Dry Sliding Wear Behavior of Cr-Al-N Diffusion Coatings against Silicon Nitride

Abstract

In this study, the friction and wear behavior of uncoated and chromium aluminum nitride (Cr-Al-N)-coated AISI D2 tool steel disks were studied using a ball-on-disk system. Thermo-reactive diffusion technique was utilized to the coat desired phases onto pre-nitrided AISI D2 steel. The morphology and the phases formed on the coating layer were characterized by optical and scanning electron microscopy along with x-ray diffraction analysis. Friction and wear tests were conducted under atmospheric conditions with 2.5, 5 and 10 N loads at 0.1, 0.3 and 0.5 m/s sliding speeds against a silicon nitride ball. A dense and homogeneous coating layer with the thickness and hardness of 11.8 +/- 1.3 mu m and 2067 +/- 160 HV0.01 was obtained. The results revealed that the friction coefficient values varied between 0.6-0.942 and 0.025-0.479 for uncoated and Cr-Al-N-coated AISI D2 steels, respectively. The wear rate of the uncoated and Cr-Al-N-coated AISI D2 steel fluctuated in the range of 5.01 x 10(-4)-3.47 x 10(-3) mm(3)/m and 9.38 x 10(-5)-9.31 x 10(-4) mm(3)/m, respectively. The wear rate of the Cr-Al-N coating was much lower than that of the AISI D2 steel.