High Temperature Hot Corrosion Research Articles

Microstructural evolution and high temperature hot corrosion behaviour of AlCoCrFeNiTi high-entropy alloy coatings

The fuels used contain undesirable impurities such as Na, V, K, S, and Mg in gas turbine engines. These impurities react with hot components under service conditions, leading to the deterioration of the thermal barrier coatings (TBCs) structure and the formation of hot corrosion damage. In this study, metallic powders containing CoNiCrAlY were deposited as bond coat on Inconel 718 superalloy material using high velocity oxygen fuel (HVOF) coating technique. High entropy alloy (HEA) powder containing AlCoCrFeNiTi was synthesized as coating material using mechanical alloying (MA) method. AlCoCrFeNiTi powders were produced using atmospheric plasma spray (APS) coating technique. The produced coating system was subjected to hot corrosion tests at 700 °C and 800 °C temperatures for different time periods in corrosive environment conditions containing Na2SO4 (sodium sulfate) and V2O5 (vanadium pentoxide). Hot corrosion behavior of the coating system was determined, damage formations and degradation processes were investigated in detail. As a result of the determination and synthesis of HEA powder materials, production of coatings, experimental studies and hot corrosion test studies under service conditions, it was seen that the Ti-containing AlCoCrFeNi HEA coating system has usable qualities without any damage such as cracking, buckling or spalling.

Influence of NiCrAlY coating on anti-corrosion of M951 alloy

M951 alloy is a cast nickel-based super-alloy widely used in gas turbines and aircraft engines, thus a suitable high temperature protective coating must be applied on its surface to enhance the corrosion resistance. In this research, NiCrAlY coating was deposited on M951 by arc ion plating. TGA at 1100 °C, cyclic oxidation at 1000 °C and hot corrosion in molten Na2SO4+25 wt% K2SO4 salt at 850 °C of M951 bare alloy and NiCrAlY coating specimens were investigated respectively. After TGA and cyclic oxidation, mixed oxides of NiO, NiAl2O4, Nb2O5 and Al2O3 formed on M951 surface, which spalled seriously during cyclic oxidation process. Thin, continuous and adhesive α- Al2O3 formed on the surface of NiCrAlY coating after both oxidation process. In molten Na2SO4+25 wt%K2SO4 salt at 850 °C, catastrophic corrosion occurred for the M951 alloy only after 10 hours, while thin and continuous θ- Al2O3 film formed on the surface of the NiCrAlY coating. In a word, NiCrAlY coating greatly improved the high temperature oxidation and hot corrosion resistance of the M951 superalloy. This study will further refine the oxidation and corrosion behaviors of M951 superalloy under different high temperature protective coatings and provides theoretical and experimental basis for the application of M951 superalloy in corrosive environments.

Influence of temperature on hot corrosion behavior of GH4169 superalloy subjected to Na2SO4–NaCl salts attack

This work studies the hot corrosion behavior of GH4169 Ni-based superalloy, deposited with a mixture of salts comprising 95 wt% Na2SO4 and 5 wt% NaCl, across three distinct temperatures (i.e., 650 °C, 800 °C and 950 °C). Corrosion and non-corrosive exposure experiments were compared, yielding data on mass loss and gain, respectively. Material characterization results revealed that the corrosion layer was mainly comprised of Cr2O3, Fe2O3, NiO, Al2O3, TiO2, NbS2 and MoS2. Notably, as the temperature ascended from 650 °C to over 800 °C, the corrosion mechanisms underwent a transition from pitting to uniform corrosion, corresponding to low-temperature hot corrosion and high-temperature hot corrosion, respectively. At 650 °C, a large number of semi-ellipsoidal corrosion pits manifested on the surface. Conversely, at 800 °C and 950 °C, the corrosion layer on the surface exhibited nearly uniform spallation. The pit growth model and spallation dynamics model were, respectively, developed based on the observed microstructure features. The models serve as tools for quantitative examination of the hot corrosion process of the superalloy at different temperatures.

High-temperature hot corrosion kinetics of PVD Ti1-xAlxN coatings on Nimonic c-263

The high-temperature hot corrosion (HTHC) behavior of Ti1-xAlxN-coated c-263 alloy was studied with- and without a Na2SO4/MgSO4 salt mixture at 850 °C in a SOx-rich atmosphere. In absence of the salt deposit, both, the bare c-263 alloy and cathodic arc evaporated Ti1-xAlxN specimens follow a quasi-cubic corrosion rate. However, when exposed to salt under identical conditions, the rates increase significantly, featuring a compounded parabolic-linear rate law for the c-263 alloy, and a parabolic-like rate behavior for Ti1-xAlxN-coated specimens. The rate-determining step of the HTHC mechanism was attributed to a nitride-to-oxide transformation, followed by a sequential fluxing of the formed oxides.

High temperature hot corrosion and oxidation of 733E831 based superalloy with TiO<sub>2</sub> thermal barrier coating

High temperature hot corrosion and oxidation of 733E831 based superalloy with TiO<sub>2</sub> thermal barrier coating

Study on High Temperature Properties of Yttrium-Modified Aluminide Coating on K444 Alloy by Chemical Vapor Deposition

This work aims to explore a method of improving the high-temperature oxidation resistance and thermal corrosion resistance of a hollow blade of gas turbine. The yttrium-modified aluminide coating was prepared on the surface of nickel-based superalloy K444 by chemical vapor deposition (CVD). The microstructure, high temperature oxidation resistance, and thermal corrosion resistance of the modified aluminide coating deposited at 950 °C, 1000 °C, and 1050 °C were compared. The microstructure and morphology of the coatings were observed and analyzed by XRD, SEM, and EDS. The results showed that adding yttrium and changing the deposition temperature had no effect on the double-layer structure (outer layer and diffusion layer) of the coating. Compared with adding yttrium, the deposition temperature had a greater effect on the coating thickness. When the deposition temperature was 1050 °C and the deposition time was 2 h, the thickness of the yttrium-modified aluminide coating increased by 33% compared to that of a single aluminide coating. The high temperature oxidation resistance and thermal corrosion resistance of the three groups of yttrium-modified aluminide coatings are better than that of the single aluminide coating. The resistance to high temperature oxidation and hot corrosion of the yttrium-modified aluminide coating deposited at 1050 °C was better than that of yttrium-modified aluminide coating deposited at 1000 °C, and both were better than that of the modified coating deposited at 950 °C. The higher the deposition temperature, the higher the yttrium content of the coating, the faster the film-forming speed of α-Al2O3, and the better the high temperature oxidation resistance and thermal corrosion resistance of the coating.

Effect of Ta content on high temperature oxidation and hot corrosion resistance of DZ411 superalloy

Effect of Ta content on high temperature oxidation and hot corrosion resistance of DZ411 superalloy

Correction: High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

Correction: High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

Electrochemical corrosion and high temperature hot corrosion behavior of NbTaTiV and CrNbTaTiV high entropy alloy

NbTaTiV and CrNbTaTiV were fabricated by arc melting and effect of Cr element on electrochemical and high temperature hot corrosion behavior were compared. Electrochemical corrosion investigations revealed that Laves phase at grain boundaries of CrNbTaTiV would underwent galvanic corrosion, resulting in a marginal reduction in corrosion resistance. The results of high temperature hot corrosion showed that within Na2SO4 + 25 wt% NaCl molten salt environment, the oxide film formed by Cr element effectively improved the surface stability, reduced the formation of unprotected loose corrosion products and the generation of low melting point chlorides with strong volatility, which improved the resistance of molten salt corrosion.

High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

Microstructural Evolution and Room Temperature Mechanical Properties in Additively Manufactured Mar M 509 With Short Cycle Heat Treatment

Abstract The Co-based superalloy Mar M 509, known for its high-temperature oxidation and hot corrosion resistance, is processed via laser powder bed fusion (LPBF). Microstructure and mechanical properties of Mar M 509 in as-printed (As-P) and heat-treated (HT) states are compared based on two build orientations (longitudinal (L) and transverse (T)) to establish structure-property links with heat treatment. The As-P condition displays a distinct cellular microstructure (500–600 nm) with 50–60 nm carbide particles adorning cell boundaries. Longitudinal (L) build has columnar grains (8–35 μm along the major axis) with a grain aspect ratio of 4, while transverse (T) orientation exhibits equiaxed, bimodal microstructure (5–10 μm and 15–25 μm grain sizes). Strong <001> texture is noted in L. Mechanical properties at room temperature differ between L and T; T (569 ± 12 HV) has 15% higher hardness compared to L (489 ± 18 HV) and 34% higher 0.2% yield strength (YS), but 30% lower elongation than L. Post a short heat treatment cycle at 1250 °C, weld bead structure and cell boundaries break down. Both L (25–33 μm along the major axis) and T orientations (5–42 μm) experience grain growth, and carbides coarsen (250–350 nm). Post-heat treatment, dislocation density decreases, indicating recrystallization; lattice parameter of matrix reduces, implying solute depletion contributing to carbide enrichment. Yield strength drops from 860 MPa to 740 MPa in L and from 1150 MPa to 840 MPa in T, with ductility rising from 14% to 23% in L.

Hot salt corrosion behavior of Ti–6Al–4V alloy treated with different surface deformation strengthening processes

In this study, the effects of shot peening (SP) and ultrasonic surface rolling process (USRP) on the high-temperature oxidation and hot salt corrosion (HSC) behavior of the Ti–6Al–4V alloy were systematically investigated. The results showed that the high-temperature oxidation resistance of this titanium alloy can be significantly improved by the above two treatments. However, the hot salt corrosion resistance of Ti–6Al–4V alloy cannot be improved by SP due to surface roughness increasement, the surface defects and the complete relaxation of compressive residual stress (CRS) at high temperature. On the contrary, the hot salt corrosion resistance of USRP treated specimen was remarkably improved because USRP treatment significantly reduced the surface roughness and introduced deep CRS field with good thermal stability. In addition, the refined surface microstructure promoted the formation of a protective oxide film, which was also beneficial for inhibiting hot salt corrosion.

High-temperature oxidation and hot corrosion behavior of the Inconel 738LC coating with and without Al2O3-CNTs

Abstract The high-temperature corrosion of turbine blades poses a serious threat to the efficiency of electrical gas power stations, which results in heavy economic losses. In the present study, the Inconel 738 low-carbon steel utilized in the turbine blades was coated on alumina (Al2O3) in a variety of percentages of carbon nanotubes (4, 6, and 8 wt%) using the plasma spray technique. The behavior of the Inconel 738LC alloy with and without artificial ash (67 wt% H2SO4 and 33 wt% V2O5) at different temperatures (650, 750, 850, and 950°C) was investigated. The cycles of hot corrosion and oxidation were achieved in an electric furnace for 10 cycles of 5 h each. After each cycle, the weight changes were measured and recorded. The SEM and XRD achieved for all the specimens were noted, before and post the corrosion.

Sc3+:Ce4+:Y3+ doped zirconia nanopowders (ScCeYSZ): Synthesis, thermal phase stability and hot corrosion behavior of spark plasma sintered body

This study aims to investigate the high-temperature phase stability and hot corrosion behavior of zirconia with triple doping of Sc3+, Ce4+ and Y3+ ions. FESEM result shows that the mean particle size of ScCeYSZ nanoparticles was 80–90 nm. Next, optimal samples regarding the highest high-temperature phase stability (1.9%Sc8.3%Ce1.8%YSZ, 1.1%Sc9.0%Ce1.8%YSZ and 0.5%Sc9.6%Ce1.8%YSZ) were consolidated at 1550 °C for 15 min via the spark plasma sintering (SPS) method. A hot corrosion test was done in the presence of 45%Na2SO4+%55V2O5 salts on three samples at 900 °C for 2 h. Also, the results of hot corrosion were compared with ceramic resulting from the nanostructured YSZ bulk sample (nanoYSZ).Based on the X-ray diffraction results, the formation of the non-transformable tetragonal phase is confirmed in the synthesized nanopowders. Also, the phase and microstructural results after hot corrosion of sintered samples show the formation of a monoclinic phase and destructive YVO4 crystals and quasi-cubic CeO2 crystals on the surface of sintered samples. The results indicated that the sample containing 1.8% scandia, 8.3% ceria, and 1.9% yttria had the highest phase stability and hot corrosion resistance (low monoclinic percentage and low leaching of stabilizer elements of Sc3+:Ce4+:Y3+ from zirconia lattice and low depth of molten salt).

Influence of Silicon and Chromium on the Na2SO4-Induced Hot Corrosion Behavior of Titanium Alloys

Titanium alloys are widely used as construction materials in the aerospace and automotive industries. They have many advantages but also have limitations related to their susceptibility to high-temperature oxidation and hot corrosion. Many efforts to increase the lifetime of components made of titanium alloys have been reported in the literature; the most promising ones involve the deposition of coatings. The present paper is focused on the development of coatings containing chromium and silicon, and their further evaluation in hot corrosion tests. It was proved that the Cr-Si coatings were more effective than Si coatings alone in protecting the titanium alloys against Na2SO4-induced hot corrosion at 800 °C. The enhanced corrosion resistance was attributed to the preferential formation of a thick and continuous SiO2 layer on the surface and—in the case of titanium aluminide alloy—the growth of an Al2O3-rich inner layer of the scale, promoted by chromium.

High temperature oxidation and hot corrosion behaviors of PEO and PEO/polysilazane preceramic-based dual-layer coatings on Ti6Al4V alloy

The high temperature oxidation and corrosion behaviors of a plasma electrolytic oxidation (PEO) coating and a PEO/polysilazane (PEO/PSZ) dual-layer coating are investigated. After exposure in NaCl+Na2SO4 salt at 600 ℃ for 240 h, PEO coating tends to generate porous and loose scales, causing cracking or even complete peeling off from the substrate, and corrosion scales follow the law of formation-shedding-reformulation. After exposure in NaCl+Na2SO4 salt at 600 ℃ for 480 h, the PEO/PSZ coating exhibits a three-layer structure including the outermost corroded layer with sandwich structures, uncorroded Al2O3 particles-containing interlayer, and PEO bottom layer, which retards the continuous penetration of corrosive media and further diffusion of oxygen to the inner bulk alloy, resulting in a remarkable reduction of oxidation and corrosion rate.

Study on high-temperature oxidation and hot corrosion characteristics of Cr60Ni40 laser cladding layer

In order to investigate the high-temperature characteristics of Cr-based alloy, Cr60Ni40 laser cladding layer (60 wt% Cr and 40 wt% Ni) were prepared and subjected to high-temperature oxidation test and hot corrosion test. The results prove that there are Cr segregation and large particles of Cr precipitated within the raw Cr60Ni40 cladding layer. During the high-temperature test, Cr2O3 protective film was generated on the surface of the cladding layer, protecting the substrate to different degrees. However, the particles precipitation of Cr caused uneven growth of Cr-rich oxide, and the Cr segregation brought about internal corrosion with Cr2O3 as the main products.

High-temperature oxidation and hot corrosion of Ni-based single crystal superalloy in the incubation stage

Early stages of high-temperature oxidation and hot corrosion of Ni-based single-crystal superalloy were studied at 900 °C by introducing sulfate coating. Detailed elemental and microstructural analysis revealed layered surface oxide, atomic diffusion, faceted Al-rich precipitation, and γ′-phase depletion, together with grain coarsening and reorientation in the near-surface region. Undulated surface, multiple layered outer oxide scale, inner CrS scale (solely localized in γ-matrix), and an additional γ′-depleted region without crystal reorientation were observed in hot corrosion rather than in high-temperature oxidation. The corrosion behavior is discussed in terms of atomic diffusion and oxide growth. The impact of sulfate-coating is elucidated.

Isothermal oxidation and hot corrosion behavior of HVOF sprayed 80Ni-20Cr coatings at 750 °C

NiCr thermal spray coatings are widely used in many different industrial areas, especially in aviation, automotive, and thermal power plants, in order to obtain abrasion resistance. The determination of high-temperature properties is of great importance in terms of determining the limits to which the coating can operate without being damaged and its structural stability. In this study, 80Ni-20Cr alloy powder was deposited onto 316L stainless steel substrates using a high velocity oxygen fuel (HVOF) spraying technique, and the coatings' oxidation and corrosion behaviors at high temperatures were assessed. In this context, while isothermal oxidation tests were conducted at 750 °C for 5, 25, 50 and 75 h, the hot corrosion behavior of the coatings was investigated for 1, 3 and 5 h at 750 °C in an environment consisting of a 55 wt% V2O5–45 wt% Na2SO4 corrosive salt mixture. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to evaluate powder feedstock and as-deposited, oxidized, and corroded coating samples' phase formation and microstructural changes. In all cases, the coated samples showed good resistance to isothermal oxidation, with no damage such as flaking and peeling. No oxide formation was observed on the coating surfaces. The oxidation started from the coating and substrate interface and proceeded towards the coating surface. Following the hot corrosion experiments, it was observed that the 80Ni-20Cr coating's reaction with the vanadate-sodium sulfate melt resulted in the formation of the corrosion product Ni3V2O8 in all time periods. As a result, under high temperature oxidation and hot corrosion environmental conditions, 80Ni-20Cr coatings have been observed to retain their durability without major damage.

Structure and durability evaluation of blast furnace slag coatings and thermal barrier coatings (TBCs) under high temperature conditions

A high temperature aggressive environment is a great challenge for the long lifetime of thermal barrier coatings (TBCs). In this study, the hot corrosion and isothermal oxidation behavior of blast furnace slag (BFS) and yttria stabilized zirconia (YSZ) coated TBC systems were systematically investigated under high temperature conditions. This study aims to analyze the evaluation of microstructural properties of thermally sprayed CoNiCrAlY/BFS and CoNiCrAlY/YSZ coatings before and after high temperature oxidation and hot corrosion tests. For this purpose, the coatings were isothermally oxidized at 900 °C for 8, 24, 50, and 75 h. Hot corrosion behavior of CoNiCrAlY/BFS and CoNiCrAlY/YSZ coatings deposited on Inconel 718 superalloy substrates were studied at 900 °C in a Na2SO4 and V2O5 molten salt environment. CoNiCrAlY/BFS and CoNiCrAlY/YSZ TBC systems exposed to Na2SO4+ V2O5 molten salt at 900 °C investigate the hot corrosion behavior. The microstructure of coatings, formation of thermally grown oxide (TGO) layer, and degradation of coatings during isothermal oxidation and hot corrosion conditions were investigated. The oxidation and hot corrosion mechanisms were discussed. BFS, could be a potential alternative for the YSZ ceramic top coating in TBCs. The TBC system with BFS can be preferred for oxidation damage due to its low cost. YSZ and BFS TBCs are highly resistant to Na2SO4 and V2O5 molten salt environment.