Influence of the yttrium cathode arc current on the yttrium content in the (Ti,Y,Al)N coating and the coating properties

Abstract

The (Ti,Y,Al)N coating was deposited at different values of the yttrium cathode arc current (65, 85, 105, and 125 A). With an increase in the arc current from 65 to 105 A, an increase in the Y content in the coating from 30 to 63 at% is observed; however, with a further increase in the arc current to 125 A, the yttrium content practically does not change. This effect can be associated with an increase in the proportion of microparticles in the plasma flow at high values of the arc current. These microparticles do not reach the surface of the substrate, falling on the walls of the chamber. With an increase in the arc current, the dominant shape of the microparticles changes. If at 65 A relatively small (up to 3 μm) microparticles of a regular spherical shape dominate, then at 85 A a noticeable amount of irregularly shaped microparticles with sizes of 3–5 μm is observed, and with a further increase in the arc current, large microparticles up to 30 μm in size are formed. The value of the modulation period of the studied coatings is 42–67 nm. The change in the modulation period λ depending on the arc current of the yttrium cathode has a character close to linear, increasing with increasing arc current. From the point of view of hardness, scratch test and wear resistance during turning, only coatings deposited at arc currents of 65 and 85 A have prospects for effective operation as a wear-resistant coating.