Influence of high-temperature oxide formation on the tribological behaviour of TiN and VN coatings

Wear and friction of TiAlN/VN coatings against Al2O3 in air at room and elevated temperatures

“…This is much higher than reported by Fateh et al [8], who observed a value of 0.5 for VN tested at 300 0 C. In contrast, Pfluger et al [26] observed a value of 1.5 at 400 0 C for TiAlN deposited by the same method used in the current work. Thus, assuming friction coefficient of TiAlN at 400 0 C is similar to 300 0 C, the friction observed for TiAlN/VN (V: 55.2 at.%) here of 1.0 appears to be mid-way between that for VN and TiAlN, implying a simple law of mixtures, 1.5 x 44.8% + 0.5 x 55.2% = 0.95.…”

“…Fateh et al [8] observed vanadium oxides, including V2O5, through Raman spectroscopy after testing of VN against Al2O3 at 400 0 C on the surface using the same wear test equipment design as used in the current work. The V2O5 was found together with an increased friction coefficient compared to 25 0 C, strongly suggesting that the V2O5 is not always necessarily associated with low friction.…”

“…Similarly, wear tests of Ti-Al-V-N monolithic films (2.40 at.% ≤ V ≤ 11.10 at.%) against an Al2O3 ball exhibited friction coefficients in the range of 0.6-0.85 at 25 0 C, which increased to 1.1 at 500 0 C and dropped to the range of 0.8-0.2 at 700 0 C (friction coefficient value depended on the concentration of V) [6]. Wear studies of VN coatings by Gassner et al [7] and Fateh et al [8] confirmed the reduced friction coefficient associated with the formation of lubricious vanadium oxides, i.e. Magne´li phases at elevated temperatures.…”

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

“…V 2 O 5 , Ag 2 Mo 2 O 7 ) [6][7][8][9]. Among these elements, particular attention has been given to the vanadium-containing coatings (Magnéli phases V n O 2n−1 ), which showed interesting tribological properties in the temperature range 500-700•C [2,[10][11][12][13][14][15]. Dissimilar series of V-based hard coatings have been developed, such as ternary…”

“…However, most of the liquid lubricants volatilize at high temperature, which leads to the dry sliding and consequent failure of the cutting tools resulting in the increasing machine down times, higher process instability, poor product quality and higher costs [1]. To face these problems, a wide range of solid lubricant coatings, such as WC/C, MoS 2 , diamond-like carbon (DLC), h-BN as well as their combinations in nanocrystalline or multilayer structures, have been developed in the last decades and successfully applied in order to improve the tribological behaviour under dry machining conditions [2][3][4][5]. However, considerable degradation of the tribological effectiveness of these coatings at elevated temperature has been reported due to their low resistance to oxidation.…”