ICMCTF2006 Session B2-1: Arc and E-Beam Coatings and Technologies

The Filtered Cathodic Vacuum Arc (FCVA) technology has been widely known to produce high quality Diamond-like amorphous carbon films (or sometimes known as amorphous-Diamond films due to its high sp³ content in excess of 80%) and is currently used by the Media industry for harddisk coatings. In this seminar, I will like to present an updated development on all aspects of the FCVA technology.

On the FCVA system, I will give a brief update on the different version, from custom-designed small deposition system to industrial high-throughput systems will be shown. On the films produced by the FCVA system, I will show different types of materials that the FCVA technique can produce beyond the deposition of Diamond-like Carbon (DLC) films. Furthermore, I will also present some applications of these materials. This includes embedded nanocomposite materials as catalyst for the growth of multi-wall carbon nanotubes for applications as electron source in vacuum microelectronics. Deposition of high quality metal oxide films for applications in photonics as optical coatings. Growth of thick, low stressed and high sp³ content Diamond-like carbon films for Microelectromechanical Systems (MEMS) applications.

Finally, I will also like to give a brief introduction to the Diamond/Diamond-like carbon group in School of Electrical & Electronics Engineering as well as a brief overview of the Nanoscience & Nanotechnology Research Cluster in Nanyang Technological University.

TiAlN coatings have been commercially very successful particularly for high speed machining applications due to their significantly improved oxidation resistance and hardness over TiN. Recently, CrAlN coatings were reported exhibiting even higher oxidation resistance than TiAlN. Moreover, CrN coatings are well known to be superior to TiN in corrosion and wear resistances, friction behavior, and toughness. Therefore, in comparison with TiAlN, better tribological properties of CrAlN coatings and their promising applicability in high speed machining could be expected.

In this work, a series of Cr_1-XAl_XN (0≤X≤0.7) coatings were deposited on high speed steel substrates by a vacuum arc reactive evaporation process from two lateral rotating elemental chromium and aluminum cathodes in a pure nitrogen atmosphere. All the as-deposited CrAlN coatings exhibited a high hardness than pure CrN, showing a maximum hardness of about 40 GPa (at around X=0.6) which is twice higher than that of the pure CrN. The wear performance under ambient conditions of the CrAlN coatings was found much better, with both lower friction coefficient and wear rate, than TiAlN coatings deposited by the same technique. The wear rate of the CrAlN coatings against alumina counterpart was about 2-3 orders in magnitude lower than that of the TiAlN coatings. The CrAlN coatings were also deposited on some WC-based end-mills. A better performance of the CrAlN-coated end-mills was observed than the TiAlN-coated ones in cutting a hardened steel material under high speed machining conditions.

Improvements have been made to the magnetic field design of a 2-sided linear filtered arc source which has been described previously,@footnote 1@ resulting in substantial improvement in plasma transmission efficiency. Magnetic flux modeling and ion output characteristics are presented. Average carbon ion currents of more than 14 amps have been obtained at a dc arc current of 200 amps. A graphite cathode having the shape of a rectangular bar was used, with dimensions of about 50cm x 3.8cm x 3.2cm. High-hardness ta-C (amorphous diamond) coatings have been deposited on the inner surface of a cylindrical carousel rotating around a central filtered arc source. Deposition rates above 1.5 microns/hour average covering more than 1 meter 2 area have been achieved with good thickness uniformity.

¹@ U.S. Patent 5,997,705, Welty, 1999.