Evaluación térmica, mecánica y eléctrica de materiales compuestos cordierita-mullita

CAMERUCCI, MA; G. URRETAVIZCAYA; CAVALIERI, A.L.

MATERIALS RESEARCH

UNIV FED SAO CARLOS

Lugar: São Paulo; Año: 2000 vol. 3 p. 124 - 130

1516-1439

Commercially available cordierite and mullite powders were used to obtain cordierite and cordierite-30wt% mullite materials by attrition milling, uniaxial pressing and sintering. Cordierite powders were the coarse (D50= 1.82 m), medium (D50= 0.9 m) and fine (D50= 0.45 m) single granulometric fractions and binary mixtures of them. Mullite powder employed in composites was the 7 h-attrition milled one (D50 = 1.3 m). Hardness (HV) and fracture toughness (KIC) were measured by Vickers indentation techniques. Composites showed higherHV and KICthan cordierite matrices. In both materials, HV and KIC diminish with the increasing porosity. Dielectric constant () and losses (tan ) were determined at 1 MHz. An increase in and tan values was registered when mullite was present in composites with respect to cordierite material. Higher the porosity,  was lower and tan increased. The thermal expansion coefficients () were determined up to 1000 °C resulting the of the composite close to that of the silicon.