Biomaterials

Biography

Biography: Raisa Chetcuti

Abstract

Bone injuries coupled with a longer life expectancy necessitate the increased longevity of implanted biomaterials in patients suffering from bone diseases such as arthritis and osteoporosis. CoCrMo alloys have been widely employed as bearing surfaces in metal-on-metal (MoM) orthopaedic implants given their optimal mechanical properties and high corrosion resistance, as well as their relatively low wear rates and the post-operative stability. Loss of material by corrosion-wear of the hip joint and metal ion release into the blood stream are of prime concern as these can cause adverse reactions in the human body such as inflammation and bone erosion as well as loosening of the implant. This study aims to reduce the material loss at the bearing surfaces by the application of a multi-layer PVD coating on an ASTM F-1537 CoCrMo substrate. A 2.3 µm thick CrN coating was deposited on top of a 3.6 µm CoCrMo precipitate free supersaturated metastable solution of carbon, otherwise known as S-phase (S), by magnetron sputtered PVD. The coated samples designated as CrN/S, displayed a higher hardness and they retained their topography in nano-scratch tests relative to the uncoated CoCrMo substrate under the same conditions. Tribocorrosion tests for uncoated CoCrMo samples against uncoated CoCrMo counterfaces as well as for coated samples against coated counterfaces were conducted in Ringer’s solution as well as in diluted Foetal calf bovine serum at 37±1 °C under reciprocating sliding conditions. Results show that under all applied potentials and in both solutions, the coated tribopairs when compared to the uncoated ones exhibited a significant decrease in material loss and excellent resistance to catastrophic failure by tribocorrosion. Figure 1 outlines the improvement exhibited by the coated samples under anodic conditions; the coated samples exhibiting a smaller wear scar and mostly polishing wear as opposed to the uncoated samples, in both solutions.