Injection-Molded Alumina Prepared with Mg-Containing Binders
Abstract:It is generally accepted that MgO additions enhance the sintering of alumina. The distribution of the low concentration required is, however, difficult to attain and critical to the final properties and microstructures. To improve the MgO distributions in ceramic injection-molded (CIM) alumina, Mg-containing precursors, Mg-stearate and Mg-acetate, were added during the kneading step of the CIM process, and the results were compared with those from adding MgO particles. Of the three additives, the Mg-stearate showed the highest sintered density and bending strength. This was attributed to its high molecular weight and it being able to mix with other binder components homogeneously in the liquid state, which leads to a better distribution of the MgO. In contrast, the MgO powder was kneaded in the solid particle form, and its distribution was not uniform. The Mg-acetate also imparted poorer MgO distribution because the liquid Mg-acetate dehydrated in the early stage of the kneading and formed solid lumps before it was well mixed into the binder system. The resulting sintered densities and bending strength using these two additives were, therefore, inferior to those for specimens in which Mg-stearate was used.
Document Type: Research Article
Affiliations: Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan
Publication date: September 1, 2005