Temperature dependent friction and wear of magnetron sputtered coating TiAlN/VN

Abstract

In this paper, a magnetron sputtered nano-structured multilayer coating TiAlN/VN, grown on hardened tool steel substrate, has been investigated in un-lubricated ball-on-disk sliding tests against an alumina counterface, to study the friction and wear behaviours at a broad range of testing temperatures from 25 to 700 0 C, followed by comprehensive analysis of the worn samples . The associated wear mechanism changed to severe wear dominated by cracking and spalling. From 500 0 C and so on, accelerated oxidation of the TiAlN/VN became the controlling process. This led first to the massive generation of oxide debris and maximum friction of µ = 1.1 at 500 0 C, and then to fast deterioration of the coating despite the lowest friction coefficient of µ < 0.3 at 700 0 C.

Electron Microscopy and Spectroscopy in the Analysis of Friction and Wear Mechanisms

“…A CSM-manufactured ball-on-disc tribometer (CSM Instruments, Peseux, Switzerland)) was employed in most of the tribotests [26][27][28][29]. The disc samples were the transition metal nitride coatings grown on pre-polished high speed steel coupons, which slid against a ball counterpart of either alumina ceramic or cemented WC carbide of 6 mm in diameter.…”

“…In this mode, an area that is rich in light elements, such as oxides, carbides, or nitrides, exhibits dark contrast, while another area containing heavy elements exhibits bright contrast. Therefore, SEM images in BSE mode provide a convenient tool to characterize the distribution of secondary phases, the presence of oxides, or other compounds [25,29]. In addition, BSE imaging can also be employed to detect cracks and metallurgical defects, such as porosity and non-metallic inclusions [30].…”

“…Then, EDX spectroscopic analysis is performed in order to determine the chemical composition, whereas TEM-EDX is superior to SEM-EDX, in that it can analyse the composition of an area as small as only a few nanometres in diameter. Furthermore, the capability in analysing light elements is enhanced, owing to the elimination of mass absorption of the low-energy X-rays [22,23,29]. In advanced analytical TEM, the incident electron beam can be configured to scan over the sample, to achieve the functions of line-scan and elemental mapping.…”

“…For example, the so-called self-adaptive lubricity can be attributed to the formation of a low-friction tribofilm [8,10,[12][13][14][20][21][22][23][24][25]. On the other hand, a tribofilm may behave with high friction and consequently results in more pronounced wear [23,25,29]. In view of the wear property, tribofilms have also been found to change the stress distribution on the wear contact zone and to be associated with the deformation of the top worn surface [15][16][17][18][19][20].…”

Oxidation and diffusion processes during annealing of TiSi(V)N films

“…CrVN [16], (V,Ti)N [17], multilayer AlN/VN [18] and quaternary single layered or multilayered AlCrVN [19,20] and TiAlVN [12,[21][22][23]. Independently of the configuration, the friction was decreased and the wear resistance improved; however, the oxidation resistance was degraded.…”