The properties and performance of Cr-based multilayer nitride hard coatings using unbalanced magnetron sputtering and elemental metal targets

Cr-based multilayer hard coatings were produced by unbalanced magnetron sputtering techniques using elemental metal materials. Cr, Ti, Mo, V, Al, and Y target materials were used for the metal sources while nitrogen was introduced at the same time to produce multilayer nitride hard coatings. The deposition process was controlled by a metal plasma optical monitor with closed loop feedback to a piezoelectric valve to form stoichiometric coatings. Physical properties of the coatings were investigated using microhardness, scratch, and Rockwell indentation tests. Wear properties of the coatings were studied using pin-on-disc tests. The coatings were deposited onto hard metal carbide cutting inserts and tool steel drills. The coated inserts were tested on a wide range of difficult-to-machine materials using a Boehringer VDF180-C CNC lathe. The machining was performed under interrupted cutting conditions and the results were compared with those obtained using an advanced commercially available arc deposited TiAlN coating. The coated drills were tested under lubricant environment with severe conditions, comparing it with similar tests on commercial arc deposited TiN coatings.