Thermal shock resistance of millita -zirconia -zircon composites

NICOLAS RENDTORFF; LILINA AGARRIDO; ESTEBAN AGLIETTI

Florianopolis , Brasil

Congreso; 52 congreso Brasiler de Ceramica; 2008

ABC

THERMAL SHOCK RESISTANCE OF MULLITE-ZIRCONIA-ZIRCON COMPOSITES.       N. M. Rendtorff (1-2); L. B. Garrido (1); E.F.  Aglietti (1-2) Con Centenario y 506 M.B. Gonnet, Provincia de Buenos Aires, Argentina, (CP: 1897); rendtorff@hotmail.com (1) Centro de Tecnología de Recursos Minerales y Cerámica (CONICET-CIC); (2) Universidad Nacional de la Plata, Argentina.   ABSTRACT   Mullite and zirconia are the basis of refractory materials used in the glass industry or when high chemical stability and corrosion resistance are necessary. In this work various mullite-zirconia/zircon compositions were investigated to improve the thermal shock resistance TS of dense composites produced by slip casting and sintering at 1600°C. Zircon (ZrSiO4) thermal decomposition adds zirconia and silica to the material. Resultant composites were characterized by physical and mechanical measurements, XRD and SEM techniques. Thermal shock TS behavior was tested by quenching in water with quenching temperature differentials ΔT from 400º to 1200ºC. The degree of damage after the thermal shock was experimentally evaluated through the variation of the Elastic modulus E which is measured by the excitation technique.. The tested materials retained their original properties for temperatures below a critical temperature ΔTc near 600ºC and 400ºC depending on the composition. All materials quenched from ΔT of 1000ºC showed more than 30% reduction in E indicating the important microstructure damage. The TSR were better for the 35 wt% zirconia   Key words: Composite ceramic material, Thermal shock resistance, Mullite-Zirconia-Zircon.