretical density nitride (N95). All designs had an FIR of 1.03 at 35 MWd/kgHM. However, the single batch discharge burnup of the assembly was much higher for the nitride cases. The burnups were 15.6, 24.5 and 32.2 MWd/kgHM for the oxide, N85 and N95 respectively.The KfK correlation for critical heat flux was applied to calculate the minimum departure from nucleate boiling ratio (MDNBR), whose value was set to be 1.45. With an acceptable core pressure drop of 400 kPa and acceptable vibration magnitude, the maximum power in an assembly and the maximum flow rate were determined. A nitride fuel had a larger MDNBR than the oxide fuel. This increase is likely a result of spectrum hardening, which was found to reduce the fractional amount of power generated in the seed region, where departure from nucleate boiling (DNB) occurs. Because of the longer neutron mean free path in the harder spectrum, more fission events occur in the blanket. The coolant density coefficient of the nitride fuel was found to have positive coefficient values in voided thimble tube cases. However, the power coefficient was negative and has the ability to limit power increases. The radially reflective assembly boundary may have made the analysis more conservative than full core analysis.

Is Angina Preventable?

Last week I looked through some of the earlier records of the hospital where you, Sir, and I and most of us here had our training. You may like to know that the interest in ischaemic heart disease which Lauder Brunton established 100 years ago is being actively perpetuated in the same ward. The area where we established the first major Coronary Care Unit in Britain a year ago is very probably the same as that where young Brunton made his classical observation concerning the use of nitride of amyl. Prevention of ischaemic heart disease, whether we are considering angina or myocardial infarction, must be taken to mean the prevention of the premature onset of the disease. Death from a heart attack at an advanced age would not necessarily seem undesirable.

ChemInform Abstract: Synthesis, Stability, and Catalytic Properties of High Surface Area Silicon Oxynitride and Silicon Carbide

Abstract The aim of this work is to extend the range of inorganic materials which find application in heterogeneous catalysis, as catalysts or catalyst supports, through use of progress in the field of advanced ceramics. Developments in synthetic routes to high surface area non-oxides (nitrides, carbides, borides) are briefly reviewed. Work on the synthesis, stability and catalytic properties of high surface area silicon oxynitride and silicon carbide is described. For the former compound, three synthetic routes were investigated: the reaction of an amorphous silica with ammonia proved to be the preferred route, giving a silicon oxynitride of ca. 150 m 2 g −1 . The surface composition of the material obtained by the latter method showed good stability, as indicated by retention of surface nitrogen under reducing or oxidising conditions at about 700°C. The oxynitride surface was unreactive towards butene-1, causing no double-bond isomerisation at 400°C. However, the material was also found to be capable of functioning as a solid basic catalyst, catalysing Knoevenagel condensations in solution at 50°C. The use of nitrides as solid basic catalysts appears to be novel, and this result suggests new applications for such materials. In the case of silicon carbide, a mesoporous form was obtained by polymer pyrolysis. The texture shows improved thermal (but not hydrothermal) stability compared to silica. The surface is less reactive than that of the oxynitride, catalysing neither the double-bond isomerisation of butene-1 nor the Knoevenagel condensation. This compound, and the oxynitride, may be useful as inert support materials for reactions involving alkenes.

Evaluation of SmCo and SmCoN magnetron sputtering coatings for SOFC interconnect applications

Cobalt or cobalt containing coatings are promising for SOFC interconnect applications because of their high conductivity. We have investigated SmCo and SmCoN coatings deposited by magnetron sputtering from a SmCo (5% Sm) target on to Crofer 22 APU substrates. The composition, structure, surface morphology, and electrical conductivity of the coated substrates were characterized by SEM/EDX, XRD and ASR measurements. Addition of Sm enhances the oxidation resistance and the Cr retention capability of the coatings. The use of nitride as a precursor stabilizes Sm during oxidation of the films, thus inhibiting diffusion of Fe, resulting in a more compact coating and lowering ASR. The combined advantages of Sm addition to cobalt and the use of a nitride as a precursor, makes SmCoN coatings a promising new interconnect coating material.

Highly Scalable ALD-deposited Hafnium Silicate Gate Stacks for Low Standby Power Applications

AbstractThe electrical performance of hafnium silicate (HfSiOx) gate stacks grown by atomic layer deposition (ALD) has been evaluated in capacitors and transistors. First, scaling potential of HfSiOx layers was studied as function of composition and thickness. It is shown that the equivalent oxide thickness scales down with decreasing layer thickness and increasing Hf-content. The gate leakage (at Vfb-1V), however, is mainly determined by the physical layer thickness. For the same equivalent oxide thickness (EOT) target, the lowest leakage is observed for the layers with the highest Hf-content. Leakage values as low as 1x10-3 A/cm2 for an equivalent oxide thickness of 1.3 nm have been obtained. Second, the thermal stability against crystallization of the ALD HfSiOx has been studied and related to their electrical properties. The thermal stability of HfSiOx decreases with increasing Hf-content that necessitates the use of nitridation. The influence of various annealing conditions on the nitrogen incorporation is also studied. Finally, the effect of HfSiOx composition and postdeposition nitridation is discussed on transistor level. TaN metal gate transistor data indicate that nitridation reduces the gate leakage and that Hf-rich HfSiOx layers show the best scaling potential, i.e., highest performance for the lowest gate leakage.

Feasibility study on nitride fuel core and recycling system toward Self-Consistent Nuclear Energy System

The concept of a nuclear fuel recycle system with a nitride fueled FBR core has been investigated as a part of related studies towards the Self-Consistent Nuclear Energy System (SCNES). Nitride fuel has been given attention because of its relatively high fuel density and high thermal conductivity. To materialize the SCNES concept, it is important to adequately use the excess neutrons produced in the chain reaction. The high fuel density of the nitride fuel brings out more of the excess neutrons and has a higher potential to transmute the long-lived fission products (LLFP's). The high thermal conductivity, in addition, provides margin of fuel melting, and gives negative feedback due to the Doppler reactivity in unprotected loss of flow accidents. In this paper, we discuss good use of nitride fuel in the SCNES.

Obtaining aluminium matriz composities reinforced with nitrides by powder metallurgy

The use of aluminium metal matrix composites as structural materials is increasing continuously, mainly in the automotive and aerospace industries. The development of new kind of reinforcements is one of the areas of greater interest in current researches. This work investigates the use of nitrides as reinforcement for composite materials, with Al 6061 matrix, obtained by powder metallurgy and extrusion, presenting their microstructural features and their mechanical characteristics.

Development of wear-resistant coatings for cobalt–base alloys

The costs and hazards resulting from nuclear plant radiation exposure with activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. However, the hardnesses of many cobalt-base wear alloys are significantly lower than conventional PVD hard coatings, and mechanical support of the hard coating is a concern. Four approaches have been taken to minimize the hardness differences between the substrate and PVD hard coating: (1) use a thin Cr-nitride hard coating with layers that are graded with respect to hardness, (2) use a thicker, multilayered coating (Cr-nitride or Zr-nitride) with graded layers, (3) use nitriding to harden the alloy subsurface followed by application of a multilayered coating of Cr-nitride, and (4) use of nitriding alone. Since little work has been done on application of PVD hard coatings to cobalt-base alloys, some details on process development and characterization of the coatings is presented. Scratch testing was used to evaluate the adhesion of the different coatings. A bench-top rolling contact test was used to evaluate the wear resistance of the coatings. The test results are discussed, and the more desirable coating approaches are identified.

Hardening single crystals of molybdenum and tungsten alloys by the method of internal saturation

1. The use of carburizing, nitriding, internal oxidation, vacuum annealing, and their combinations makes it possible to form a structure of disperse segregations with specified parameters in the surface layers of single-crystal molybdenum and tungsten alloys and thus control their properties. 2. The use of nitriding (including that followed by a low-temperature vacuum annealing) is expedient for parts operating at a temperature of at most 1400–1450°C (depending on the composition of the single crystals). 3. The use of nitriding by the studied regimes for reinforcing single crystals of molybdenum and its alloys is inexpedient. 4. The use of internal oxidation for reinforcing single crystals of molybdenum alloys is expedient for parts operating at a temperature of at most 1450°C for the Mo−Nb system and at most 1650°C for the Mo−Zr system. Single crystals of alloys in the W−Zr, W−Hf, and W−Ta (together with Re) systems can also be reinforced with the help of internal oxidation. 5. A stabilizing low-temperature vacuum annealing after internal oxidation makes it possible to increase the service temperature of single crystals of the Mo−Nb−Zr−C system to 1600–1650°C. 6. Saturation in a nitrogen- and oxygen-bearing atmosphere (simultaneously or in turn) provides a layer consisting of several zones with the specified distribution of properties, including the hardness, which increase with the thickness of the part and protect it from cracking. 7. The use of the determined laws for hardening molybdenum inserts for pressure steel casting has increased their service life by a factor of 3–3.5.

Epitaxial growth of gallium nitride thin films on A-Plane sapphire by molecular beam epitaxy

In this article, we propose a crystallographic model to describe epitaxy of GaN on (112̄0) sapphire (A plane). The (11̄02) cleavage plane in sapphire is shown to extend to the GaN lattice as the (112̄0) plane, facilitating the formation of cleaved facets. It is shown that, although the lattice mismatch is much smaller than in the case of epitaxy on (0001), the difference in the planar symmetry in this case results in high-strained bonds near the interface. The use of nitridation and a low temperature buffer is therefore necessary. A systematic study of GaN growth on the A-plane sapphire by plasma-assisted molecular beam epitaxy was carried out to study the effects of plasma nitridation of the substrate and the growth of a low temperature GaN buffer on the structure and optoelectronic properties of the films. Transmission electron microscopy (TEM) studies indicate that films grown on substrates which were not nitridated prior to growth have a significant fraction of zinc-blende domains and poor orientation relationship with the substrate. On the contrary, nitridation leads to films with superior structural and optoelectronic properties. The low temperature GaN buffer, grown on nitridated substrates, was found to also have a pronounced effect on the optoelectronic properties of the GaN films, especially in those with low carrier concentrations. The correlation between TEM and photoluminescence studies suggests that the transition at 3.27 eV can be attributed to the cubic domains in the films.

Strengthening steel 38Kh2MYuA by nitriding in various media

At the present time critical parts of various machines and equipment operating under conditions of wear under cyclic loads are often produced from low-alloy steel 38Kh2MYuA. Its operating properties are usually improved by surface strengthening by the method of nitriding. A wide range of nitrogen-saturating atmospheres has been developed for this purpose, with each diffusion medium characterized by special process properties. The present paper is an analysis of data on nitriding structural steel 38Kh2MYuA in gas, liquid, ionic, vacuum, and powder nitrogen-bearing media. Recommendations are given for practical use of nitriding of the studied steel so as to obtain the requisite operating properties.

Effect of prior surface plastic deformation on the structure and contact durability of nitrided steel 16Kh2N3MFBAYu-Sh (VKS-7)

The state of the surface layer is of special importance in connection with the use of nitriding as the final operation in the manufacturing cycle for the preparation of reliable heavily loaded components. In this work the effect of surface plastic deformation (SPD) on the structure and contact durability of nitrided steel 16Kh2N3MFBAYu-Sh (VKS-7) was investigated.

Processing and Oxidation of Nitride Stabilized 18Cr-20Ni Stainless Steel

AbstractThe present investigation explores the use of nitride precipitates for grain-size stabilization in a 18Cr-2ONi austenitic stainless steel for high temperature applications in oxidizing atmospheres. The potential for reductions in alloying contents of such steels has become a focus of research out of concern for the conservation of strategic alloying elements such as Cr. In order for the alloy to maintain superior oxidation resistance, it must sustain a fine grain size by virtue of effective grain boundary pinning by stable precipitates.Al and Ti microalloyed 18Cr-20Ni steels have been nitrided using rapid solidification processing (spray forming) and subjected to thermomechanical treatments to precipitate nitrides from the supersaturated solid solutions. The spray formed deposits were cold rolled to increase the density of dislocations, which act as sites for nucleation of nitride precipitates. The alloys were then annealed to nucleate and grow the precipitates, followed by cold rolling and recrystallization to generate a stable, fine grained microstructure. The Ti-microalloyed steel demonstrated high-temperature grain size stability by maintaining a grain size of≈7μm after 600h at 1000°C.The Ti-microalloyed steel has been subjected to isothermal oxidation in air at 900°C. The results of preliminary oxidation experiments are reported. The spray deposited and thermomechanically processed alloy demonstrated high-temperature oxidation behavior superior to conventionally processed (hot rolled and annealed) alloys.