Na2SO4 deposit‐induced hot corrosion of BN‐coated α‐SiC
Abstract
BN coated α‐SiC was exposed to ~2.5 mg/cm2 of Na2SO4 for 0.75‐144 hours between 700°C and 1100°C in a 0.1% SO2‐O2 gaseous environment. A combination of SEM, EDS, ICP‐OES, XRD, and optical profilometry was used to determine that BN induced a previously unobserved form of Na2SO4 deposit‐induced hot corrosion of SiC below the melting temperature of Na2SO4 (Tm = 884°C). Above the melting temperature of Na2SO4 BN did little to alter the hot corrosion behavior of SiC, due to B2O3 volatility. Substrate attack below the melting temperature of Na2SO4 was found to result in rivulet recession features, whereas deep, localized pitting occurred above the melting temperature of Na2SO4. Initially, the mixture of Na2SO4 and BN led to the formation of a Na2O‐ and B2O3‐containing liquid silicate and accelerated corrosion which after prolonged exposure, resulted in the partial crystallization into a lath‐like tridymite and cristobalite mixture. Prolonged exposure resulted in a flattening of SiC consumption rates after exposure for several hours at 1000°C and after several days at 800°C, resulting in decreased SiC oxidation/corrosion kinetics.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 27, 2020
- Source ID
- 10.1111/jace.17576
Entities
People
- Elizabeth J. Opila
- Lucas A. Herweyer
Organizations
- Office of Naval Research
- University of Virginia