Interaction of low-expansion NZP ceramics with Na2SO4 at 1000 degrees C

The interaction between several low-expansion NZP materials and Na2SO4 at 1000 degrees C in pure O-2 was studied, Ba1.25Zr4P5.5Si0.5O24 experienced extensive cracking and delamination upon reaction with Na2SO4. On the other hand, Ca0.5Sr0.5Zr4P6O24 remained intact in terms of visual appearance and had no significant weight loss or gain, However, the ion exchange between Na+ ions and Ca+2 ions was observed to be sufficiently rapid to allow the penetration of the Na+ ions into the test specimens in 100 h, The segregation of Ca to the specimen surface was observed due to the ion exchange, Ca0.6Mg0.4Zr4P6O24 was also tested, but its stability could not be properly assessed because the as-received specimens contained a significant amount of MgZr4P6O24 as an impurity phase.