THE PROPERTIES OF A WROUGHT BIOMEDICAL COBALT-CHROMIUM ALLOY

Two wrought biomedical cobalt-chromium alloys have been developed, and their mechanical properties and corrosion resistance determined by me ans of tensile and hardness tests and by electrochemical potential-tim e curves for isolated specimens in a 6.0 wt % NaCl solution at room te mperature. In comparison with a current dental alloy, SC-H, and the ba sic type 18-8 austenitic stainless steel, it is shown that alloy II (c hemical composition in wt % : 0.11 C, 22.07 Cr, 15.20 Ni, 3.75 Mo, 9.3 0 W, balance Co) has superior properties. The alloy has a high strengt h together with a good ductility which permits adequate workability. A lso, both cobalt-chromium alloys show a passive behaviour in 6.0 wt % NaCl solution, whereas the basic type 1 8-8 austenitic stainless steel shows a fluctuating potential and is thus susceptible to pitting, mak ing it unsuitable for surgical implants.