Niobium Alloys Research Articles

Verification of energy efficiency of a low-thrust liquid-propellant engine with the deflector-centrifugal injecting pattern

The article gives information about developed in Design Bureau Chemical Machinery behalf A.M. Isaev deflector centrifugal pattern mixing of propellants nitrogen tetroxide and unsymmetrical dimethylhydrazine, in which established liquid rocket engines (LREST) in a wide range of rods from 25 to 400 N. Design Bureau Chemical Machinery behalf A.M. Isaev on the basis of joint with KUAI (now SSAU named after Korolev, Samara) and studies on the characterization of the primary oxidant film on the deflector, the parameters of the secondary oxidant film on the inner wall of the combustion chamber, the parameters of the film cone spray nozzle centrifugal fuel in a venue with a secondary film oxidant parameters of the layer of liquid-phase mixing the oxidizer and fuel components on the inner wall of the combustion chamber was established mathematical model calculations of liquid-phase mixing of the components in the mixing element LREST with centrifugal deflection circuit mixing the components on the wall of the combustion chamber. Based on this Design Bureau Chemical Machinery behalf A.M. Isaev developed technique of calculations and design of LREST with centrifugal deflection circuit mixing fuel. Using this method in Design Bureau Chemical Machinery behalf A.M. Isaev designed iPart LREST 25, 50, 100, 200, 400N, with deflector centrifugal mixing scheme. Parametric studies were conducted LREST of 25, 50, 100, 200, 400 N to determine the degree of influence of various design and operational parameters of the element, such as the angle of leakage jets on the deflector angle leakage of primary films on the wall of the combustion chamber, the mean free path of the secondary oxidant film the wall of the chamber performance-liquid phase mixing of the fuel components. The results of experimental studies have confirmed the increased energy efficiency of small thrust jet engine thrust of 25, 50, 100, 200, 400 N with deflection centrifugal mixing scheme, expressed in a high specific impulse of more than 3000 m / s at the same time a large margin the temperature of engine components. Maximum temperature of the wall of the combustion chamber is at 1200 С that is provided by a large margin 600 С (permissible material temperature chamber - niobium alloy with molybdenum coating bi-silicified MoSi2 1800 С).

50 n thrust correction engine for the "Luna-resurs" lunar module descent engine

Research to develop a 50 N thrust correction low-thrust liquid rocket engine with a deflector-centrifugalscheme of mixing nitrogen tetroxide and unsymmetrical dimethylhydrazine propellants on the inner wall of thecombustion chamber has been conducted at the Chemical Machinery Design Bureau named after A.M. Isaev. Inthe deflector-centrifugal mixing scheme developed at the Chemical Machinery Design Bureau the oxidizer getsto the conical deflector via the jet nozzle and is transformed into a primary film running off the edge of thedeflector onto the inner wall of the combustion chamber where it is transformed into a secondary film that flowsalong the wall of the chamber to the point of meeting the film from the centrifugal fuel spray nozzle coaxial withthe combustion chamber. Upon meeting the films of oxidizer and fuel continue flowing along the wall of thecombustion chamber at the same time penetrating each other and carrying out the liquid-phase mixing with theformation of transformation products of hypergolic fuel. Thus, practically all the fuel gets to the inner wall of thecombustion chamber, participating in its cooling and removal of a considerable part of the heat flow directedalong the wall of the combustion chamber from its critical section in the direction of the nozzle head. The enginehas the highest (in its class) geometric nozzle expansion ratio ( Fа =200) among analogues of domesticproduction, meanwhile preserving acceptable dimensions and weight characteristics. The combustion chamber inthe engine designed is made of a niobium alloy with a protective heat resistant coating - molybdenum disilicideMoSi2 deposited on the inner surface while niobium disilicide NbSi2 formed by silicon impregnation of aniobium alloy is used on the outer surface. During the firing tests the jet centrifugal scheme of organizing thework process in the combustion chamber designed at the Chemical Machinery Design Bureau confirmed itsefficiency in a 50 N-thrust engine. The adopted design and technological solutions in creating a 50N thrustengine ensured high power and energy-mass characteristics, as well as stable engine performance in a wide rangeof pressures of fuel entering the engine: up to 70.3 N in power augmentation and up to 45.9 N in throttling

Effect of vacuum arc remelting and processing parameters on structure and properties of high purity niobium

Niobium and niobium alloys are normally produced by vacuum arc remelting (VAR) process. In the present work, the effect of various process parameters such as arc voltage, arc current (melt rate) and fill ratio on arc stability during VAR process and solidification structure of remelted niobium ingot is investigated. The effect of thermomechanical processing of VAR ingot on microstructure and mechanical properties is also investigated. It has been established that arc voltage is a function of arc length. For melting of niobium in 110 and 150mm diameter crucibles, the optimum arc voltage is in the range of 34–37V. It has been observed that the arc voltage needed for melting niobium is much higher than that used for melting stainless steels, reactive metals and superalloys. It has also been observed that for a given arc voltage, fill ratio has no significant influence on the melt rate of consumable electrode. However, arc current has significant influence on the melt rate and consequently on the solidification structure of the ingot. Thermomechanical processing of the VAR ingot is shown to result in significant increase in room temperature strength and ductility. However, the processing temperatures do not have any significant influence on the tensile properties.

Measuring flow and pressure of lithium coolant under developmental testing of a high-temperature cooling system of a space nuclear power plant

Sub-megawatt space NPP use lithium as a coolant and niobium alloy as a structural material. In order to refine the lithium-niobium technology of the material and design engineering, lithium-niobium loops were worked out in RSC Energia, and they were tested at a working temperature of lithium equal to 1070–1300 K. In order to measure the lithium flow and pressure, special gauges were developed, which made possible the calibration and checkout of the loops without their dismantling. The paper describes the architecture of the electromagnetic flowmeter and the electromagnetic vibrating-wire pressure transducer (gauge) for lithium coolant in the nuclear power plant cooling systems. The operating principles of these meters are presented. Flowmeters have been developed for channel diameters ranging from 10 to 100 mm, which are capable of measuring lithium flows in the range of 0.1 to 30 L/s with the error of 3% for design calibration and 1% for volume graduation. The temperature error of the pressure transducers does not exceed 0.4% per 100 K; the nonlinearity and hysteresis of the calibration curve do not exceed 0.3 and 0.4%, respectively. The transducer applications are illustrated by the examples of results obtained from tests on the NPP module mockup and heat pipes of a radiation cooler.

Development of Niobium Alloyed Press Hardening Steel with Improved Properties for Crash Performance

Press hardening steel has become a much used material in car body manufacturing due to its excellent safety and lightweight potential. In some recent car models press hardening steel has reached already a weight share of more than 20% in the body structure while it is estimated that it could reach even around 40% in the future. However conventional press hardening steel based on the alloying concept 22MnB5 was designed originally not for automotive application. In spite of the high strength level, press hardening steel has generally low toughness due to the relatively high carbon content and its martensitic microstructure. Particularly important is the ductile-to-brittle transition temperature at low temperature, which might lead to unexpected failure in cold climate regions. Furthermore, hydrogen embrittlement is a major concern in press hardening steel as previous results indicated that only a few ppm of hydrogen could induce delayed cracking. Generally it is important that impact energy should be absorbed by the material to avoid unexpected disintegration of the structure. This material capability is usually characterized by the toughness. All these characteristics have not yet been systematically investigated in press hardening steel. Consequently, no attempts have been made to optimize conventional press hardening steel for obtaining better toughness, lower ductile-to-brittle transition temperature and reduced sensitivity to hydrogen induced cracking.A generally proven approach of improving the resistance against brittle failure in high strength steel is the refinement of microstructure, which can be efficiently achieved by Nb microalloying. This paper will introduce modified alloy designs for press hardening steel and explain fundamentally the metallurgical effects of Nb microalloying on the improvement of crack propagation resistance, bendability and delayed cracking behavior induced by hydrogen penetration in press hardening steel. The results reveal better toughness, improved bending behavior and increased resistance against hydrogen embrittlement.

Progress on the Precious Metals Used in High-Temperature Protective Coatings

Nickel-based super alloy, niobium alloy, refractory metal and carbon fiber reinforced composite are the most common structural materials used in aviation and spaceflight fields. Reduced oxidation and corrosion resistance at high temperature are limiting factors to the application of theses materials. Adapted protective coatings such as pure precious metal coatings, precious metal alloy and precious metal composite coatings can be applied on the surface of theses materials. New advances of oxidation protective coating in recent years are reviewed in this paper, combined with some research on the preparation of iridium

Effect of Niobium on the Defect Chemistry and Oxidation Kinetics of Tetragonal ZrO2

Zirconium–niobium alloys are currently proposed for applications in water-cooled nuclear reactors. However, the mechanisms by which Nb impacts the corrosion resistance of these alloys are yet to be clarified. In this work, we utilize a thermodynamic framework informed by density functional theory calculations to predict the effect of Nb on the equilibria of charged defects in tetragonal ZrO2, and discuss how the changes in the defect concentrations affect the protectiveness of this oxide that grows natively on Zr alloys during oxidation. Our analysis shows that Nb dissolves predominantly in the oxidation state 5+ as a substitutional defect on the Zr sublattice, with charge compensation achieved by the negatively charged Zr vacancies. Moreover, Nb dissolution is limited to the oxygen-rich conditions, i.e., in the oxide surface facing oxidizing environment. We validate this finding by performing X-ray photoelectron spectroscopy on oxidized Zr–Nb alloys. The introduction of Nb in tetragonal ZrO2 is found to enhance the concentration of Zr vacancies and of free electrons and to decrease the concentration of oxygen vacancies. We conclude that the net effect of Nb on the corrosion kinetics of Zr alloys is favorable if the rate limiting process is oxygen transport, while Nb would be detrimental if electron transport limits the oxidation kinetics.

Effect of boron addition on the oxidation resistance of silicide protective coatings: A focus on boron location in as-coated and oxidised coated niobium alloys

Multilayered silicide coatings are developed to protect Nb alloys from high temperature oxidation. Their efficiency is improved using a second halide-activated pack-cementation step consisting in a boronizing treatment. This work focuses on the location and quantification of boron in the multi-layered silicide coating in order to study the role of boron. The observations are performed on the cross sections of coated samples, in both as-coated and oxidised (Air–1200°C–100h) states. Characterisation of boron is performed in a FEG-SEM using a coupled WDX-EDX system. It was observed that EDX cannot be used to locate B in a matrix containing Nb, but WDX has sufficient spectral resolution to do it. The synthesis of calibration specimens (TiB2, NbB2 and (Nb0.5 Ti0.5)B2) was required for boron quantitative analysis. The analytical conditions are reported and justified. The compositions determined for borides formed in the coating were relevant with the phase diagrams and the thermodynamic data available for this system. If present in the oxidation products, boron should be in very low amounts because it was not observed during the investigation. Nevertheless, it can be suggested that for high temperature application, the formation of highly stable borides in the coating subsurface is helpful because, in case of crack formation, borides promptly form a boro-silicate glass with a low melting temperature, which is responsible for the self-healing of the oxide scale.

Coatings based on niobium oxides and phosphates formed on niobium alloy

Coatings were formed by plasma electrolytic oxidation in electrolytes containing Ni(II) hexametaphosphate complexes. Depending on the n = [P6O186−]]/[Ni2+] molar ratio in the electrolyte, layers with specific niobium, phosphorus, and nickel contents and of a particular thickness were produced. Upon annealing in air at a temperature of 500 or 800°C, either Nb2O5, or Nb2O5 +NbO(PO4) + P2O5 · 9Nb2O5, or Nb2O5 + NbO(PO4), or Nb2O5 + Ni2P2O7 crystal phases are formed in the coatings depending on the electrolyte composition and temperature of annealing. These surface systems formed on niobium for 10 min at room temperature as a result of a one-stage process in ecologically safe electrolytes can be catalytically active.

An investigation on microstructures and mechanical properties of explosive cladded C103 niobium alloy over C263 nimonic alloy

Futuristic aerospace applications such as advanced turbojet and scramjet engines used in subsonic, supersonic, and trans-atmospheric flights require materials with ever-increasing temperature and load bearing capabilities for improved performance. The materials C103 niobium alloy and C263 nimonic alloy are widely employed in the manufacturing of scramjet engine components. Efforts to join these two materials by fusion welding process have revealed that they are metallurgically incompatible due to the extreme propensity to form brittle intermetallics. The possibility of interdicting interlayer is explored to overcome the formulation of intermetallics and the attempts have not yielded fruitful results. Explosive welding/cladding is one of the possible ways to join these materials, as it is a solid state joining process.The present work aims at studying structure–property correlations in an explosive weld of C103 niobium alloy and C263 nimonic alloy. Explosive welding was carried out taking both the materials in solution-annealed condition. Microstructural studies were carried out to evaluate the integrity of weld joint. Mechanical properties such as shear strength of weld interface was found to be superior and ram tensile strength was observed to be marginally inferior compared to the strength of weaker component of the weld joint. The micro-hardness was observed to be high at the bond interface on C263 nimonic alloy side. The three point bend tests were conducted on the weld joint in such a way that the cladding was subjected to tension, which has not shown any cracks at the interface.

Investigation of early cell–surface interactions of human mesenchymal stem cells on nanopatterned β-type titanium–niobium alloy surfaces

Multi-potent adult mesenchymal stem cells (MSCs) derived from bone marrow have therapeutic potential for bone diseases and regenerative medicine. However, an intrinsic heterogeneity in their phenotype, which in turn results in various differentiation potentials, makes it difficult to predict the response of these cells. The aim of this study is to investigate initial cell-surface interactions of human MSCs on modified titanium alloys. Gold nanoparticles deposited on β-type Ti-40Nb alloys by block copolymer micelle nanolithography served as nanotopographical cues as well as specific binding sites for the immobilization of thiolated peptides present in several extracellular matrix proteins. MSC heterogeneity persists on polished and nanopatterned Ti-40Nb samples. However, cell heterogeneity and donor variability decreased upon functionalization of the gold nanoparticles with cyclic RGD peptides. In particular, the number of large cells significantly decreased after 24 h owing to the arrangement of cell anchorage sites, rather than peptide specificity. However, the size and number of integrin-mediated adhesion clusters increased in the presence of the integrin-binding peptide (cRGDfK) compared with the control peptide (cRADfK). These results suggest that the use of integrin ligands in defined patterns could improve MSC-material interactions, not only by regulating cell adhesion locally, but also by reducing population heterogeneity.

Cytotoxic, hematologic and histologic effects of niobium pentoxide in Swiss mice

The use of metal devices in medical application is increasing but it remains incompletely understood the physiological effects of component degradation. Niobium (Nb) alloys have already been investigated in the 1980's and recent studies demonstrated the potential of Nb as an implant material. The purpose of this study was to determine cytotoxic, hematologic and histologic effects of niobium in Swiss mice. Animals were treated with a single dose of 3 % niobium oxide (Nb2O5) diluted in PBS, i.p. Cytotoxic assay, hematologic and histologic evaluation were done 3, 7 and 12 days after niobium treatment. Data have shown increased number of cells after niobium treatment, but there was no difference in cell viability. Furthermore, it was not observed hematological modification 3, 7 or 12 days after niobium treatment. Despite the fact that animals treated with niobium for 3 and 7 days showed mild degeneration in hepatocytes, mice kept alive for 12 days showed liver cells regeneration. Our results suggested that niobium cytotoxicity was not progressive because 12 days after treatment there was an evident liver regeneration. Data obtained indicated that niobium may be promising alternatives to biomedical applications.

J0410401 ニオブ合金の損傷力学モデリング([J041-04]工業材料の変形特性・強度およびそのモデル化 損傷・疲労・破壊,機械材料・材料加工部門)

The elasto-viscoplastic constitutive equation based on the concept of continuum damage mechanics was formulated for the niobium alloy (C103) which was used for a thruster chamber material in a satellite. Fatigue life analysis based on damage mechanics was conducted to simulate the experimental data obtained by the strain controlled fatigue tests using round bar specimens made of the niobium alloy. The material parameters in the constitutive equation are determined based on the experimental data. Stress-Strain curves and damage value evolutions were also evaluated and the validity of material parameters was illustrated by comparing calculated values with test results.

Formation of white oxide layer on Zr-14Nb alloy using thermal treatment.

This study aimed to develop a novel abutment material with good esthetic and mechanical properties by producing a white oxide layer on a zirconium-14 mass% niobium (Zr-14Nb) alloy substrate using a thermal oxidation process. Oxidation temperatures ranged 700-1000°C and oxidation time ranged 30-180 min. The color of the oxide layer varied depending on temperature and time. A white oxide layer was obtained under appropriate conditions. The oxide layer thickness increased with increased temperature and time, as revealed by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Moreover, X-ray diffraction and X-ray photoelectron spectroscopy revealed that the oxide layer was predominantly monoclinic ZrO2, tetragonal ZrO2, and Nb2O5. The oxide layer revealed good abrasion resistance and high adhesion to the substrate. This novel process for producing white materials with good mechanical properties will be useful for abutments and prostheses in dental implant treatment.

Erosion Wear Analysis of Coated and Uncoated Ductile Materials at Different Velocities and Angles

Wear is the gradual, layer-by-layer destruction of the surface of metallic materials by mechanical action of erodents,or passage of slurry. The wear of metals occurs upon the frictional rubbing of surfaces, wear, and cavitations, as well as upon the action of strong gas or liquid currents upon a surface, especially at high temperatures and pressures. Various parts of jet engines, nuclear reactors, and steam turbines boilers and pipes in the thermal power plants and cement industries where the pipe carries the slurry were subjected to destruction by erosion. Increased resistance of parts against erosion can be achieved by improving process technology or unit design and by selecting more suitable material; heat treatment also increases resistance against erosion. Structural materials have been developed that provide durable operation of parts under erosive conditions, such as some niobium and molybdenum alloys. In the present work the effect of erosion wear on 18Cr8Ni based steel strip coated with Epoxy polyester and powder coating has been investigated experimentally. Comparison of the erosion resistance and loss of metal for different mass flow rate and angle’s are done.

Potential Use of Porous Titanium–Niobium Alloy in Orthopedic Implants: Preparation and Experimental Study of Its Biocompatibility In Vitro

BackgroundThe improvement of bone ingrowth into prosthesis and enhancement of the combination of the range between the bone and prosthesis are important for long-term stability of artificial joints. They are the focus of research on uncemented artificial joints. Porous materials can be of potential use to solve these problems.Objectives/PurposesThis research aims to observe the characteristics of the new porous Ti-25Nb alloy and its biocompatibility in vitro, and to provide basic experimental evidence for the development of new porous prostheses or bone implants for bone tissue regeneration.MethodsThe Ti-25Nb alloys with different porosities were fabricated using powder metallurgy. The alloys were then evaluated based on several characteristics, such as mechanical properties, purity, pore size, and porosity. To evaluate biocompatibility, the specimens were subjected to methylthiazol tetrazolium (MTT) colorimetric assay, cell adhesion and proliferation assay using acridine staining, scanning electron microscopy, and detection of inflammation factor interleukin-6 (IL-6).ResultsThe porous Ti-25Nb alloy with interconnected pores had a pore size of 200 µm to 500 µm, which was favorable for bone ingrowth. The compressive strength of the alloy was similar to that of cortical bone, while with the elastic modulus closer to cancellous bone. MTT assay showed that the alloy had no adverse reaction to rabbit bone marrow mesenchymal stem cells, with a toxicity level of 0 to 1. Cell adhesion and proliferation experiments showed excellent cell growth on the surface and inside the pores of the alloy. According to the IL-6 levels, the alloy did not cause any obvious inflammatory response.ConclusionAll porous Ti-25Nb alloys showed good biocompatibility regardless of the percentage of porosity. The basic requirement of clinical orthopedic implants was satisfied, which made the alloy a good prospect for biomedical application. The alloy with 70% porosity had the optimum mechanical properties, as well as suitable pore size and porosity, which allowed more bone ingrowth.

Microstructure and properties of nanocrystalline copper–niobium alloy with high strength and high conductivity

A nanocrystalline Cu–10wt%Nb alloy, with high strength and high conductivity, was prepared by mechanical alloying and subsequent hot pressing. The microstructure and properties of the alloys after consolidation at different temperatures were investigated. The alloy, subjected to hydrogen-annealing of milled powders at 560°C for 1h and then vacuum hot-pressing sintering under 30MPa pressure and 900°C for 2h, has a microhardness of 334 HV, a tensile strength of 1102MPa, a yield strength of 1043MPa, and an electrical conductivity of 57% IACS (International Annealing Copper Standard). The as processed alloy is characterised by Nb nanoparticles dispersed in the nanocrystalline Cu matrix. The high strength of Cu–Nb alloy is related with the microstructure, i.e. the nanocrystalline grains produce the grain boundary strengthening, while the Nb nanoparticles produce the precipitation strengthening. The grain boundaries and the nanoparticles are also found to influence the electrical conductivity of the alloy considerably.

Site Change of Hydrogen Owing to Lattice Distortion in Niobium Alloys

The site occupancy of hydrogen in Nb alloyed with oversized Ta (atomic radius; \(r_{\text{Nb}}=1.43\) A and \(r_{\text{Ta}}=1.44\) A), Nb0.50Ta0.50H0.021 and Nb0.50Ta0.50H0.053, has been investigated at room temperature by the channelling method utilizing a nuclear reaction 1H(11B,α)αα with a 11B beam of an energy of 2.02 MeV. It was observed that, in both specimens, approximately 100% of H atoms are located at tetrahedral (\(T\)) sites. The half-widths of X-ray reflection lines have been measured for the non-hydrogen-doped Nb0.50Ta0.50 specimens. The half-widths for the Nb0.50Ta0.50 specimens are smaller than those for Nb alloyed with approximately the same concentration of undersized Mo atoms (\(r_{\text{Mo}}=1.36\) A), Nb0.52Mo0.48, and close to the value for pure Nb. This result indicates that, in the Nb0.50Ta0.50 specimens, the lattice is undistorted or very weakly distorted as compared with the Nb0.52Mo0.48 specimens. From the present results on the half-widths and the site occupancy of hydrogen in ...

The dependence of the electron beam remelting parameters on the surface residual stress and hardness of NbSi2 coatings on niobium alloys

NbSi2 coatings were prepared on niobium alloy surface by a fused slurry method. Electron beam remelting process is explored to modify the morphology and the phase composition of the coated layer. After electron beam treatment, the amount of porosity and cracks of the coatings are reduced, and the grain is finer. With accelerating voltage of the electron beam increasing, Nb5Si3 phase can be detected in the NbSi2 coatings. The results of residual stress and surface hardness provide a good evidence to explain the microstructure evolution and surface modification of the coatings.

Effect of internal oxidation on the microstructure and mechanical properties of C-103 alloy

The effect of internal oxidation on the microstructure and mechanical properties of niobium alloy, C-103 has been investigated. Tensile specimens and test coupons of alloy containing different levels of oxygen (100–2500ppm) were characterized with respect to microstructure and mechanical properties. It has been observed that for oxygen contents in the range ∼400–1000ppm, hafnium oxide precipitated exclusively along the grain boundaries, while for oxygen content of ∼2500ppm, precipitates formed both at the grain boundaries and within the grains near surface region of the alloy. The internal oxidation has resulted in embrittlement of the alloy resulting in considerable lowering of strength as well as ductility. Further, the strength and ductility are found to decrease progressively with the increase in average oxygen content of the alloy.