Null-thermal expansion coefficient LAS-nSiC composite by slip-casting

Abstract

In the present work, lithium aluminosilicate (LAS) reinforced with SiC nanoparticles (nSiC) is successfully prepared by slip-casting for the first time. The stability of aqueous suspension is investigated in terms of its rheological properties. The isoelectic point (IEP) of β-Eucryptite particulate system was found to be at pH 6.1. To obtain the best processing conditions, LAS-nSiC suspension with 55 wt% of solids and 0.06 wt% of Tetramethyl ammonium hydroxide (TMAH) as dispersant is recommended. The slurry is slip-casted in plaster of Paris molds and sintered at 1430ºC for different holding times in controlled atmosphere. Microstructure, mechanical and coefficient of thermal expansion (CTE) properties of the sintered samples have been evaluated. LAS-nSiC composite sintered at 1430ºC shows dense and free-cracked microstructure with a CTE close to zero.