Microstructural and tribological properties of sputtered AlCrSiWN films deposited with segmented powder metallurgic target materials

Abstract

When synthesizing magnetron sputtered films with a complex stoichiometry, integrating the desired coating constituents into one target material is favorable in order to avoid nanolaminar film depositions and to enable a homogenous film growth. In contrast to alloyed targets, segmented plug targets allow to merge elements with different physical properties in one target material. Two targets, amalgamating 20 and 48 hot-pressed 85.6Cr9.9Si4.5W (at. %) plugs, respectively, into a monolithic aluminum target were fabricated and employed in a direct current magnetron sputtering process to deposit AlCrSiWN films on high-speed steel (AISI M3:2, 1.3344). The cathode powers for the Al(CrSiW)20 and Al(CrSiW)48 targets were varied between 7.5 and 17.5 W/cm2 to analyze how differently composed targets and various cathode powers affect the microstructure and tribological properties of the sputtered films.The results revealed that the chemical composition as well as the thickness of the films strongly depend on the target setup. All AlCrSiWN films exhibited a Cr/Si/W ratio of approximately 84/11/6. The Cr and Al contents were dominant (19–29 at. %), while the Si and W contents varied between 2 and 3 at. %. Especially the Al/Cr ratio of the films is affected by the varying Al/CrSiW surface area ratio of the manufactured plug targets. Furthermore, the mechanical properties are significantly influenced by the Al/Cr ratio, which is responsible for a dense coating growth and the crystalline structure of the films. All AlCrSiWN films were (111) textured indicating a B1 (Al, Cr, W)N structure, which exhibited a finer crystalline growth with an increasing cathode power on the Al(CrSiW)20 target. Tribological analyses of the films against Al2O3 balls further revealed that thinner films resulted in a decreased wear coefficient.