Oxidation Resistance Properties Research Articles

(Invited) Comparative High Temperature Properties of Iron-Chromium-Aluminum and Zirconium Alloys

Light water reactors (LWR) have been using zirconium (Zr)-based alloys for the cladding of the fuel for more than six decades. Zirconium alloys oxidize rapidly in presence of water and steam at temperatures above 400°C and therefore they do not respond well to scenarios of loss of coolant accident conditions. In the 1950s and 1960s iron-chromium-aluminum (FeCrAl) alloys were explored to replace Zr alloys manly because the former has better oxidation resistance and better mechanical properties than the latter. The use of FeCrAl for LWR fuel cladding has been revived in the last decade following the 2011 accident at the Fukushima Daiichi site. This work will show comparative data to illustrate the advantages of FeCrAl in high temperature scenarios considering oxidation resistance, mechanical properties, and interactions with the fuel pellet.

Surface oxidation behavior of spark plasma sintered AlCrCuFeMnWx high entropy alloys at an elevated isothermal temperature

The high-temperature surface oxidation behavior of high-entropy alloys (HEAs) with compositions of AlCrCuFeMnWx (x = 0, 0.05, 0.1, and 0.5) was studied at 800 °C as an isothermal temperature for 50 h. The high entropy alloys (HEAs) were synthesized by mechanical alloying (MA) followed by spark plasma sintering (SPS). This study focused on the effect of oxidation resistance properties with different elevated temperatures on the high entropy alloy over the surfaces. The XRD and Raman analysis confirmed the formation of various oxides like Al2O3, Cr2O3, Fe2O3, and CrO2 mainly. The HEAs follow the single-stage parabolic law at 800 °C. To achieve better resistance against the heat, rather than adding more amount of refractory elements. Consequently, AlCrCuFeMnWx HEAs showed excellent oxidation resistance at elevated temperatures in a specific amount of tungsten. Different values of mass gain, loss, and complex oxidation kinetics were observed for the varying W-containing HEAs. These alloys formed inhomogeneous oxide scales possessing different regions with porous oxide layers and some areas revealed thin oxide scales due to the formation of discontinuous Mn, Cr, and Al-rich scales evidence found through the SEM images. It is noted that complicated oxides formed considerably more frequently on the W0 alloy than on other alloys, indicating that the addition of tungsten in the presence of Cr may inhibit the growth of certain types of multiphasic oxides and prevent spallation.

The oxidation resistance and mechanical properties of MoNx/AlN multilayer gradient films prepared by magnetron sputtering

In order to investigate the properties of MoNx/AlN multilayer gradient films, MoNx/AlN gradient films with 4, 8, 12, 16 and 20 gradient layers were prepared by double-target co-sputtering. The phase structure, morphology, and element composition of films before and after oxidation were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and energy dispersive spectrometer (EDS). The mechanical properties of films were characterized by nanoindenter. The results indicate that the MoNx/AlN multilayer gradient films are composed of face-centered cubic Mo2N and hexagonal AlN. With increasing the number of gradient layers, and the columnar structure of films gradually becomes uniform and dense. The average grain size of MoNx in gradient films decreases first, then increases slightly and finally decreases. The oxidation resistance of gradient films is better than that of pure MoNx film. And with increasing the number of gradient layers, the oxidation resistance of MoNx/AlN gradient films is gradually enhanced. The hardness of MoNx/AlN gradient films first decreases from 23.68 ± 1.18 GPa of 4-layer film to 16.68 ± 0.83 GPa of 12-layer film and then increases to 21.12 ± 1.06 GPa of 20-layer film.

Microstructure, high-temperature corrosion resistance and oxidation properties of (TiVZrCrAl)N high entropy nitride coatings with different N2/Ar ratios

The (TiVZrCrAl)N high-entropy nitride coatings were prepared on Zr-4 alloy substrates by reactive magnetron sputtering with different N2/Ar pressure ratios I values. The microstructure, nanohardness, high-temperature corrosion and steam oxidation resistance properties of the coatings were investigated. The results showed that the thickness of the coating first decreaseds and then increaseds with decreasing N2/Ar pressure ratio, but the hardness first increaseds and then decreaseds. All the coatings exhibited B1-NaCl structure. When I = 1/12, the (TiVZrCrAl)N coating had excellent high-temperature corrosion resistance and steam oxidation performance. The high-temperature steam oxidation mechanisms of the (TiVZrCrAl)N coatings were analyzed in detail.

Development of PE‐based antibacterial and antioxidant films with L‐ascorbic acid‐p‐hydroxybenzoate addition

AbstractIn this work, a PE‐based antibacterial and antioxidant material was successfully developed. L‐Ascorbic acid and p‐hydroxybenzoic acid were used as raw materials to synthesize L‐ascorbic acid‐p‐hydroxybenzoate (LPHB) by direct esterification method. LPHB was added to polyvinyl alcohol (PVA) solution and coated on corona‐treated low‐density polyethylene (LDPE) film coated with primer layer to prepare a composite film. The effects of different concentrations of LPHB on the performance of composite films were investigated to determine the optimal amount of addition, and then to prepare both antibacterial and antioxidant films. The antimicrobial properties of LPHB were analysed. The antibacterial, antioxidant, mechanical, barrier properties and morphology of the films were characterized and analysed. The results showed that the addition of LPHB significantly improved the antibacterial and anti‐mould properties, oxidation resistance, and barrier properties of the composite film compared to the LDPE film. The best overall performance of the composite film was achieved when the content of LPHB was 1.5%, the antibacterial rate against Escherichia coli and Staphylococcus aureus reached 99%, and the free radical scavenging rate reached 67.22%. In addition, the cling film added with LPHB has better antioxidant and antibacterial properties, which has obvious effect on bread preservation and has potential for application in food packaging.

Synthesis of Imidazole-Compound-Coated Copper Nanoparticles with Promising Antioxidant and Sintering Properties.

In this study, we present a facile method for preparing oxidation-resistant Cu nanoparticles through a liquid-phase reduction with imidazole compounds (imidazole, 2-methylimidazole, 2-phenylimidazole, and benzimidazole) that serve as protective and dispersing agents. Through a complexation reaction between Cu atoms, the imidazole compounds can form a protective film on the Cu nanoparticles to prevent the particles from rapidly oxidizing. We compared the effects of the four kinds of imidazole compounds on the oxidation resistance and sintering properties of Cu particles. The Cu particles prepared with benzimidazole could be stored in the air for 30 days without being oxidized. After sintering at 300 °C and 2 MPa, the joint of the particles could reach a shear strength of 32 MPa, which meets the requirements for microelectronic packaging.

Development of EPDM composites reinforced by CNTs@SiO2 for thermal protection systems of aerospace propulsion: Significant improvement in oxidation and ablation resistance properties

Carbon Nanotubes (CNTs) reinforced Polymer-Matrix Composites (PMCs) is widely used as insulation materials in thermal protection system of aerospace propulsion. However, CNTs are prone to oxidation and have high thermal conductivities, which makes it difficult to improve the ablation resistance of insulation materials that contain CNTs. SiO2 was encapsulated onto the surface of CNTs (CNTs@SiO2), which were then added to Ethylene Propylene Diene Monomer (EPDM) rubber to prepare the insulation materials. Thermogravimetric analysis and ablation test were used to evaluate the resistance of the insulation materials to thermal oxidation and ablation. Additionally, scanning electron microscopy was performed to analyze their microstructures. Results revealed that the addition of CNTs@SiO2 could visibly reduce the effects of hot corrosion and ablation on insulation materials. The C-CNTs@SiO2-1 formulation had the best ablative resistance. Further, compared with the unencapsulated formulation (C-CNTs-10), the C-CNTs@SiO2-1 formulation reduced the line ablation rate by 51% to 0.0130 mm/s after oxygen-acetylene experiments. Lastly, the ablation mechanism was investigated based on the effects of the CNTs@SiO2 additive on their properties. Thus, the improvement in ablation performance may be attributed to CNTs@SiO2-induced decreases in thermal conductivity, improvement in the hot corrosion resistance in the char layer, and changes in the microstructure.

Fundamental design strategies for advancing the development of high entropy alloys for thermo-mechanical application: A critical review

Nearly three decades since the discovery of high entropy alloys (HEAs), it has greeted a broad interest in the field of materials research as a better alternative to conventional alloy materials due to the exceptional combinatorial properties they offer in terms of lightweight, high-specific strength in elevated temperatures, excellent oxidation and corrosion resistance properties (among others). Leveraging on the “four core effects”: high-entropy effect, sluggish/hysteretic diffusion effect, severe-lattice-distortion effect and cocktail effect which define the special features responsible for their outstanding properties, HEAs have been successfully employed for high-temperature applications in automobile and in the aerospace. An emerging sub-field of HEAs is the incorporation of a secondary strengthening phase that can be provided by the precipitation of intermetallic (IM) compounds to enhance the microstructure which will concomitantly affect the properties of a material (thermal, chemical and mechanical properties) for broader engineering applications. In this article, design concepts brewed from thermo-physical parameters calculation and computational thermodynamics using a CALPHAD-based tool were reviewed as fundamental design strategies in the development of IM-containing HEAs.

Development of Co–Ni–Al–V–Ta–Cr-based superalloys with high-temperature strength and excellent oxidation resistance

In this study, the effects of V on the microstructure, lattice misfit, solvus temperatures, and oxidation behaviors of the Co–Ni–Al–V–Ta-based superalloys are investigated. The results show that all these alloys exhibit the γ’/γ two-phase structures. More importantly, the γ’ solvus temperature increases, and the oxidation resistance is significantly improved with the reduction of V concentration. Subsequently, the Ti (2 at.%) was added into Co–40Ni–10Al–4Ta–1V–12Cr alloy to further raise the properties of the superalloy. It is found that the Co–40Ni–10Al–4Ta–1V–12Cr–2Ti alloy exhibits a higher solvus temperature reaching 1200 °C of the γ′ phase, a low density of 8.48 g/cm3, a low lattice misfit of only +0.37 %, as well as exceptional oxidation resistance and mechanical properties.

On the correlations between mechanical properties, oxidation behaviors and high temperature wear resistance of AlCrSiTiN coatings: A combinatorial study

Pinpointing the critical influencing factors of the high temperature tribological properties has always been the critical issues for hard protective coatings used in high temperature applications. The synergistic effect of simultaneous chemical attack and mechanical damage to the coatings would make it difficult to predict the performance and the durability of the protective coatings. In this study, a systematical investigation of the effect of chemical composition on the mechanical properties, oxidation resistance, and high temperature tribological properties is conducted through combinatorial approach for AlCrSiTiN coatings. It is found that in addition to the properties of the coatings, the whole system of wearing counterpart/coating/substrate plays a vital role in the high temperature tribological behaviors. However, a general observation of the inferior high temperature wear resistance for the coatings with poor mechanical properties and oxidation resistance still holds.Overall, this study provides a general guideline for designing protective hard coatings with superior high temperature tribological properties.

Cyclic oxidation resistance and self-healing properties of HfB2-doped glass composite coatings at 900 °C

HfB2-doped glass coating exhibits superior cyclic antioxidative performance compared to pure glass coating. The HfB2 particles inhibit the precipitation of crystals with low thermal expansion coefficient, mitigating the risk of fish-scaling failure. In addition, the HfB2-doped glass composite coating, with high contents of amorphous phases, maintains its viscous flow properties even after multiple high temperature cyclic oxidations, which enables it to self-heal. Moreover, the oxidation product (B2O3) of HfB2 enhances network connectivity of the glass system, providing more unsaturated sites for the chemical bonding of the self-healing process.

Influence of eutectoid structures on the mechanical properties and oxidation behavior of Hf-27%Ta and Hf-42%Ta alloys

Hf–Ta alloys have recently received much attention due to their favorable oxidation resistance and mechanical properties at temperatures beyond 1200 °C. However, at lower temperatures the oxidation resistance becomes poor and the alloys experience brittle to ductile transition. Both effects are likely due to their two-phase structure formed during eutectoid transformation. In the present work, we report mechanical properties and oxidation behavior of Hf-27%Ta and Hf-42%Ta (compositions are in atomic percent), which experience eutectoid transformation at ∼1083 °C and contain two phases, Hf-rich HCP and Ta-rich BCC, below this temperature. Alloys of the compositions corresponding to these two eutectoid phases, Hf-90%Ta (BCC) and Hf-3%Ta (HCP), were also produced and studied for comparison. The results show that in the temperature range of 25–1000 °C (i.e., below the eutectoid transformation) the compression strengths of Hf-90%Ta and Hf-3%Ta are considerably smaller than the strength of Hf-27%Ta or Hf-42%Ta, while above the eutectoid transformation, where the Hf-27%Ta and Hf-42%Ta alloys have single-phase BCC structures, the Hf-90%Ta and Hf-3%Ta become stronger than either Hf-27%Ta or Hf-42%Ta. It was concluded that the interfaces in the eutectoid structure of Hf-27%Ta produce considerable strengthening, which can exceed the strengths of the phases which comprise the microstructure. At 800 °C and 1000 °C, Hf-90%Ta oxidized rapidly in comparison to Hf-3%Ta due to the extensive formation of Ta2O5. It is suggested that the observed poor oxidation behavior of Hf-27%Ta below the temperature of the eutectoid transformation is likely controlled by the oxidation kinetics of the Hf-90%Ta BCC phase in the eutectoid structure of this alloy.

Multiphase hybrid model and thermal insulation simulation of elytra-mimetic ceramic fiber aerogel

In our previous work, the coaxial electrostatic spinning method was applied to construct nanofiber/SiBCN ceramic aerogel with an elytra-mimetic structure. The material presented excellent mechanical, insulation, oxidation resistance, and other properties. Based on preliminary experiments and literature reports, the integrated heat transfer behavior of nanofiber/SiBCN composite ceramic aerogels in high-temperature environments was affected by several factors, such as coaxial fiber size properties, fiber particle content, interactions, and spatial distribution. Moreover, the above factors overlapped and interacted with each other, and it was hard to generalize a clear law of action through traditional experiments and characterization. Therefore, the paper constructed a representative volume unit (RVE) model based on the complex spatial distribution characteristics of composite aerogels, using fractal theory, Rosseland equation theory, and multiphase model theory. This paper investigated the fiber and particle content, the size characteristics of the coaxial fibers, and the overall heat transfer process in high-temperature environments using the finite element method. The finite element simulated the effective thermal conductivity of multiphase aerogel composites under multiple parameters, such as fiber occupancy, fiber core-shell diameter ratio, temperature, and heat transfer mode. We obtained the property parameters of the complex composition of the material through fractal theory. The model was combined with finite elements to study the fiber particle content, the size characteristics of coaxial fibers, and the integrated heat transfer process in high-temperature environments. The fibers improved the absorption and reflection of thermal radiation with increasing fiber mass fraction, leading to improved ability of ceramic fiber aerogel to extinguish light. The fibers had a larger area to absorb and reflect thermal radiation. Based on the excellent extinction ability of SiC fibers, the composite ceramic aerogel had improved thermal performance at a specifically fiber-to-shell diameter ratio through a comprehensive multifactor simulation analysis.

Oxidation resistance and mechanical properties of AlTiZrHfTa(-N) high entropy films deposited by reactive magnetron sputtering

(AlTiZrHfTa)1−xNx refractory high entropy films (RHEFs) were deposited by direct current magnetron sputtering in various nitrogen ratios (RN2 = N2/(Ar+N2)) on flat glass, silicon and sapphire substrates. The nitrogen-free film is amorphous while the nitrides are single-phased solid solutions with Face-Centered Cubic (FCC) structures. The hardness increases from 6.4 GPa for the nitrogen-free film to 25.3 GPa for the film obtained at RN2 = 20%. A preferred orientation from (111) to (200) occurs when RN2 increases from 5% to 50%. H/E and H3/H2 reports show high values for the film deposited at RN2 = 20% compared to that at 10%. However, this latter has the best compromise in terms of mechanical properties related to a lower residual stress value. The nitrides films obtained with RN2 ≥ 5%, are thermally stable at 800 °C for 3 h under vacuum. Compared to the metallic film they show an improved oxidation resistance. In fact, the Kp constant of the nitride (RN2=20%) is lower (1.22 10−7 g2 cm−4 h−1) than that of the nitrogen-free film (1.77 10−6 g2 cm−4 h−1). The corresponding activation energies (Ea) are respectively calculated at 94.8 KJ. mol−1 and 45.5 KJ.mol−1. After oxidation process, TEM analysis reveal the formation of homogeneous mixed oxide.

First-principles investigation of the structural stability and mechanical properties of TM3Al2C(TM=Mo, Cr and W) carbides

Although Mo3Al2C MAX phase is a promising high temperature ceramics because of the high temperature strength and excellent oxidation resistance, the structural and mechanical properties of Mo3Al2C-type carbide is unknown. Here, we apply the first-principles method to study the structural stability, mechanical and thermodynamic properties of TM3Al2C MAX phase. Three refractory metals (TM=Mo, Cr and W) are considered. The calculated results show that the formation enthalpy follows the sequence of Mo3Al2C<Cr3Al2C<W3Al2C. Naturally, the structural stability of TM3Al2C carbides is determined by the formation of TM-Al bond, TM-C bond and TM-TM bond. Importantly, it is found that three TM3Al2C carbides are mechanical stability because the calculated elastic constants of these carbides meet the Born stability criteria. The calculated elastic constant C11 of W3Al2C is 321.0 GPa, which is larger than the elastic constant C11 for Mo3Al2C and Cr3Al2C. Importantly, the bulk modulus of W3Al2C is 249.9 GPa, which is larger than the elastic modulus of Mo3Al2C and Cr3Al2C. In addition, three TM3Al2C carbides show better ductility. Naturally, the bulk modulus of TM3Al2C is related to the TM-C bond and TM-TM bond in a a-b plane. However, the strength of shear modulus of TM3Al2C depends on the TM-C bond and TM-Al bond along the b- axis.

Microstructures and performances of pressureless sintered MoSi2-Al2O3 composites

MoSi2-Al2O3 composites with various volume fractions of Al2O3 from 0 to 40 vol% were fabricated by pressureless sintering at 1550 ℃. MoSi2 powder was prepared by silicothermic reduction of MoS2. Microstructure, mechanical properties, electrical resistivity and oxidation behavior of composites were experimentally examined to investigate the influence of Al2O3 addition. The results demonstrated that proper introduction of Al2O3 contributed to improving the oxidation resistance and mechanical properties. Among them, MoSi2-20 vol%Al2O3 composite presented excellent comprehensive properties and oxidation resistance. The oxide scale consisting of SiO2 and Al2O3 was formed on the substrate and effectively prevented the inward diffusion of oxygen.

Thermomechanical characterization and conventional rolling of a novel β-solidifying γ-TiAl alloy with excellent comprehensive properties

The development of the β-solidifying γ-TiAl alloys with good oxidation resistance and thermal deformation ability has always been crucial for the practical application. However, increasing the content of the antioxidant elements, such as Nb, Al, etc., tends to be detrimental to the deformability of the alloys. In this work, a novel Nb, Mn containing β-solidifying TiAl alloy with the nominal composition of Ti-43Al-1.5Mn-3Nb-0.2C-0.2Si-0.1B (at. %) (named as NbMn-TiAl) is invented, which goes through the single β phase as well as the α phase during solidification, resulting in the final as-cast microstructure of nearly full lamellar structure (NFL). Subsequently, the isothermal compression tests were performed within a temperature range of 1100 °C–1300 °C and a strain rate range of 0.001 s−1-10 s−1, the hot processing maps and constitutive equation were established. Moreover, the deformation mechanisms were clarified, including the bending/kinking of the α2/γ lamellar colonies, the dynamic recrystallization (DRX) of γ phase and α phase at different temperatures. Rolled bars with a diameter of 12 mm were then directly fabricated from the ingot by conventional hot rolling process. The as-rolled bars exhibited excellent oxidation resistance and mechanical properties that outperform many available TiAl alloys manufactured using various methods.

Synthesis, oxidation resistance and mechanical properties of a Cr2AlC-based MAX-phase coating on TiAl

In this study, the oxidation resistance of a Cr2AlC-based MAX-Phase coating on the Ti–48Al–2Cr–2Nb (at. %) alloy was investigated at 700 °C and 800 °C in air. Coatings were synthesized by a combination of DC magnetron sputtering and ex-situ annealing in Ar. The oxidation resistance of the TiAl alloy was greatly improved due to the formation of a protective Al2O3/Cr2O3-scale at both temperatures. During oxidation Al diffuses from the coating into the substrate triggered by the higher Al activity of the Cr2AlC-phase compared to the TiAl substrate. Due to the severe Al-depletion Cr7C3, Cr23C6 as well as Cr2Al become the predominant phases in the coating. As a result of this, the very promising mechanical properties of the coated samples were negatively influenced by the brittle nature of such phases leading to a decrease in the fracture strain.

Constructing lignin based nanoparticles towards flame retardant thermoplastic polyurethane composites with improved mechanical and oxidation resistant properties

A multifunctional lignin derivative nanoparticle (C-P-Lignin) was synthesized by grafting phenyl dichloro sphosphineoxid and 1, 4-dimethoxyacetylene stepwise on the lignin, then it was applied to prepare the thermoplastic polyurethane (TPU) composite with improved mechanical properties, oxidation resistance, and flame retardancy. The tensile strength, the elongation at break, and the toughness of the TPU/2C-P-Lignin sample reached 28.3 MPa, 941 %, and 139.0 MJ/m2 respectively, which were increased by 39.0 %, 3.4 %, and 33.9 % respectively compared with that of the control TPU sample. The anti-fatigue property was also improved. More importantly, the mechanism of the improved mechanical properties was also calculated and simulated by FTIR and Materials Studio software. The TPU/2C-P-Lignin sample exhibited superior oxidation resistance during the process of photoaging and thermal oxidative aging. Furthermore, the peak heat release rate and the smoke production rate for theTPU/2C-P-Lignin sample was reduced by 50.0 % and 53.8 % compared with that of the control TPU. The reason was that the C-P-Lignin is conducive to the formation of uniformly distributed carbon layers. It is expected that this work can provide a new method for expanding the utilization of waste wood as a multifunctional lignin-based filler to improve fire safety and extend the service life of TPU polymers.

Simultaneous regulation of strength and ductility of laser powder bed fusion manufactured Haynes 230 alloy

Haynes 230 alloy is widely used in aero-engines with high strength, fatigue resistance, oxidation resistance and other properties. However, the powder metallurgy process limits its application due to hot cracks and low strength. In this work, crack inhibition and mechanical properties improvement of the laser powder bed fusion (L-PBF) manufactured Haynes 230 alloy using 25 groups of different laser energy densities and scanning strategies were investigated. Results show that the high density, nearly crack-free, fine microstructure, and excellent strength and ductility were achieved by a laser energy density of 59.4 J/mm3 and rotation angle of 90° for the L-PBF manufactured Haynes 230 alloy. The microstructure was composed of γ matrix, carbides (M6C, M23C6), and La2O3 nanoparticles. Interestingly, many carbides were found to be mainly uniformly distributed at the grain or sub-grain boundaries with the following orientation relation: [011]γ//[011]M23C6. Simultaneously, by adjusting laser energy density and scanning strategy, the liquid film, low-melting eutectic phase, hot stress concentration, and high-angle grain boundaries (HAGBs) were suppressed, and the hot cracks were reduced. In addition, yield strength and ultimate tensile strength enhancement of the L-PBF manufactured Haynes 230 alloy was attributed to the synergistic effect of solid solution strengthening, dislocation strengthening, Orowan strengthening, and grain refinement. Whereas ductility enhancement was the main effect of defect inhibition, grain refinement, and nanoprecipitate. This work has verified the feasibility of crack inhibition and mechanical properties improvement of the L-PBF manufactured Haynes 230 alloy by various laser energy densities and scanning strategies.