Selective Laser Sintering of Ceramic Materials

Abstract

This paper will focus on efforts to develop the alumina - ammonium phosphate
\nmaterial system for Solid Freeform Fabrication. When the powder mix is irradiated
\nwith a laser beam, ammonium phosphate ( m.p. "" 190 0 C ) melts and forms a glassy
\nphase between the alumina grains. The "green part" obtained by laser processing is
\nthen subjected to secondary heat treatment to optimize the properties of the final
\ncomposite. The effect of various material, laser and machine parameters on the density,
\nstrength, surface finish and microstructure of the final part are described. One of the
\napplications for selective laser sintering is its use in directly manufacturing ceramic
\nmolds for the investment casting process. We will describe some of the the results we
\nhave obtained so far in fabricating composite ceramic molds directly and using them to
\ncast metals.