Scratch adhesion testing of nanophase diamond coatings on steel and carbide substrates
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Scratch adhesion testing of nanophase diamond coatings on steel and carbide substrates F. Davanloo and C.B. Collins Center for Quantum Electronics, University of Texas at Dallas, P. O. Box 830688, Richardson, Texas 75083-0688
K.J. Koivusaari Microelectronics and Material Physics Laboratories and Electronic Materials, Packaging and Reliability Techniques Research Group of Infotech Oulu, Department of Electrical Engineering, University of Oulu, PL 444, FIN-90571 Oulu, Finland (Received 30 November 1998; accepted 21 May 1999)
Films of nanophase diamond are deposited in vacuum onto almost any substrate by condensing multiply charged carbon ions carrying keV energies. These ions are obtained from the laser ablation of graphite at intensities in excess of 1011 W cm−2. The high energies of condensation produce interfacial layers between the film and substrate materials, resulting in levels of adhesion that can support the protection of substrates subjected to harsh environmental conditions. In this article, we give details of the scratch adhesion testing performed on steel and carbide substrates coated with nanophase diamond. A commercially available scratch tester was used and a data analysis was presented to quantitatively assess and measure the adhesion of films on these important substrates. The characterization studies in this work demonstrated nanophase diamond as a highly adherent coating suitable for industrial applications.
I. INTRODUCTION AND REVIEW
Nanophase diamond films have been produced by accelerating and quenching an intense laser plasma of C3+ and C4+ onto a cold substrate.1–8 Microstructural studies of these films have shown them to be composed of hard dense nodules with grain sizes on the order of 10–50 nm. The diamond characteristics of this material have been evaluated by several analytical methods. Measurements agree in supporting sp3 contents of higher than 75%.3–5 Deposited without catalysts and without columnar habits of growth, films display a scale of diamondlike properties that increases with the energies of condensation. Nanophase diamond seems to be a unique product of energetic condensation from C3+ and C4+ ions produced in a laser plasma. Original samples of this material were called amorphous ceramic diamond, an appellation shortened to “amorphic diamond” for convenience.1–7 However, the subsequent improvements have succeeded in bringing the hardness of such films above 78 GPa, and the term “nanophase diamond” seems more appropriate.9–10 The importance of this nanophase diamond material has been suggested by reports of its unique mechanical properties.5–6 It was shown that a combination of low internal stress and high bonding strength produced coatings with exceptional resistance to wear and erosion. These properties, together with the room 3474
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J. Mater. Res., Vol. 14, No. 8, Aug 1999 Downloaded: 27 Mar 2015
temperature growth environment, make this material suitable for use as a protective coating in curre
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