Assessment of the mechanical and in vitro degradation behaviour of ceramic/metal joints for the encapsulation of telemetric systems to be used in orthopaedics

摘要

The present work describes the development and mechanical evaluation, of ceramic/metal (C/M) brazed joints to be used as biocompatible encapsulation systems. The alumina/Ag-Cu-Ti/316 stainless steel joints were produced at 850 deg C/40 min in a vacuum furnace. The mechanical properties of the C/M joints were previously characterised using a shear-strength test. In the present study rotating beam fatigue experiments were carried out. These tests were performed to simulate the behaviour of the joints while under physiological cyclic loading. Standard S-N curves were obtained for several applied loads. The degradation behaviour of the joints was also evaluated in corrosion tests carried out in a HBSS at 37+-2 deg C. The produced joints were further characterised by SEM/EDS before and after the degradation experiments. The fatigue results indicate that the instrumented implants will be able to work for 94 to 200 days under the typical mechanical solicitation of a nail-plate located on a recovering patient. Furthermore, the corrosion experiments shown that the joints are very stable when tested in vitro in a simulated physiological media.