Techniques for Manufacturing FGM Bioceramics

Several novel methods for the production of calcium phosphate based functional gradient materials have been explored. The processes involved the use of polyurethane foams with a different number of pores per inch which were joined together in a variety of ways to form unique templates prior to vacuum impregnation with a ceramic slip. Before processing, rectangular blocks of foam were joined by stitching or trapezoidal blocks were compressed into rectangular shapes to produce a gradient of porosity along the length of the template. Four-point bend testing of the sintered samples which combined two porous structures showed them to have comparable mechanical properties to homogeneous ceramics based on foam templates with uniform pore sizes, with no evidence of weakness at the interface. The method was further developed to make a cylindrical sample with two diverse porous structures which more closely mimic the natural bone morphology. The two very different areas, which represented cortical and cancellous bone, had good structural integrity at the interface.