Morphology and Dissolution Rate of Wear Debris from Silicon Nitride Coatings

Silicon nitride (SiNx) coatings have recently been introduced as a potential material for joint implant bearing surfaces, but there is no data on wear debris morphology nor their dissolution rate, something that could play a central role to implant longevity. In this study, wear debris was generated in a ball-on-disc setup in simulated body fluid. After serum digestion the debris was analyzed with scanning electron microscopy and energy-dispersive X-ray spectroscopy. The particle dissolution rate was evaluated using inductively coupled plasma techniques, on model SiNx particles. The wear debris from SiNx coatings was found to be round, in the nm range and formed agglomerates in the submicrometer to micrometer range. Model particles dissolved in simulated body fluid at a rate of: c(t) = 39.45[1 – exp(−1.11 × 10–6t)], where [c(t)] = mg/L and [t] = s. This study can be used as a preliminary prediction of size, shape, and dissolution rate of wear debris from SiNx coatings.