Estimation of MoS2 Coating Performance on Bronze and Steel in Vacuum at High Temperatures

Abstract

We compared two modes of magnetron sputter deposition of MoS2 on substrates made of steel AISI 316L and bronze CuAl9NiFe4Mn1 with different initial roughness Ra 0.05–2.32 µm. The deposition was carried out at a bias voltage of −20 and +100 V, and the deposition rate of these modes differed by 30%. Measurements of the friction coefficient and lifetime tests were made in accordance with ASTM G133. Measurements of the friction coefficient and lifetime tests in vacuum at load 7H, temperature of samples 250 °C, and pressure in the chamber <10−6 Pa were carried out according to ASTM G133. The adhesive strength, the chemical composition of the coatings before and after tribological tests, the degree of crystallinity of the coatings, and the distance between the planes were evaluated. Mechanical and structural properties of coatings are discussed concerning the deposition mode parameters. The average coefficient of friction of the MoS2 coatings in steady-state friction did not exceed 0.051 for all samples. The influence of the sample pretreatment method on the growth of molybdenum disulfide crystals was revealed.

Effects of Nitrogen Modification of Porous PVD–MoS2 Coatings on the Tribological Behavior under Rolling–Sliding Conditions in Vacuum

“…The matching pattern of the basebody and counterpart for each coati and load case, therefore, represent that coating transfer occurred (see Figures 6 and 7) a will henceforth be referred to as such. The visible darker residual spots on the counterparts (Figure 5a,c,e,g) indicate a partial coating transfer, as shown in previous studies in which an investigation of coating transfer with energy dispersive spectroscopy or transmission electron microscopy was observed [6,41,58]. The matching pattern of the basebody and counterpart for each coating and load case, therefore, represent that coating transfer occurred (see Figures 6 and 7) and will henceforth be referred to as such.…”

“…Both coatings showed smooth surfaces with a similar roughness value (R a ), indicating that the applied modification with nitrogen caused no significant effect on the roughness. Apart from that, the roughness values are within the known range for sputter-deposited MoS 2 coatings produced under similar conditions [6,52]. Measuring the coating thickness, the difference between the pure and the nitrogenmodified MoS 2 coating was obvious, and it was noticeable that the modification corresponds to a 32.5% reduced coating thickness for an almost identical deposition time.…”

“…Both coatings showed smooth surfaces with a similar roughness value (Ra), indicating that the applied modification with nitrogen caused no significant effect on the roughness. Apart from that, the roughness values are within the known range for sputter-deposited MoS2 coatings produced under similar conditions [6,52]. As illustrated in Figure 2, the average profile of 50 cross-section measurements was obtained at four points on each specimen, offset by 90 • to each other.…”

“…The solid lubricant molybdenum disulfide (MoS 2 ) is widely employed in challenging environments where conventional oil and grease lubrication are ineffective or undesirable [1,2]. Application proved particularly effective at low temperatures [3,4], high temperatures [5,6], and, especially, under vacuum conditions, for instance, in space applications [7][8][9][10]. Therefore, a common technique for applying such coatings is the (reactive) physical vapor deposition (PVD) process.…”

The Technological Factors and Operating Conditions Influence on the Molybdenum Disulfide Coatings Tribological Properties

“…Sputtering modes and surface preparation have a significant impact on the antifriction MoS2 coatings tribological properties [4].…”