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Proceedings Paper

Nanophase diamond films produced by laser deposition
Author(s): Carl B. Collins; Farzin Davanloo; J. H. You; H. Park
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Paper Abstract

Films of nanophase diamond can be prepared in vacuum by the laser ablation of graphite at intensities in excess of 1011 W cm-2. A variety of structural morphologies can result that depend upon the kinetic energies and charge states employed. The most promising is a nanophase diamond that we originally termed `amorphic diamond.' It is composed of nanometer scale nodules of sp3 bonded carbon. The high energy of condensation from the laser plasma source provides both for the chemical bonding of such films to a wide variety of substrates and for low values of residual compressive stress, 0.6 - 0.8 GPa. This paper reports the solution of a lingering problem with the hardness of nanophase diamond. The packing density of nodules in the finished ceramic depends upon process variables and so hardness can fluctuate. With critical control at the point of ablation, films are produced that are too hard to measure. In this work, raw data produced with an advanced nanoindentation technique was analyzed with the conventional procedure and a hardness value of 125 GPa was obtained. Exceeding the hardness of natural diamond this value was so large as to raise concern for the validity of the conventional model used to interpret data. To avoid model dependent interpretation, a differential loading pressure, independent of depth, was used to give a lower limit on the hardness directly from the raw data. Comparable values of this lower limit, near 75 GPa have been measured on crystalline diamond prepared by CVD and on nanophase diamond deposited by our laser plasma method. The combination of hardness and resiliency together with a coefficient of friction near 0.1, seems to make nanophase diamond an attractive coating for use in current industrial applications.

Paper Details

Date Published: 10 August 1994
PDF: 10 pages
Proc. SPIE 2097, Laser Applications, (10 August 1994); doi: 10.1117/12.183136
Show Author Affiliations
Carl B. Collins, Univ. of Texas/Dallas (United States)
Farzin Davanloo, Univ. of Texas/Dallas (United States)
J. H. You, Univ. of Texas/Dallas (United States)
H. Park, Univ. of Texas/Dallas (United States)


Published in SPIE Proceedings Vol. 2097:
Laser Applications
Artur A. Mak, Editor(s)

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