Dense Alumina-Mullite Composite Ceramics from Alumina and Spodumene-albite Feldspar binary mixtures: Processing and Properties

M.F. HERNANDEZ; P.V. LÓPEZ; M.A. VIOLINI; G. SUAREZ; M.S. CONCONI; N. RENDTORFF

SCIENCE OF SINTERING

INT INST SCIENCE SINTERING (I I S S)

Año: 2019 vol. 51

0350-820X

A processing strategy for obtaining alumina-spodumene ceramics from finecommercial powders is presented. In this work, a spodumene addition to calcined aluminapowder was performed and their proportion was explored between 15 and 45 wt%. Theindustrial spodumene presented secondary phases, mainly albite and quartz. Mechanicalproperties were evaluated. Although they were lower than those of sintered alumina, based onthe achieved values an adequate behavior in structural applications can be assumed,especially taking into account that the better mechanical behavior was coupled with the lowerthermal expansion. Relatively low thermal expansion (≈ 5 x 10-1°C-1) behaviors wereobserved in one of the developed materials. Noncrystalline phases containing lithium weredetected. We assume that all the lithium oxide incorporated through the spodumene is in theglassy phase after the sintering of the materials. This difference in lithium concentration inthe composition of the resulting glass affected the thermal expansion of the developedmaterials. Particularly with low lithium content (30 wt% of additive) the materialperformance was enhanced. This, together with the mechanical behavior, encouragesstructural applications with high thermomechanical solicitations. With the informationgathered, a wide range of materials with specific properties can be obtained by modulatingthe spodumene-alumina proportion only