Fracture toughness of CoCr alloy-PMMA cement interface.

An unsymmetric cantilever geometry was used experimentally to determine the critical energy release rate values for cobalt chromium alloy-polymethylmethacrylate cement (CoCr alloy-PMMA) interfaces with satin finished, grit blasted, and plasma sprayed surface treatments applied to the CoCr alloy. Critical energy release rates of 0.013, 0.181, and 0.583 N/mm were found for the satin finish, grit blasted, and plasma sprayed CoCr alloy-PMMA interfaces, respectively. A finite element model of the experimental test specimen was used to determine the crack tip phase angles (-8.73 degrees to -27.1 degrees) that indicated that the tensile load applied to the specimens resulted in a tensile (mode I) and in-plane shear (mode II) loading at the crack tip. The experimental data suggest that a satin finish CoCr alloy-PMMA interface has minimal resistance to crack propagation when compared to grit blasted or plasma sprayed surface treatments.