Structure and microhardness of bioinert coatings of Ti-Ta-N system

Abstract

Abstract The coatings of Ti-Ta-N system have been obtained for the first time. Production of bioinert coatings of Ti-Ta-N system was realized by means of promising technique of electroexplosion spraying and subsequent electron-ion-plasma modification with nitrogen ions. Titanium of VT6 grade was used as a substrate for spraying of coatings. Electroexplosion spraying with use of tantalum foil leads to formation of tantalum coating on titanium substrate. Subsequent electron-ion-plasma modification with nitrogen ions results in synthesis of the following phases: TiN, Ta and β-Ti. Average microhardness values of the coatings formed vary from 449 kgf/mm2 (E = 11.47 %) to 530 kgf/mm2 (E = 10.02 %). Electroexplosion processing promotes the increase in titanium substrate microhardness near coating – substrate interface. In volume of titanium substrate the microhardness decreases to values corresponding to reference data. Irradiation of electroexplosive tantalum coating by electron beam with subsequent nitriding leads to homogenization of structure. Optimum mode of irradiation should be considered the one at powder density of electron beam of 0.5 MW/cm2. At lower value of power density the electron beam melts the electroexplosion coating to insufficient depth. At higher values of power density the electron beam leads to boiling of the melted coating and formation of larger quantities of pores. These phenomena are caused by thermal and physical characteristics of titanium substrate.