uy Annéa, Kim Vanmeens elb, J ef Vleugelsc, Omer Van der Biestd

K.U.Leuven, Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, B- 3001 Heverlee, Belgium

Abstract: Many materials are used in medicine for a variety of applications ranging from total replacement of hard or soft tissues (such as bone plates, pins, joint, dental implants, etc.), repair, diagnostic or corrective devices (such as pacemakers, heart valves, etc.). Not only are the mechanical properties important, but also the material should be biocompatible with the human body and stable for a long period. Due to their excellent properties such as high strength, biocompatibility and stability in physiological environments, ceramics are investigated as bone substitute materials. In this way, ceramic components have been us ed for total hip replacement components in Europe since the early 1970s. Alumina and zirconia monoliths are mainly used for thes e components. However, zirconia can undergo low temperature degradation in aqueous environment. Current research is focusing on increasing the strength and wear resistance, meanwhile reducing the size and extending the lifetime of ceramic components. Instead of ceramic monoliths, ceramic composites like zirconia toughened alumina and other alumina matrix composites are currently investigated. Another possibility is to us e components bas ed on alumina and zirconia with a functionally graded composition. The composition gradient can be established during shaping by means of electrophoretic deposition (EPD) to obtain a pure alumina surface region and a homogeneous alumina/zirconia core with in- termediate continuously graded regions to generate thermal residual stresses after sintering. The gradient profiles are de- signed to obtain maximum compressive surface stress es and minimum tensile stress es in the core of the component to in- creas e the strength and wear resistance compared to pure alumina components.

Keywords: biomaterials, functionally graded materials, prosthes es, alumina, zirconia