A gelcasting method of making an internally graded article includes the steps of: preparing at least two slurries, each of the slurries including a different gelcastable
powder suspended in a gelcasting solution, the slurries characterized by having comparable shrinkage upon
drying and
sintering thereof;
casting the slurries into a mold having a selected shape, wherein relative proportions of the slurries is varied in at least one direction within the selected shape; gelling the slurries to form a
solid gel while preserving the variation in relative proportions of the slurries;
drying the gel to form a dried
green body; and
sintering the dry
green body to form a
solid object, at least one property thereof varying because of the variation in relative proportions of the starting slurries. A gelcasting method of making an internally graded article alternatively includes the steps of: preparing a
slurry including a least two different phases suspended in a gelcasting solution, the phases characterized by having different
settling characteristics;
casting the
slurry into a mold having a selected shape; allowing the
slurry to stand for a sufficient period of time to permit desired gravitational
fractionation in order to achieve a vertical compositional gradient in the molded slurry; gelling the slurry to form a
solid gel while preserving the vertical compositional gradient in the molded slurry;
drying the gel to form a dried
green body; and
sintering the dry green body to form a solid object, at least one property thereof varying along the vertical direction because of the compositional gradient in the molded slurry.