CENTRO DE TECNOLOGIA DE RECURSOS MINERALES Y CERAMICA
Unidad Ejecutora - UE
Thermal shock behavior of dense mullite-Zirconia composites obtained by two processing routes
N. M. RENDTORFF; L. B. GARRIDO; E. F. AGLIETTI
Elsevier Ltd and Techna Group S.r.l.
Año: 2008 p. 2017 - 2024
Mullitezirconia composites were prepared using two different processing routes such as reaction sintering (RS) of alumina and zircon and direct sintering of mullitezirconia grains. For the RS process, alumina and zircon (AZ) as raw materials were used, while in the other route mullitezirconia-electrofused grains (MZ) previously mixed with a second ceramic phase as a binder were employed. These both types of ceramics were produced by slip casting in plaster molds and finally sintered at 1600 ºC for 2 h. In this work, the microstructure and the resistance to thermal shock for both high-density mullitezirconia composites were studied. For materials characterization, density, XRD and SEM techniques were employed. Thermal shock behavior was determined by quenching in water with DT of 2001200 ºC and for 110 repeated cycles for each DT used. The variation of damage with thermal shock severity was followed by measuring the dynamic elastic modulus E using the impulse excitation method. The two processing routes resulted in ceramic composites with similar phase contents, but with microstructural differences. The dependence of elastic modulus on severity of thermal shock was in accordance with literature predictions, where below a critical quenching temperature difference (DTc) no degradation in the elastic behavior was found. The thermal shock resistance increased when zircon was used as bonding phase, rather than alumina or aluminazircon mix employed. employed.