High Temperature Hot Corrosion Research Articles

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.

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.

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.

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.

Nanomechanical Characterization of High-Velocity Oxygen-Fuel NiCoCrAlYCe Coating

MCrAlY (M = Ni or/and Co) coatings have played an indispensable role in the high-temperature protection system for key components of aero-engines due to their excellent high-temperature oxidation and hot corrosion resistance. Nanoindentation is a useful and highly efficient method for characterizing the nanomechanical properties of materials. The rich information reflecting materials can be gained by load-displacement curves. In addition to common parameters such as elastic modulus and nanohardness, the indentation work and creep property at room temperature can also be extracted. Herein, nanomechanical properties of NiCoCrAlYCe coatings using high-velocity oxygen-fuel (HVOF) spraying were investigated systematically by nanoindentation. The microstructure of as-sprayed NiCoCrAlYCe coatings present mono-modal distribution. Results of nanoindentation reveal that the elastic modulus and nanohardness of NiCoCrAlYCe coatings are 121.08 ± 10.04 GPa and 6.09 ± 0.86 Gpa, respectively. Furthermore, the indentation work of coatings was also characterized. The elastic indentation work is 10.322 ± 0.721 nJ, and the plastic indentation work is 22.665 ± 1.702 nJ. The ratio of the plastic work to the total work of deformation during indentation is 0.687 ± 0.024, which can predict excellent wear resistance for NiCoCrAlYCe coatings. Meanwhile, the strain rate sensitivity determined by nanoindentation is 0.007 ± 0.001 at room temperature. These results can provide prediction of erosion resistance for MCrAlY coatings.

Grain size dependant high-temperature hot corrosion (HTHC) degradation behavior in Alloy 617 during exposure in Na2SO4 + NaCl + V2O5 salt mixture

In the present investigation, the implication of grain size on the high-temperature hot corrosion (HTHC) response in Alloy 617 is studied. Towards this, specific thermal and thermo-mechanical processing schedules were employed to attain a wide range of grain sizes (7–70 µm), while maintaining other microstructural features like Σ3 n (n ≤ 3) boundary fraction, retained strain, and precipitate fraction nearly at constant. Subsequently, these specimens were exposed to Na 2 SO 4 + NaCl + V 2 O 5 (75 wt% + 20 wt% + 5 wt%) salt mixture at 1273 K for 24 h. Post-corrosion analyses reveal the formation of a highly porous and thick oxide scale on the as-received (AR) specimen (~32 µm), a relatively less porous and non-uniform oxide scale on the very coarse-grained specimen (~70 µm), and a homogeneous and dense Cr-rich scale on the very fine-grained microstructure (~7 µm). Such a protective scale on the very fine-grained specimen, developed due to the enhanced diffusivity of Cr, obstructs the entry of corrodents and thereby minimizes the percolation depth (~60 µm). The percolation depth is relatively higher (~130 µm) in the very coarse-grained specimen due to the development of a porous and non-uniform oxide scale. However, its percolation depth is still lower than the AR specimen (~ 305 µm), because of the reduced grain boundary area available for the diffusion of the corrosive species into the substrate. The AR specimen has exhibited the maximum percolation depth due to the simultaneous presence of fine and coarse grains, leading to the failure of both the aforementioned resistive mechanisms i.e., the accelerated formation of a protective Cr-rich scale and lesser availability of diffusion paths for the ingression of the corrosive species. • Very fine and very coarse-grained microstructures are resistant to HTHC damage. • AR specimen with inhomogeneous grain size distribution underwent maximum damage. • Grain refinement accelerates Cr-oxide formation that blocks entry of corrodants. • Grain coarsening decreases the channels for ingression of corrodants into the alloy. • Inhomogeneous grain size distribution in AR fails to activate resistive mechanisms.

High temperature oxidation and hot corrosion behaviors of Fe65.7Ni11.7Ti1Mo6.6Co15 high entropy alloy

Understanding the surface oxidation and hot corrosion properties of the Fe65.7Ni11.7Ti1Mo6.6Co15 high entropy alloy (HEA) at high temperatures and hot corrosion media could provide useful insights into designing the high performance of the metallic materials, which is indispensable for its wide applications. Herein, at about 1923 K, the HEA was prepared by vacuum induction melting with five principal metals (Fe, Ni, Ti, Mo, and Co) in the solid-solution form. The high temperature oxidation tests at 823 K, 923 K, and 1023 K, and the hot corrosion tests using mixtures of NaCl and Na2SO4 as the hot corrosion media at 923 K were carried out, respectively. High temperature oxidation and hot corrosion behaviors were investigated via surface and cross-section morphologies observation, oxidation and corrosion products tests, and chemical composition distribution maps analysis. The effect of temperature on the oxidation resistance, as well as the effect of the content of NaCl in the mixed salt medium on the hot corrosion resistance were revealed. The results show that the HEA exhibited good high temperature oxidation resistance at 923 K according to mass gain and products after oxidation. The higher content of NaCl in the mixed salt medium can bring more intense hot corrosion. In addition, more oxygen and molten salts can be migrated via cracks and dense pores, which is not conducive to enhancing the high temperature oxidation resistance and hot corrosion resistance.

Effect of Zr, Ti, Ta and Mo addition on high-temperature oxidation and hot corrosion behavior of NiAlY alloys

NiAlY alloys with the addition of Zr, Ti, Ta and Mo were prepared by arc melting. The oxidation and NaCl-induced hot corrosion behavior of the alloys were investigated at 650 ℃, with the focus on the effect of element-doping and phase. With the addition of Ti, Ta and Mo, the oxidation resistance of the tested alloys was effectively enhanced compared to the undoped NiAlY alloy. However, the NiZrAlY alloy showed very poor oxidation resistance. Under the NaCl-induced hot corrosion test, the NiTaAlY and NiMoAlY alloys exhibited an improved hot corrosion resistance, while the NiZrAlY and NiTiAlY alloys showed very poor hot corrosion resistance. Moreover, the NiAl and Ni 5 Y phases exhibited different behavior during the oxidation and NaCl-induced hot corrosion tests. • A new type NiXAlY system doped with different alloying elements was designed in this work. • The oxidation and hot corrosion behaviors of NiAlY alloys with different alloying elements addition such as Zr, Ti, Ta and Mo were investigated at 650 ℃. The effects of different alloying elements on oxidation and hot corrosion resistance were investigated. • Y displayed a negative effect in both oxidation and hot corrosion resistance. The degradation mechanisms of Y-rich areas in the oxidation and hot corrosion tests were different.

Investigation of oxidation and hot corrosion behavior of molybdenum coatings produced by high-velocity oxy-fuel coating method

Thermal spray coatings methods are frequently used in automotive, aerospace, and marine vehicles. The most obvious damage mechanisms of coating systems, which are exposed to many damages during use, are high-temperature oxidation and corrosion. While the oxygen element coming from the atmosphere creates the high-temperature oxidation damage in the coating systems, the molten salts such as Na2SO4 and V2O5 coming from low-quality fuels constitute the high-temperature hot corrosion damage mechanism. In this study, its behavior against high-temperature oxidation and hot corrosion damage mechanisms was investigated by coating Molybdenum (Mo) on a 316 L stainless steel substrate with the High-Velocity Oxy-Fuel technique, which is an innovative thermal spray coating method. Both damage mechanisms were carried out isothermally at 650 °C. Oxidation tests were carried out for 5, 25, and 50 h, while hot corrosion tests were carried out for 1, 3, and 5 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), Elemental mapping, and Energy Distribution Spectroscopy (EDS) analysis was performed on molybdenum-coated samples before and after both tests. The results obtained were evaluated and discussed in light of the literature.

A novel approach combining grain boundary engineering and grain boundary serration to enhance high-temperature hot corrosion resistance in Alloy 617

In this work, a novel idea of combining two established microstructural engineering approaches viz., grain boundary engineering (GBE) and grain boundary serration (GBS) through optimization of thermomechanical and thermal processing in Alloy 617 is investigated and the superior resistance of GBE+GBS microstructure to the high-temperature hot corrosion is demonstrated. To achieve the GBE+GBS microstructure, the GBS treatment was introduced as a part of the GBE processing schedule (i.e., incomplete GBE+GBS) and following the GBE treatment (i.e., complete GBE+GBS). The extent of GBS is found to be similar in all the processed specimens. However, the extent of GBE is observed to be lower in the specimens undergoing incomplete GBE+GBS. This is due to the occurrence of recrystallization and consequent infrequent multiple twinning. On the other hand, a higher extent of GBE is achieved in the specimens subjected to complete GBE+GBS owing to the retention of the optimized GBE microstructure following the GBS treatment. The synergistic influence of GBE and GBS on the hot corrosion behavior is assessed by exposing the as-received (AR) as well as optimized grain boundary engineered and serrated (GBES) specimens to a salt mixture at 1273 K. The percolation depth after 24h and 48h exposure is significantly lower in the GBES specimen (∼55 µm and ∼115 µm, respectively) than the AR condition (∼305 µm and ∼630 µm, respectively). This is ascribed to the incorporation of Σ3n (n ≤3) and serrated boundaries in the GBES microstructure which obstructed the infiltration of harmful species into the alloy.