Influence of bias voltage on microstructure and properties of AlTiSiN nanocomposite coatings prepared by MPP

The work aims to regulate the microstructure and optimize the mechanical properties of AlTiSiN nano-composite coatings. AlTiSiN nanocomposite coatings were deposited through Modulated Pulsed Power Magnetron Sputtering by varying the substrates bias voltage from-50 V to-250 V. XRD, SEM, EDS, AFM, film comprehensive performance tester and ball and disc friction tester were used to test the microstructure, composition, surface morphology, mechanical and tribological properties. From the results, the influence of bias voltage on element composition was not obvious. For microstructure, the diffraction peaks on the crystal face of AlTiSiN coatings prepared under different bias voltage broadened obviously and nano-crystalline appeared. The diffraction peak on the crystal face of the coating prepared under the condition of-200 V was in the shape of steamed bread peak, which indicated that the crystallization property of the coating was obviously reduced, and the coating had an amorphous-like structure. When the bias voltage rose to-250 V, the high energy ions bombarded the growth surface of the coating continuously, causing the growth surface of the coating to heat up obviously and resulting in obvious improvement of crystallization performance. The surface of the coating was smooth and compact, with the surface roughness as low as 1.753 nm. For mechanical property, with the increase of substrate bias, the hardness of the coating gradually decreased after reaching the maximum value. The maximum hardness and H/E* ratio were 25.9 GPa and 0.13, respectively. As for the wear properties, the lowest wear rate of 4.7×10-15 m3/(N.m) could be achieved when the bias voltage was-200 V. Changing the substrate bias can effectively regulate the microstructure of the coatings and then optimize the microstructure, mechanical properties and tribological properties of the coatings. © 2020, Chongqing Wujiu Periodicals Press. All rights reserved.