Reactive Mixture Research Articles

Effect of N2 reactive gas flow rate on the structural, optical and wettability properties of silicon carbon oxynitride thin films

In the current research, the silicon carbon oxynitride (SiCON) thin film was deposited on the silicon (Si) substrate by radio frequency (RF) reactive magnetron sputtering method. To comprehensively assess the impact of nitrogen flux rate on thin film characteristics, a suite of advanced analytical methods was utilized. The GIXRD analysis confirmed that the SiCON thin film is amorphous in structure. Additionally, Raman spectroscopy detected no graphite nanocrystals within the film. Ellipsometry measurements further showed that the refractive index of the thin films rises with increased nitrogen flux in the reactive gas, indicating a direct correlation between nitrogen concentration during deposition and optical properties. Based on the designs made with McLeod's software, the amount of reflection can be reduced up to 5.7 % at the wavelength of 4 μm and up to 8.5 % in the wavelength range of 3–5 μm for an optimal thickness thin film. The atomic force microscopy (AFM) examination revealed that the surface roughness of the thin films decreases as the nitrogen flux in the reactive gas mixture increases. Additionally, measurements of the water contact angle (WCA) indicated that the SiCON thin films exhibit a hydrophilic state.

Valorization of Fine-Fraction CDW in Binary Pozzolanic CDW/Bamboo Leaf Ash Mixtures for the Elaboration of New Ternary Low-Carbon Cement

This paper presents the characterization of a binary mixture of construction and demolition waste (CDW) and bamboo leaf ash (BLAsh) calcined at 600 °C (novel mixture) and the study of its pozzolanic behavior. Different dosages in a pozzolan/Ca(OH)2 system were employed. The aim is the valorization of fine-fraction CDW that achieves a more reactive binary mixture and allows an adequate use of CDW as waste, as CDW is a material of limited use due to its low pozzolanic activity. The pozzolanic behavior of the mixture was analyzed using the conductometric method, which measures the electrical conductivity in the CDW + BLAsh/CH solution versus reaction time. With the application of a kinetic–diffusive mathematical model, the kinetic parameters of the pozzolanic reaction were quantified. This allowed a quantitative evaluation of the pozzolanic activity based on the values of these parameters. To validate these results, other experimental techniques were used: X-ray diffraction, thermogravimetry and scanning electron microscopy. Also, mechanical compressive strength assays were carried out. The results show an increase in the pozzolanic activity of binary mixes of CDW + BLAsh for all the dosages used in comparison to the pozzolanic activity of CDW alone. The quantitative assessment (kinetic parameters) shows that the binary mixture CDW50 + BLAsh50 is the most reactive (reaction rate constant of 7.88 × 10−1 h−1) and is superior to the mixtures CDW60 + BLAsh40 and CDW70 + BLAs30. Compressive strength tests show higher strength values for the ternary mixes (OPC + CDW + BLAsh) compared to the binary mixes (OPC + CDW). In view of the results, the binary blend of pozzolans CDW + BLAsh is suitable for the manufacture of future low-carbon ternary cements.

Evaluating the effect of ignition energy on gaseous hydrogen–oxygen detonations

The effect of ignition energy on the cellular structure of hydrogen-oxygen and hydrogen-oxygen-argon detonations was investigated experimentally over a range of initial conditions. The increase in ignition energy resulted in increased detonation propagation velocities, leading to overdriven detonations for most of the reactive mixtures. The detonation cell width decreased for mixtures subjected to higher ignition energy. A substantial reduction in the detonation cell width was observed for mixtures at a lower initial pressure. The coefficient of variation of the measured detonation cell width decreased with ignition energy, indicating greater regularity and uniformity in cellular structure. The observed reduction in the cell width can be attributed to the propagation of an overdriven detonation in the reactive mixtures due to high ignition energy.

Jet ignition characteristics of ammonia-hydrogen passive pre-chamber: Emphasis on equivalence ratio and hydrogen/ammonia ratio

Ammonia-hydrogen blend fuels offer the potential for zero-carbon emissions in internal combustion (IC) engines. To improve combustion performance, considerable attention has been focused on pre-chamber jet ignition technologies. Passive pre-chamber featuring a simple structure can be installed in the spark plug hole without modifying the cylinder head. However, the jet ignition characteristics of ammonia-hydrogen passive pre-chambers are not fully understood, and there is a lack of visualized evidence on how critical parameters (e.g., equivalence ratio and hydrogen/ammonia ratio) impact ignition processes. This work investigated the effects of equivalence ratio and hydrogen/ammonia ratio on ammonia-hydrogen jet ignition characteristics in a rapid compression machine with passive pre-chamber. High-speed photography and instantaneous pressure acquisition were employed to capture detailed ignition and combustion evolutions. Results show that under low hydrogen/ammonia ratio conditions, there exists a combustion regime with noticeable fluctuations in jet penetration, indicating degenerate ignition performance. As the hydrogen/ammonia ratio increases from 0 % to 20 %, the ignition delay time of mixtures in the main chamber is reduced by 70 %, suggesting an improved overall ignition performance. Regarding the equivalence ratio, more pronounced effects on jet ignition and flame propagation are identified under lean-burning conditions. For mixtures at the hydrogen/ammonia ratio of 20 %, as the equivalence ratio increases from 0.6 to 0.8 and from 0.8 to 1.0, the decay rates for 10 %–90 % combustion duration are 82.5 % and 20.6 %, respectively. Besides, with the increase of equivalence ratio, flame initiation is shifted from the jet head to the side surface. The role of hydrogen/ammonia ratio and equivalence ratio is different, with the former modifying mixture reactivity while the latter affecting ignition energy.

NO Formation in Combustion Engines Fuelled by Mixtures of Hydrogen and Methane

The present work addresses the production of nitrogen oxides in ICEs burning hydrogen mixed with methane. A mathematical model that allows the calculation of nitrogen oxide emissions from such combustion was built; this model uses the extended chemical kinetic mechanism of Zeldovich. Numerical simulations were carried out on the production of NO, varying the following variables: proportion of H2 to CH4, the equivalence ratio of the reactant mixture, the compression ratio, and the engine speed. The essential purpose was to assess how NO production is affected by the mentioned variables. The main assumptions were (i) Otto cycle; (ii) instantaneous combustion; (iii) chemical equilibrium reached just at the end of combustion; (iv) the formation of NO only during the expansion stroke of pistons. Results were obtained for various proportions of hydrogen and methane, various equivalence ratios, speeds of rotation, and compression ratios of an engine. In short, the results obtained in the current work show that the lowering of the equivalence ratio leads to a lower concentration of NO; that increasing the compression ratio also lowers the concentration of NO; that NO production occurs until shortly after the beginning of the expansion stroke; and finally, that the NO concentration in the engine exhaust is not very sensitive to the H2/CH4 ratio in the fuel mixture.

Preparation and Characterization of Novel Poly(thiourethane)-Poly(isocyanurate) Covalent Adaptable Networks: Effect of the Catalysts.

Poly(thiourethane)-based covalent adaptable networks are synthesized by reacting a trimer of hexamethylene diisocyanate (Desmodur N3300) containing isocyanurate groups in its structure with 1,6-hexanedithiol. The catalysts evaluated for this process include dibutyltin dilaurate (DBTDL), lanthanum triflate (La(OTf)3), and a thermal precursor of 1,8-diazabicyclo[5.4.0]undec-7-ene (BGDBU). The use of DBTDL results in the initiation of curing upon mixing, while the other two catalysts exhibit a latency period in the reactive mixture, with curing starting at about 90°C. Notably, the use of the lanthanum salt produces an additional minor exothermic reaction at 80°C. This phenomenon corresponds to the trimerization of isocyanates rending isocyanurates, leaving a portion of unreacted thiols. Materials prepared with BGDBU or La(OTf)3 present shorter relaxation times than those prepared with DBTDL. Nevertheless, the materials containing the lanthanum salt do not reach complete relaxation, likely due to the reinforcement of the permanent network through increased isocyanurate content. The formation of isocyanurates produces a stoichiometric imbalance, leaving unreacted thiols. This transforms the exchange process into a dual mechanism involving a dissociative process of thiourethanes to isocyanate and thiol, along with an interchange through thiol attacking the thiourethane group. The materials exhibit good recyclability and self-healing characteristics.

Magnetron carbon structures obtained by high-frequency magnetron sputtering in Argon and Nitrogen

Purpose of research. Creation and characterization of carbon nanostructures by high-frequency magnetron sputtering from a carbon target in argon on a silicon substrate and in a reactive nitrogen environment, obtained on a Ni catalyst buffer layer. Methods. High-frequency magnetron sputtering on a silicon substrate with changes in control parameters: sputtering time power and working gas pressure Ar and N. Research was carried out using X-ray phase analysis, atomic force microscopy and holographic microscopy, Raman scattering. Results. The formation of carbon nanotubes, including single-walled ones, was confirmed by the method of Raman scattering of light along the lines ID 1363 and IG 1564 cm-1, as well as ωRDМ 308 and 227 cm–1. Using atomic force microscopic images, the fractal dimension of the nanofilms was calculated, which indicated their 3D nature. Based on X-ray phase analysis of magnetron nanofilms, the dimensions of the coherence region, texture, microdeformations and interplanar deformation distortions were determined. Conclusion. In carbon magnetron nanofilms, deformations of both signs occur: both compressive (∆a < 0) and tensile (∆a > 0). Carbon magnetron nanofilms are represented, among other things, by single-walled carbon nanotubes, the chirality of which in an argon environment is (6, 6), and in a reactive mixture of nitrogen and argon on a Ni buffer layer (7, 7). It was discovered that in high-frequency magnetron mode, silicon carbide is formed in both inert and reactive environments.

Chemically reactive and aging macromolecular mixtures I: Phase diagrams, spinodals, and gelation

Chemically reactive and aging macromolecular mixtures I: Phase diagrams, spinodals, and gelation

An experimental platform for semi-autonomous kinetic model refinement combining optimal experimental design, computer-controlled experiments, and optimization leads to new understanding of N[formula omitted]O + O

Automated platforms could enable the unprecedented pace required for modeling the countless proposed alternative fuels relevant to future technologies, but existing platforms rely exclusively on automatically generated computational data and lack experimental validation. Here, we introduce an experimental platform for rapid kinetic model refinement that combines optimal experimental design, computer-controlled experiments, and optimization—each of which are tailored in novel ways to form a cohesive platform together. The optimal experimental design considers (1) realistic uncertainties in both experimental conditions and measurements and (2) diverse reactant mixtures that can include “chemical sensitizers,” which are not necessarily reactants in a specified Quantity of Interest (QoI) but sensitize kinetic information relevant to a QoI. Similarly, our High-Throughput Jet-Stirred Reactor (HT-JSR) features (1) rapid multi-species diagnostics that can measure dozens of species within minutes, (2) a flow delivery system that can prepare up to ∼10-component reactant mixtures, and (3) computer-controlled operation of all components. Finally, a post-processing code automatically retrieves data from the instruments, quantifies uncertainties in both experimental conditions and measurements, and produces self-contained files usable for optimization in our MultiScale Informatics software. This platform is demonstrated for the rate constant for N2O + O ⇌ N2 + O2 as the QoI where, unlike for N2O + O ⇌ NO + NO, proposed values at ∼1000 K span ∼5 orders of magnitude yet give equally good agreement with previous experimental data—suggesting that previous experiments fail to constrain the branching ratio of N2O + O. The results show that optimal conditions with more species as both reactants and analytes—particularly NO2 as both a reactant and analyte—enable unambiguous discrimination of the main products of N2O + O. Specifically, the data preclude N2 + O2 as the main products at ∼1000 K—contrary to most recently proposed values.Novelty and significance statementWe introduce a novel experimental platform for rapid kinetic model refinement that combines optimal design, computer-controlled experiments, and optimization—each uniquely tailored to form a cohesive platform. It notably employs high levels of automation, high-throughput multi-species diagnostics, and uniquely diverse reactant mixtures to accelerate scientific discovery. This platform is shown to achieve a goal that no previous experiment has: decipher the main products of N2O + O. This success—attributable to the platform’s unique design principles—demonstrates the effectiveness of this experimental platform as a tool for accelerating scientific discovery and kinetic model development.

Experimental study on hydrogen–oxygen spontaneous ignition limits in supercritical water using a wall-cooled reactor

Hydrogen is a promising fuel for many industrial applications because of its carbon-free properties. The characteristics of hydrogen–oxygen reaction in supercritical water were thoroughly investigated using a newly constructed experimental facility. Three typical temperature profiles were obtained, representing different reaction states: mild oxidation, transition state, and intense combustion. The spontaneous ignition limit was mapped based on 42 experimental data points. The minimum ignition temperature decreases with increasing fuel concentration, reaching as low as 517 °C at a hydrogen concentration of 23.2 mol%. The reliability of the spontaneous ignition limit was confirmed by the first hydrogen hydrothermal flame images obtained. The initial reactor temperature and fuel concentration increase allows the hydrogen–oxygen reaction to transition from mild oxidation to intense combustion. The oxygen excess ratio does not affect the reaction states, but it affects the temperature profile and hydrogen conversion efficiency. The introduction of cooling water changes the concentration and temperature of the reactant mixture in the reactor, thus affecting the stability of the hydrothermal flame.

Implications of Using Scalar Forcing to Sustain Reactant Mixture Stratification in Direct Numerical Simulations of Turbulent Combustion

A recently proposed scalar forcing scheme that maintains the mixture fraction mean, root-mean-square and probability density function in the unburned gas can lead to a statistically quasi-stationary state in direct numerical simulations of turbulent stratified combustion when combined with velocity forcing. Scalar forcing alongside turbulence forcing leads to greater values of turbulent burning velocity and flame surface area in comparison to unforced simulations for globally fuel-lean mixtures. The sustained unburned gas mixture inhomogeneity changes the percentage shares of back- and front-supported flame elements in comparison to unforced simulations, and this effect is particularly apparent for high turbulence intensities. Scalar forcing does not significantly affect the heat release rates due to different modes of combustion and the micro-mixing rate within the flame characterised by scalar dissipation rate of the reaction progress variable. Thus, scalar forcing has a significant potential for enabling detailed parametric studies as well as providing well-converged time-averaged statistics for stratified-mixture combustion using Direct Numerical Simulations in canonical configurations.

Detonation properties and nitrogen oxide production in ammonia–hydrogen–air mixtures

Ammonia is a promising compound for chemical storage of renewable energy produced from non-continuous sources. However, the low reactivity of ammonia requires to use ammonia–hydrogen blends as a fuel for combustion applications. The present study corresponds to a first numerical assessment of the potential of ammonia–hydrogen–air mixtures as reactive mixtures for detonation engine applications. Both ideal and curved detonation models were employed to calculate the detonation properties, entropy production, and NOx production for mixtures with varying amounts of ammonia and hydrogen under a wide range of initial thermodynamics conditions. Interestingly, our calculations show that the entropy production and the amount of nitrogen oxides produced at the Chapman–Jouguet state respectively decreases and increases with the proportion of hydrogen in the ammonia–hydrogen blend. These aspects could have a great impact on engine efficiency and air pollution and should be considered with care. Our results also demonstrate that only mixtures with relatively low amounts of ammonia, i.e., XNH3 lower than 0.25 of the fuel blend, can be employed for detonation engine applications.

Zirconium Oxynitride Thin Films for Photoelectrochemical Water Splitting.

Transition metal oxynitrides are a promising class of functional materials for photoelectrochemical (PEC) applications. Although these compounds are most commonly synthesized via ammonolysis of oxide precursors, such synthetic routes often lead to poorly controlled oxygen-to-nitrogen anion ratios, and the harsh nitridation conditions are incompatible with many substrates, including transparent conductive oxides. Here, we report direct reactive sputter deposition of a family of zirconium oxynitride thin films and the comprehensive characterization of their tunable structural, optical, and functional PEC properties. Systematic increases of the oxygen content in the reactive sputter gas mixture enable access to different crystalline structures within the zirconium oxynitride family. Increasing oxygen contents lead to a transition from metallic to semiconducting to insulating phases. In particular, crystalline Zr2ON2-like films have band gaps in the UV-visible range and are n-type semiconductors. These properties, together with a valence band maximum position located favorably relative to the water oxidation potential, make them viable photoanode candidates. Using chopped linear sweep voltammetry, we indeed confirm that our Zr2ON2 films are PEC-active for the oxygen evolution reaction in alkaline electrolytes. We further show that high-vacuum annealing boosts their PEC performance characteristics. Although the observed photocurrents are low compared to state-of-the-art photoanodes, these dense and planar thin films can offer a valuable platform for studying oxynitride photoelectrodes, as well as for future nanostructuring, band gap engineering, and defect engineering efforts.

Experimental Observation of the Turbulent Jet Ignition for Extending the Lean Combustion Tolerance with Carbon Dioxide Diluted Mixture

ABSTRACT Exhaust Gas Recirculation (EGR) technology is widely employed to reduce NOx emissions from engine combustion, and a major challenge of this technology is to achieve stable ignition and high burning rate at higher EGR dilution ratios. Turbulent jet ignition (TJI) is a reliable ignition resource for improving ignition stability and burning rate. Therefore, in the present work, the ability of pre-chamber turbulent jet ignition for extending the lean combustion tolerance at different EGR dilution ratios was investigated in a constant volume combustion chamber. The experimental results indicate that the methane-fueled pre-chamber and the hydrogen-fueled pre-chamber cannot improve the combustion conditions as expected. On the other hand, when an appropriate quantity of air or oxygen is injected, the EGR tolerance limit can be extended due to a decrease in the EGR concentration and an increase in the mixture reactivity in the pre-chamber. However, at higher EGR dilution ratios, more air or oxygen is required to be injected to increase the mixture reactivity in the pre-chamber, which decreases the equivalence ratio of the mixture in the pre-chamber and limits further extension of the EGR tolerance. For the mixture in the active pre-chamber under EGR dilution, the competition mechanism between EGR concentration and equivalence ratio is the key that affects turbulence intensity and chemical reactivity, thereby determining the ignition and combustion results. During the extension of the EGR tolerance limit, the variations in turbulence and chemistry are accompanied by a series of ignition modes, involving jet re-ignition, re-ignition failure, and misfire. Compared to the passive pre-chamber with an EGR tolerance limit of 18%, the air-assisted pre-chamber extended the limit to 23% and the oxygen-assisted pre-chamber to 30%.

Variable Time-stepping Exponential Integrators for Chemical Reactors with Analytical Jacobians

Chemical combustion problems are known to be stiff and therefore difficult to efficiently integrate in time when numerically simulated. Implicit methods, such as backwards differentiation formula (BDF), are widely considered to be the state-of-the-art methods owing their capability of taking relatively large time-steps while maintaining accurate combustion characteristics. Exponential time integration methods have recently demonstrated the ability to accurately and efficiently solve large scale systems of ordinary differential equations. This study introduces a novel adaptive time stepping exponential integrator named EPI3V. Its performance is measured on spatially homogeneous isobaric reactive mixtures involving three hydrocarbon fuel mechanisms. The full combustion process is simulated using gas compositions with sufficient temperature to obtain auto-ignition. Simulations are run until the steady state is obtained, then a comparison of the computational efficiency and accuracy between a BDF and EPI3V method is made. The novel EPI3V method exhibits comparable computational efficiency to a well-established implementation of the variable time-stepping BDF implicit methods for two of the mechanisms investigated. In certain situations it even demonstrates a slight advantage over the implicit solver. However, in one specific case, the EPI3V shows relative performance degradation compared to the implicit method, but it still converges for this case. These results indicate that exponential time integration methods may be applicable to a larger variety of combustion problems.

Ignition characteristics of ammonia-methanol blended fuel in a rapid compression machine

Ammonia has attracted wide attention in recent years as a carbon-free fuel. However, the low reactivity and combustion inertness of ammonia pose challenges to its applications in engines. Adding highly reactive fuels, such as renewable carbon–neutral methanol, offers a potential solution. To investigate the ignition characteristics of ammonia-methanol blended fuel, ignition delay time measurement and fast gas sampling under stoichiometric conditions with four ammonia blending ratios (20 % ammonia, A20; 40 % ammonia, A40; 80 % ammonia, A80; 95 % ammonia, A95) were carried out on a rapid compression machine under engine-relevant conditions. The effective thermodynamic conditions were 15–25 bar and 810–970 K. The concentrations of fuels NH3, CH3OH, and intermediate species N2O, CO, as well as products N2, CO2 were detected using gas chromatography. Chemical analysis was performed based on simulations using five ammonia-methanol reaction mechanisms. The ignition delay time results showed that the addition of methanol shortened the ignition delay time, with only a little change in ignition delay time beyond 20 % methanol content. Methanol significantly promoted the production of OH radical, leading to the enhancement of the overall mixture reactivity. The sampling results showed different consumption patterns of ammonia and methanol during the ignition process at different mixing ratios. For A80, methanol was consumed from the early stage of the ignition process, while ammonia consumption was negligible in the early stage. Conversely, for A95, ammonia consumption began in the early stage. This suggests that methanol and its intermediate species inhibited the consumption of ammonia, however, ammonia promoted the consumption of methanol. Chemical analysis further revealed that the inhibitory effect of methanol on ammonia consumption was weakened with the decrease of methanol proportion.

MATHEMATICAL MODELING AND EVALUATION OF THERMODYNAMIC PERFECTION OF A CHEMICAL REACTOR

The development of a formalized mathematical model for quantitative and qualitative assessment of the thermodynamic perfection of a gas chemical reactor is described in the article. The reactor was considered as an energy technology system, that is, in the unity of the transformation of matter and energy. Mathematical modeling and evaluation of the thermodynamic perfection of a chemical reactor is generalized to a class of known chemically active gas systems characteristic of ammonia synthesis, sulfur dioxide oxidation, methanol synthesis, nitric oxide oxidation, etc. The equilibrium degree of transformation of a substance and exergy are taken as the determining parameters for modeling and evaluating the thermodynamic perfection of a chemical reactor. These parameters are functions of temperature and reflect the opposing tendencies of the process when it changes, the evaluation of which allows us to quantify the finding of the maximum exergy in the coordinates (E-T) when justifying the optimal temperatures of the process. The model was tested on a specific example of a sulfur dioxide oxidation reactor in the production of sulfuric acid. The public Octave programming environment was used for computer modeling. The developed mathematical model is recommended to be used in the operational preparation and optimization of the initial data for the design of gas reactors. The mathematical model can be supplemented with a mathematical model developed by the authors earlier for quantifying the current profile of the degrees of transformation of the target component of a chemically active reactive gas mixture in the course of its movement in a polytropic tubular reactor of the "pipe in a pipe" type. After testing and setting up the model in practice, it can be used in an automated control system for chemical reactors, including when creating adaptive control systems. For citation: Andreev A.S., Aksenchik K.V. Mathematical modeling and evaluation of thermodynamic perfection of a chemical reactor. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 114-120. DOI: 10.6060/ivkkt.20246705.6964.

Thermal and Physical Properties of CO2-Reactive Binary Mixtures

Thermal and Physical Properties of CO₂-Reactive Binary Mixtures

Propagation instabilities of the oblique detonation wave in partially prevaporized n-heptane sprays

Two-dimensional oblique detonation wave (ODW) propagations in partially prevaporized n-heptane sprays are numerically simulated with a skeletal chemical mechanism. The influences of the droplet diameter and total equivalence on oblique detonation are considered. The initiation length is found to increase first and then decrease with increasing initial droplet diameter, and the effect of droplet size is maximized when the initial droplet diameter is approximately $10\ \mathrm {\mu } {\rm m}$ . As the initial droplet diameter varies, unsteady and steady ODWs are observed. In the cases of unsteady ODWs, temperature gradients and non-uniform distributions of the reactant mixture due to droplet evaporation lead to formation of unsteady detonation propagation, therefore leading to fluctuations in the initiation length. The fluctuations in initiation length decrease as the pre-evaporation gas equivalence ratio increases for the unsteady cases. The results further suggest that the relationship between the evaporation layer thickness along the streamline and the corresponding theoretical initiation length can be used to identify an unsteady or steady ODW in cases with large droplets that evaporate behind an oblique shock wave or ODW under the effects of different initial droplet diameters.

Production and Characterization of Ni0.50 Al0.50 and Ni0.55 Al0.45 Powders by Volume Combustion Synthesis

Nickel aluminide (NiAl) is an essential intermetallic material with a high melting point and excellent high temperature corrosion resistance. It is a solid solution of Ni and Al in 40-61 mol.% Ni range. In this study, Ni0.50Al0.50 and Ni0.55Al0.45 powders were formed by using nickel and aluminum elemental powders through volume combustion synthesis (VCS). MgO powder was utilized as the thermal diluent. According to adiabatic temperature calculations, MgO was added to the reactant mixture in 10-40 vol.% range for preventing the melting and sintering of the formed Ni0.50Al0.50 and Ni0.55Al0.45 particles. After VCS, the products were ground into powder form and leached in 3M HCl solution in order to remove the MgO particles. After VCS, the samples which were obtained with 10 - 30 vol.% MgO addition were quite hard and difficult to grind. This indicated the partial sintering of the formed particles. It was relatively easier to grind into powder form the samples which contained 40 vol.% MgO. Therefore, it was determined that the most suitable MgO ratio for the formation of Ni0.50Al0.50 and Ni0.55Al0.45 powders was 40 vol.%. Formed powders were mostly in 5-100 µm particle size range. The formation of single phase pure powders was confirmed by the XRD analyses. A shift of about 0.1 degrees to higher 2-theta values was determined in the XRD peaks of the Ni0.55Al0.45 powder as compared to the Ni0.50Al0.50 phase, after annealing the powders. The results were in agreement with the crystallographic data.