Friction properties of nano-hydroxyapatite reinforced poly(vinyl alcohol) gel composites as an articular cartilage

Nano-hydroxyapatite reinforced poly(vinyl alcohol) gel (nano-HA/PVA gel) composite has been proposed as a promising biomaterial, especially used as an articular cartilage repair biomaterial. In this paper, nano-HA/PVA gel composite was prepared by in situ synthesis method and incorporation with freeze–thaw cycle process. The effects of various factors on the friction coefficient of the gel composites and stainless steel ball counterpart were investigated by a ball–plate friction and wear tester. The variations of the friction coefficient with influence factors were explored by Hertzian contact theory and elastohydrodynamic lubrication theory. The results show that the friction coefficient of the gel composites is positively to the normal load and inversely proportional to the sliding speed and the diameter of stainless steel ball. Furthermore, the friction coefficient of the gel composites is obviously lower than that in distilled water or in physiological saline, whereas, friction coefficient has little difference between in distilled water and in physiological saline.