SURFACE MORPHOLOGY, ADHESION AND ELEMENTAL COMPOSITION OF AlCrN COATINGS OBTAINED FROM FILTERED CATHODIC ARC PLASMA

Abstract

Aluminum-chromium nitride coatings were obtained under plasma separation conditions of a stationary cathodic arc discharge. It is shown that the existing magnetic filtering system of the UVNIPA-1-001 vacuum equipment allows reducing the number of macroparticles - a by-product of cathode erosion - by (1.7 – 2) times, depending on the nitrogen pressure. For this filter, the removal of macroparticles with a size of less than 1 micron remains a problem. Their density remains quite high (about 22,000 mm^-2) and decreases slightly with increasing nitrogen pressure. AFM methods have shown the presence of pores of submicron sizes, which are formed by macroparticles when they are reflected by the surface of the base. From an analysis of the elemental composition of the coatings, it was established that there is a stratification of the plasma flow of two-component metal plasma into the ionic components of chromium and aluminum, leading to a significant deviation of the composition of the coatings from the composition of the target towards a strong deficiency of aluminum. In this case, filtration has a beneficial effect on bringing the coating composition closer to stoichiometric AlCrN. Filtered plasma coatings have higher adhesion to a tool steel base. The best achieved adhesion result is 29 N for the AlCrN coating obtained at a nitrogen pressure of 21 mPa, which is 1.5 times higher than the adhesion force of coating samples without plasma separation.