Development of ultrananocrystalline diamond (UNCD) coatings for multipurpose mechanical pump seals

J.W.Elam 2,
A.Erdemir 2,
J.A.Carlisle 2,
O.Auciello 2,
J.A.Libera 2,
J.N.Hryn 2

1 I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Krzhizhanovsky str., 3, Kyiv, 03142, Ukraine
2 Argonne National Laboratory, Energy Techology Division, Argonne, IL 60439, United States

Wear: Elsevier, 2011, Т.270, #3-4


The reliability and performance of silicon carbide (SiC) shaft seals on multipurpose mechanical pumps are improved by applying a protective coating of ultrananocrystalline diamond (UNCD). UNCD exhibits extreme hardness (97 GPa), low friction (0.1 in air) and outstanding chemical resistance. Consequently, the application of UNCD coatings to multipurpose mechanical pump seals can reduce frictional energy losses and eliminate the downtime and hazardous emissions from seal failure and leakage. In this study, UNCD films were prepared by microwave plasma chemical vapor deposition utilizing an argon/methane gas mixture. Prior to coating, the SiC seals were subjected to mechanical polishing using different grades of micron-sized diamond powder to produce different starting surfaces with well-controlled surface roughnesses. Following this roughening process, the seals were seeded by mechanical abrasion with diamond nanopowder, and subsequently coated with UNCD. The coated seals were subjected to dynamic wear testing performed at 3600 RPM and 100 psi for up to 10 days during which the seals were periodically removed and inspected. The UNCD-coated seals were examined using Raman microanalysis, scanning electron microscopy, optical profilometry, and adhesion testing before and after the wear testing. These analyses revealed that delamination of the UNCD films was prevented when the initial SiC seal surface had an initial roughness >0.1 m. In addition, the UNCD surfaces showed no measurable wear as compared to approximately 0.2 m of wear for the untreated SiC surfaces.



1. A.R. Krauss, O. Auciello, D.M. Gruen, et al., Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices, Diamond Relat. Mater. 10 (2001) 1952–1961.

2. A.V. Sumant, D.S. Grierson, J.E. Gerbi, et al., Surface chemistry and bonding configuration of ultrananocrystalline diamond surfaces and their effects on nanotribological properties, Phys. Rev. B: Condens. Matter Mater. Phys. 76 (2007) 235429.

3. P. Bajaj, D. Akin, A. Gupta, et al., Ultrananocrystalline diamond film as an optimal cell interface for biomedical applications, Biomed. Microdevices 9 (2007) 787–794.

4. D.S. Grierson, A.V. Sumant, A.R. Konicek, et al., Tribochemistry and material transfer for the ultrananocrystalline diamond-silicon nitride interface revealed by X-ray photoelectron emission spectromicroscopy, J. Vac. Sci. Technol. B 25 (2007) 1700–1705. 

5. V. Sumant, D.S. Grierson, J.E. Gerbi, et al., Toward the ultimate tribological interface: surface chemistry and nanotribology of ultrananocrystalline diamond, Adv. Mater. 17 (2005) 1039–1045.

6. A. Erdemir, M. Halter, G.R. Fenske, et al., Durability and tribological performance of smooth diamond films produced by Ar-C-60 microwave plasmas and by laser polishing, Surf. Coat. Technol. 94–5 (1997) 537–542.

7. A. Erdemir, G.R. Fenske, A.R. Krauss, et al., Tribological properties of nanocrystalline diamond films, Surf. Coat. Technol. 120 (1999) 565–572.

8. A.V. Sumant, A.R. Krauss, D.M. Gruen, et al., Ultrananocrystalline diamond film as a wear-resistant and protective coating for mechanical seal applications, Tribol. Trans. 48 (2005) 24–31.