Dense-porous multilayer ceramics by green shaping and salt leaching

Dense Porous multilayer ceramic structures were fabricated using a simple novel ceramic dough process for the first time, where the hydrophobic ceramic dough was mixed with hydrophilic porogen like salt to form porous structure. Dense dough and porous mixture were processed in the ambient atmosphere and layered in green state before drying. Salt leaching for porogen removal was performed in warm water followed by binder burnout and sintering. Micro CT and electron microscopy revealed an intimate contact at the interface and 51–63 ​Vol% porosity in the porous layer was achieved with 44–48% open porosity. Intimacy was further supported by mechanical testing in compression mode where the crack propagated through the porous layer adjacent to the interface. The interfacial bonding between layers is independent of the individual layer thickness without cambering or warping. This simple dough processing produced bimodal pores after sintering with large macropores of diameter 250–500 μm and small macropores in the range of 1–3 μm on the pore walls, suitable for bone and vascular ingrowth. A further possibility of machining the dense body in a green state and fabricating a dental implant analogue with a porous apical portion for bone ingrowth were successfully explored.