Formation Of ZrN Research Articles

Synthesis of ZrN–SiO2 core–shell particles by a sol–gel process and use as particle‐based structured coloring material

AbstractZrN–SiO2 core–shell particles were prepared, where the ZrN core nanoparticles and SiO2 shell were designed to exhibit localized surface plasmon resonances (LSPRs) and structural coloring. The heating of ZrO2 nanoparticles with Mg3N2 under a nitrogen gas flow produced ZrN nanoparticles with a diameter in the range of 10–20 nm. The dispersion of ZrN nanoparticles in water exhibited an absorption maximum at approximately 700 nm owing to LSPRs. An SiO2 shell was formed on the ZrN nanoparticles using a sol–gel process. Scanning transmission electron microscopy confirmed the formation of ZrN–SiO2 core–shell particles containing ZrN particles with a diameter of approximately 10 nm. The SiO2 shell thickness was controlled by varying the reaction time to form SiO2. The use of particles as a structural component of a structural color material owing to the high uniformity of the size of obtained core–shell particles was investigated. The obtained ZrN–SiO2 core–shell particles were arrayed on a glass substrate using a layer‐by‐layer method. The particle‐stacked film of the ZrN–SiO2 core–shell particles exhibited the maximum reflection depending on the particle size of the SiO2 shell.

Synthesis, Characterization and Dissolution behavior of Nitrides of U-Zr and U-Pu-Zr metallic alloy fuels for Aqueous reprocessing

The aqueous based PUREX process is an alternate choice to pyro-reprocessing of metallic alloy fuels (U-Zr/U-Pu-Zr). Direct dissolution of metallic alloy fuels in a nitric acid medium is not feasible due to vigorous reaction exhibited by the alloys when exposed to this medium. Conversion of metallic alloys into their oxides is a challenging method due to poor dissolution of oxides in nitric acid. Excellent dissolution of nitrides compared to oxides of metallic alloy fuels lead to exploit the nitride route for aqueous reprocessing. Hence, a novel method was adopted to prepare the nitrides of unirradiated U-Zr and U-Pu-Zr alloys via hydridation using UH3, as source-cum-getter instead of hydrogen cylinder. In this context, nitrides of unirradiated U-Zr/U-Pu-Zr metallic alloys were prepared by nitridation via hydridation. Initially, nitrides of U and Zr metals were synthesized and the formation of ZrN and U2N3 and UN phases were confirmed by powder X-ray diffraction measurements. Subsequently, nitrides of unirradiated U-Zr and U-Pu-Zr alloys were synthesized and characterized by X-ray diffraction, scanning electron microscopy and particle analyzer. The dissolution behavior of nitrides of Zr, U, U-Zr and U-Pu-Zr alloys were examined in nitric acid (12 M) medium under reflux conditions at 383 K for 8 h. The present study highlights the potential of the nitride route for efficient dissolution of actinides (U and Pu) and it is very important to develop flow sheets for the aqueous reprocessing of metallic alloys fuels.

High-temperature degradation behavior of PEO-coated ZIRLO alloy in N2 and N2+steam environments at 900 and 1000 °C

A compact oxide coating of ∼10 μm thick on ZIRLO alloy was fabricated by plasma electrolytic oxidation (PEO). The morphologies, compositions, phase constituents before and after exposures in N2 and N2+steam environments at 900 and 1000 °C were characterized. The PEO coating greatly enhanced the corrosion resistance of ZIRLO alloy in the N2+steam atmosphere at 900 and 1000 °C. The kinetic curves transformed from parabolic behavior for bare alloy and exponential behavior for PEO-coated alloy at pre-transition stage to linear at post-transition stage, due to the formation of ZrN and its re-oxidation.

Temperature‐dependent mechanical and oxidation behavior of in situ formed ZrN/ZrO2‐containing Si3N4‐based composite

AbstractIn this work, Si3N4 and Zr(NO3)4 were used as raw materials to prepare ZrN/ZrO2‐containing Si3N4‐based ceramic composite. The processing, phase composition, and microstructure of the composite were investigated. Hardness and fracture toughness of the ceramics were evaluated via Vickers indentation in Ar at 25°C, 300°C, 600°C, and 900°C. During spark plasma sintering, Zr(NO3)4 was transformed into tetragonal ZrO2, which further reacted with Si3N4, resulting in the formation of ZrN. The introduction of ZrN enhanced the high‐temperature mechanical properties of the composite, and its hardness and fracture toughness reached 13.4 GPa and 6.1 MPa·m1/2 at 900°C, respectively. The oxidation experiment was carried out in air at 1000°C, 1300°C, and 1500°C for 5 h. It was shown that high‐temperature oxidation promoted the formation and growth of porous oxide layers. The microstructure and phase composition of the formed oxide layers were investigated in detail. Finally, it was identified that the obtained composite exhibited a higher thermal diffusivity than that of monolithic Si3N4 in the temperature range of 100°C–1000°C.

Impact of PSI-KIT Nitriding model on hypothetical Spent Fuel Pool accident simulation

In past years the Paul Scherrer Institute (PSI, Switzerland) and the Karlsruhe Institue of Technology (KIT, Germany)) collaborated to develop a model to account for the active role of nitrogen in the air oxidation of a Zircalloy cladding. The “PSI-KIT Nitriding Model for Zirconium based Fuel Cladding” model was implemented at PSI into PSI-MELCOR 1.8.6.In order to make a preliminary evaluation of the effect of the new model on the evolution of full-scale spent fuel pool accidents, one spent fuel pool event was analyzed using the PSI research version of PSI-MELCOR 1.8.6, which includes the nitriding model. To adapt an existing input deck for the calculations, a sensitivity study was conducted to find an optimal nodalization for the analyses. The nitriding model results were compared to those calculated with the MELCOR 1.8.6-PSI without the new nitriding model.The results demonstrate the effect of the nitriding reactions in spent fuel pool accident progression. Moreover, they confirm the impact of ZrN formation during cladding oxidation in air when the oxidation reactions lead to oxygen starvation inside the fuel assemblies. The nitriding reaction led to higher chemical heat generation during the accident and to an earlier failure of the cladding than when the effect of nitrogen reactions was not considered.It should be noted that the nitriding model, as implemented in the PSI version of MELCOR 1.8.6 has not yet been conclusively validated. Thereby the results presented in this paper should be treated as a preliminary demonstration of the capabilities of the model.

Reactive metal additive manufacturing: Surface near ZrN–metallic glass composite formation and mechanical properties

ZrN formation in a Zr-based bulk metallic glass is observed after processing using reactive laser powder bed fusion. Two processing routes employing nitrogen as a reactive process gas are explored: (1) Standard inert processing in argon followed by reactive remelting in nitrogen and (2) reactive processing in nitrogen. Incorporation of nitrogen is depth-dependent and both approaches result in a dispersion of ZrN nanocrystals in the amorphous matrix close to the surface. The process parameters can be adjusted to control the volume fraction of crystalline phases formed. Hence, it is shown that reactive additive manufacturing can be utilised to form bulk metallic glass–ceramic composites in surface near regions. Thereby we demonstrate that the reactive gas atmosphere utilised during additive manufacturing enables local tailoring of structure, composition, and mechanical properties in the vicinity of the surface.

Microstructure and Mechanical Properties of ZrCuSiN Coatings Deposited by a Single Alloy Target

Recently, research has been conducted on nanocomposite thin films containing new additive elements in ZrN. In this paper, a method for depositing ZrCuSiN nanocomposite coatings using a ZrCuSi single target is presented. The ZrCuSi target that was used to easily deposit a ZrCuSiN coating in a mixed gas atmosphere (Ar + N2) was produced by a simple arc melting method (casting process). The effect of the nitrogen content was investigated by depositing a ZrCuSiN coating using alloy targets at various nitrogen gas flow rates (2, 4, 6, and 8 sccm). X-ray diffraction analysis of the ZrCuSiN coatings revealed a ZrN structure with a preferable orientation (200). As the nitrogen flow rate increased, the formation of o-Zr3N4 was dominant in the ZrN formation. A nitrogen gas flow rate of 4 sccm produced a coating with optimal ZrN and a-Si3N4 coordination and maximum hardness (41 GPa). Reciprocal friction tests of all coatings and uncoated carburized SCM415 steel in a 5W30 lubrication atmosphere demonstrated that the 4 sccm coating had the lowest friction coefficient (0.002). Therefore, our method has the potential to be an alternative surface coating technique for materials used in automotive engine parts and various other wear protection applications.

Local atomic structures and degradation behaviors of Ti1 − xZrxN coatings under laser thermal shock

The degradation behaviors of Ti1−xZrxN coatings due to repeated thermal stress were investigated in terms of local atomic structural changes according to Zr substitution. The coating specimens deposited by TiZr compound targets with different Zr wt% ratios had the same growth orientations of TiN and ZrN, namely (111), (200), and (220). The lattice parameter and microhardness increased as the Zr ratio increased, which was attributed to the lattice distortion and increase in texture degree of the crystallites in the coating layer by Zr substitution to Ti sites. The coating with 10wt% of Zr showed spalling of the coating layer after repeated thermal shocks, and delamination was suppressed as ZrN formation increased. It was expected that the interatomic distance between (Ti, Zr)-N would decrease as Zr substitution to Ti sites increased, indicating an atomic diffusion path. The depth profiles revealed that the diffusion distance of the coating (Ti, Zr, N) and the substrate (Fe, Cr) elements decreased according to the Zr substitution.

Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN.

Thermal shock behaviors of Ti1−xZrxN coatings by accelerated test based on pulsed laser ablation

The degradation behaviors of Ti1−xZrxN coatings on SUS304 were investigated through an accelerated test method using a pulsed laser to induce thermal shock. The accelerated test was designed based on the Arrhenius model, and the changes in surface roughness were measured to determine the failure of the coating specimens. The predicted lifetimes obtained by a statistical analysis of the failure time data were increased by a factor of ~1.5 according to the increase in the Zr ratio from 10 to 50wt%. The increase of the lattice parameters and hardness for the as-deposited specimens indicated lattice volume expansion and distortion according to the Zr addition, respectively. Depth profiles for the coating (Ti, Zr) and the substrate (Fe, Cr) atoms revealed that the atomic diffusion distance by laser ablation decreased with lattice distortion. Delamination of the coating layer was only observed in the specimen with 10wt% of Zr after repeated thermal shock. The coating thickness decreased with surface cracks and was suppressed in the specimens with 30 and 50wt% of Zr by the increase of ZrN formation.

On the mechanism of zirconium nitride formation by zirconium, zirconia and yttria burning in air

The combustion of Zr and (Zr+ZrO2) powdery mixtures in air was accompanied by major ZrN stabilization. The synthesis of cheap ZrN with the high yield in air was facile and utile. The influence of Y2O3 additive on the content of ZrN the solid combustion products (SCP) was investigated. The reagents and SCP were analyzed by BET, DTA–TGA, XRD, SEM and EDS. Burning temperature was measured by thermal imager. The yield of ZrN in the SCP has been varied by the time regulation of the combustion process. The burning samples were quenched at a certain time to avoid the re-oxidation of the obtained ZrN by oxygen. The quenching of the burned (Zr+ZrO2) samples with the Y2O3 additive was allowed increasing the ZrN yield in SCP up to 66wt%. The chemical mechanism of ZrN formation in air was discussed and the probable source of ZrN massive formation is suggested.

Interfacial stability and diffusion barrier ability of Ti1−xZrxN coatings by pulsed laser thermal shock

Interfacial characteristics and diffusion behavior of Ti1−xZrxN coatings under thermomechanical stress were investigated, in terms of morphologies and depth profiles, after pulsed laser ablation. TiZrN coatings were deposited on SUS304 substrates, using TiZr compound targets with Ti:Zr wt.% ratio of 90:10, 70:30, and 50:50. XRD patterns showed the same growth orientations of TiN and ZrN as (111), (200), and (220) in all coating specimens. The lattice parameters and the microhardness increased through solid solution with the substitutions of Zr to the Ti sites. Spalling of the coating layer was observed in the specimen of 10% wt.% Zr ratio after laser ablation. Delamination was suppressed as the substitution of Zr increased, and it could be attributed to the formation of ZrN which can promote heat transfer in the coating layer faster than TiN. SIMS depth profiles revealed that the diffusion distance of the coating (Ti, Zr) and the substrate (Cr, Fe) atoms decreased, due to diffusion path reduction by the solid solution effects.

A study of the microstructure evolution of hard Zr–B–C–N films by high-resolution transmission electron microscopy

Pulsed reactive magnetron sputtering was used to deposit Zr–B–C–N films as a function of the N2/Ar ratio in the plasma. The microstructure evolution of the films was studied by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and nanoindentation. Zr–B–C–N films with a chemical composition (in at.% without 1–2 at.% H and<1 at.% O and Ar) of Zr61B27C6N3, Zr41B30C8N20, Zr26B26C5N42 and Zr24B19C6N49 were produced using a nitrogen fraction of 0%, 5%, 10% and 15%. The Zr61B27C6N3 film consists of fcc B-rich Zr(B,C,N) nano-columnar structures concealed by an amorphous matrix. The fcc B-rich Zr(B,C,N) columns exhibit a preferred orientation with their [111] parallel to the film growth direction. The Zr41B30C8N20 film possesses the highest hardness and consists of nano-needle structures (∼40nm long and ∼10nm wide) separated by amorphous boundaries. The nano-needles have a face-centered cubic (fcc) structure and are composed of ZrN and/or Zr(B,C,N) nano-domain structures (∼2nm) that are semi-coherently joined via Zr–N monolayer interfaces. The Zr26B26C5N42 film is composed mainly of refined crystalline ZrN nano-needle structures (∼2nm) embedded in an amorphous structure, and the Zr24B19C6N49 film has an amorphous-like structure. In the Zr41B30C8N20 film, the formation of ZrN and/or Zr(B,C,N) nano-domain structures, semi-coherently joined via Zr–N monolayer interfaces within the nano-needle structures, play a critical role in achieving high hardness and modulus. The annihilation of such a structure and the introduction of additional amorphous structure into the films by changing the N/Zr ratio via varying the N2 fraction in the gas mixture result in a significant decrease in the mechanical properties.

Corrosion study of ZrN deposited on 304L stainless steel

The ZrN films were deposited on type 304L stainless steel using dc magnetron sputtering technique at different substrate temperatures from room temperature up to 600°C. The ZrN films have been analysed for their composition, microstructure, surface morphology and their corrosion resistance in different nitric acid concentrations. The grazing incidence angle X-ray diffraction analysis showed the texture orientation of (111) or (200) plane depending on the substrate temperature. The atomic force microscopy analysis reveals the formation of ZrN agglomerates with no visible cracks or pores. However, increase in grain size (10–20 nm) and roughness (10–50 nm) with increase in the substrate temperature was observed. The potentiodynamic polarisation and electrochemical impedance spectroscopy results indicated that the corrosion resistance of different ZrN films, although high in 1 mol L−1 HNO3, suffered a marked decrease in 8 mol L−1 HNO3 concentration.

Influence of chemical composition and deposition conditions on microstructure evolution during annealing of arc evaporated ZrAlN thin films

The influence of substrate bias and chemical composition on the formed microstructure and resulting hardness of arc evaporated Zr1−xAlxN films in the compositional span 0.12≤ x ≤0.74 is investigated. A cubic ZrAlN phase is formed at low aluminum contents (x ≤ 0.38) whereas for a high Al-content, above x = 0.70, a single-phase hexagonal structure is obtained. For intermediate Al-contents, a two-phase structure is formed. The cubic structured films exhibit higher hardness than the hexagonal structured ones. A low bias results in N-rich films with a partly defect-rich microstructure while a higher substrate bias decreases the grain size and increases the residual stress in the cubic ZrAlN films. Recrystallization and out-diffusion of nitrogen from the lattice in the cubic ZrAlN films takes place during annealing at 800 °C, which results in an increased hardness. The cubic ZrAlN phase is stable to annealing temperatures of 1000 °C while annealing at higher temperature results in nucleation and growth of hexagonal AlN. In the high Al-content ZrAlN films, formation of ZrN- and AlN-rich domains within the hexagonal lattice during annealing at 1000 °C improves the mechanical properties.

Laser Remelting of Zirconia Surface: Investigation into Stress Field and Microstructures

Investigation into the laser remelting of zirconia surfaces in a nitrogen gas environment is carried out. The thermal stress fields during and after the laser treatment process are predicted numerically. The microstructural and morphological changes in the laser-treated region are examined using optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The residual stresses are determined using the XRD technique. It is found that the residual stress predicted remains high along a depth of 50 µm below the laser-treated surface. The predictions of residual stress agree well with the XRD data. A fine dendritic structure is formed in the vicinity of the surface, which contributes to the surface hardness. In addition, transformation of t-ZrO2 to c-ZrO2 at high temperature is accompanied by the formation of ZrN in the surface vicinity.

Thermal stability and mechanical properties of arc evaporated ZrN/ZrAlN multilayers

ZrN 1.20/Zr 0.44Al 0.56N 1.20 multilayer films as well as ZrN 1.17 and Zr 0.44Al 0.56N 1.20 films were deposited by reactive arc evaporation on WC–Co substrates. Samples were post-deposition annealed for 2 h at 800–1200 °C. As-deposited and heat treated films were characterized by scanning transmission electron microscopy, X-ray diffraction and nanoindentation. The thermal stability was studied using a combination of differential scanning calorimetry, thermogravimetry, and mass spectrometry. The as-deposited Zr 0.44Al 0.56N 1.20 film exhibits a nanocomposite structure of cubic and wurtzite ZrAlN. During annealing, the formation of ZrN- and AlN-rich domains results in age hardening of both the Zr 0.44Al 0.56N 1.20 and the ZrN/ZrAlN multilayers. The age hardening is enhanced in the ZrN/ZrAlN multilayer due to straining of the ZrAlN sublayers in which a maximum hardness of 31 GPa is obtained after annealing at 1100 °C.

ChemInform Abstract: Preparation of a Soluble Precursor by an Aminolysis Reaction of Zr(NEt2)4 and Its Pyrolytic Conversion into ZrN.

A novel soluble precursor with a Zr-N-Zr backbone structure was prepared by an aminolysis reaction of Zr(Net2)4 with PriNH2. Pyrolysis of the precursor under NH3-N2 atmospheres led to the formation of ZrN as a main crystalline phase with a ceramic yield of 45.2%. Aggregated particles consisting of very minute particles with diameters of 50-300 nm were obtained.

Study of carbon concentration on the nanostructural and corrosion properties of Zr(C, N)/ss304 films

The improvement of corrosion resistance of ZrN 1- x C x films (0 ≤ x ≤ 1) on AISI stainless steel (ss) 304 is studied as a function of methane flow rate introduced into mixture of argon and nitrogen gases (Ar + N 2 ). The films were deposited using ion beam sputtering technique at 400 °C and their corrosion resistance has been investigated via electrochemical test using 0.5 M H 2 SO 4 solution. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were performed to study the micro and nano-structures of the films. Film stoichiometry was determined by Rutherford backscattering (RBS) technique using SIMNRA code. An average grain size of 7 nm was calculated for deposited films using Scherrer's formula. X-ray diffraction results showed the presence of a transition crystalline phase from ZrN to ZrC phase corresponding to the formation of ZrN 1- x C x crystalline phase. The electrochemical test revealed that the film corrosion resistance increased with increasing x values. Furthermore, micrographs obtained by SEM did not indicate any damage on the sample surface due to corrosive agent attacks for x > 0.6.

2.45 GHz microwave sintered Si3N4-ZrO2 composites

An investigation has been made of the use of 2.45 GHz microwave energy to sinter Si 3 N 4 -ZrO 2 (4 mol% Y 2 O 3 stabilized) composites with 5 mass% MgO as a densifying aid at 1600°C to avoid the formation of ZrN. XRD phase analysis showed the presence of ZrN in all the sintered samples. Higher temperature developed within the specimen favored the reaction between Si 3 N 4 and ZrO 2 to form ZrN. SEM microstructures revealed elongated β-Si 3 N 4 grains with high aspect ratio. Indentation fracture toughness of the composites increased with increasing weight fraction of ZrO 2 . Cracks were propagated intergranularly through Si 3 N4/ZrO 2 interfaces and transgranularly through ZrO 2 grains with many microcracks in the process zone of the main crack. The results indicated that the dominant toughening mechanisms operating were crack deflection and bridging in the case of 0 mass% ZrO 2 and 10 mass% ZrO 2 whereas crack deflection, bridging and microcrack toughening were observed when the amount of ZrO 2 in the composites increased to 25 and 40 mass%.