Experimental and Finite Element Wear Study of Silicon Nitride Against Alumina for Hip Implants with Bio-Lubricant for Various Gait Activities

This paper presents an experimental approach to predict the friction and wear coefficients followed by finite element modeling (FE) to analyze the wear of silicon nitride sliding against alumina bearing components up to 2 years considering risky gait activities. First, the friction and wear coefficients were determined for four loading conditions - 15, 20, 25 and 30 N for 20 km (equivalent to 2 years of implant life) using ball-on-disc (BOD) tribometer with 0.9% (NaCl) saline solution to simulate a lubricating bearing contact similar to hip joint. These BOD loads were equivalent to gait loads which were named as four groups- A (as similar to sitting down or getting up), B (as similar to stair ascending and descending with load), C (as similar to carrying load 50 kg) and D (as similar to load transfer 50 kg). Interestingly, the experimental results showed the friction and wear coefficients obtained from BOD tests were found to be much lower for higher gait loads due to the formation of discontinuous tribofilm on the worn surface. Later, finite element simulation was carried out and the findings revealed that physically demanding gait activity of load transfer 50 kg had the least maximum linear and volumetric wear. Group A gait activity showed maximum linear and volumetric wear among all the groups. From these results, it is quite evident that, people engaged in physically demanding gait activities, may prefer silicon nitride and alumina combination for hip joint replacement which showed reduced wear for risky activities.

Automated summary

This study investigated the friction and wear behavior of silicon nitride sliding against alumina bearing components under high gait loads through experiments and finite element analysis. The results showed that the silicon nitride and alumina combination exhibited lower friction and wear coefficients under high loads, making it a suitable choice for hip joint replacement in physically demanding activities.