The purpose of this study was to develop a simple and economic method for the preparation of porous bioceramics with controllable macrostructure. Raw materials, including very small organic foam balls as the pore-creating reagent, wax (or paraffin) as the solvent, and oleic acid as the surface active agent, were selected along with bioactive materials such as β-TCP ceramic powder as the main component. The selected components were mixed into a slurry at 30–120ºC and shaped into a green body with a hot die-casting machine at 30–90ºC. The green body was then sintered and porous bioceramics were obtained. The main characteristics of porous bioceramics such as weight loss, compressive strength, connection and size of pores, percolation rate of water, apparent porosity and bulk density were measured. The results indicated that the apparent porosity and the specific surface area were large; the pores were connected in three dimensions and the compressive strength was >1.6 MPa. This study demonstrated that the methods used here are simple and effective in generating porous bioceramics with controllable macrostructures.

This study focuses on the main factors determining the apparent porosity of porous bioceramics prepared using small organic foam spheres as the pore-making reagent, in order to determine the best technical parameters for preparing porous bioceramics. In every experiment, only one of these factors (the time of heating, the sintering temperature, the mass ratio between small organic foam spheres and beta-tricalcium phosphate (β-TCP) powder, and the rate of the temperature rise) was changed, while the others were kept constant. In each case the apparent porosity was tested and the relation between the specific variable and apparent porosity was observed. Finally, the optimum technical parameters were deduced. The apparent porosity shows an inverse linear relation to the time of heating and the sintering temperature, and is approximately proportional to the mass ratio between the small organic foam spheres and the β-TCP powder and the rate of temperature rise. These factors have important influences on the apparent porosity. The optimum conditions were: heating time (soak time) 120 min, sintering temperature 850ºC, mass ratio 0.25, and a rate of temperature increase of 120ºC h–1.

AB ST R ACT : The purpose of this study was to develop a simple and efficient method for manufacturing porous bioceramics, in which small organic foam spheres were taken as the poremaking reagent and green bodies were made by hot die-casting in moulds. The raw materials (small organic foam spheres, paraffin, oleic acid and b-TCP powder) were mixed into a slurry at 30-120ºC and moulded into green bodies using a hot die-casting machine at 30À90ºC; the green bodies were then sintered and the porous bioceramics obtained. The main characteristics (structure and size of pores, water permeability, apparent porosity and shrinkage) were tested. The results indicated that the apparent porosity was high and directly proportional to the mass ratio between the small organic foam spheres and the b-TCP powder. The pores connected with each other in three dimensions; the size, distribution of the shapes and structures of the pores were clearly related to the dimensions of the small organic foam spheres. The water permeability was proportional to the hot die-casting pressures and the shapes of the samples could easily be controlled by selecting different moulds. This study indicated that the method can be used to manufacture porous bioceramics with controlled pore structures and different shapes effectively and easily by adding different amounts and sizes of small organic foam spheres, mixing the raw materials evenly, and by selection of the hot die-casting pressure and by the use of different moulds.