Fabrication of near net shape magnesium aluminate (MgAl₂O₄) spinel components via aqueous processing

Abstract

Abstract

Net shape fabrication of magnesium aluminate (MgAl₂O₄) spinel (MAS) components like domes and radomes is of great importance because they are employed in certain important strategic applications. Environmentally and economically benign net-shape forming techniques such as aqueous gelcasting (GC) and hydrolysis induced aqueous gelcasting (GCHAS) cannot be employed to MAS powder as it reacts with water during processing and makes the process cumbersome. The processes reported in the literature to overcome this problem and for successful fabrication of net shape MAS components like thin wall radomes/crucibles following aqueous colloidal processing routes such as GC and GCHAS are reviewed in this paper. This article also reviews the effect of surface treatment of MAS powder against hydrolysis and of consolidation route on net shape forming capability and the sintering ability of MAS powder. Furthermore, various other net shaping techniques reported for MAS are also reviewed in this article.

Keywords:

• MgAl₂O₄ spinel
• Near net shape
• Hydrolysis induced aqueous gelcasting
• Surface treatment
• Freeze granulation
• Aqueous gelcasting

Author thank Dr G. Sundararajan, Director, ARCI, for his kind approval to publish this review article, and Professor J. M. F. Ferreira, Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro, Portugal, for his valuable suggestions while writing this review.