ZrN Phase Research Articles

Wear and Corrosion Resistance of ZrN Coatings Deposited on Ti6Al4V Alloy for Biomedical Applications

Zirconium nitrides films were synthesized on Ti6Al4V substrates at a bias voltage of −50 V, −80 V, −110 V and −150 V by the direct current (DC) reactive magnetron sputtering technique. The as-deposited coatings were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The wear and corrosion resistance of the obtained ZrN coatings were evaluated to determine the possibility for their implementation in modern biomedical applications. It was found that the intensity of the diffraction peak of the Zr-N phase corresponding to the (1 1 1) crystallographic plane rose as the bias voltage increased, while the ZrN coatings’ thickness reduced from 1.21 µm to 250 nm. The ZrN films’ surface roughness rose up to 75 nm at −150 V. Wear tests showed an increase in the wear rate and wear intensity as the bias voltage increased. Corrosion studies of the ZrN coatings were carried out by three electrochemical methods: open circuit potential (OCP), cyclic voltammetry (polarization measurements) and electrochemical impedance spectroscopy (EIS). All electrochemical measurements confirmed that the highest protection to corrosion is the ZrN coating, which was deposited on the Ti6Al4V substrate at a bias voltage of −150 V.

Effect of pulse laser nitriding on the superheated steam corrosion behavior of Zr alloy

Zirconium (Zr) alloy fuel cladding is exposed to harsh environments such as high temperature and high pressure for a long time. Surface modification technology can effectively improve its high-temperature oxidation resistance. In this work, pulse laser nitriding technology was used to perform laser nitriding treatment on Zr alloys at different laser energies. The effect of different energy levels of laser nitriding treatments on the superheated steam corrosion resistance of Zr alloys was studied. First-principles was used to reveal the mechanism of how the diffusion layer improves the performance of Zr alloys in resisting superheated steam corrosion after nitriding treatment. Results indicate that the surface of Zr alloys treated with laser nitriding exhibits a molten feature. When the laser energy is 100 mJ, N mainly exists in the form of a diffusion layer in the Zr alloy substrate. As the laser energy rises to 200 mJ and above, the ZrN phase is generated. After 1000 h of superheated steam corrosion, the corrosion weight gain of the 100 mJ sample was reduced by approximately 50 % compared to the Zr alloy. The corrosion weight gain of the 400 mJ sample increased by approximately 12 %. The presence of the ZrN phase accelerates the oxidation degradation rate of Zr alloy. When N atoms exist as a diffusion layer, the transition from tetragonal zirconia to monoclinic zirconia can be suppressed. First-principles calculations showed that when O and N atoms coexist in the Zr alloy substrate, their binding performance with surface O is significantly decreases, thus further improving the 100 mJ sample's resistance to superheated steam corrosion.

Wear-resistant ZrN/Ti functionally graded coating prepared on TA18 alloy by double glow plasma alloying

Despite being an excellent structural material, α-Ti alloy is with low shear deformation resistance, resulting in susceptibility to friction damage during service, and limits its further application. A wear-resistant ZrN/Ti functionally graded coating (FGC) was prepared on TA18 alloy by double glow plasma alloying technique in this paper. The morphology, phase structure, mechanical properties and wear behavior of ZrN/Ti FGCs were studied and analyzed. The results proved that a gradient structure formed in the coating: the topmost layer was ZrN ceramic phase, in the transition layer were ZrN, TiN, and Ti2N phases, and in the inner layer was α-Ti phase. The coating was dense and metallurgically bonded with the substrate. It exhibited better load bearing capacity and fracture toughness. Upon conclusion of wear tests under different loads, only slight damage was observed on the coating. The main wear form of the coating was delamination wear, and the ZrN layer on the topmost surface was not worn through. More specifically, the Zr pre-diffusion treatment was used to increase the content of ZrN in the transition layer, reducing the unfavorable Ti nitride phase formed. Therefore, the stress concentration caused by the difference in elastic modulus between the different phases was relieved. Thus, ZrN/Ti FGC with continuous properties and good wear resistance was successfully synthesized.

Effects of Ni content on microstructure and fracture toughness of the ZrN/TiNiN nano-multilayer films

ZrN and TiNiN nanolayers are alternately deposited on silicon substrate by magnetron sputtering. A series of ZrN/TiNiN nano-multilayer films with different Ni contents are prepared by varying the Ni:Ti volume ratio of the targets. The effects of Ni content on the microstructures and mechanical properties of ZrN/TiNiN nano-multilayer films are studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nanoindentation instrument. The results show that with the increase of Ni content, the crystallization degree of ZrN phase first increases and then decreases. Besides, the hardness, elastic modulus and toughness of the films also increase first and then decrease with Ni content increasing. When Ni:Ti= 1:24, the ZrN/TiNiN nano-multilayer films obtain the highest hardness, elastic modulus and fracture toughness, which are 23.2 GPa, 317.8 GPa and 2.29 MPa·m1/2, respectively. This is mainly attributed to the best columnar crystal growth of the ZrN/TiNiN nano-multilayer film. The TiNiN layer changes into face centered cubic structure under the template of ZrN layer, and grows in coherent epitaxy with ZrN layer.

Electronic and elastic properties of metastable Zr3N4: a joint experimental and theoretical study.

The electronic structures and elastic properties of metastable Zr3N4 phases have been investigated using the first-principles calculations with the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional, in comparison with those of the stable ZrN phase. All three metastable Zr3N4 phases (including orthorhombic, spinel and Th3P4-type phases) are found to be semiconducting with bandgaps of 1.72-1.94 eV. In particular, the computationally indirect bandgap of 1.72 eV of orthorhombic Zr3N4 is consistent with the experimental value of 1.8 eV. The detailed analyses of the electronic structures reveal that the change of electrical conductivity from metallic ZrN to semiconducting Zr3N4 is mainly due to the electron transfer from Zr to N atoms, which weakens the Zr-Zr interactions and reduces the proportion of metallic bonding. In addition, the elastic properties of Zr3N4 and ZrN phases have been calculated. The theoretical hardness values of ZrN and orthorhombic Zr3N4 are 18.06 and 6.98 GPa, respectively, agreeing well with the experimental values of 19.26 and 7.90 GPa. This work may further promote the understanding of the promising Zr-N material system.

Effect of the C/N ratio modification on the corrosion behavior and performance of carbonitride coatings prepared by cathodic arc deposition

This study focuses on investigating carbonitride coatings, specifically CNTi-(Zr, ZrNb, and ZrSi), as promising candidates for enhancing the durability and efficiency of Ti6Al4V materials used in nuclear fusion technology. X-ray diffraction analysis identified distinct phases, including TiN, ZrN, ZrC, and TiC. The corrosion studies showed complete degradation of the TiN, ZrC, and ZrN phases in the TiZrCN coating after tests, while the TiC phase exhibited relative stability. The surface morphologies and elemental mapping analysis demonstrated the loss of homogeneity in element distribution after corrosion process. The addition of Si and Nb elements into TiZrCN significantly influenced the coatings' corrosion behavior, with breakaway corrosion observed in CNTi- (Zr and ZrSi) coatings and localized corrosion in CNTi-(ZrNb) coatings. Notably, the CNTi-(ZrSi) coating formed an oxide phase in the presence of NaCl, whereas the CNTi-(ZrNb) coating exhibited continuous resistance and a low corrosion rate. Irradiation was carried out for the generation of active isotopes, showing that no radioactive isotopes were formed in any of the investigated samples.

An Assessment of the Bactericidal and Virucidal Properties of ZrN-Cu Nanostructured Coatings Deposited by an Industrial PVD System

Pathogenic microbes, such as bacteria and viruses, can spread quickly via contaminated surfaces. Most of these pathogenic microorganisms can survive on surfaces for a long time. Touching these surfaces can lead to the transmission of the microorganisms to the human body and cause serious illnesses. ZrN-Cu coatings containing different amounts of Cu were deposited using an industrial PVD system, and their ability to inhibit bacteria and inactivate the SARS-CoV-2 virus was tested. Microstructural studies showed the formation of two distinct ZrN and Cu phases when Cu content was sufficiently high. Hardness and elastic modulus were inversely proportional to the Cu content. The coatings showed outstanding bactericidal properties against Escherichia coli and Pseudomonas aeruginosa, especially when Cu content was more than 12 at.% and exposure time was longer than 40 min. The coatings, however, did not exhibit any significant virucidal properties. Good mechanical properties, along with excellent antibacterial effects, make these coatings suitable for use as self-sanitizing surfaces on objects that people regularly touch and that are prone to bacterial contamination. Their use would thus allow for only minimal transmission or multiplication of bacteria, and the treated surface would not serve as another source of infection.

A functionally graded coating from ZrN to Ti: Experimental characterization, erosion behavior and design concept

In functionally graded coatings (FGCs), the elemental composition, or structure, within a coating changes progressively as a function of depth, allowing for the property gradual transition from coating to matrix. One method for preparing FGCs with continuous component distribution is double glow plasma alloying (DGPA) technique. In this work, a sandwich-like ZrN/Ti FGC was fabricated, consisting of a single ZrN ceramic layer on the topmost layer, a ceramic/metal intermediate transition layer, and a metallic Ti layer in the inner layer. The transition layer derived from atom diffusion made the metallurgical bonding for entire coating, which endowed the coating with high adhesion. The erosion tests exhibited that the coating improved the erosion resistance of substrate effectively, which was attributed to the high hardness and elastic work consumption. Besides, the transition layer with coexistence of metal and ceramic phases deflected the radial crack propagation, and thus increased the plastic work consumption. The thermodynamic calculation using two sub-lattice and Miedema models showed that controlling the Zr diffusion thickness over N diffusion thickness can increase the ZrN phase content and reduce the unfavorable TiN and Ti2N phase. The experiment results and design concept described herein for characterizing FGCs can be used to promote the understanding and design of other FGCs.

From design to characterization of zirconium nitride/silicon nitride nanocomposites

ZrN/Si3N4 nanocomposites have been prepared by chemically crosslinking two polysilazanes with a zirconium-based compound and subsequent heat-treatment at temperatures ranging from 1000 to 1600 °C. The polymer synthesis has been systematically investigated using FT-IR, solid-state NMR, and elemental analyses. Then, the pyrolysis under ammonia at 1000 °C trigering the thermo-chemical polymer-to-ceramic conversion was examined, leading to X-ray amorphous ceramics with yields governed by the chemistry of the neat polysilazane. Investigations of the structural evolution of the single-phase amorphous ceramic network above 1000 °C by X-ray diffraction and Raman spectroscopy pointed out that the ZrN phase already segregated at 1400 °C and formed highly crystalline ZrN/Si3N4 nanocomposites at 1600 °C. HRTEM investigations validated the unique nanostructural feature of the nanocomposites made of ZrN nanocrystals distributed in α- and β-Si3N4 phases. Our preliminary investigations of the optical properties showed that these structural changes allowed tuning the optical properties of ZrN/Si3N4 nanocomposites.

Fabrication of (Zr,Ti)B2–ZrN–BN composites through reactive spark plasma sintering of ZrB2 and TiN

Mechanical properties and sintering behavior of additive-free and TiN-doped ZrB2 ceramics were studied. Reactive spark plasma sintering method was applied for manufacturing of ceramics at 1850 °C for 6 min under 40 MPa. The impact of TiN addition on the microstructure evaluation, densification, and mechanical feathers was investigated. A porous monolithic ZrB2 with a relative density of 76.5 % was manufactured, while the introduction of 5 wt% TiN resulted in enhancement of relative density to 93.1 %. The formation of (Zr,Ti)B2 solid solution and in-situ h-BN and ZrN phases was proven by microstructural assessments and X-ray diffractometry. Minimizing the grain growth and improving the densification, as the results of TiN addition, led to enhancement in mechanical properties. The values of bending strength, fracture toughness, and Vickers hardness boosted from 187.6 MPa, 1.9 MPa.m½, and 10.1 GPa for additive-free ZrB2 to 606.5 MPa, 4.5 MPa.m½, and 18.8 GPa for (Zr,Ti)B2–ZrN–BN composite.

Biocompatibility and electron microscopy studies of epitaxial nanolaminate (Al0·5Ti0.5)N/ZrN coatings deposited by Arc-PVD technique

The ability to combine layers with high mechanical strength and additional physicochemical properties, such as biocompatibility, makes the use of multilayer coatings attractive for various applications. The transition from single layer to nanolaminate architecture can improve the mechanical performance of the coatings by increasing the number of interfaces and decreasing the modulation period of the layers. The microstructural study of the nanolaminate (Al 0·5 Ti 0.5 )N/ZrN coating with a modulation period λ of ≃ 20 nm was carried out using the TEM-HRTEM method. It was found that the coatings of (Al 0·5 Ti 0.5 )N/ZrN series consisted of two phases: the fcc-(Ti,Al)N solid solution obtained by isomorphic substitution of Ti atoms with Al ones in the TiN crystal lattice and the cubic ZrN phase. ZrN layers had a high texture structure with [111]-preferred growth texture and made a dominant effect on the nucleation and growth of (Al 0·5 Ti 0.5 )N layers. The epitaxial growth process was the most pronounced for fcc-(Ti,Al)N (111)||fcc-(ZrN) (111) and fcc-(Ti,Al)N (200)||fcc-(ZrN) (200) grains. Finally, the new coating demonstrated high biocompatibility, failure to toxicity and supported U2OS osteogenic cells proliferation within 7 days of cultivation.

AlN with high strength and high thermal conductivity based on an MCAS-Y2O3-YSZ multi-additive system

The additive composition of an AlN ceramic substrate material was optimized to achieve high strength and thermal conductivity. MgO-CaO-Al2O3-SiO2 (MCAS) glass and Y2O3 were used as basic additives for improved sintering properties and thermal conductivity, thereby allowing for AlN to be sintered at a relatively low temperature of 1600 °C without pressurization. Yttria-stabilized zirconia (YSZ) was added (0–3 wt%) to further improve the strength of the AlN ceramic. YSZ and Y2O3 reacted with AlN to produce ZrN, Y4Al2O9, and Y3Al5O12 secondary phases. The formation of these yttrium aluminate phases improved the thermal conductivity by removing oxygen impurities, while ZrN formed at the AlN grain boundaries provided resistance to grain boundary fractures for improved strength. Overall, the AlN ceramic with 1 wt% MCAS, 3 wt% Y2O3, and 1 wt% YSZ exhibited excellent thermal and mechanical properties, including a thermal conductivity of 109 W/mK and flexural strength of 608 MPa.

Nanoscale architecture of ZrN/CrN coatings: microstructure, composition, mechanical properties and electrochemical behavior

The main aim of this study is to develop ZrN/CrN nanolayered coatings with bilayers periods 10 bilayers (10 L), 20 bilayers (20 L) and 30 bilayers (30 L) over AISI 304 stainless steel and also evaluating the effect of nanolayers architecture on their electrochemical behavior. The nanolayers were deposited from chromium and zirconium targets using the cathodic arc evaporation physical vapor deposition (Arc-PVD) technique in a nitrogen atmosphere. The nanolayer microstructure and morphology were evaluated using X-ray diffraction (XRD), atomic force microscopy (AFM), and field emission scanning electron microscopy (FE-SEM). The chemical composition was studied by energy-dispersive X-ray spectroscopy (EDS) tests. The electrochemical characterization was carried out by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests in 3.5 wt. % NaCl solution in order to investigate changes in the electrochemical behavior as a function of the deposited bilayers number. The existence of CrN and ZrN phases with FCC lattices in the nanolayers were identified by the XRD patterns. The FE-SEM observations showed that the multilayered coatings were deposited at an excellent periodicity. The electrochemical tests indicated that the corrosion resistance of ZrN/CrN nanolayers is enhanced by increasing the number of bilayer periods that can be ascribed to the decrease in the pinholes and blocking the penetration path of corrosive solution.

Corrosion Improvement of 304L Stainless Steel by ZrSiN and ZrSi(N,O) Mono- and Double-Layers Prepared by Reactive Cathodic Arc Evaporation

Zr-based nitrides and oxynitrides were deposited by reactive cathodic arc evaporation in monolayer and double-layer structures with the aim of increasing the corrosion protection of 304L stainless steel (SS) in a biomedical aggressive environment. All coatings had a total thickness of 1.2 µm. Compared to the bare substrate, the surface roughness of the coated samples was higher, the presence of microdroplets being revealed by scanning electron micrography (SEM). The X-ray diffraction investigation of the ZrN phases revealed that the peaks shifted towards lower Bragg angles and the lattice constants increased as a result of Si and O2 inclusion in ZrN lattice, and of the ion bombardment characteristic of the cathodic arc method, augmented by the applied bias substrate. SS/ZrSiN/ZrSi(N,O) showed the best corrosion performance in an acidic environment (0.9% NaCl and 6% H2O2; pH = 4), which was ascribed to the blocking effect of the interfaces, which acted as a corrosion barrier for the electrolyte ingress. Moreover, the aforementioned bilayer had the highest amount of Si and O in the composition of the top layer, forming a stable passive layer with beneficial effects on corrosion protection.

Fabrication of (TixZr1−x)B2-(ZrxTi1−x)N composites by reactive spark plasma sintering of ZrB2-TiN

In this study, microstructural and mechanical properties of (ZrxTi1−x)N-(TixZr1−x)B2 composite fabricated by reactive spark plasma sintering (SPS) of ZrB2 and TiN was investigated. ZrB2 and TiN starting materials with equimolar ratio were sintered at 2000 °C for 8 min under a pressure of 30 MPa. An expansion (about 4%) was observed during the sintering process of the composite in the temperature range between 1290 °C and 1625 °C, which was attributed to the reaction of the starting materials. XRD pattern of the fabricated composite revealed the formation of TiB2 and ZrN phases after the sintering process. It was found that (Ti0.91Zr0.09)B2 and (Zr0.92Ti0.08)N phases are formed after sintering. High values of Vickers microhardness (28 ± 0.2 GPa), flexural strength (706 ± 51 MPa) and fracture toughness (8.49 ± 0.92 MPa m1/2) were achieved for this composite. Fracture of the (ZrxTi1−x)N and (TixZr1−x)B2 phases and crack path deflection mechanisms was founded as dominant toughening mechanisms in this composite.

ZrN Phase Formation, Hardening and Nitrogen Diffusion Kinetics in Plasma Nitrided Zircaloy-4.

Plasma nitridation was conducted to modify the surfaces of Zircaloy-4. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman analysis were used to characterize microstructures and phases. Surface indentation and cross-sectional indentation were performed to evaluate mechanical property changes. Nitridation forms a thin layer of ZrN phase, followed by a much deeper layer affected by nitrogen diffusion. The ZrN phase is confirmed by both TEM and Raman characterization. The Raman peaks of ZrN phase show a temperature dependence. The intensity increases with increasing nitridation temperatures, reaches a maximum at 700 °C, and then decreases at higher temperatures. The ZrN layer appears as continuous small columnar grains. The surface polycrystalline ZrN phase is harder than the bulk by a factor of ~8, and the nitrogen diffusion layer is harder by a factor of ~2–5. The activation energy of nitrogen diffusion was measured to be 2.88 eV. The thickness of the nitrogen-hardened layer is controllable by changing the nitridation temperature and duration.

A Study of Prediction Model Improvement for Air-Oxidation Breakaway in a Postulated Spent Nuclear Fuel Pool Complete Loss of Coolant Accident

The temperature of zirconium alloy cladding on the postulated spent nuclear fuel pool complete loss of coolant accident is abruptly increased at a certain time and the cladding is almost fully oxidized to weak ZrO2 in the air. This abrupt temperature escalation phenomenon induced by the air-oxidation breakaway is called a zirconium fire. Although an air-oxidation breakaway kinetic model correlated between time and temperature has been implemented in the MELCOR code, it is likely to bring about unexpected large errors because of many limitations of model derivation. This study suggests an improved time–temperature correlated kinetic model using the Johnson–Mehl equation. It is based on that the air-oxidation breakaway is initiated by the phase transformation from the tetragonal to monoclinic ZrO2 at the oxide–metal interface in the cladding. This new model equation is also evaluated with the Zry-4 air-oxidation literature data. This equation resulted in the almost similar air-oxidation breakaway timing to the actual experimental data at 800 °C. However, at 1000 °C, it showed an error of about 8 min. This could be inferred from the influence of the ZrN phase change due to the nitrogen existing in air.

Effects of Nitrogen Flow Ratio on Structures, Bonding Characteristics, and Mechanical Properties of ZrNx Films

ZrNx (x = 0.67–1.38) films were fabricated through direct current magnetron sputtering by a varying nitrogen flow ratio [N2/(Ar + N2)] ranging from 0.4 to 1.0. The structural variation, bonding characteristics, and mechanical properties of the ZrNx films were investigated. The results indicated that the structure of the films prepared using a nitrogen flow ratio of 0.4 exhibited a crystalline cubic ZrN phase. The phase gradually changed to a mixture of crystalline ZrN and orthorhombic Zr3N4 followed by a Zr3N4 dominant phase as the N2 flow ratio increased up to >0.5 and >0.85, respectively. The bonding characteristics of the ZrNx films comprising Zr–N bonds of ZrN and Zr3N4 compounds were examined by X-ray photoelectron spectroscopy and were well correlated with the structural variation. With the formation of orthorhombic Zr3N4, the nanoindentation hardness and Young’s modulus levels of the ZrNx (x = 0.92–1.38) films exhibited insignificant variations ranging from 18.3 to 19.0 GPa and from 210 to 234 GPa, respectively.

The influence of nitrogen on the morphology of ZrN coatings deposited by magnetron sputtering

ZrN coatings with the thickness of about 3 μm were deposited on hardened steel substrates by reactive magnetron sputtering at the constant magnetron power of 700 W and at the substrate bias voltage about − 10 V with different nitrogen flow rate from 3 to 6 sccm. The surface investigations were carried out using scanning electron microscopy, atomic-force microscopy, nanoindentation and glancing-angle X-ray diffraction. It was found that the texture of ZrN phase, the mechanical properties and the size of grains in the polycrystalline ZrN coatings can be controlled using different nitrogen flows.

Influence of Zr Doping on the Tribological Properties of Amorphous Carbon-Nitride Coating

This study aimed to understand the influence of small amount of Zr doping of amorphous carbonitride (a-CN) coatings on the structure, and mechanical and tribological behavior. The coatings were prepared using a four-target close-field unbalance magnetron sputtering system; two graphite, one Ti and one Zr targets were used. GDOS, SEM, XRD and XPS were used. A surface profilometer, a nanohardness tester, and a pin-on-disk wear tester were used. It was found the Zr doping resulting in the formation of ZrC and ZrN phases within the coating and the increase in the sp3 bonding fraction. The nanohardness was increased and the wear performance was largely improved.