Improved stability of plasma-sprayed dicalcium silicate/zirconia composite coating

Dicalcium silicate/zirconia composite coatings were produced on Ti–6Al–4V substrates using atmospheric plasma spraying. Different weight ratios of zirconia (50 wt.%, 70 wt.%, 90 wt.%) were mechanically blended with dicalcium silicate (C2S) powders as feedstocks. The composite coatings were immersed in a simulated body fluid (SBF) and a Tris–HCl solution for the in vitro appraisement of stability and long-term performance in a biological environment. The ion concentration changes of Ca, Si, and P in SBF and Tris–HCl solution were monitored using inductively-coupled plasma atomic emission spectroscopy (ICP–AES). Compared to the pure C2S coating, our results show that the dissolution rate of the composite coatings is effectively reduced and the stability is improved by the addition of zirconia. The high content of zirconia in the coatings ensures the long-term performance in biological environment, while dissolution of C2S in the coatings results in a higher Ca ion concentration in SBF and rapid precipitation of bone-like apatite on the composite coating surfaces indicating good bioconductivity of the coatings.