The Interaction of High Temperature Corrosion and Mechanical Properties of Alloys

1982 ◽  
pp. 507-543 ◽  
Author(s):  
H. W. Grünling ◽  
K. H. Keienburg ◽  
K. K. Schweitzer
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperature Corrosion

Deterioration of Local Mechanical Properties of HVOF-Sprayed Stellite 6 after Exposure to High-Temperature Corrosion

2015 ◽  
Vol 662 ◽  
pp. 115-118 ◽  
Author(s):  
Zdeněk Česánek ◽  
Jan Schubert ◽  
Šárka Houdková ◽  
Olga Bláhová ◽  
Michaela Prantnerová
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperature Corrosion ◽  
Corrosion Testing ◽  
Time Interval ◽  
Coating Properties ◽  
Operational Conditions ◽  
Stellite 6 ◽  
Coating Surface ◽  
Before And After

Coating properties determine its behavior in operation. The simulation of future operational conditions is therefore the best quality test. The evaluation during operation is usually not possible to perform, and the coatings are therefore frequently characterized by their physical or mechanical properties. This text deals with the high temperature corrosion of HVOF sprayed Stellite 6 coating and with changes of its local mechanical properties before and after the corrosion testing. High temperature corrosion is defined as a corrosion in the presence of molten salts. In this case, the mixture of salts in composition of 59% Na2(SO)4 with 34.5% KCl and 6.5% NaCl was used. Two exposure temperatures 525 °C and 575 °C were selected and the tests for both temperatures were performed in the time interval of 168h in the autoclave. The coating with salt mixture layer was analyzed using scanning electron microscopy and nanoindentation. The high temperature resistance of Stellite 6 coating was evaluated according to the changes in the coating surface and by the occurrence of individual phases formed on the coating surface during the test. Generally, it can be said that the Stellite 6 alloys deposited by HVOF technology show selective oxidation under the salt film. This fact was also proved in this study. Furthermore, the nanoindentation measurements of Stellite 6 coating were performed before and after the corrosion testing. These measurements were used to evaluate the change of local mechanical coating properties.

Effect of high temperature corrosion in liquid lithium on mechanical properties of beryllium

2010 ◽  
Vol 85 (7-9) ◽  
pp. 1702-1706 ◽  
Author(s):  
I.B. Kupriyanov ◽  
V.N. Kudryavtsev ◽  
L.A. Kurbatova ◽  
I.E. Lyublinski
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperature Corrosion ◽  
Liquid Lithium

scholarly journals Microstructure and Mechanical Properties of the Ductile Al–Ti–Mo–Nb–V Refractory High Entropy Alloys

2021 ◽  
Author(s):  
Grzegorz Cieślak ◽  
Juliusz Dąbrowa ◽  
Monika Jawańska ◽  
Agnieszka Parzuchowska ◽  
Dariusz Oleszak
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Low Temperature ◽  
High Temperature Corrosion ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Al Content ◽  
Microstructure And Mechanical Properties ◽  
Measured Stress ◽  
Vital Component

AbstractA number of non-equimolar refractory high entropy alloys (RF HEAs) from the Al–Ti–Mo–Nb–V system are synthesized, with the selected compositions aimed to balance the conflicting requirements of the low-temperature ductility and high-temperature corrosion protection. Based on the thermodynamic modeling and experimental results, all the obtained alloys are characterized by the single-phase B2 structure with V acting as the main phase stabilizer. The microstructure and mechanical properties appear to be controlled mainly by the Al content, which is especially visible on the example of hardness, with a maximum value of 545 HV for Al20Ti5Mo25Nb25V25 composition. For the selected Al20Ti5Mo25Nb25V25 and Al10Ti30Mo20Nb20V20 alloys, the measured stress–strain curves indicate the highly coveted, ductile room temperature behavior, with the values of ultimate strain measured under compression mode being 9.17 and 9.00 pct, respectively, and compressive fracture strain of 13.38 and 13.25 pct, respectively. The obtained results suggest that it is possible to include Al as a vital component of refractory HEAs without compromising their low-temperature ductility. The next intended step will be the characterization of the high-temperature corrosion behavior in order to investigate the potential selective oxidation capabilities of such materials.

scholarly journals Розробка технології дисперсного модифікування жароміцних нікелевих сплавів для лопаток газотурбінних двигунів

2021 ◽  
pp. 49-53
Author(s):  
Наталія Євграфівна Калініна ◽  
Олександр Васильович Калінін ◽  
Тетяна Валеріївна Носова ◽  
Стелла Ігорівна Мамчур ◽  
Наталія Іванівна Цокур
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Heat Resistance ◽  
Nickel Alloys ◽  
Effective Means ◽  
Primary Crystallization ◽  
High Temperature Corrosion ◽  
Rotor Blades ◽  
Initial State ◽  
Heat Resistant

The paper proposes means of improving the properties of nickel alloys for aircraft gas turbine engines by improving the existing alloys. The efficiency of an aircraft engine depends on the quality of the turbine rotor blades, which are made of heat-resistant alloys. According to the studies, the obtained results of pilot tests of a complex of mechanical properties, high-temperature corrosion of a multicomponent high-temperature nickel alloy ХН59МВТКЮЛ (Ni-Cr-W-Co-Al-Ti-Mo systems). The paper proposes the use of modifiers. An effective means of dispersing the structural components of alloys at the macro and micro levels is the modification of multicomponent alloys with dispersed and nano dispersed compositions. Based on titanium nitride powder, a technological regime for modifying nickel melt with dispersed compositions of plasma chemical synthesis has been developed. The modifier was used in tablet form. Investigated different dosages of the modifier: 0.1…0.03 % by weight. The proposed method allows, with minimal losses at the melting stage, to introduce the required amount of modifier. The temperature and time parameters of the modification are 16500С, the modifier action time is 5…7 minutes. Investigations of the complex mechanical properties and the peculiarities of the formation of the structure of the modified alloy have been carried out. According to the research results, significant refinement of the alloy grain was obtained in comparison with the initial state. The modification led to an increase in mechanical properties: strength by 10 %, impact strength by 35...40 %. Comparison of the nano-modified alloy with the obtained one made it possible to increase the corrosion resistance of the ХН59МВТКЮЛ alloy in an oxidizing environment. At a temperature of 1000 0С, the corrosion depth decreased by 15 %. An increase in resistance to high-temperature corrosion is associated with a more uniform distribution of excess phases in the structure of the modified alloy. The mechanism of action of refractory particles of a modifier in a nickel melt, which are the nuclei of primary crystallization, has been established. The results of the work are of practical value in the manufacture of rotor blades from high-quality heat-resistant nickel alloys with increased parameters of heat resistance and heat resistance.

Degradation of HVOF Sprayed Hastelloy C-276 Local Mechanical Properties after Exposure to High Temperature Corrosion

2018 ◽  
Vol 784 ◽  
pp. 147-152
Author(s):  
Zdeněk Česánek ◽  
Jan Schubert ◽  
Olga Bláhová
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Thermal Spraying ◽  
High Temperature Corrosion ◽  
Time Interval ◽  
Salt Mixture ◽  
Coating Surface ◽  
Salt Film ◽  
Eds Analysis ◽  
Oxygen Fuel

Hastelloy C-276 coating was deposited on stainless steel 1.4923 using HP/HVOF (High Pressure / High Velocity Oxygen Fuel) thermal spraying technology to increase high corrosion resistance. Possible influence of high temperature corrosion on local mechanical properties change of Hastelloy C-276 was also evaluated in this article. High temperature corrosion is corrosion in the molten salts environment. The salt mixture of 59 % Na2SO4 with 34.5 % KCl and 6.5 % NaCl was used in this study. The selected exposure temperatures were 525 °C and 575 °C and the tests for both temperatures were conducted in autoclave for the time interval of 168 h. The coating and salt mixture layer was analyzed using scanning electron microscope (SEM), EDS analysis and nanoindentor (MTS Nanoindenter XP). High temperature resistance of Hastelloy C-276 coating was evaluated based on the changes in coating surface and according to the occurrence of various phases created on the coating surface during this test. It can be assumed that Hastelloy C-276 coating deposited by HVOF technology shows selective oxidation under the salt film.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

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