Good Oxidation Resistance Research Articles

Simple Laser-Induced Hexagonal Boron Nitride Nanospheres for Enhanced Tribological Performance

Hexagonal boron nitride, as a layered material with a graphite-like structure, exhibits good mechanical, lubricating and oxidation resistance properties, and is thus expected to become one of the top choices for green lubricating oil additives. However, its poor dispersibility in oil and difficulties in preparing spherical particles when constructing hexagonal boron nitride limit its application. In this paper, spherical hexagonal boron nitride nanoparticles are constructed via a simple laser irradiation method. Under laser irradiation, raw irregular hexagonal boron nitride particles were reshaped into nanospheres via a laser-induced photothermal process and rapid cooling in a liquid-phase environment. Under the optimal concentration, the coefficient of friction and wear spot diameter decreased by 26.1% and 23.2%, and the surface roughness and wear volume decreased by 29.2% and 23.8%, respectively. The enhanced tribological performance is mainly due to the ball bearing, depositional absorption and repair effect of the spherical particles. This simple laser irradiation method provides a new method by which to prepare spherical hexagonal boron nitride lubricating oil additives.

The formation of spinel CuxMn3-xO4 at 750 °C in the designed CuMn layers for solid oxide fuel cell applications

The Cu-Mn based spinel coatings without Cr show good application prospects due to their high conductivity and thermal expansion coefficient matching with metallic interconnectors. Based on the Cu-Mn-O phase diagram, the CuMn alloy layers with different Cu/Mn ratios were designed by electro-deposition and high energy micro-arc alloying (HEMAA) processes. The Mn-33Cu-17Co layer was prepared by HEMAA for thermal growth of the CuMn spinel oxides, and the fine-grained 430 layer was prepared by HEMAA as an interlayer at the interface between the 430 SS substrate and the coating. The microstructure and composition of the composite layers were analyzed. The results show that after oxidation treatment at 750 °C for 500 h, the oxide products of the Mn-33Cu-17Co layer were mainly cubic spinel Cu1.4Mn1.6O4 and CuO, which were different from those of the Mn-35Cu oxide layer, spinel Cu1.2Mn1.8O4 and Mn2O3. The aggregation of Cu-rich oxides was not found in the cross-section and on the top surface of the Mn-33Cu-17Co oxide layer, and the outer spinel layer was uniform and compact. The designed Mn-33Cu-17Co layers, Mn-35Cu layers and Mn1.5Cu1.5 layers showed good high temperature oxidation resistance and electrical conductivity.

Machining of nickel-based super alloy inconel 718 using alumina nanofluid in powder mixed electric discharge machining

Inconel 718 is a nickel-based superalloy with exceptional mechanical qualities, including high tensile and impact strength, as well as good oxidation and corrosion resistance. EDM is widely used to cut hard materials of this type by common parameters affecting spark, current, duty cycle etc, whereas MRR, SR can be greatly improved by using sufficient fluid properties of the dielectric. Incorporation of alumina nanoparticles with deionized water may improve machining performance, with no prior research on machining characteristics of Inconel 718 using alumina nanofluid in EDM. The machinability of Inconel 718 via the electrical discharge machining process, as well as the performance of alumina nanofluid as a dielectric medium, have been evaluated using deionized water with a concentration of 0.5%. In this study, based on the effect of various input parameters such as and on the MRR, TWR and SR, and the RSM has been used to conduct the experiments. A maximum MRR of 0.048 g min−1, a TWR of 0.00632 g min−1 and an SR of 3.271 μm are achieved. Overall, the use of alumina nanofluid can improve machining performance in EDM, due to the reduction of abnormalities such as crack formation and molten metal debris in the machined surface of Inconel 718.

Investigation on Mechanical Properties and Oxidation Behavior of 1.2 and 1.7 GPa Grades Coating-Free Press-Hardened Steels

Al-Si-coated boron-alloyed steels are the most widely used press-hardened steels (PHSs), which offers good oxidation resistance during hot forming due to the presence of the near eutectic Al-Si coating. In this study, a recently developed novel un-coated oxidation resistant PHS, called coating-free PHS (CF-PHS), is introduced as an alternative to the commercial Al-Si coated PHSs. With tailored additions of Cr, Mn, and Si, the new steel demonstrates superior oxidation resistance with a sub-micron oxide layer after the conventional hot stamping process. Hence, it does not require shot blasting before the subsequent welding and E-coating process. Two CF-PHS grades have been developed with ultimate tensile strengths of approximately 1.2 and 1.7 GPa, respectively. Both grades have a total elongation of 8–9%, exceeding the corresponding Al-Si-coated PHS grades (1.0 GPa/6–7%, 1.5 GPa/6–7%). Furthermore, the bendability of CF-PHS was similar to the corresponding Al-Si PHS grades. On the other hand, performance evaluations relevant to automotive applications, such as weldability, the E-coat adhesion, and tailor-welded hot stamp door ring, were also conducted on the CF-PHS steel to satisfy the requirements of manufacturing.

Thickness Effects on Oxidation Behavior and Consequent γ’ Degradation of a High-Al Ni-Based Single Crystal Superalloy

High temperature oxidation is considered to play an essential role in the thickness debit effect on the creep rupture life of Ni-based single crystal (SC) superalloys. In order to clarify thickness effects, thin-walled specimens of different thickness (t = 0.1, 0.3, 1.0 mm) were prepared. Cyclic and isothermal oxidation tests of a high-Al Ni-based SC superalloy IC21 were carried out at 900 °C and 1100 °C in order to study the thickness effects on the oxidation behavior and consequent microstructural degradation. Thin-walled specimens of S01-N exhibited a good oxidation resistance when the protective scale-forming elements were enough in the matrix. Specimen thickness tuned the oxidation kinetics by changing the spallation behavior but had few influences on the thermodynamics. The easier stress relief via creep deformation in thin specimens is the main reason behind this phenomenon. Moreover, the obvious temperature effects on the multilayer oxide scales caused the different thickness-related spallation behaviors. Weaker microstructural degradation appeared and was further mitigated by reduced specimen thickness. Sufficient Al content is considered to be indispensable for the formation of protective α-Al2O3 scale with less degradation of matrix during the high temperature oxidation of thin-walled Ni-based SC superalloy castings.

SiC fibers with different diameters exhibiting excellent high-temperature resistance and oxidation resistance

SiC fibers have important application in aerospace and other high-tech equipment due to their excellent mechanical properties and thermal resistance. In this work, SiC fibers with diameters of 9, 14, 60 μm were prepared in order to investigate the influence of different diameters on the precursor-derived SiC fibers. The results showed that the polycrystalline structure and near stoichiometric composition of the SiC-9 and SiC-14 fibers were achieved by the “one-step” approach. However, the sintering for SiC-60 fiber was insufficient due to the largest diameter. Moreover, the tensile strength of SiC fibers decreased from 1.88 GPa to only 0.28 GPa with increment of the fiber diameter. The fibers exhibited excellent high temperature resistance with tensile strength retention reaching over 94% after being kept at 1900 °C in argon for 1 h. Furthermore, the SiC fibers with sintered and densified microstructure showed good oxidation resistance. This work could help to further optimize the structure of the polycrystalline near stoichiometric SiC fibers for higher mechanical and thermal performance.

Recent Progress of Polymer Electrolytes for Solid-State Lithium Batteries

The critical challenges for lithium-ion batteries today are how to improve the energy densities and solve the safety issues, which can be addressed through the construction of solid-state lithium metal batteries with solid polymer electrolytes (SPEs). Significant efforts have been devoted to the design and synthesis of SPEs, in which their electrochemical windows and corresponding compatibilities with both electrodes are crucial, particularly when taking high-voltage transition metal oxides as cathodes. In this review, the SPEs with different electrochemical windows are summarized and categorized, including (i) anode stable SPEs with good lithium metal compatibilities, (ii) cathode stable SPEs with good oxidation resistances, (iii) multilayer SPEs simultaneously withstanding reduction of a lithium anode and oxidation at high voltage. The impacts of polymer molecular structures and compositions on the SPE properties and performance are discussed. The development of high-performance SPEs that can stabilize or form stable interfacial passivation layers with both cathodes and anodes simultaneously is the desired candidate of future applications.

Plasma-assisted cutting for impurity reconstruction of an as-cast cerium–lanthanum alloy

The high chemical activity and oxide impurities inside cerium–lanthanum (Ce–La) alloys make it difficult to achieve high surface finishing with diamond turning. Plasma-assisted cutting, in which the plasma is applied to regulate the longitudinal impurity distribution of the surface layer and improve its machinability in diamond turning, is proposed for machining as-cast Ce–La alloys. The effect of the rotational speed on built-up edge is discussed, and a surface with surface roughness of 6.5 nm in Sa is successfully achieved. Experimental results show that the machined modified alloy possesses good oxidation resistance, benefiting various applications in green energy.

Application of Multiple Nitrogen-based Coatings for Cemented Carbide Tools: A Review

As the main-stream of the machining coating, nitrogen-based coatings have irreplaceable advantages, such as high hardness, high strength, and good oxidation resistance recently. This paper introduces common multiple nitrogen-based coatings which including TiAlN, CrAlN, TiAlSiN, CrAlSiN and CrTiAlN coatings for cemented carbide tools. The microstructure and property of coating is depended on its chemical composition. Generally, compounds of different structures are formed between the various elements of the coating, and these have different forms of existence and properties: titanium and chromium exist in nitrides (face-centered cubic structure), aluminium solubilizes in TiN/CrN, and amorphous Si3N4 can make difference in fine grain strengthening. The Al2O3 and SiO2 can improve oxidation resistance.

α-In2O3 monolayer: A promising material as field-effect phototransistor and out-of-plane piezoelectric device

Two-dimensional (2D) semiconductors have opened promising avenues for designing advanced functional devices due to their novel electronic features. In this work, the 2D α-In2O3 monolayer is systematically studied using first-principles calculations. Our calculations show that the α-In2O3 monolayer exhibits a stable configuration with good oxidation resistance. The electronic structure calculations identify that α-In2O3 monolayer is a semiconductor with a direct bandgap of 1.41 eV, which makes the α-In2O3 monolayer to be as a promising candidate in modern bottom/top gate technologies. Interestingly, the partial charge density shows that the valence band maximum and conduction band minimum locate at the different atomic region, and the electron carrier mobility of the α-In2O3 monolayer is much larger than hole carrier mobility, indicating that the electrons and holes can be effectively separated. Additionally, the α-In2O3 monolayer has excellent optical absorption coefficient among the infrared and visible range. Hence, the α-In2O3 monolayer can be used as field-effect phototransistor. Moreover, the asymmetric atomic-layer configuration and strong inner covalent bond of the α-In2O3 monolayer induce a superior out-of-plane piezoelectric response (e31 = 1.81 × 10-10C·m−1, d31 = -0.89 pm·V−1), make α-In2O3 monolayer as a promising material as out-of-plane piezoelectric device.

From Mo-Si-B to Mo-Ti-Si-B Alloys: A Short Review.

Mo-Si-B alloys have attracted considerable research interest during the last several decades due to their high melting points, excellent high-temperature strength and relatively good oxidation resistance. However, insufficient room-temperature fracture toughness and high-temperature oxidation resistance restrain their further application. Generally, a sufficient volume fraction of BCC-Mo solid-solution phase, providing the ductility, and a high Si content, responsible for the formation of passive oxide scales, is difficult to achieve simultaneously in this ternary system. Recently, macroalloying of Ti has been proposed to establish a novel phase equilibrium with a combination of enough BCC phase and intermetallic compounds that contain a large amount of Si. In this article, the development history from the ternary Mo-Si-B to the quaternary Mo-Ti-Si-B system was reviewed. It was found that the constitution phases could be easily tailored by changing the Ti content. In this regard, better performance of mechanical properties and oxidation resistance can be obtained through proper alloy design. In-depth understanding of the advantages of the quaternary alloys over their ternary ancestors may contribute to bringing about a new concept in designing novel ultra-high-temperature structural materials.

Super‐Wideband Electromagnetic Absorbing TiC/SiOC Ceramic/Glass Composites Derived from Polysiloxane and Titanium Isopropoxide with Low Thickness (<1 mm)

Herein, TiC/SiOC ceramic/glass composites with excellent electromagnetic wave (EMW) absorbing performance are fabricated by pyrolysis of polycarbosiloxane and titanium (IV) isopropoxide (TTIP). By taking advantage of the polymer‐derived route, the phase compositions and microstructures are easily tuned. The composites are investigated by X‐ray diffraction (XRD) analysis, scanning electron microscope, and transmission electron microscopy/energy dispersive spectroscopy. Nanoscaled TiC is formed and uniformly distributed without clustering within the SiOC matrix. Thermogravimetric Analysis (TGA) and in situ XRD results revealed good thermal stability and oxidation resistance mechanism. The presented material system (TiC/SiOC) shows a super‐wide microwave absorption bandwidth (EAB) of 13.5 GHz, including the entire Ka‐band (26.5–40 GHz) with a low thickness requirement (<1 mm). The superior EMW absorption properties of the ceramics are attributed to the optimal interface polarization, as well as the ordering, concentration, and interconnectivity of the conductive network, which all determine the electrical conductivity in the composites.

Study on the mechanism of ultra-high temperature ablation of ZrB2–SiC–TaSi2 coatings by low-pressure plasma spraying on the C/C composites

To improve the high-temperature oxidation resistance of C/C composites, ZrB2–SiC (ZS) and ZrB2–SiC–TaSi2 (ZST) ultra-high temperature ceramics coatings were prepared on their surfaces using induction plasma spheroidization and low-pressure plasma spraying (LPPS). Ablation behaviors of the ZS and ZST coatings were evaluated at 1800°C, 2000°C, and 2200°C using the oxyacetylene flame, we found that the ZS coatings had good ablation resistance at 1800°C, but rapidly failed at 2000°C. Whereas, the ZST coating always performed good oxidation and ablation resistance at even 2000°C with a mass ablation rate of 4.68 × 10-5 g/s and a linear ablation rate of -1.63 × 10-5 mm s-1. The enhancement of the high temperature ablation resistance property was attributed to the introduction of the TaSi2, which improved the density of the coatings prepared by LPPS, reduced the volatilization of the glassy phase at high temperature, and enabled ZrO2 to form a dense oxide layer.

Spark plasma sintering of polycrystalline La0.6Ce0.3Pr0.1B6–ZrB2 composites

AbstractThis paper has studied the densification, microstructure, and properties of polycrystalline La0.6Ce0.3Pr0.1B6–ZrB2 composites prepared by spark plasma sintering (SPS). The highest relative density of 98.7% is obtained at the SPS condition of axial mechanical pressure 50 MPa, sintering temperature 1900°C and holding time 5 min. The Vickers hardness decreases linearly from the maximum value of 21.49 GPa to the value of 8.24 GPa with the tested temperature increased from room temperature to 1000°C. The effects of crack deflection and bridging have resulted in the fracture toughness of 4.56 MPa m1/2 of dense polycrystalline La0.6Ce0.3Pr0.1B6–ZrB2 composite. The J1kV of 7.02 A/cm2 obtained at 1600°C, the work function of 2.743 eV determined by ultraviolet photoelectron spectroscopy, and the good oxidation resistance below 1100°C in air have revealed that the dense polycrystalline La0.6Ce0.3Pr0.1B6–ZrB2 composite has a good potential to be a promising hot cathode material.

Mechanical, structural and oxidation behavior of ultra high-temperature ceramic Ti–B–Si hard composite

The synthesis of Ultra-High Temperature Ceramic (UHTC), Titanium Diboride–Si composite TiB2–Si (Ti–B–Si) composite was carried out by Self-propagating high-temperature synthesis SHS). The structural, mechanical, oxidation behavior is studied. A very dense Ti–B–Si composite with very fine grain structure (1–3 μm), high hardness (∼29 GPa) & (648.8 GPa) modulus and good oxidation resistance up to 900 °C was synthesised by SHS process.

Microstructure and oxidation behavior of Co–Cr–Ta ternary alloys

The improvement of oxidation resistance of alloys is one of the key points to develop components for ultra-high temperature applications. The formation of a CrTaO4 oxide layer has attracted attention because of its thermal stability and good protection against oxidation above 1000 °C where more commonly used protective oxide layers such as Cr2O3 show their limits. This study investigates the microstructure evolution and oxidation resistance of the Co-Cr-Ta ternary alloys in comparison to the Calphad predictions. The Co-Cr-Ta samples tested here are composed of an FCC Co-rich phase and a C15 laves phase, and an increase of Cr content was linked to the formation and growth of an additional σ phase. Thermogravimetric analysis, together with the isothermal oxidation tests in air at 1200 °C proved that alloys exhibited good oxidation resistance formed a continuous CrTaO4 layer. Also, optimization of Co-Cr-Ta composition with improved oxidation resistance was attempted using data-driven strategy and the results demonstrated the potential of such approach for the future of alloy design.

Tool Wear in Nickel-Based Superalloy Machining: An Overview

Nickel-based superalloys have been widely used in the aerospace, petrochemical, and marine fields and others because of their good oxidation resistance, corrosion resistance, stability, and reliability at various temperatures. However, as a nickel-based superalloy is a kind of processed material, in the cutting process a large amount of cutting heat is generated due to the interaction between the tool and the workpiece. At the same time, the low thermal conductivity of the workpiece causes a large amount of cutting heat to accumulate at the contact point, resulting in serious tool wear, reduced tool life, frequent tool changes, and other problems, which increase the production cost of the enterprise. This paper introduces the tool wear mechanisms (abrasive wear, adhesive wear, plastic deformation, chemical wear, etc.) in the machining process of nickel-based superalloys and summarizes the research status of failure mechanisms, tool wear optimization, etc. Based on a review of the existing research, it was found that the purpose of adding tool coatings, optimizing tool materials and cutting parameters, or improving the cutting environment is to control the heat during the processing of nickel-based superalloys to improve the tool environment and prolong the service life. The development prospects of tool wear prevention measures in the field of nickel-based alloy machining are also described.

Tunable shell thickness of Fe-N@SiO2 nanoparticles for strong and stable microwave absorption properties with enhanced oxidation resistance

Core-shell composites Fe-N @ SiO 2 with 500 nm average sizes of cores have been successfully prepared by a combination of hydrothermal, gaseous nitriding and Stöber methods. The Fe-N cores are composed of Fe 4 N as major phase and FeN as minority. The thickness of SiO 2 shell increases continuously with increase of the tetraethyl orthosilicate weight. Relative to the natures of Fe-N, Fe-N @ SiO 2 composites show slightly weaker ferromagnetic capacity, but much higher oxidation resistance. The Fe-N sample exhibits extremely high relative permittivity. With filling loading of 50 wt%, it has a moderate microwave absorption performance with a maximum reflection loss about −10 dB. Owing to low conductivity, non-magnetic property and superior anti-oxidation ability of the SiO 2 shell, the core-shell structures have considerably degraded permittivity, and nearly unchanged permeability. These changes bring a much better impedance matching between the permittivity and permeability, and further bring a greatly enhanced microwave absorption performance. All of the Fe-N @ SiO 2 composites have strong absorption abilities. They are quite stable with variation of shell thickness. The composite of 52 nm shell thickness has maximum reflection loss of −23.1 dB at 17.2 GHz, and effective absorption bandwidth (<−10 dB) of 2.4 GHz with absorber thickness 5.5 mm. The present study gives an insight on the roles of silica material influencing the iron-based absorber’s absorption ability. • Fe-N @ SiO 2 nanoparticles with tunable shell thickness were synthesized. • Ferromagnetic Fe-N @ SiO 2 composites have good oxidation resistance. • Core-shell absorbers exhibit strong and stable absorption performance. • Mechanism for SiO 2 modification of absorption performance was revealed.

Tuning the mechanical properties of Mo-W alloyed Ni-based multilayered films upon post-annealing at 600 °C via modulation of individual layer thickness

Ni-based multilayered film is attractive due to its high good thermal conductivity, oxidation resistance and mechanical properties. However, the influence of individual layer thickness on the microstructure thermal stability and mechanical properties have seldom been investigated. Hence, the 5 at.% Mo and 5 at.% W co-added in Ni/NiAl multilayers with individual layer thicknesses ranging from 10 nm to 160 nm were synthesized using co-sputtering. Upon post-annealing at 600 °C, the phase separation of γ-Ni solid solution in multilayer occurs, precipitating dispersed nano-sized α-W phases in major when individual layer thicknesses are lower than 40 nm. The periodical layer interfaces of these multilayers are maintained with excellent thermal stability. The hardness of multilayer is enhanced with reduction of individual layer thicknesses due to grain boundary relaxation, increased layer interfacial barriers and W-related precipitations as obstruction for dislocations movement, showing anneal hardening significantly. Due to crack deflection at the layer interfaces, less brittle W-relative phase precipitation and bare columnar crystals growth, the superior toughness is achieved for 600 °C annealed multilayer with individual layer thicknesses of 40 nm. Therefore, 5 at.% MoW co-alloyed Ni-based multilayer are suitable for high-temperature applications with excellent mechanical properties by modulation of individual layer thicknesses.

Molecular dynamics simulations on the connectivity of topologically close-packed clusters in TiAl3 alloys

Presently, there has been increasing attention on TiAl3, which is commonly used for fabricating power aviation devices owing to its good oxidation resistance and outstanding mechanical properties in high-temperature. As the microstructures determine the macroscopic properties of a material, we investigated the connectivity of icosahedral central atoms in TiAl3 using conventional methods in this study. The topologically close-packed (TCP) structures are present in supercooled liquids, metallic glasses, and metallic liquids. They are intrinsic to liquid metals and are an essential character of the structure in metallic glasses (MGs). However, because of the lack of the concept of connectivity of the TCP structures, we investigated connectivity from the icosahedral central atoms to TCP structures, and a formula was proposed to calculate the connectivity of the TCP structures. Based on the results, low temperatures and cooling rates are conducive to generate high connectivity between icosahedral central atoms and TCP structures. The proposed formula can characterize the connectivity of the TCP structures. These findings open new opportunities for conducting research on the connectivity of clusters in binary alloys.