Cyclic Oxidation Behavior Research Articles

Long-term oxidation resistance of CrAl(Si)N coatings deposited on TiAl-based alloy at 950 °C

CrAl(Si)N coatings were deposited on Ti-48Al-2Cr-2Nb alloy by arc ion plating. Long-term cyclic oxidation behaviors of the CrAl(Si)N-coated alloy were investigated at 950 °C. The oxidation resistance of the Cr0.4Al0.5Si0.1N coating was significantly better than that of the Cr0.5Al0.5N coating. The addition of Si to the CrAlN coating promoted the formation of an almost continuous inner Al2O3 layer in the oxide scale. The continuous and dense Cr2O3/Al2O3 oxide layer acted as a diffusion barrier and retarded the inward diffusion of oxygen and outward diffusion of the coating elements. However, interdiffusion between the CrAl(Si)N coatings and the alloy was serious and a thick interdiffusion zone formed.

Investigation of Cyclic Oxidation and Hot Corrosion Behaviour of Plasma-Sprayed NiCrAlY/Cr3C2/h-BN/Mo Coatings on T22 Boiler Steel Alloy

Investigation of Cyclic Oxidation and Hot Corrosion Behaviour of Plasma-Sprayed NiCrAlY/Cr3C2/h-BN/Mo Coatings on T22 Boiler Steel Alloy

Microstructure, high-temperature cyclic oxidation, and hot corrosion behaviors of Inconel 718 alloy produced by laser-induction hybrid cladding

The microstructure evolution, cyclic oxidation, and hot corrosion behavior of the unheated-treated (As-built) and solution + double aging (SDA)-treated Inconel 718 alloys fabricated through laser-induction hybrid cladding (LIHC) were investigated. It was found that the as-built Inconel 718 alloy exhibits a columnar dendritic with intergranular Laves phase. After SDA-treated, γ", γ′, δ and carbide phases precipitated, the Laves phase became fine and dispersed. After cyclic oxidation, the Cr2O3 scales were formed on both as-built and SDA-treated LIHC-produced Inconel 718 alloy, which could provide good cyclic oxidation resistance for the Inconel 718 alloy. However, the as-built and SDA-treated LIHC-produced Inconel 718 alloy suffered severe hot corrosion in 95 wt% Na2SO4 + 5 wt% NaCl mixed salt solution and many corrosion products were generated, including Cr2O3, NiCr2O4, NaNbO3, Na2CrO4, NiFe2O4, Fe3O4, and NiO. Nevertheless, the SDA-treated sample showed better cyclic oxidation and hot corrosion resistance than the as-built sample, owing to the more compact Cr2O3 scale.

Investigation of High-Temperature Oxidation Behavior of Additive Manufactured CoCrMo Alloy for Mandrel Manufacturing.

The cyclic oxidation behavior of an additive manufactured CoCrMo alloy with 0.14 wt.% C was investigated at 914 °C for 32 cycles, each lasting 10 h, resulting in a total exposure time of 320 h. The oxidation rate was assessed for mass gain after finishing each 40 h oxidation cycle. It was experimentally determined that the oxidative process at 914 °C of this CoCrMo alloy follows a parabolic law, with the process being fast at the beginning and slowing down after the first 40 h. The microstructural analysis revealed that in the as-printed state, the phases developed were primarily the γ matrix and minor traces of ε phase. The oxidative process ensured an increase in the ε phase and precipitation of carbides which produced a 12% increase in the material's hardness after the first 40 h of exposure at 914 °C. The oxidation process led to the development of an oxide scale comprising a dense Cr2O3 layer and a porous layer of CoCr2O4 spinel, the latter spalling after the 240 h of exposure. Despite this spallation, the oxide scale continued to develop in the presence of O, Cr, and Co. The experimental analysis provided valuable insights regarding the material's behavior under prolonged exposure at high temperature in air, demonstrating its suitability as a candidate for additive manufactured mandrels used for bending metallic pipe fitting elbows.

High-Temperature Cyclic Oxidation Behavior and Microstructure Evolution of W- and Ce-Containing 18Cr-Mo Type Ferritic Stainless Steel.

Due to the recurrent starting and stopping operations of automobiles during service, their engines' hot ends are continually subjected to high-temperature cyclic oxidation. Therefore, it is crucial to develop ferritic stainless steels with better high-temperature oxidation resistance. This study focuses on improving the high-temperature cyclic oxidation performance of 18Cr-Mo (444-type) ferritic stainless steel by alloying with high-melting-point metal W and the rare earth element Ce. For this purpose, a high-temperature cyclic oxidation experiment was designed to simulate the actual service environment and investigate the high-temperature cyclic oxidation behavior and microstructure evolution of 444-type ferritic stainless steel alloyed with W and Ce. The oxide structure and composition formed during this process were analyzed and characterized using scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS) and electron probe X-ray micro-analyzer (EPMA), in order to reveal the mechanism of action of W and Ce in the cyclic oxidation process. The results show that 18Cr-Mo ferritic stainless steel alloyed with W and Ce exhibits an excellent resistance to high-temperature cyclic oxidation. The element W can promote the precipitation of the Laves phase between the matrix and the oxide film, and the small-sized Laves phase can inhibit the interfacial diffusion of oxidation reaction elements and prevent the inward growth of the oxide film. The element Ce can refine oxide particles and reduce the thickness of the oxide film. CeO2 particles within the oxide film can serve as nucleation sites for the formation of oxide particles from reactive elements, and they also contribute to pinning the oxide film, thereby enhancing its adhesion.

Influence of Thermal Aging Treatments on Intergranular Corrosion and Cyclic Oxidation Behavior of Low Nickel and Nickel-Free Austenitic Stainless Steels

Influence of Thermal Aging Treatments on Intergranular Corrosion and Cyclic Oxidation Behavior of Low Nickel and Nickel-Free Austenitic Stainless Steels

Cyclic oxidation behaviour of N-type (Zr,Ti)Ni(Sn,Sb) and P-type (Zr,Ti)Co(Sn,Sb) thermoelectric materials

In this study, the fabricated Hf-free N-type (Zr,Ti)Ni(Sn,Sb) and P-type (Zr,Ti)Co(Sn,Sb) thermoelectric materials were subjected to cyclic oxidation testing at 500 °C for 10, 30, and 50 cycles. The oxidation behaviour of the materials was systematically investigated by evaluating mass gain to study the oxidation kinetics and by analysing surface morphology, phase constitution and elemental distribution to investigate the oxidation mechanism. The results indicated that both of the materials were severely oxidised during the cyclic oxidation testing, and the mass gain followed the parabolic kinetics and the parabolic rate constant (kp) being 0.006165 mg2cm−4s−1 and 0.000109 mg2cm−4s−1 for the N-type and the P-type TE materials, respectively. Alternated multilayers of Ni3Sn4+SnO2+(Zr,Ti)O2 and CoSb + SnO2+Sb2O4+(Zr,Ti)O2 were identified on the surface of the N-type and P-type materials, respectively, after the cyclic testing, which would deteriorate the thermoelectric performance of the materials. The outcome of this study strongly suggests that it is essential to improve the oxidation resistance and the thermal stability of the N-type (Zr,Ti)Ni(Sn,Sb) and P-type (Zr,Ti)Co(Sn,Sb) thermoelectric materials for high-temperature applications.

Cyclic Oxidation and Hot-Corrosion Behavior of HVOF-Sprayed NiCrAl Coating on Industrial Boiler Tube Steels

Cyclic Oxidation and Hot-Corrosion Behavior of HVOF-Sprayed NiCrAl Coating on Industrial Boiler Tube Steels

Thermal barrier coating on Inconel 718: understanding cyclic oxidation kinetics

This study investigates the cyclic oxidation behaviour of a thermal barrier coating (TBC) system applied to Inconel 718 alloy substrates. The TBC comprises a NiCr bond coat and a YSZ top coat, applied using the air plasma spray method. Cyclic oxidation studies involve subjecting the coated samples to repeated heating and cooling cycles, with mass gain measurements taken after each cycle. Vibrational modes and surface morphology are analysed before and after oxidation. Results reveal a gradual increase in mass gain up to the 4th cycle, attributed to interface bonding and diffusion-limited growth. Thermal cycling induces stresses, leading to micro cracking and accelerated oxidation. Oxidation kinetics follows both parabolic and linear laws, with rates decreasing over cycles. Kl values consistently exceed Kp, indicating faster linear growth. The study enhances understanding of TBC behaviour under cyclic oxidation conditions, critical for improving durability in practical applications.

The cyclic oxidation behavior and kinetics of W-Cr-Nb-Y2O3 alloys processed by powder metallurgy route

In the present investigation, yttria (Y2O3) has been added to the W-Cr-Nb alloys to study the cyclic oxidation behavior of on W-Cr-Nb- Y2O3 alloys processed by the powder metallurgy route. The cyclic oxidation tests are performed at 800 °C, 1000 °C, and 1200 °C for 15 h in the air. The oxidation kinetic analysis and implementation of a double Voigt function to calculate the domain size (crystallite size) and microstrain are also investigated. The results show that the cyclic oxidation tests on the sintered W-Cr-Nb-Y2O3 samples have exhibited that [(W0.5Cr0.5)90Nb10]98 - (Y2O3)2 alloy is marginally more oxidation resistant than [(W0.7Cr0.3)90Nb10]98 - (Y2O3)2 alloy at temperatures 800 °C and 1000 °C. In contrast, the [(W0.7Cr0.3)90Nb10]98 - (Y2O3)2 composite shows more oxidation resistance than [(W0.5Cr0.5)90Nb10]98 - (Y2O3)2 composite at temperature 1200 °C, apparently due to the formation of a large number of protective oxides like Cr2WO6, 2NbO5.7WO3 and Y2WO6, and absence of WO3 oxide on the former composite at 1200 °C in air. The values of oxidation exponent n ≈ 2 obtained for the oxidation tests on the [(W0.5Cr0.5)90Nb10]98 - (Y2O3)2 indicate that approximately parabolic rate law is being followed in the range of 800–1200 °C. In the case of [(W0.7Cr0.3)90Nb10]98 -(Y2O3)2 alloy (1 < n < 2) indicates that the rate of oxidation is faster than that predicted by the parabolic rate law but slower than that expected from the linear relationship between mass change per unit area (Δm/S) and time (t).

Cyclic Oxidation Kinetics and Thermal Stress Evolution of TiAl Alloys at High Temperature

The oxidation resistance of TiAl alloys is crucial for their commercial application. In this paper, a cyclic oxidation test with stable air circulation was designed to investigate the cyclic oxidation behavior of the TNM alloy and 4822 alloy at 800 °C and to analyze the phase, morphology, and thermal stress evolution of the oxide layer. The oxidation weight gain curves of both alloys are found to be in parabolic form, and the oxidation reaction orders of the TNM alloy and 4822 alloy are 2.374 and 1.838, respectively. The Nb and Mo elements enhance the antioxidant performance of the TNM alloy by inhibiting the dissolution and diffusion of oxygen, Ti, and Al atoms in the TiAl alloy. The thermal stress evolution of the two alloys during the heating and cooling phases of the cyclic oxidation process are calculated separately, and it is found that the thermal stresses in the TNM alloy are smaller than those in the 4822 alloy, while the maximum thermal stresses appear at the oxide/substrate interface rather than inside the oxide scale, which quantitatively explains the oxidation peeling resistance of the two alloys.

Cyclic and Isothermal Oxidation Behavior of a Directionally Solidified Ni-Al-Ti-Co-Cr Superalloy

Nickel based superalloys are widely used in such applications as gas turbine blades due to their excellent mechanical properties at elevated temperatures. Oxidation is one of the life limiting factors at such temperatures since it accelerates failure mechanisms, e.g. fatigue and creep. In this project, oxidation behavior of Ni-3Al-4.8Ti-9.5Co-14Cr (wt.%) superalloy was investigated under various testing conditions. The alloy was investment-cast with preferential crystal growth direction [100]. Isothermal oxidation tests were carried out at 800°C for 150h. Cyclic oxidation tests were then conducted between 100-800°C for 150 one-hour cycles. An additional one-hour cycle was tested to replicate real-life working condition of the alloy, which consisted of heating the samples up to 800°C followed by slow cooling to 400°C. During the testing, samples were periodically taken from the furnace and weighted with an accuracy of 10-4 g to calculate the weight gain and to analyze the microstructure of formed oxide. Scanning electron microscopy (SEM) combined with energy-dispersive spectroscopy (EDS) and X-ray diffraction were used to study the microstructure of oxidation products. The results reveal that the highest amount of weight gain is obtained in isothermal testing, while the lowest in cyclic. Diffusion of Ti and Ni to the free surface results in the early-stage formation of needle-shaped oxide phases followed by severe oxidation of Cr and Al. The layer of chromium oxide is continuous while aluminum oxide is blocky at the deepest position from the free surface. Cracks form at the interface of carbide particles and gamma phase near the free surface of cyclic oxidation samples due to concentration gradient of Ni and Al. Precipitate-free zone are observed near the free surface of all the samples at the end of the tests, but internal oxidation does not occur significantly in all the samples. It is found that temperature fluctuation increases oxide spallation, which causes crack formation. At the same time, in isothermal testing, dense, crack-free layer of oxide form on the surface of superalloy.

Effects of YSZ deposition process on reactive elements distribution and cyclic oxidation behaviors of a thermal barrier coating system

Three coatings including topcoat-free NiCoCrAlYHfZr bond coat and the thermal barrier coating (TBC) system consisting of an 8 wt% Y2O3 stabilized ZrO2 (8YSZ) topcoat and either a NiCoCrAlYHfZr or a NiCoCrAlY bond coat were prepared in this study. The localized enrichment of Hf-rich precipitations within NiCoCrAlYHfZr bond coat was significantly alleviated after the YSZ deposition, instead, the nano-sized HfO2 precipitations formed and linearly distributed along the initial thermal grown oxide (TGO)/bond coat interface. Cyclic oxidation behaviors of the three coatings were evaluated at 1100 °C. The results showed that a uniform TGO with fine reactive elements (REs)-rich inclusions was generated in YSZ-NiCoCrAlYHfZr TBC system, alleviating the negative effects resulted from the localized enrichment of Hf-rich precipitations. Besides, co-doping HfZr in NiCoCrAlY bond coat prevented the formation of spinel since HfZr segregating at Al2O3 grain boundaries inhibited the outward diffusion of Ni, Co and Cr from the bond coat, thus significantly improving durability of the TBC system.

Influence of pre-aluminizing on elemental diffusion behavior and fracture mechanism of thermal barrier coatings

The development of high-performance aero-engines raises the urgent requirement of coatings deposited on blades, containing both thermal barrier coatings (TBCs) on the external surface and aluminide coatings in the internal winding cooling channels. A TBC system with a low activity aluminizing process before deposition of conventional TBC was developed here to evaluate the feasibility of co-deposition technology. The thermal cyclic oxidation behavior of co-deposited “Al-modified TBC” was examined at 1100 °C and compared to that of conventional TBC. The cross-sectional microstructure evolution and elemental diffusion behavior of the modified TBC were also investigated. Even though the underlying aluminizing layer can serve abundant Al for the upper NiCoCrAlYHf layer to eliminate “Al depletion” in conventional TBC, which is a main reason for spallation, the Al-modified TBC system exhibited shorter thermal cycling life than conventional TBC. The spallation mechanism was discussed. Cracks caused by the fast growth rate of thermally grown oxide (TGO), Cr-rich precipitates resulted from the decreased γ/γ′-phase in the coating, and Re-rich precipitates originated from outward diffusion through the aluminide layer were mainly responsible for the failure.

Study on the oxidation behavior of a novel thermal barrier coating system using the nanocrystalline coating as bonding coating on the single-crystal superalloy

A novel thermal barrier coating system with a double columnar structure was developed on a single-crystal superalloy N5 to investigate its cyclic oxidation behavior. The bond coating is a columnar nanocrystalline coating deposited by magnetron sputtering, with the same chemical composition as the superalloy N5. Compared to the NiCrAlY/YSZ thermal barrier coating, this novel system does not experience elemental interdiffusion during high-temperature exposure. Additionally, the high density of grain boundaries in the bond coating promotes the selective oxidation of Al, which significantly improves its oxidation resistance and the rumpling resistance of the thermal barrier coating.

Cyclic Oxidation Behavior of HVOF Thermally Sprayed WC Cermet Based on AISI 1045 Steel

Thermal spray coating technology High-Velocity Oxygen Fuel (HVOF) has become one of solution for metal protect and parts recondition that work in critical environments such as oxidative, erosive, and corrosive. One of the thermal spray coatings (TSC) application has been carried out to improve the oxidation resistance of the Induce Draft Fan (IDF) as a part on coal fired steam power plant unit. Cermet WC10Co4Cr and WC17Co are intended to sustain the AISI 1045 steel substrate against the oxidative environment. In this works, the cyclic oxidation at a temperature 500oC were conducted to reveal the oxidation resistance behavior of the coatings. Several mechanical tests are also presented including surface roughness of the coatings, coatings microhardness, and coatings adhesion. The coatings morphology was also characterized using SEM microscope, as well as X-ray diffraction (XRD) for phase analysis after the oxidation test.

Effect of molybdenum on cyclic oxidation behavior of 4th generation nickel-based single crystal superalloys

The cyclic oxidation behavior of fourth-generation nickel-based single crystal superalloys with 2–4 wt% Mo content were studied at 900 ℃ and 1100 ℃. At 900 ℃, with the increase of Mo content, the oxide layer accumulates more growth stress, resulting in the interface between the outer oxide layer and the inner oxide layer more prone to crack initiation. At 1100 ℃, the oxidation layer accumulates more growth stress and thermal stress, so the oxidation layer occurs large scale spalling, which is more severe in 4Mo alloy. The results show that the increase of Mo content of alloy promotes the oxidation of containing W-Re alloy, which promotes the volatilization of oxides and the spalling of oxide, decreases the protection of oxide layer, and deteriorates the oxidation resistance of the alloy.

Enhancing long-term cyclic oxidation performance of a dual-phase PtAl coatings at 1200 ℃ by Ru modification

Dual-phase PtAl coatings with Ru modification (RPT coatings) have been prepared on a nickel-based superalloy by electroplating Ru/Pt layers before the chemical vapor deposition aluminizing process. Cyclic oxidation performance of the RPT coatings at 1200 ℃ is investigated in comparison with unmodified PtAl coatings. The results show that RPT coatings display excellent cyclic oxidation behavior at 1200 ℃, little spallation of surface oxides can be observed within 500 cycles. It can be attributed to the effects of Ru on hindering the Al diffusion and the lower tensile stress at the oxide/coating interface in RPT samples.

Effect of Nd Addition on the Microstructure and Cyclic Oxidation Behavior of NiAl–Cr(Mo) Eutectic Alloys

Effect of Nd Addition on the Microstructure and Cyclic Oxidation Behavior of NiAl–Cr(Mo) Eutectic Alloys

Cyclic oxidation of slurry silicide-aluminide coatings formed on Ti-6Al-4V alloy

ABSTRACT A proprietary slurry cementation method was used to produce silicide-aluminide coatings on alloy Ti-6Al-4V. The cementation processes were carried out at 900–1100 °C for 2–6 h. The coatings exhibited a stratified configuration characterised by a phase arrangement that demonstrates favourable attributes pertaining to mechanical and corrosion resistance capabilities, namely, the presence of aluminium-enriched phases at the coating surface and titanium-enriched phases proximity to the substrate. The cyclic oxidation behaviour at 800 °C for 30 twenty-two-hour cycles was investigated. The characterisation of the structure of coatings was carried out through the use of scanning microscopy, X-ray microanalysis, and X-ray diffraction techniques. The coatings have excellent resistance to cyclic oxidation, resulting from the gradient structure and the establishment of a protective alumina layer on the surface. The coatings were characterised by good resistance to thermal shocks. The microcracks formed during thermal shocks were filled with an alumina, which renders the coatings self-healing.