Recent Advances in UHMWPE/UHMWPE Nanocomposite/UHMWPE Hybrid Nanocomposite Polymer Coatings for Tribological Applications: A Comprehensive Review.

In the recent past, polymer coatings have gained the attention of many researchers due to their low cost, their ability to be coated easily on different substrates, low friction and good anti-corrosion properties. Various polymers such as polytetrafluroethylene (PTFE), polyether ether ketone (PEEK), polymethylmethacrylate (PMMA), polyurethane (PU), polyamide (PA), epoxy and ultra-high molecular weight polytheylene (UHMWPE) have been used to develop these coatings to modify the surfaces of different components to protect them from wear and corrosion. However, among all these polymers, UHMWPE stands out as a tribologist's polymer due to its low friction and high wear resistance. These coatings have found their way into applications ranging from microelectro mechanical systems (MEMS) to demanding tribological applications such as bearings and biomedical applications. Despite its excellent tribological properties, UHMWPE suffers from limitations such as low load bearing capacity and low thermal stability. To overcome these challenges researchers have developed various routes such as developing UHMWPE composite and hybrid composite coatings with several types of nano/micro fillers, developing composite films system and developing dual film systems. The present paper is an effort to summarize these various routes adopted by different researchers to improve the tribological performance of UHMWPE coatings.