Aqueous tape casting of reaction bonded aluminium oxide (RBAO)

Reaction bonding of alumina (RBAO) has been proved to be a successful route to make high-performance alumina. However, the aluminium metal in the starting mixtures prevents using aqueous processing techniques in the initial phase. Here a route is presented for aqueous tape casting of RBAO by hydrophobization of the starting powder and preparing a suitable tape cast suspension. Thermal analysis (TGA/DSC) showed that it is possible to combust the organic phase prior to oxidation of the aluminium, opening routes to laminated ceramic-metallic composites. TGA/DSC combined with imaging (SEM) and phase analysis (XRD) also showed that the oxidation of the aluminium in RBAO occurs in two steps. Sintering experiments showed anisotropic grain growth at 1550 °C, resulting in a lower density than sintering at 1500 °C or 1600 °C. The bending strength of the sintered tape increased with temperature, resulting in a bending strength of 290 MPa after sintering at 1600 °C.