Tribological Properties of Amorphous-SiC-Based Coatings on Al<sub>2</sub>O<sub>3</sub> Substrates in Normal Saline

Amorphous SiC (a-SiC)-based coatings containing not only Si-C bonds but also C-Si-O, C-C, and Si-O 2 bonds were deposited on Al 2 O 3 substrates via pulsed laser deposition.Sliding tests using SiC ceramic balls in normal saline revealed that the coating exhibited a low friction coefficient of 0.05-0.06 at a shorter running-in process than SiC bulk ceramic plates.The specific wear rate of the coating was also lower than that of the SiC plate.Reactive molecular dynamics simulations revealed that the C-Si-O bonds in the coating facilitated the generation of Si-O units, which contained Si-O bonds but no Si-C bonds, through tribochemical reactions with water, resulting in superior tribological properties in normal saline compared to those of SiC plates.These findings demonstrate that a-SiC-based coatings containing C-Si-O bonds are promising as low-friction and low-wear coatings for biomedical implants such as ceramic joint prostheses.