Silver based composites with varying concentration of graphite and/or MoS2 were prepared by powder metallurgy method. Impacts of composition on the tribological performance of the composites in ambient air and vacuum were investigated. The lowest friction in air was achieved by Ag–20G (vol.-%) composite, while Ag–20MoS2 exhibited the best lubricity in vacuum. XPS evaluation revealed the oxidation of MoS2 in air and a decrease concentration of graphite on the surface of the wear tracks under vacuum. As the proportion of graphite to MoS2 increased, the friction coefficient and the wear rates ascended gradually in air while decreased sharply under vacuum. As compared with other compositions, Ag–15MoS2–5G exhibited a comparable stable and good tribological performance as the environmental condition changed for its friction coefficient and wear rate remained around 0·14 and 5×10−6 mm3 N−1 m−1.
HiltonM. R. and FleischauerP. D.: ‘Applications of solid lubricant films in spacecraft’, Surf. Coat. Technol., 1992, 54–55, 435–441.
2.
DonnetC.: ‘Advanced solid lubricant coatings for high vacuum environments’, Surf.Coat. Technol., 1996, 80, 151–156.
3.
JohnP. J., PrasadS. V., VoevodinA. A. and ZabinskiJ. S.: ‘Calcium sulfate as a high temperature solid lubricant’, Wear, 1998, 219, 155–161.
4.
SingerI. L., FayeulleS. and EhniP. D.: ‘Wear behavior of triode-sputtered MoS2 coatings in dry sliding contace with steel and ceramics’, Wear, 1996, 195, 7–20.
5.
MamedovV.: ‘Microstructure and mechanical properties of PM Fe-Cu-Sn alloys containing solid lubricants’, Powder Metall., 2004, 47, 173–179.
6.
KutschejK., MittererC., MulliganC. P. and GallD.: ‘High-temperature tribological behabior of CrN-Ag self-lubricating coatings’, Adv. Eng. Mater., 2006, 8, 1125–1129.
7.
MuratoreC. and VoevodinA. A.: ‘Chameleon coatings: Adaptive surfaces to reduce friction and wear in extreme environments’, Ann. Rev. Mater. Res., 2009, 39, 297–324.
8.
VoevodinA. A., HuJ. J., FitzT. A. and ZabinskiJ. S.: ‘Nanocomposite tribological coatings with chameleon friction surface adaption’, J. Vac. Sci. Technol. A, 2002, A20, 1434–1444.
9.
TheilerG. and GradtT.: ‘Friction and wear of PEEK composites in vacuum environment’, Wear, 2010, 269, 278–284.
10.
DonnetC., Le MogneT. h. and MatinJ. M.: ‘Superlow friction of oxygen-free MoS2 coatings in ultrahigh vacuum’, Surf. Coat. Technol., 1993, 62, 406–411.
11.
XuJ., ZhuM. H., ZhouZ. R., KapsaP. h. and VincentL.: ‘An investigation on fretting wear life of bonded MoS2 solid lubricant coatings in complex conditions’, Wear, 2003, 255, 253–258.
12.
WindomB. C., SawyerW. G. and HahnD. W.: ‘A Raman spectroscopic study of MoS2 and MoO3: applications to tribological systems’, Tribol. Lett., 2011, 42, 301–310.
13.
EndrinoJ. L., NainaparampilJ. J. and KrzanowskiJ. E.: ‘Microstructure and vacuum tribology of TiC-Ag composite coatings deposited by magnetron sputtering-pulsed laser deposition’, Surf. Coat. Technol., 2002, 157, 95–101.
14.
GulbińskiW. and SuszkoT.: ‘Thin films of Mo2N/Ag nanocomposite – the structure, mechanical and tribological properties’, Surf. Coat. Technol., 2006, 201, 1469–1476.
15.
BasnyatP., LusterB., KertzmamZ., StadlerS., KohliP., AouadiS., XuJ., MishraS. R., EryilmazO. L. and ErdemirA.: ‘Mechanical and tribological properties of CrAlN-Ag self-lubricating films’, Surf. Coat. Technol., 2007, 202, 1011–1016.
16.
LiJ. L., XiongD. S., HuangZ. J., KongJ. and DaiJ. H.: ‘Effect of Ag and CeO2 on friction and wear properties of Ni-base composite at high temperature’, Wear, 2009, 267, 576–584.
17.
MuratoreC., VoevodinA. A., HuJ. J., JonesJ. G. and ZabinskiJ. S.: ‘Growth and characterization of nanocomposite yttria-stabilized zirconia with Ag and Mo’, Surf. Coat. Technol., 2005, 200, 1549–1554.
18.
VoevodinA. A., O'NeillJ. P. and ZabinskiJ. S.: ‘WC/DLC/WS2 nanocomposite coatings for aerospace tribology’, Tribol. Lett., 1999, 6, 75–78.
19.
BakerC. C., HuJ. J. and VoevodinA. A.: ‘Preparation of Al2O3/DLC/Au/MoS2 chameleon coatings for space and ambient environments’, Surf. Coat. Technol., 2006, 201, 4224–4229.
20.
ZhengX. H., TuJ. P., LaiD. M., PengS. M., GuB., HuS. B.: ‘Microstructure and tribological behavior of WS2-Ag composite films deposited by RF magnetron sputtering’, Thin Solid Films, 2008, 516, 5404–5408.
21.
ScharfT. W., KotulaP. G. and PrasadS. V.: ‘Friction and wear mechanisms in MoS2/Sb2O3/Au nanocomposite coatings’, Acta. Mater., 2010, 58, 4100–4109.
22.
GardosM. N.: ‘The synergistic effects of graphite on the friction and wear of MoS2 films in air’, Tribol. Trans., 1988, 31, 214–27.
23.
MuratoreC. and VoevodinA. A.: ‘Molybdenum disulfide as a lubricant and catalyst in adaptive nanocomposite coatings’, Surf. Coat. Technol., 2006, 201, 4125–4130.
24.
AouadiS. M., PaudelY., SimonsonW. J., GeQ., KohliP., MuratoreC. and VoevodinA. A.: ‘Tribological investigation of adaptive Mo2N/MoS2/Ag coatings with high sulfur content’, Surf. Coat. Technol., 2009, 203, 1304–1309.
25.
RossS. and SussmanA.: ‘Surface oxidation of molybdenum disulfide’, J. Phys. Chem., 1955, 59, 889–892.
26.
QiangY. H., GeS. R. and XueQ. J.: ‘Microstructure and tribologial behebiour of nitrocarburizing quenching duplex treated steel’, Tribol. Int., 1999, 32, 131–136.
27.
SkinnerJ., GaneN. and TaborD.: ‘The microfriction of graphite’, Nature, 1971, 232, 195–196.
