Influence of the bias voltage on the structure and the tribological performance of nanoscale multilayer C/Cr PVD coatings

KOK, Y. N., HOVSEPIAN, P. E., LUO, Q., LEWIS, D. B., WEN, J. G. and PETROV, I. (2005). Influence of the bias voltage on the structure and the tribological performance of nanoscale multilayer C/Cr PVD coatings. Thin Solid Films, 475 (1-2), 219-226.

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Link to published version:: 10.1016/j.tsf.2004.08.042

Abstract

Nanoscale multilayer C/Cr coatings have been deposited by utilising the combined steered cathodic arc/unbalanced magnetron sputtering technique. The coating microstructure and tribological performance have been investigated as a function of the bias voltage, ranging from U-b=-65 to -350 V. The XRD results revealed that C/Cr coatings are amorphous at low U-b, but became more crystalline when the Ub increased to -350 V. High-resolution XTEM analysis indicated coating densification and smoothening as well as formation of novel amorphous nanostructure, in which carbon-rich clusters are surrounded by a Cr-rich matrix, leading to the formation of self-organised multilayer structure as the bias voltage was increased from -65 to -350 V. An increase of the bias voltage from -65 to -350 V resulted in an increase in the hardness from 8 to 25 CiPa and Young's modulus, E from 186 to 319 GPa. A pin-on-disc test showed that the friction coefficient was reduced from 0.22 to 0.16 when the bias voltage was increased from -65 to -95 V However, a further increase in the bias voltage to -350 V led to an increase in the friction coefficient to 0.31. The lowest wear coefficient K(c)similar to6.25 x 10(-17) m(3) N-1 m(-1) was achieved at U-b = - 120 V. Standard HSS drills, 8 mm in diameter, coated with C/Cr have been tested using solution annealed AISI 304 stainless steel as the work piece material. An improvement of the lifetime by a factor of similar to9 has been achieved as compared to the uncoated tools. In this test, the C/Cr coating outperformed a number of commercially available PVD coatings, such as TiCN, TiAlCrN and showed similar performance to TiAlCrYN. (C) 2004 Elsevier B.V. All rights reserved.

Item Type: Article
Additional Information: 4th Asian-European International Conference on Plasma Surface Engineering SEP 28-OCT 03, 2003, Jeju City, SOUTH KOREA
Research Institute, Centre or Group: Materials and Engineering Research Institute > Thin Films Research Centre > Nanotechnology Centre for PVD Research
Materials and Engineering Research Institute > Materials Analysis and Research Services
Identification Number: 10.1016/j.tsf.2004.08.042
Depositing User: Ann Betterton
Date Deposited: 16 Feb 2010 14:55
Last Modified: 10 Sep 2010 16:09
URI: http://shura.shu.ac.uk/id/eprint/1126

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