Effects of Hot Corrosion on the Room Temperature Strength of Structural Ceramics
Abstract
A variety of advanced structural ceramics were treated in air at 1000C for 500 hours with and without various amounts of sodium sulfate. Room temperature flexure strength was determined before and after treatments. Results show that Ce-=TZP and alumina are resistant to strength degradation after exposure to sodium sulfate, however Si3N4 and, to a lesser degree, Y-TZP are not. The Y-TZP had a strength loss of 25% after 500 hours at 1000C with 10 to 20 mg/cm2 of Na2S04. This loss is about 10% greater than that experienced by specimens when treated at 1000C for 500 hours without sodium sulfate present, and is probably due to the leaching of Y2O3 from the zirconia which allows the tetragonal zirconia to transform to the monoclinic phase. Under similar conditions, the silicon nitride experienced a loss of 655 when sodium sulfate was added. This strength loss is 25% greater than the loss after thermal exposure in the absence of sodium sulfate. The additional strength loss here is due to the formation of larger corrosion pits. Keywords: Ceramic materials; Zirconia; Alumina; Silicon nitride; Corrosion; Mechanical properties; Flexural strength. (JES)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1989
- Accession Number
- ADA212568
Entities
People
- Gary L. Leatherman
- Jeffrey J. Swab