Thermal cycling behavior and hot corrosion performance of the plasma sprayed Er₂Si₂O₇coatings deposited on C_f/SiC composites

Abstract

a b s t r a c tRare-earth based disilicates are promising coating materials for C f /SiC composites. In this study, Er 2 Si 2 O 7 coating was deposited on the C f /SiC substrate by atmospheric plasma spraying using the solid-state reaction synthesized powders. Sintered Er 2 Si 2 O 7 coupons derived from the synthesized powders were subjected to dilatometric studies showing the average value of 4.3 ppm/ • C for the coefficient of thermal expansion. The coated C f /SiC coupons were thermally cycled between 400 • C and 1500 • C on a burner rig facility until failure of coating. Meanwhile, hot corrosion performance of the free standing plasma sprayed Er 2 Si 2 O 7 coating coupon was evaluated by using molten vanadate salt with loading of 15 mg/cm 2 at 800 • C. Analytical techniques such as X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy were applied to study the microstructural characteristics of the powders and coatings before and after thermal cycling and hot corrosion tests. Coatings' degradation as a result of thermal cycling and hot corrosion tests was investigated in terms of microstructure and microchemistry transformations.

Holistic comparison of environmental barrier coating material candidates through design of a figure of merit

“…is much less studied. [116][117][118][119][120][121][122][123][124] This degradation mechanism is often considered to be of low importance due to the volatilization of Na 2 SO 4 and other salts at the upper use temperature of CMC/EBC systems. However, industrial gas turbines operate at high pressures, raising the dewpoint temperature significantly relative to one atmosphere.…”

“…CMAS resistance of EBCs has been well studied as an important degradation mechanism above the melting temperature of CMAS (∼1200°C), 115 however, degradation of EBCs via reaction with other lower melting compounds such as Na 2 SO 4 (T m = 884°C) is much less studied 116–124 . This degradation mechanism is often considered to be of low importance due to the volatilization of Na 2 SO 4 and other salts at the upper use temperature of CMC/EBC systems.…”

Liquid Nitrogen-Mediated Thermal Shock for Instantaneous Detachment of Multi-walled Carbon Nanotube Films from Substrates and Their Application in Supercapacitors

“…Rapid expansion or contraction, typically known as thermal shock, can rupture the interface between two substances with different thermal expansion/contraction rates, although the process may damage certain coatings. − Liquid nitrogen is a coolant with a boiling point of −195.79 °C and effectively ruptures interfaces. Also, nitrogen gas generates a relatively uniform uplifting force that can facilitate separation processes as it boils .…”