A new near net-shape forming process for alumina

Abstract

The application of a new near net-shape forming process to alumina is studied. In this process, ceramic slurries are prepared with a low melting point wax. The quantities of wax of the consolidated bodies are reduced to the desired residual wax contents by contact with papers (or cloths) at a controlled temperature, the dewaxed green bodies of proper residual wax contents then being formed into near net-shape by plastic forming and/or machining. The effects of the particle size, the particle distribution, the wax content of the slurry and the residual wax content of the green bodies before plastic forming such as extrusion on the dewaxing behavior and on the mechanical characteristics are examined. Powder of a bimodal particle distribution has an advantage of a rapid dewaxing rate and giving defect-free dewaxed green bodies. The flexural strength of the sintered bodies, however, increase as the content of fine particles increases. The wax content of the extruded green bodies before the last stage of the dewax process is the most effective factor on the mechanical properties of the sintered bodies. © 1998 Elsevier Science S.A. All rights reserved.