Superior Oxidation Resistance Research Articles

A novel characterization method for oxidation products of TiBw reinforced TA15 matrix composite

The manuscript presented the application of in-situ TAG (high-temperature oxidation analyzer) and TG-MS-FTIR (Thermogravimetry, Mass spectrometer and Fourier transform infrared spectrometer) techniques for further characterization of TiBw oxidation products in TA15 matrix composite. The volatile ingredient and chemical bonding measurement results revealed the existence of B2O3 and H3BO3, which generated during the oxidation process of TiBw/TA15 composite. Compared with TiCp/TA15 composite, the cyclic oxidation kinetic and microstructure observation results indicated that TiBw/TA15 composite had superior oxidation resistance, which resulting from well-designed network structure.

Phase Transitions and Oxidation Behavior During Oxyacetylene Torch Testing of TaC–HfC Solid Solutions

Tantalum carbide (TaC) and hafnium carbide (HfC) have some of the highest melting temperatures among the transition metal carbides, borides, and nitrides, making them promising materials for high‐speed flight and high‐temperature structural applications. Solid solutions of TaC and HfC are of particular interest due to their enhanced oxidation resistance compared to pure TaC or HfC. This study looks at the effect of Hf content on the oxidation resistance of TaC–HfC sintered specimens. Five compositions are fabricated into bulk samples using spark plasma sintering (2173 K, 50 MPa, 10 min hold). Oxidation behavior of a subset of the compositions (100 vol% TaC, 80 vol% TaC + 20 vol% HfC, and 50 vol% TaC + 50 vol% HfC) is analyzed using an oxyacetylene torch for 60 s. The TaC–HfC samples exhibit a reduction in the oxide scale thickness and the mass ablation rate with increasing HfC content. The improved oxidation resistance can be attributed to the formation of a Hf6Ta2O17 phase. This phase enhances oxidation resistance by reducing oxygen diffusion and serving as a protective layer for the unoxidized material. The superior oxidation resistance of TaC–HfC samples makes these materials strong contenders for the development of high‐speed flight coatings.

Micro characteristics and macro performance of HR3C/T92 steel joints after 100000 hours service at high temperature

In this study, HR3C/T92 dissimilar steel joint samples were taken from ultra-supercritical 1000 MW units of domestic power plants, and the microstructures, tensile property, hardness, and antioxidant performance as well as safety assessment of the welded joints were studied using OMR, SEM, UTM, and other equipment. The results reflected that the micromorphology characteristics and hardness of HR3C/T92 dissimilar steel joints are unaffected after 100000 hours of service. Nevertheless, tensile and impact tests revealed that the joints are prone to brittle fracture. Tensile fracture occurred on the weld fusion line of T92 steel, and the impact absorption energy was lower than the standard requirements. HR3C steel exhibited superior oxidation resistance and corrosion resistance. Moreover, there was no observable oxide layer on the inner wall of the pipe, and the outermost layer of the outer wall had an intact structure. The inner wall of the T92 steel pipe had a 300-μm-thick oxide layer comprising Fe2O3 and (Fe, Cr) oxides. The extrapolated performance of the dissimilar steel joint samples after operation for 200000 hours at high temperatures also met the service requirements.

Supersaturation and dissolvable α-Cr phase enable superior oxidation resistance in FeCrNi medium-entropy alloys

Increasing Cr content in Fe-based alloys is expected to improve oxidation and corrosion resistances, but its effectiveness always degrades because of the over-doping induced precipitation of harmful σ-FeCr and Cr23C6 phases. In this study, the precipitation and oxidation behaviors of FexCrNi alloys were systematically investigated. It is found that the precipitation behavior could be controlled by adjusting the Cr content. The α-Cr phase precipitates at 800 °C in supersaturated FeCrNi medium-entropy alloy (MEA), while it is absent in Fe3CrNi alloy due to the lower Cr content. FeCrNi MEA shows much better oxidation resistance than Fe3CrNi, the oxidation rate constant of FeCrNi is two to three orders lower than that in the Fe3CrNi alloy. The oxidation activation energy of FeCrNi (545 kJ/mol) is much higher than that of the Fe3CrNi alloy (80 kJ/mol), which can be attributed to the synergistic effects of α-Cr dissolution, high configuration entropy and Cr supersaturation. Unlike σ-FeCr and Cr23C6 in stainless steels, the metastable α-Cr phase can be controllably introduced in FeCrNi as a “Cr resource”, and will dissolve during long-term oxidation to provide the required Cr element for the stabilization of the Cr2O3 scale. These discoveries shed new insights into the innovative design of stainless materials for heat-resistance structural applications.

Macro encapsulated Cu-based phase change material for high temperature heat storage with characteristic of self-sealing and high durability

The objective of this research is to develop encapsulated phase change materials with applications exceeding 1000 °C that can be applied to concentrated solar power systems and industrial waste heat recovery. In this study, a macro-encapsulation phase change storage material with a copper-based core and an alumina-based shell was developed by slip-casting method and filling mixture of copper beads and Cu-40 %Al powder. The capsule was able to achieve self-sealing by local oxidation reaction at the entrance without leakage. After aging tests at 1100 °C for up to 1000 h, no leakage or damage was found and mass increase of the encapsulate phase change material was only 4.5 %, confirming the superior durability and oxidation resistance of the encapsulated phase change material. The heat storage density of the copper-based phase change material was evaluated as high as 147 J/g. The heat storage capacity did not decrease after 1000 h and ten cycles of aging. The mechanism of its high durability was explored by morphological observations and Raman spectroscopy. In the original material, a small amount of aluminum was oxidized with priority to alumina which significantly enhanced the durability of the capsules. This macro-encapsulated phase change material exhibits excellent thermal storage performance, as well as self-sealing and durability properties, which are of great significance for improving the efficiency of thermal energy recovery above 1000 °C.

Directional movement of gold nanoparticles on the silicon substrate due to the Laplace pressure: A molecular dynamics simulation study

Due to superior ductility, oxidation resistance, and conductive properties, gold nanoparticles are widely used in semiconductor devices. From printing inks to electronic chips, gold nanoparticles are widely used as conductors. Nowadays, with the size of electronic chips getting smaller, gold nanoparticles have become an essential component in chip design. For example, they can connect resistors, conductors, and other electronic chip components. However, interactions of gold nanoparticles with curved substrates at high temperatures have rarely been studied. In our study, we simulated interactions of gold nanoparticles at high temperatures on a curved silicon substrate. It is observed that at above the metlting point, gold nanoparticles moved directionally under the effect of curvature gradients, and the curved surface can be used to control the coalescence of gold nanoparticles. The size, temperature of gold nanoparticles, and curvature gradients of the substrate are altered to observe their effects on gold nanoparticle movement. According to the results, we conclude that surface curvature gradients induce the Laplace pressure, and the Laplace pressure drives liquid gold nanoparticles to move directionally.

High-temperature performance of Pt-modified Ni-20Co-28Cr-10Al-0.5Y coating: Formation mechanism of Pt-rich overlayer and its effect on thermally grown oxide failure

A Pt-modified NiCoCrAlY coating was prepared on N5 via arc ion plating (AIP), Pt-electroplating, and subsequent vacuum annealing treatments. To perform a comparison between the properties of the modified and normal NiCoCrAlY coatings, the isothermal oxidation performances of the Pt-free and Pt-modified NiCoCrAlY coatings were evaluated at 1100 °C in static air. The results indicate that the Pt-rich overlayer on the Pt-modified NiCoCrAlY coatings exhibited superior oxidation resistance, and the adherent, thinner scale of α-Al2O3 inhibited the formation of detrimental (Ni, Co)(Cr, Al)2O4 spinel oxide. Furthermore, the addition of Pt effectively delayed the Al2O3 oxide phase transformation from θ to α in the early stage and markedly decreased the level of residual stress. The mechanism of forming the Pt-rich overlayer and its effect on thermally grown oxide (TGO) failure during high-temperature oxidation are discussed in detail, and the effect of Pt on improving the TGO growth, stress evolution, and spallation resistance are highlighted.

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.

Enhanced oxidation resistance of low‐carbon MgO–C refractories with Al3BC3–Al antioxidants: A synergistic effect

AbstractThe synergistic effects of Al3BC3–Al antioxidants on optimizing the oxidation resistance of low‐carbon MgO–C refractories were investigated. The results indicated that the oxidation index and rate constant of low‐carbon MgO–C refractories with optimized Al3BC3–Al additions were 13% and 1.10 × 10−4 cm2 min−1 at 1400°C for 3 h, respectively, which is much lower than that of Al or Al3BC3 containing ones. Single Al3BC3 is not a suitable antioxidant for low‐carbon MgO–C refractories; however, if Al3BC3 was initially protected and Al reacted as the antioxidant, enhanced oxidation resistance at high temperature can be achieved. The formation of dense MgO–MgAl2O4–Mg3B2O6 layer contributed to superior oxidation resistance, and the temperature for the generation of this layer was as low as 1100°C due to liquid and vapor phase–assisted reactions with Al3BC3–Al. Furthermore, a self‐repairing function was achieved at 1600°C with the combination of Al3BC3–Al additions in spite of the faster oxidation rate.

Superior oxidation resistance of the chemically complex but structurally simple Ti-Al-Ta-Ce-Si-La-B-nitride

Alloying (Ti,Al)N with Ta, CeSi2 or LaB6 is beneficial for both hardness and thermal stability. Here we show that their different mechanisms allow for a cumulative improvement when alloyed together, which is especially pronounced for the oxidation resistance. During isothermal oxidation treatments in ambient air at 900 °C (for up to 25 h), Ti0.44Al0.44Ta0.12N allows for a parabolic scale growth rate constant kp of 6.039 × 10-5 µm2/s. This is reduced to 2.074 × 10-5 and even 0.399 × 10-5 µm2/s when alloying with 2 mol% CeSi2 respectively CeSi2 + LaB6 (1 mol% each). The oxide scale growth kinetics for the latter can be even better described by a logarithmic or cubic law. In the as-deposited state the CeSi2 and CeSi2 + LaB6 alloyed (Ti,Al,Ta)N are single-phase fcc structured providing an indentation hardness of 32.6 ± 1.5 and 37.8 ± 1.5 GPa, combined with an indentation modulus of 496 ± 22 and 496 ± 14 GPa, respectively. After vacuum-annealing at 1000 °C, their hardness is still 33.0 ± 1.6 and 34.8 ± 1.1 GPa, and noticeable formation of hexagonal AlN and TaNx phases can only be detected by X-ray diffraction when annealed at temperatures above 1200 °C.Using CeSi2 and LaB6 instead of their elemental form is furthermore beneficial for the target production itself, as Ce and La are highly reactive.

Oxidation Behavior of the Polycrystalline Ni-Base Superalloy VDM® Alloy 780

VDM® Alloy 780 is a newly developed polycrystalline Ni-base superalloy with high contents of Co, Cr, and Al intended for operating temperatures up to 750 °C. The alloy is precipitation strengthened by the γ′ phase, which is analyzed by atom probe tomography. Additionally, δ and η phases are utilized for grain boundary pinning. It is shown that the δ and η phases precipitate either plate like or in a fine lamellar structure inside each other. VDM® Alloy 780 shows superior oxidation resistance in comparison with Udimet 720Li and A718Plus, as seen by a lower mass gain and thinner oxide layers at 800 °C and 900 °C. This superior behavior is analyzed in detail by TEM and STEM investigations of the oxide scales from which it is concluded that the Al/Ti ratio in these alloys plays an important role on the oxidation behavior.

Novi nalazi o koroziji feritnih varova od nerđajućeg čelika - pregled

This study covers the review of the degradation of ferritic stainless-steel weldments between 2015 and 2022. The industrial and automotive sectors make extensive use of ferritic stainless steel (FSS) due to its superior oxidation and corrosion resistance, low price, high thermal conductivity, and low thermal expansion. However, it has been reported that ferritic stainless steel is harder to weld than austenitic stainless steel and that doing so would probably result in a weaker welded joint owing to the coarsening of grains high welding temperatures. According to past research, the amount of heat applied during the welding procedure affected how soon the FSS (409 M) weldment degraded after being exposed to NaCl (3.5%) medium. The coarsening of the grains was considered to be the cause of this. When the shielding gas' CO2 content increased, the intergranular corrosion of the FSS weld metal was found to increase. Welds made with the ER430LNb filler metal had significantly lower intergranular corrosion of FSS (AISI 441) than those made with the ER430Ti filler metal. It was discovered that boiling Cu-CuSO4 - 50% H2SO4 solution increased the corrosion rate for the FSS (AISI 430) weldment more than boiling 40% HNO3 Solution. Weldments made of FSS (AISI 430) were found to be negatively affected by the CuCuSO4 - 50% H2SO4 environment in terms of intergranular corrosion attack.

Steam and air oxidation behaviour of thermal spray chromium carbide-based composite coatings

Thermal spray chromium carbide-based composites have been widely used industrially because of their superior oxidation resistance at elevated temperatures compared to other metal matrix composite coatings. In this work, the serviceability of HVOF sprayed coatings from an atomized chromium carbide-based feedstock (Cr23C6-40NiCr) was compared with those from a conventional Cr3C2-25NiCr agglomerated and sintered feedstock. Coatings were exposed to 540 °C and 610 °C for 168 h in both air and steam environments. These conditions are indicative of industrial power plant working conditions to assess their real-time performance. Quantitative Rietveld analysis of the Cr23C6-40NiCr coating XRD patterns indicated a comparable concentration of Cr23C6 in both the powder and coating, implying minimal carbide dissolution. However, the Cr3C2 content in the conventional Cr3C2-25NiCr coating was markedly reduced compared to the initial powder composition, indicating that carbide dissolution occurred to a greater extent. Air oxidation led to the formation of coarse surface oxide, due to the initial formation of Ni-based oxides before a continuous Cr2O3 layer could develop underneath. A notably finer and more uniform oxidized surface composed only of Cr2O3 was formed during steam treatment across both coating types. More importantly, the oxide scale was intact and crack-free in Cr23C6-40NiCr compared to Cr3C2-25NiCr. Moreover, despite Cr23C6 being the main carbide phase and the high binder content (40%NiCr), the microhardness of the Cr23C6-40NiCr coating was comparable to that of the conventional Cr3C2-25NiCr coating, both in the as-sprayed and heat exposed states.

Polycarbosilane-derived ceramic coatings with crack-free morphology for improving oxidation resistance of steel

• Polycarbosilane-derived coatings with crack-free morphology were fabricated. • Addition of glass filler has the ability to fill the cracks in the coatings. • Polycarbosilane-derived coatings significantly improve the oxidation resistance of steel. Polycarbosilane-derived (PCS-derived) coatings with crack-free morphology and superior oxidation resistance were prepared on the Q235 steels by a dip-coating method. The effects of glass filler content on the phase composition, surface morphology, interface and oxidation resistance of the coatings were investigated. The fabricated coatings mainly consist of crystalline phases of SiC and Al 2 O 3 . The content of Al 2 O 3 phase increases with the increase in glass filler content. Addition of glass filler has the ability to fill the cracks resulting from the shrinkage of polycarbosilane during pyrolysis, and crack-free coatings can be obtained. Moderate addition of glass filler in the PCS-derived coatings can significantly improve the oxidation resistance of Q235 steel.

Stable carbon encapsulated titanium carbide MXene aqueous ink for fabricating high-performance supercapacitors

• A simple method to synthesize phenolic carbon encapsulated Ti 3 C 2 T x (Ti 3 C 2 T x @C) inks • Ti 3 C 2 T x @C exhibited superior oxidation resistance even after 100 days of aging • Ti 3 C 2 T x @C exhibited a specific capacitance of 736 F g –1 in a three-electrode system • A flexible interdigitated micro supercapacitor (MSC) was printed using Ti 3 C 2 T x @C inks • Ti 3 C 2 T x @C MSC device displayed high cycling stability (83% after 10,000 cycles) Ti-based MXenes have shown great promise in electrochemical applications, including (photo)electrocatalysis and energy storage. However, their practical application has been hindered by their rapid oxidation in the presence of water and O 2 . In this work, we propose a method to solve the problem through a one-step hydrothermal treatment of MXene (Ti 3 C 2 T x , where T x is –OH or –F) in the presence of agarose. The hydrothermal treatment results in the in situ capping of the phenolic carbon layer on the Ti 3 C 2 T x to form Ti 3 C 2 T x @C, which improves its chemical stability by protecting the Ti atoms from oxidation with water and O 2 , and thus enhances its electrochemical performance by avoiding re-stacking of the Ti 3 C 2 T x @C sheets. The as-prepared Ti 3 C 2 T x @C exhibits high oxidation resistance with >95% performance when stored in an aqueous medium for at least 100 days. Ti 3 C 2 T x @C provides a specific capacitance of 736 F g –1 in 1 M H 2 SO 4 electrolyte over a voltage window of 0.5 V. Having excellent water dispersibility and high electrochemical activity, Ti 3 C 2 T x @C is ideal for the preparation of stable MXene inks for the fabrication of high-performance interdigitated electrodes through inkjet printing. The flexible micro-supercapacitor constructed from Ti 3 C 2 T x @C ink exhibits excellent cyclic stability up to 10,000 charge-discharge cycles without a significant decrease in specific capacitance.

Microstructure and high temperature oxidation behavior of laser cladding C22 coating

C22 coating was successfully prepared on TP347H tube by laser cladding. The main goal was to assess the possibility of using laser cladding C22 coating for high temperature oxidation protection of boiler tubes in ultra-supercritical power plant. The microstructure, phase composition, microhardness and high temperature oxidation behavior of C22 coating were investigated. The microstructure evolution, phase constitution and high temperature oxidation behavior of C22 coating and TP347H samples were investigated. The oxidation experiment were carried out at 600 °C, 700 °C, 800 °C for 168 h. The results revealed that C22 coating mainly contain Ni-Cr-Co-Mo solid solution. The average microhardness of coating surface is 1.5 time that of substrate. Coating exhibited superior oxidation resistance at 600-800 °C. A dense and continuous Cr 2 O 3 film was observed in inner layer of coatings. C22 coating can be used as an excellent oxidation resistant coating with wide application prospect. Coating exhibited superior oxidation resistance due to the formation of a dense and continuous Cr 2 O 3 film in inner layer at 600-800 °C.

Microstructural and mechanical investigations on the heat treatment rejuvenation of a long-term service-exposed GTD-111 Ni-based superalloy

Increasing firing temperature has been known to increase gas turbine machines' power generation and cycle efficiency. The Ni-based superalloys are excellent candidate materials with superior mechanical properties, oxidation, and corrosion resistance for elevated temperature applications. GTD-111 is a Ni-base superalloy that is utilized at high temperatures and stresses as a hot section blade of heavy gas turbines. However, working in such harsh environments is extremely degrading and causes microstructural and mechanical deterioration during long-term operation. In order to regenerate the microstructure and mechanical properties after specific service hours, rejuvenation heat treatments are applied. Nevertheless, a few reports investigated the effect of rejuvenation heat treatments on microstructure and mechanical properties of turbine blade components after long-time exposure, which are made of cast GTD-111 Ni-base superalloys. This study investigated the effect of various rejuvenation heat treatments on the microstructural changes, and high temperature-low stress creep properties of service-exposed GTD-111 turbine blades. The different parameters, such as solution temperature, cooling rate, and aging, are considered. It was found that a proper selection of solution temperature, cooling rate, and aging heat treatment can restore the microstructure and mechanical properties of a service-exposed blade close to an un-exposed condition. Among all heat treatment regimes, full solution at 1190 °C for 2 h (cooling rate 14 °C/min) + aging at 845 °C for 24 h (air cooling) showed the optimum restoration parameters from both microstructural and mechanical aspects.

Antibacterial and antioxidative biogenic films for room-temperature strawberry preservation

The shelf life of strawberries is prone to be shortened by microbial infection and respiratory metabolism, significantly restricting its availability. Advanced preservation films hold considerable promise to overcome this problem. Herein, a biogenic ternary tannic acid/chitosan-citric acid (TA/CS-CA) preservation film was developed and demonstrated remarkable room-temperature strawberry preservation. CS dissolved in CA solution was able to form a fast in-situ film with TA owing to their strong hydrogen bonding. The excellent antibacterial activity (about 90 % for both E. coli and S. aureus) combined with superior oxidation resistance (the DPPH∙ scavenging activity of 90.0 %) were inherited from their ingredients. Consequently, the edible rate of TA/CS-CA film-coated strawberries upon storing at 19–25 °C for 7 days and the freshness lifetime increased to 74.1 % and 112.0 h, which were about twice those of uncoated strawberries, respectively. Moreover, this film exhibited favourable washability and inherent biocompatibility, making it promising as a high-performance preservation material.

Refinement of carbide precipitates in high-Nb TiAl by cyclic aging treatments

High-Nb TiAl alloys are considered as new generation of γ-TiAl alloys for applications at higher service temperatures owing to their superior high-temperature oxidation and creep resistance. Addition of C element can further improve its high temperature creep resistance through solid solution strengthening and precipitation strengthening, but the coarse carbide precipitates are not conducive to the mechanical performance improvement. This paper provides a method for refinement of carbide precipitates via solution and cyclic aging treatments in an as-cast Ti-45Al-8Nb-0.9C (at%) alloy. Coarse primary carbides that precipitated during casting were eliminated through solution treatment, while numerous submicron secondary carbides were precipitated through cyclic aging treatments. The crystallographic orientation relationship between the precipitated submicron secondary carbides and the high-Nb TiAl matrix was determined by various transmission electron microscopy characterization methods. This refinement method provides a possible way for refinement of other precipitates in TiAl alloys.

Effect of LaB6 addition on compressive creep behavior with simultaneous oxide scale growth of spark plasma sintered ZrB2‐SiC composites

AbstractA study has been carried out to examine the effect of LaB6 addition on the compressive creep behavior of ZrB2‐SiC composites at 1300–1400°C under stresses between 47 and 78 MPa in laboratory air. The ZrB2‐20 vol% SiC composites containing LaB6 (10% in ZSBCL‐10 and 14% in ZSBCL‐14) besides 5.6% B4C and 4.8% C as additives were prepared by spark plasma sintering at 1600°C. Due to cleaner interfaces and superior oxidation resistance, the ZSBCL‐14 composite has exhibited a lower steady‐state creep rate at 1300°C than the ZSBCL‐10. The obtained stress exponent (n ∼ 2 ± 0.1) along with cracking at ZrB2 grain boundaries and ZrB2‐SiC interfaces are considered evidence of grain boundary sliding during creep of the ZSBCL‐10 composite. However, the values of n ∼ 1 and apparent activation energy ∼700 kJ/mol obtained for the ZSBCL‐14 composite at 1300–1400°C suggest that ZrB2 grain boundary diffusion is the rate‐limiting mechanism of creep. The thickness of the damaged outer layer containing cracks scales with temperature and applied stress, indicating their role in facilitating the ingress of oxygen causing oxide scale growth. Decreasing oxidation‐induced defect density with depth to a limit of ∼280 μm, indicates the predominance of creep‐based deformation and damage at the inner core of samples.