info:eu-repo/semantics/article
Fly ash cenospheres coatings by EPD-microwave sintering process for SiC corrosion resistance
Autor
ALEJANDRA CHAVEZ VALDEZ
GREGORIO VARGAS GUTIERREZ
Resumen
Abstract
Fly ash cenospheres coatings are a promising material in improving the oxidation and corrosion
resistance of SiC. In this work, fly ash cenospheres coatings were deposited on SiC substrates by
electrophoretic deposition process at 500 V during 30 seconds, 1, 2 and 3 minutes. These coatings
were characterized by SEM to observe the surface morphology. The coatings were sintered at 1000,
1100 and 1200°C during 3 hours by microwave heating. After sintering, the coatings were
characterized by XRD. Cross sections of the substrate/coating samples were analyzed by
SEM/EDS. The coatings with the best deposition and sintering conditions were evaluated by
oxidation and hot corrosion resistance tests. The oxidation test was performed in air at temperatures
from 1000 to 1300°C during 100 hours. In addition, fly ash cenospheres coatings on SiC and
uncoated SiC substrates were subjected to a hot corrosion test at 1000°C during 100 hours in
Na2SO4. The coatings showed good adhesion after sintering; the main phases of the coating were
mullite and SiO2. The uncoated substrates were found to gain weight due to the formation of SiO2 at
the surface. In contrast, SiC samples coated with fly ash cenospheres showed no weight gain and
exhibited no signs of cracking or spallation following the oxidation tests. After the high temperature
corrosion test in Na2SO4, the uncoated SiC showed signs of oxidation and corrosion while the
coated remained unreacted in the presence of molten Na2SO4, indicating that the electrophoretic
deposition fly ash cenospheres acted as a hot corrosion barrier for SiC substrates.