Friction and Wear Properties of WC/C Nano-Scale Multilayer Coatings on Technical Surfaces

Abstract

This article reports on the tribological performance of a WC/C multilayer coating with a periodicity WC/C = 15/5 nm deposited on bearing steel substrates. These substrates were initially polished to achieve different RMS roughness values ranging from 15 to 900 nm. Tribological tests were performed using a precision reciprocating microtribometer under ambient conditions with a steel ball as a counter-sample. The worn sample surfaces were examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX). The results indicate that the combined effects of the real contact area, lubricating effect of the coating, as well as the formation of a transfer layer and its subsequent removal, all contribute to a dependence of surface roughness on the coefficient of friction (CoF).

THE EFFECT OF PRESSURE, BIAS VOLTAGE AND ANNEALING TEMPERATURE ON N₂ AND N₂+SiH₄ DOPED WC/C DC MAGNETRON SPUTTERED LAYERS

“…The original values of COFs have increased from 0.1 -0.25 to 0.3 -0.7 at a distance of 10 m (Figure 2). In the case of sample 2, with mean value of hardness HIT ≈ 22 GPa, the lowest COF = 0.3 was achieved along a track over 30 m and, this is in good correspondence with previous investigations [3,10,12,31].…”

“…Tungsten carbide (WC) is a very attractive refractory material for industrial applications of thin hard layers to steel [1][2][3][4][5][6][7][8][9][10][11][12] and Al alloys. WC has an excellent combination of properties, such as high hardness, a high Young's modulus, and a low COF.…”

“…It is these characteristics of WC which improve the other properties of materials [13]. WC layers have been deposited using chemical vapor deposition (CVD) [14][15][16][17][18][19][20][21][22] and physical vapor deposition (PVD) techniques [1][2][3][4][5][6][7][8][9][10][11][12][13][23][24][25][26][27][28][29][30][31]. Plasma enhanced CVD of tungsten hexacarbonyl has also been used for the deposition of WC/C layers at lower temperatures compared to those used in CVD techniques [15][16][17][18][19][20][21].…”

“…The hardness of the layer was 10 GPa. Additionally, Shengguo Zhou et al [9] evaluated nc-WC coating at C = 75 %, and Kosinskiy et al [10] presented a WC/C layer where H = 6.9 GPa and E = 212 GPa were measured.…”

Microstructure and Mechanical Properties of Annealed WC/C PECVD Coatings Deposited Using Hexacarbonyl of W with Different Gases

“…2550 °C) [ 1 ]. Out of all PVD methods, the most used methods are direct current magnetron sputtering (DCMS) [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] and radiofrequency magnetron sputtering (RFMS) [ 9 , 11 , 12 , 13 , 14 , 15 ] with Ar. Reactive sputtering of W, C, or WC from a target, in the presence of hydrocarbon [ 2 ] or other added gases [ 3 , 4 , 14 ], is used, too.…”