Friction and Wear Performance of Nano Hydroxy Apatite (nHAp) Polyoxymethylene Composites on 316L Steel

Abstract

Biomedical applications are important aspects in mankind. The word “Biomedical” is recently been used in the researches where the materials are made or synthesized from biological sources or these materials are used for various treatment of living beings. Recently in biomedical applications, polymers have paved their way in various applications such as implants, grafts, connective tissues etc. and hence, understanding the tribological properties of these polymers becomes an important factor to estimate their performance index. Polymethyl methacrylate (PMMA), poly ether ether ketone (PEEK) and Ultra-high-molecular-weight polyethylene (UHMWPE) has been extensively used for biomedical applications but polyoxymethylene (POM) has not been explored in depth till date. This chapter focusses on investigating the tribological properties of nano hydroxy apatite (nHAp) added polyoxymethylene (POM) composites using a pin on disc tribometer. nHAp prepared from egg shells by wet-precipitation method, were added in various weight percentages (1%, 2%, 3%, 4%, and 5%) to POM. Several pins made of POM reinforced with nHAPwere used to investigate the tribological properties using a pin on disc tribometer. A 316L stainless steel disc was used as counter surface to these pins during the tribo test. The shore hardness of the POM composites were measured which exhibited an increase in hardness with the increase in concentration of nHAp in POM. The tribo tests results exhibited a decrease in the coefficient of friction (CoF) up to a certain concentration of nHAp (4% this case), beyond which the coefficient of friction increased. In case of wear rate, the lower concentrations of nHAp showed less wear rate but the wear rate increased with the increase in concentration of nHAp. 1–4% nHAp included POM pins exhibited as low as 77% wear rate compared to POM compsite which did not contain any nHAp particles. The presented results indicates that POM can be a good choice for several biotribo pairs, however the biocompatibility of POM is to be explored. The present work will be helpful in making various composites for implants once the biocompatibility of POM is established.