Tribological checks have been carried out employing a ball-on-disc T-11 tester. The balls were manufactured from metal, Whilst the discs were made from metal, aluminium oxide, zirconium oxide, polyamide and poly(methyl methacrylate). The description on the unit and also the procedures is offered inside the literature (Szczerek and Tuszyński in https://grahamh382ovb5.blogoscience.com/profile