The effect of humidity on the friction and life of unbonded molybdenum disulphide films

Pritchard, C.; Midgley, J. W.

doi:10.1016/0043-1648(69)90430-x

Cited by 63 publications

(22 citation statements)

References 8 publications

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“…The poor performance of the MoS 2 coatings may be owing to the high humidity environment of the experiment. As pointed out by Pritchard et al [12], the coefficient of friction could increase from about 0.1 to 0.5 as relative humidity changes from 0 to 40%. Co-sputtering of molybdenum disulphide and polytetrafluoroethane (PTFE) [13], nickel [14], gold [15] and more recently titanium, et al [16,17] improves the lubrication properties of molybdenum disulphide considerably.…”

Section: Contact Anglementioning

confidence: 82%

Exploring the Antisticking Properties of Solid Lubricant Thin Films in Transfer Molding

Zhang

Zeng

Tang

et al. 2002

Int. J. Mod. Phys. B

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In the plastic molding industry, plastic parts like pager and handphone cases, plastic containers, etc. are formed in a mold by applying temperature and pressure. The transfer molding is the standard workhorse for the electronics industry. Although the transfer molding is widely used, it is far from being optimized. Mold sticking is a serious practical problem in this industry. A solution to the problem is to apply mold-releasing agents on the mold to act as a lubricant layer between the plastic and the mold. This easily results in stains and degraded surface finish. This paper investigates the effectiveness of solid thin films on reducing the adhesion between polymer and mold steel of different surface roughness. WS 2 , MoS 2 , and DLC coatings are deposited on test surfaces via unbalanced magnetron sputtering before polymer blocks are molded on and pulled apart using an Instron Machine. The force required to separate the plastic part and the mold steel is used as an indication of the stickiness. After the separation, the coating surface is also examined under microscope for stains and polymer residues. The coatings are characterized using Raman spectroscopy and contact angle measurements. Generally, the stickiness increases with initial surface roughness for all coatings. Initial test indicates that the DLC coating has the highest contact angle with water (100°) and the best anti-sticking properties among the samples tested, and could reduce the stickiness by 80% as compared to bare steel.

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Section: Contact Anglementioning

confidence: 82%

Exploring the Antisticking Properties of Solid Lubricant Thin Films in Transfer Molding

Zhang

Zeng

Tang

et al. 2002

Int. J. Mod. Phys. B

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“…Two regions where debris particles moved relative to the hemisphere are outlined by circles and boxes, respectively. The circled region shows debris accumulating (1, 2), moving to the right (3), then extruding into a broad patch (4,5). The boxed region shows debris (1) moving to the right (2), then extruding into a shape that resembles a sideways 'U' before exiting the box; the motion of the debris is reversed on the return traversal.…”

Section: Variable Humidity Tests: Dry/humid/dry Air Slidingmentioning

confidence: 99%

“…However, the tribological properties of MoS 2 are degraded severely when humidity is present [3,4]. Studies by Fusaro [5] showed that oxygen and moisture have a detrimental effect on transfer film morphology and rheology, leading to lubricant failure.…”

Section: Introductionmentioning

confidence: 99%

In Situ Analysis of Third Body Contributions to Sliding Friction of a Pb–Mo–S Coating in Dry and Humid Air

2007

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Reciprocating sliding tests of ion-beam deposited (IBD) Pb-Mo-S coatings were performed with an in situ tribometer that allows real-time visualization and Raman analysis of the sliding contact through a transparent hemisphere. Experiments were performed in dry air, ambient air (*50% RH) and mixtures of dry and humid air cycled between low and high humidity. Third bodies formed in the sliding contact were monitored through an optical microscope and analyzed by Raman Spectroscopy. Third body velocity accommodation modes were identified and correlated with friction behavior in dry and ambient air. The dominant velocity accommodation mode in both dry and humid air was interfacial sliding between the outer surface of the transfer film and the wear track; this interface, based on present and earlier studies, is crystalline MoS 2 . Therefore, the friction coefficient was controlled by the interfacial shear strength of MoS 2 sliding against MoS 2 . Humid air sliding was accompanied by a rise in the friction coefficient and a small but observable second velocity accommodation mode: shear/extrusion of the transfer film. It is concluded that the friction rise in humid air was due to an increase in the interfacial shear strength, and that the rise in friction caused the third body to deform rather than the deformation causing the friction to rise.

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“…Pritchard & Midgley (1969) reported that the friction of molybdenum disulphide was governed essentially by the amount of water physically adsorbed. The authors concluded that humidity affects the adhesion component of friction and therefore the intercrystallite forces; the wear rate of the lubricant layer also increases as more water is adsorbed.…”

Section: High Temperature Scratch Testsmentioning

confidence: 99%

Study of solid lubrication with MoS2 coating in the presence of additives using reciprocating ball-on-flat scratch tester

Shankara

Menezes

Simha

et al. 2008

Sadhana

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Abstract. Molybdenum disulphide (MoS 2 ) based solid lubricant mixtures containing zirconia and graphite were prepared in the laboratory and coated on steel specimens. The experiments were done using reciprocating scratch test for various numbers of cycles. The results showed that the addition of zirconia and graphite into the MoS 2 lubricant has improved its properties in terms of both friction and wear. In addition, it was observed that the presence of moisture affects the life of the lubricating film. It was shown that at high temperature the moisture evaporation enhanced the coating performance of the film.

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The effect of humidity on the friction and life of unbonded molybdenum disulphide films

Cited by 63 publications

References 8 publications

Exploring the Antisticking Properties of Solid Lubricant Thin Films in Transfer Molding

Exploring the Antisticking Properties of Solid Lubricant Thin Films in Transfer Molding

In Situ Analysis of Third Body Contributions to Sliding Friction of a Pb–Mo–S Coating in Dry and Humid Air

Study of solid lubrication with MoS2 coating in the presence of additives using reciprocating ball-on-flat scratch tester

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