Properties of ZrC coatings deposited by reactive magnetron sputtering on Ni-Ti alloy substrates

In order to increase hardness and wear resistance, research was conducted on the production of ZrC coatings on medical Ni-Ti alloy by reactive magnetron sputtering. The coatings should exhibit straining capability in a range similar to the magnitude associated with the shape memory effect while maintaining good adhesion to the Ni-Ti alloy.ZrC coatings were deposited by reactive magnetron sputtering in an acetylene atmosphere on Ni-Ti and Si alloy samples. Investigations were carried out in relation to the phase composition (XRD) and the structure (SEM) of the coatings. Hardness, the E-modulus, internal stresses, adhesion (the scratch test, the Rockwell test) and tribological tests (ball-on-disk) of the ZrC coatings deposited at acetylene flow rates in the range 1.5-6.3 sccm were investigated.The XRD investigations confirmed that the coatings contained ZrC phase crystallites. The highest hardness of the ZrC coatings (26.1 GPa) is more than 10 times greater than that of the Ni-Ti alloy (2.3 GPa). The Scratch and Rockwell tests prove good adhesion of the ZrC coatings to Ni-Ti alloy substrates. The dry friction coefficient of ZrC coatings, determined by the ball-on-disk method, is many times lower (0.1-0.3) compared to that of Ni-Ti substrates (0.96). Coatings deposited at acetylene flow rates above 3.5 sccm show an order of magnitude lower wear ratios compared to Ni-Ti substrates.It is planned to carry out additional investigations in relation to the chemical and phase composition using WDX and XPS methods of the ZrC coatings deposited and an EDS analysis from the friction pair surfaces after tribological ball-on-disk tests.The structure and properties of ZrC coatings, deposited using reactive magnetron sputtering, indicate that they can be used to coat, for example, endodontic instruments made of Ni-Ti alloy. Research in this direction is continuing.ZrC coatings significantly increase the hardness and wear resistance of Ni-Ti alloy substrates while maintaining good adhesion. They may be used in various fields of technology and medicine, thus significantly increasing the durability of Ni-Ti alloy components/objects that have so far been in use.