Hot corrosion phenomena of Nb-Ti-Si based alloy and its silicide coating induced by different corrosive environments at 900 °C

2018 ◽  
Vol 44 (7) ◽  
pp. 7978-7990 ◽  
Author(s):  
Yanqiang Qiao ◽  
Jianping Kong ◽  
Xiping Guo
Keyword(s):  
Hot Corrosion ◽  
Silicide Coating ◽  
Corrosive Environments

Stress Rupture Behavior of Disk Superalloys Exposed to Low-Temperature Hot Corrosion Environment

2020 ◽  
Author(s):  
Dipankar Dua ◽  
Mohammad Khajavi ◽  
Gary White ◽  
Deepak Thirumurthy ◽  
Jaskirat Singh
Keyword(s):  
Low Temperature ◽  
Hot Corrosion ◽  
Inconel 718 ◽  
Gas Turbines ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Corrosive Environments ◽  
The Impact ◽  
Temperature Surface

Abstract Siemens Energy has a large fleet of aero-derivative gas turbines. The performance and durability of these power turbines largely depend on the capability of hot section components to resist high-temperature surface attacks and to maintain their mechanical properties. Hot corrosion attack occurs due to exposure of turbine components to sulfur-bearing fuels/air together with other corrosive compounds during turbine operation. This paper investigates the impact of low-temperature hot corrosion on the stress rupture of commonly used gas turbine disk alloys, including Inconel 718, Incoloy 901, and A-286. The results indicate that Inconel 718 and Incoloy 901 maintain their creep strength advantage over A-286 in a low-temperature hot corrosion inducing environment at 1100°F. All three materials exhibited an equivalent life reduction in the corrosive environments at 1100°F. Moreover, the results demonstrate that the stress-rupture life of materials in hot-corrosion environments depends on the combined and cumulative effects of corrosion-resistant and hardening elements.

A novel Zr-Y modified silicide coating on Nb-Si based alloys as protection against oxidation and hot corrosion

2020 ◽  
Vol 177 ◽  
pp. 108948
Author(s):  
Jiahua He ◽  
Xiping Guo ◽  
Yanqiang Qiao ◽  
Fa Luo
Keyword(s):  
Hot Corrosion ◽  
Silicide Coating

Environmental Effect of Hot Corrosion on Creep and Fatigue Failure of Thermal Barrier Coating Systems

2006 ◽  
Vol 522-523 ◽  
pp. 353-360
Author(s):  
Satoru Takahashi ◽  
Masayuki Yoshiba ◽  
Wataru Kakuta ◽  
Sayuri Matsuoka ◽  
Yoshio Harada
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Nucleation Site ◽  
Major Constituent ◽  
Failure Behavior ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Failure Life ◽  
Corrosive Environments ◽  
Tbc Systems

In order to clarify the failure behavior of plasma sprayed thermal barrier coating (TBC) systems under the complicated modes of thermal-mechanical-chemical loadings, the stress rupture property evaluation and failure analysis were conducted for Y2O3-ZrO2 (YSZ) and CaO-SiO2-ZrO2 (C2S-CZ) TBC systems in air and two kinds of high-temperature corrosive environments. Static creep loading was found to bring about the typical creep failure for TBC systems even in the aggressive environment so called hot corrosion almost in similar manner to the case in air. On the contrary, it was revealed that the dynamic fatigue loading tends to cause a significant failure life reduction of TBC systems both in air and in corrosive environments. For YSZ TBC system, the penetration crack preexisting through the top-coat layer tends to provide a nucleation site for the fatigue crack even in air, and more significantly a short circuit path for the corrosive species in hot corrosive environment. For C2S-CZ system, on the contrary, the top-coat / bond-coat interface tends to provide easily the nucleation site for a main crack to propagate thereafter toward both the alloy interior and outer surface. Under lower stress level at 950°C, however, the oxide-induced crack closure together with crack tip blunting attributed mainly to the high reactivity of Ca compounds as a major constituent of the TC is effective to suppress substantially the crack propagation, so as to cause the prolonged failure life as compared to YSZ system even in aggressive gaseous environment.

scholarly journals Hot Corrosion of SrTiO3 Perovskite in Na2SO4 + 50 wt.% V2O5 and Na2SO4 + 10 wt.% NaCl Environments at 900°C

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
M. Krishna Prasad ◽  
K. Srinivasa Rao ◽  
Madhusudhan Reddy ◽  
Gosipathala Sreedhar
Keyword(s):  
Phase Stability ◽  
Hot Corrosion ◽  
Corrosion Attack ◽  
Corrosive Environments

This study examines the phase stability of perovskite SrTiO3 in Na2SO4 + 50 wt.% V2O5 and Na2SO4 + 10 wt.% NaCl environments at 900°C. Hot corrosion results show the formation of Sr2VO4, SrV2O6, and SrTiV5O11 phases in Na2SO4 + 50 wt.% V2O5 environment and Sr3Ti2O7, Na4TiO4, and TiO2 phases in Na2SO4 + 10 wt.% NaCl environment. Morphological observations revealed the austerity of hot corrosion attack on SrTiO3. The Sr2+ ions leached out from SrTiO3 and reacted with corrosive environments. These observations clearly indicate the destabilization of SrTiO3 in both environments.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

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