High Temperature Oxidation Behavior Research Articles

High-temperature Oxidation Properties of TiC-reinforced Mo Matrix Composites with Cr Element Added

This work studied Mo-TiC-xCr (x = 0.0, 0.5, 1.0 wt.%) matrix composites with different component gradients prepared by Spark Plasma Sintering (SPS). The high-temperature oxidation test was conducted at 1200 ℃ in the atmosphere to study the influence of Cr on the high-temperature oxidation behavior of TiC-reinforced Mo matrix composites. The phase composition and morphology of the oxide film were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), and the goal was to determine the effect of the Cr content on the high-temperature oxidation properties of the Mo-TiC-xCr (x = 0.0, 0.5, 1.0 wt.%) matrix composites. The results showed that with increasing oxidation time, the oxide film on the surface of Mo alloy will crack and fall off easily, and the porosity gradually increases. Oxygen underwent vigorous oxidation through the pores and the inside of the matrix, and a protective MoO2 internal oxide film disappeared. With increasing Cr content, the high-temperature oxidation performance of the Mo alloy improved, the thickness of the oxide film decreased, warping of the surface oxide film was inhibited, the porosity decreased, and volatilization of MoO3 was inhibited. After oxidation, the surface oxide film was mainly composed of TiO2, MoO3, Cr2O3 and Cr2(MoO4)3 phases. The TiC particles dispersed in the matrix were oxidized to TiO2 to inhibit the oxidation of the alloy. The Cr formed a protective oxidation film of Cr2O3, which effectively reduced the porosity and delayed the volatilization of the MoO3, thus improving its oxidation performance.

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.

Improving high-temperature oxidation behavior by modifying Al and Co content in Al-Co-Cr-Fe-Ni high-entropy alloy

• Oxidation performance of Al-Co-Cr-Fe-Ni system at 1173–1373 K was investigated. • At temperature less than 1273 K, oxidized alloys covered by unstable oxide products. • At temperature higher than 1273 K, oxidation was controlled by Al 2 O 3 or Cr 2 O 3 . • Phase stability beneath oxide layer contributed to oxidation performance • Electron valence concentration affected oxidation behavior of Al-Co-Cr-Fe-Ni system. Composition modification was introduced to improve the oxidation resistance by varying Al and excluding Co from the Al-Co-Cr-Fe-Ni system. Since adjusting the composition shifted the valence electron concentration (VEC) of the alloys, the dual-phase structure of the alloys is expected to be more stable. At low temperatures ( T < 1273 K), the alloys formed mixed oxide products. As oxidation temperature increased, only Cr 2 O 3 or Al 2 O 3 dominated the alloy's surface. Compared to equiatomic AlCoCrFeNi (5-Equi), non-equiatomic AlCoCrFeNi (5-B 40) and four-component AlCrFeNi (4-B 2013) had better oxidation resistance due to monocrystalline-Al 2 O 3 formation. Besides the role of oxide formation, maintaining BCC and B2 phases within the alloys is also beneficial to supporting the stable Cr 2 O 3 or Al 2 O 3 .

Oxidation resistance of the 316L manufactured by cold-rolled and selective laser melting in CO2 and air

The high-temperature oxidation behavior of 316 L manufactured by cold-rolled and selective laser melting in CO 2 and air was investigated. Scanning electron microscopy, X-ray diffraction, and energy disperse spectroscopy were employed to characterize the oxidation products on investigated 316 L. Results showed that oxidation kinetics of all samples followed a parabolic law from 600 ℃ to 900 ℃. At 700 ℃, cold-rolled 316 L exposed a better oxidation resistance, while selective laser melting 316 L was more resistant to oxidation at 600 ℃, 800 ℃ and 900 ℃. The above oxidation behavior may be caused by the recrystallization of cold-rolled 316 L and high density of grain boundaries in selective laser melting 316 L.

Analysis on Oxidation Behavior of HR3C Steel at 700°C in Water Vapor

HR3C is an advanced heat-resistant alloy, and its high-temperature oxidation resistance directly determines the service performance of the material. Therefore, exploring the high-temperature oxidation behavior of HR3C is of great significance for the theoretical research and practical application of the material. The oxidation kinetic curve, oxide film morphology, oxide film composition, and oxide film phase composition of HR3C samples in the supply state after being oxidized in water vapor at 700°C for 50h, 150h, 250h, 350h, 450h, 550h and 600h were analyzed by SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy) and XRD (X-ray diffraction). The results show that the oxidation kinetic curve of the material conforms to the parabolic law, the oxide film first forms a lamellar oxide, and the lamellar oxide film grows alternately to form a loose and porous oxide film surface, the oxide is composed of three oxides: Fe₃O₄, FeCr₂O₄ and Fe₂O₃. The FeCr₂O₄ is a spinel compound, which can form a dense oxide film, and the diffusion coefficient of metal ions in it is small, which hinders the diffusion and mass transfer of ions, thereby improving the high temperature oxidation resistance of stainless steel. The element Cr is mainly enriched in the inner oxide layer, and the element Fe is relatively high in the outer oxide layer.

High-temperature oxidation behavior and corrosion resistance of in-situ TiC and Mo reinforced AlCoCrFeNi-based high entropy alloy coatings by laser cladding

In-situ TiC particles and Mo-enhanced AlCoCrFeNiMox(TiC)2-x high entropy alloy (HEA) coatings (x = 0, 0.5, 1, 1.5, and 2) were prepared via laser cladding. The effects of changes in x on the phase, microstructure, microhardness, high-temperature oxidation resistance and corrosion resistance of the HEA coatings were investigated. The results showed that the main phase of the coatings was the BCC phase; moreover, the Mo-rich area gradually increased and the size and morphology of the TiC particles underwent a series of changes with the increase in x. In addition, the σ and NiCrCoMo phases appeared when x = 1.5 and 2, respectively. Mo promoted the formation of a protective oxide layer and improved the stability of the passivation film, whereas the second phase increased the defects of the coatings, which determined the difference in the high-temperature oxidation resistance and corrosion resistance of the coatings. With an increase in x, the high-temperature oxidation and corrosion resistances of the coatings first increased and then decreased. The coating exhibited the best high-temperature oxidation resistance and corrosion resistance when x = 1, and its high-temperature oxidation resistance and corrosion resistance were respectively 5–12 times and 15–83 times better than those of the other coatings.

Deposition of Iridium Coating on Pure Tungsten and High-Temperature Oxidation Behavior at 1300 K

Iridium (Ir) coating was electrodeposited on tungsten (W) substrate for resistance to high-temperature oxidation. The reduction of iridium was studied using an electrochemical cyclic voltammetry (CV) measurement technique. The structure characterization and performance testing were carried out by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a high-temperature oxidation test. The results showed that the reduction of tetravalent iridium ions to metallic iridium included three reduction steps. The deposited iridium coating had a fine polycrystalline + amorphous structure, no grain orientation phenomenon was observed after electrodeposition, and the microstructure was isotropic. The iridium-coated tungsten metal had excellent resistance to high temperatures at 1300 K, which was attributed to the better chemical stability of the oxide film generated on the surface of the iridium coating.

A Comprehensive Study on High-Temperature Oxidation Behavior of Ceramic Molds for Hot Embossing.

Structural ceramics are potential mold materials for hot embossing, due to their superior mechanical strength as well as low thermal expansion coefficient. However, the service time of molds, especially those in high-temperature hot embossing, strongly depends on their oxidation resistance. As a result, the oxidation behaviors of various ceramics (e.g., SiC, ZrO2, AlN, Al2O3, Si3N4 and WC) were investigated by conducting cyclic oxidation experiments in this study. Mass changes of ceramic samples thermal treated under different temperatures were measured by thermogravimeter (TGA) and precision electronic balance. The structural and chemical compositions of ceramic samples were detected by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDXS). The surface morphology of the samples was characterized by scanning electron microscopy (SEM), and the surface roughness of the samples was measured by white light interferometry. The mechanical properties of the samples were evaluated by a microhardness tester and nanoindentation instrument. It is noted that Al2O3 shows negligible oxidation within 1000 °C. ZrO2 maintains a decent surface roughness of below 32 nm and a stable hardness within 1000 °C. SiC has the highest hardness at high temperatures, and its surface roughness increases notably above 800 °C. The surface roughness of Si3N4 and AlN soars between 600 °C and 800 °C. The surface finish of WC is significantly deteriorated above 600 °C. Therefore, the appropriate embossing temperature of Al2O3 ceramics is below 1000 °C, that of ZrO2 ceramics is between 800 °C and 1000 °C, that of SiC ceramics is below 800 °C, that of Si3N4 and AlN ceramics is between 600 °C and 800 °C, and that of WC ceramics below 600 °C.

Comparative analysis of CoCrAlY coatings at high-temperature oxidation behavior using different reinforcement composition profiles

Comparative analysis of CoCrAlY coatings at high-temperature oxidation behavior using different reinforcement composition profiles

High-temperature steam oxidation behavior of an FeCrAl alloy with controlled addition of Mo

High-temperature steam oxidation behavior of an FeCrAl alloy with controlled addition of Mo

High Temperature Oxidation Behavior of CrMnFeCoNi High-Entropy Alloy

High Temperature Oxidation Behavior of CrMnFeCoNi High-Entropy Alloy

High-Temperature Oxidation Behaviour of a TiAl-Based Alloy Subjected to Aluminium Hot-Dipping

In this research the oxidation resistance at high temperature of a TiAl-based alloy has been improved by hot-dipping the alloy in molten aluminium and by performing an interdiffusion process. After selecting the best process parameters, a compact TiAl3 coating characterized by an almost constant thickness was formed on the surface. Isothermal oxidation tests, carried out at 900, 950 and 1000 °C, showed that the coated alloy is able to form a continuous and thin alumina layer that is very protective. Microstructural investigations highlighted that, above 900 °C, long residence times at high temperature determine the diffusion through the TiAl3 layer of Cr that favours migration toward the outer surface of Al and thus the formation of a self-healing alumina layer.Graphical

Oxidation Behavior of FeCoNiCrMo High-Entropy Coatings by Atmospheric Plasma Spraying on Zircaloy-4 in Steam at 1100 °C

As a potential accident-tolerant fuel cladding material, we studied the method of preparing FeCoNiCrMo coatings on zircaloy-4 substrates by atmospheric plasma spraying (APS) technology to explore the high-temperature oxidation behavior of the FeCoNiCrMo coatings at 1100 °C in high-temperature steam. Various surface analysis techniques such as X-ray diffraction, electron probe microanalysis, and scanning electron microscopy were used to analyze the phase composition and microstructure of the oxidized products. The oxidation behavior of the FeCoNiCrMo coatings and the diffusion of the FeCoNiCrMo coatings to the zircaloy-4 substrates were analyzed. After oxidation at 1100 °C, a dense Cr2O3 oxide layer was formed on the coating’s surface, which grew from 1.5 to 3 μm after 15 to 60 min of oxidation, and the FeCoNiCrMo coatings and the substrates diffused simultaneously. The oxidation tests showed that the FeCoNiCrMo coatings prepared by APS can effectively delay the oxidation of zircaloy-4 substrates.

Effect of Pre-Oxidation on High-Temperature Oxidation Behavior of Al-Si Coating on Nickel-Based Superalloy.

Under the condition of long-time high-temperature oxidation, oxidation in Al-Si coating will lead to degradation of the coating. To solve this problem, the Al-Si coating was treated before the oxidation experiment at different pre-oxidation temperatures and times. The structure, morphology and element distribution of the oxide film were characterized by XRD, SEM and EPMA, and the oxidation kinetics curves were drawn. The results show that the oxidation resistance of the pre-oxidized samples is improved in the process of constant temperature oxidation at 1000 °C. When the pre-oxidation temperature is set at 950 °C, the mass gain of the samples is the lowest, and the accelerated decomposition of Cr2O3 caused by high pre-oxidation temperature is avoided. After oxidation for 300 h, the oxide film on the surface is still continuous and dense without peeling. The samples pre-oxidized at 950 °C for 7 h show the best oxidation resistance in a 1000 °C constant temperature oxidation process, more α-Al2O3 oxides are generated on the coating surface and the element diffusion between the matrix and the coating caused by overly long oxidation time is avoided.

Effects of Ni and Cr on the high-temperature oxidation behavior and mechanisms of Co- and CoNi-base superalloys

The high-temperature oxidation behaviors of Co- and CoNi-base alloys with different Ni and Cr additions were investigated by isothermal oxidation in air at 900 and 1000 °C. The structure, composition, and element distribution in the three layers within the oxide scales in different alloys have been explored in detail by electron microscopy, especially with regard to the fine oxide particles in the intermediate layer. Based on the microstructure and phase constitution of the oxide scales, the synergetic effects of alloying elements on the oxidation mechanisms and resistance have been elucidated in detail with the aid of CALPHAD calculation.

Effect of TiC on the high-temperature oxidation behavior of WMoTaNbV refractory high entropy alloy fabricated by selective laser melting

The refractory high-entropy alloys possess both high melting points and excellent high-temperature properties. As a result, they are expected to become a new generation of high-temperature materials. Along these lines, in this work, selective laser melting (SLM) was used to prepare WMoTaNbV and TiC/WMoTaNbV-based alloys, while the influence of the SLM process parameters on the surface morphology, internal defects distribution and microstructure of the alloy was thoroughly analyzed. On top of that, the long-term high-temperature oxidation behavior of the two alloys at 600°C was studied. The extracted results showed that the process parameters had a serious impact on the surface quality and internal defects of the refractory high-entropy alloys. By optimizing the process parameters, the final surface roughness value of the WMoTaNbV-based alloy was 9.148 μm (Sa). On the contrary, the surface roughness value of the TiC/WMoTaNbV compound was 14.218 μm (Sa). It is also interesting to notice that the incorporation of TiC could significantly reduce the number of cracks within the TiC/WMoTaNbV alloy. Moreover, the WMoTaNbV-based alloy was mainly composed of dendritic structures, while the TiC/WMoTaNbV-based alloy consisted of cellular structures. The main oxidation products of the WMoTaNbV-based alloy were the Ta16W18O94 and Nb14W3O47 ternary oxidation products. After the TiC particles were added, the Ti-containing oxidation products such as TiO2, Ti2Nb10O29. etc. within the TiC/WMoTaNbV-based alloy increased significantly, preventing thus effectively the alloy from being seriously oxidized. The cellular structures, carbides and TiO2 phase are helpful in improving the oxidation resistance of the TiC/WMoTaNbV-based alloy.

Non-uniform high-temperature oxidation behavior of twin wire and arc additive manufactured Ni3Al-based alloy

Ni3Al-based alloy fabricated by twin wire and arc additive manufacturing exhibited periodic remelting bands (RB) with unique microstructural characteristics. In this work, the deposited Ni3Al-based alloy was oxidized at 1100 °C for different times to investigate the high-temperature oxidation difference caused by RB. The differences in the microstructure, grain orientation, oxidation behavior, and oxidation mechanism between RB and non-RB were systematically studied. The results showed that these RB, epitaxially grown on the non-RB during each deposition layer, displayed similar Goss textures but a higher proportion of γ + γ′ dual-phase microstructure compared to non-RB. The oxidation of the deposited Ni3Al-based alloy obeyed parabolic growth kinetics at 1100 °C for 10 h and the oxidation scales were consisted of external NiO layer, intermediate NiAl2O4 layer with dispersed Al2O3 and TiO2 particles and internal Al2O3 layer. The outward diffusion of Al and Ti elements during the oxidation process led to the decomposition of γ′ precipitations and the formation of γ′-reduced layer beneath the Al2O3 layer. The cross-section microstructure of oxidation scales indicated that the RB displayed thicker scales and poorer oxidation resistance than non-RB. The oxidation rate of the deposited Ni3Al-based alloy was controlled by the outward transport rate of the total cations (Ni2+, Al3+, and Ti4+) through the Al2O3 layer. Initial oxidation and diffusion interface analysis demonstrated that the γ + γ′ dual-phase had a higher outward transport rate of the cations, which was responsible for the thicker oxide scales on the RB.

Characterization of the High-Temperature Oxidation Behavior of Inconel 625® Fabricated by Additive Manufacturing and Conventional Methods

Characterization of the High-Temperature Oxidation Behavior of Inconel 625® Fabricated by Additive Manufacturing and Conventional Methods

High Temperature Oxidation Behaviors of Powder Metallurgical γ-TiAl Based Alloys: Effects of Surface Defects on Morphology of the Oxide Scale

In the present work, γ-TiAl-based alloys with nominal composition of Ti-48Al-2Cr-2Nb (at.%) were prepared by vacuum hot pressing sintering using pre-alloyed powders under different pressures. The alloys were oxidized under cyclic conditions at 900 °C in the air for up to 100 h. The effects of surface defects on the morphology of the oxide scale were investigated. It was found that the alloys with increased porosities had increased mass gains after oxidation as a result of the increased area of oxidation reaction and the thickness of the scale, as well as the formation of micro-oxide clusters with an increased amount and size. These micro-clusters, which made the oxide layer rough, grew in the positions of surface defects. The diffusion of elements to the inner face of the defects led to the formation of large TiO2 and Al2O3 particles and was responsible for the formation of oxide clusters. The phenomenon and corresponding mechanism proposed here have previously been unreported, and they may play a guiding role in investigations concerning the oxidation behaviors of TiAl alloys with defects.

Role of Nb in promoting protective scale formation on Al2O3-forming austenitic alloys

The high-temperature oxidation behavior of Fe–25Ni–17Cr–7.7Al–0.03Zr alloys with and without 0.5 or 1 at% Nb addition was investigated at 800 °C in air. Nb addition was found to promote the formation of an external Al2O3 scale. The Nb-free alloy formed a scale consisting of a thick Fe/Ni-rich oxide layer and a Cr2O3 layer, beneath which Al was internally oxidized. However, a continuous protective Al2O3 scale was developed below a thin Cr2O3 layer on the 1 Nb alloy, which significantly decreased the oxidation rate. Examination of the initial oxidation process during heating to 800 °C revealed that all of the alloys formed a Cr2O3 layer and an amorphous Al2O3 layer upon heating to 650 °C, but these layers became discontinuous upon further heating to 800 °C for the Nb-free alloy. The beneficial role of Nb was ascribed to its ability to maintain the initially formed thin Cr2O3 layer by the formation of a Nb-containing Cr-rich oxide layer at the interface between the Cr2O3 and amorphous Al2O3 layers. This Nb-containing Cr-rich layer prevented the breakdown of the transient amorphous Al2O3 layer until its transition to a protective crystalline Al2O3 scale.