Electrophoretic deposition as a novel near net shaping technique for functionally graded biomaterials

Due to their excellent properties of high strength, biocompatibility and stability in physiological environments, ceramics are investigated as bone substitute materials. In this way ceramic components have been used for total hip replacement components since the early 1970s. Alumina and zirconia monoliths are mainly used for these components. However, zirconia can undergo low temperature degradation in aqueous environment and alumina is brittle. To increase the strength, functionally graded Al2O3/ZrO2 ball-heads and acetabular cup inserts were made in this work by electrophoretic deposition (EPD). A composition gradient in alumina and zirconia was engineered to obtain a pure alumina surface region and a homogeneous alumina/zirconia core with intermediate continuously graded regions to generate thermal residual stresses at the surface after sintering. Experimental work revealed that a sequence of counter-electrodes was necessary to EPD complex shaped functionally graded material (FGM) components. To obtain deposits with a shape different from the deposition electrode, the deposit was grown up to the counter-electrode and the design of the counter-electrodes was supported by electrical field calculations to generate a constant electric field at the surface of the deposition electrode.