scholarly journals Effect of Vacuum Annealing on Microstructure and Hot-Salt Corrosion Behavior of CoNiCrAlY/YSZ/LaMgAl11O19 Double-Ceramic Coating

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 951
Author(s):  
Guanming Xue ◽  
Yingchao Sun ◽  
Ling Xiang ◽  
Zhiguo Wang ◽  
Suying Hu ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Vacuum Annealing ◽  
Ceramic Coatings ◽  
Potential Effect ◽  
Volume Shrinkage ◽  
Salt Mixture ◽  
Salt Corrosion ◽  
Annealed Coating ◽  
Microcrack Formation ◽  
Sprayed Coatings

This study investigated the potential effect of vacuum annealing on the microstructure and hot salt corrosion behavior of CoNiCrAlY/YSZ/LaMgAl11O19 (LMA) double-ceramic coatings. A hot-salt corrosion test revealed that sprayed coatings exhibited an unsatisfactory anti-corrosion performance, and the LMA layer underwent severe fracture and corrosion degradation. Vacuum annealing induced a prominent recrystallization of the amorphous phase in LMA layer, triggering severe volume shrinkage and microcrack initiation. The recrystallization and volume shrinkage of the LMA layer were aggravated by an increase in the annealing temperature. The annealed coating with a higher fraction of the LaMA phase showed superior resistance to hot-salt corrosion. However, the salt mixture diffused simultaneously along the microcracks and eventually eroded into the YSZ layer. These results confirmed that vacuum annealing significantly enhanced the hot-salt corrosion resistance of the LMA layer. However, it deteriorated the barrier effect of the salt mixture through microcrack formation.

scholarly journals Study on Molten Salt Corrosion Behavior of Several Stainless Steel Alloys

2021 ◽  
Vol 1885 (3) ◽  
pp. 032005
Author(s):  
Dandan Men ◽  
Jian Xiong ◽  
Wenyi Peng ◽  
Lingyun Bai
Keyword(s):  
Stainless Steel ◽  
Molten Salt ◽  
Corrosion Behavior ◽  
Steel Alloys ◽  
Salt Corrosion

Application of Plane Fractal Geometry to Adhesion Strength of Thermal Sprayed Coatings

2000 ◽  
Author(s):  
S. Amada ◽  
T. Hirose
Keyword(s):  
Cross Section ◽  
Fractal Geometry ◽  
Surface Characteristics ◽  
Ceramic Coatings ◽  
Average Surface Roughness ◽  
Roughened Surface ◽  
Fractal Characteristics ◽  
Sprayed Coatings ◽  
Thermal Sprayed Coatings ◽  
Height Data

Abstract Adhesion of ceramic coatings considerably depends on the surface characteristics of blasted substrates. The roughened surfaces have two kinds of topographical characteristics, one is of their cross section and the other is of planar. The roughened surfaces is generated by angled grit-blasting process which can be expected to improve the adhesion of ceramic coatings. The topography of the roughened surfaces has fractal characteristics in their cross section and has been more effectively related to the adhesive strength of ceramic coatings than average surface roughness traditionally used. This paper presents that fractal characteristics is evaluated in the planar topography of the blasted surfaces and shows that the planar fractal characteristics is closely related adhesion of ceramic coatings. The planar fractal dimension is evaluated by SIA (Slit Island Analysis) which needs the height data on the roughened surface. Those data are obtained by a laser-microscope in confocal type.

Hard Arc-Sprayed Coating with Enhanced Erosion and Abrasion Wear Resistance

2000 ◽  
Author(s):  
S. Dallaire
Keyword(s):  
Ceramic Coatings ◽  
High Energy ◽  
Arc Spraying ◽  
Cored Wire ◽  
Industrial Sectors ◽  
Wear Protection ◽  
Abrasion Wear ◽  
Sprayed Coating ◽  
Impact Angles ◽  
Sprayed Coatings

Abstract Exposed to particle erosion environments, metal-sprayed coatings are damaged by micro-machining and ploughing at low impact angles. The generation and propagation of subsurface lateral cracks at high impacting angles damage single-phase ceramic coatings. Therefore, multicomponent coatings deposited by high-energy processes have been widely used to provide wear protection in most of the applications. As commercial arc-sprayed coatings have been used to a limited extent in applications involving erosion and abrasion wear, developing attractive wear resistant arc-sprayed coatings has been found necessary. A cored wire formulation, referred to as Alpha-1800, has been developed to produce tailored arc-sprayed coatings that are tough enough to resist particle impacts at 90° and sufficiently hard to deflect eroding particles at low impact angles. Typical 1 mm-thick coatings composed of ductile and hard phases with Knoop hardness reaching 1800 kg/mm2 were easily produced by arc spraying the cored wire with air. Coatings were: 1) erosion tested at 25°C and higher temperatures at impact angles of 25° and 90° in a gas-blast erosion rig, 2) slurry erosion tested at impact angles of 25° and 90°, 3) abrasion wear tested using the ASTM G-65 test procedure. Results show that coatings produced with the new cored wire are at least 5 times more erosion resistant and 10 times more abrasion resistant than coatings produced by arc spraying commercial cored wires. The performance of the new arc-sprayed coating can be compared with that of high-energy WC-based coatings. Being thermally stable up to 850°C, arc-sprayed coatings produced with the new cored wire are attractive for applications in many industrial sectors up to high temperatures.

scholarly journals Hot Corrosion Behavior of BaLa2Ti3O10 Thermal Barrier Ceramics in V2O5 and Na2SO4 + V2O5 Molten Salts

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 351 ◽  
Author(s):  
Hui Liu ◽  
Jin Cai ◽  
Jihong Zhu
Keyword(s):  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Molten Salts ◽  
Main Reaction ◽  
Thermal Barrier ◽  
Dense Layer ◽  
Reaction Products ◽  
Corrosion Medium ◽  
Barrier Coating ◽  
Salt Corrosion

BaLa2Ti3O10 ceramics for thermal barrier coating (TBC) applications were fabricated, and exposed to V2O5 and Na2SO4 + V2O5 molten salts at 900 °C to investigate the hot corrosion behavior. After 4 h corrosion tests, the main reaction products resulting from V2O5 salt corrosion were LaVO4, TiO2, and Ba3V4O13, whereas those due to Na2SO4 + V2O5 corrosion consisted of LaVO4, TiO2, BaSO4 and some Ba3V4O13. The structures of reaction layers on the surfaces depended on the corrosion medium. In V2O5 salt, the layer was dense and had a thickness of 8–10 μm. While in Na2SO4 + V2O5 salt, it had a ~15 μm porous structure and a dense, thin band at the bottom. Beneath the dense layer or the band, no obvious molten salt was found. The mechanisms by which the reaction layer forms were discussed.

scholarly journals Hot-salt corrosion of alloys PT-7M, 42ХНМ, Inconel 690, Incoloy 800

2019 ◽  
Vol 121 ◽  
pp. 04015
Author(s):  
Oleg Bykh ◽  
Aleksandr Bakhmetev ◽  
Natin Sandler ◽  
Petr Tryaev ◽  
Anna Ershova ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Entire Temperature Range ◽  
Water Steam ◽  
Testing Conditions ◽  
Temperature Range ◽  
Saturated Water ◽  
Salt Corrosion ◽  
Inconel 690 ◽  
Incoloy 800

The Article contains the results of the study performed for the samples made from alloys PT-7М, 42ХНМ, Inconel 690, Incoloy 800 for resistance against hot salt corrosion in the mixture of crystallized NaCl and KBr salts, in ratio 300:1 by weight, and in the temperature range from 150 °С to 300 °С, both in contact with the air and in a leak-tight autoclave in the atmosphere of saturated water steam. Regularities of hot salt corrosion behavior in the alloys under the study were detected under testing conditions. The atmosphere of saturated water steam inhibits development of halt salt corrosion of alloy ПТ-7М in the entire temperature range of the testing.

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