Papers

ICMCTF2002 Session B4-1: Emerging Technologies & Critical Issues in Vapor Deposition

Monday, April 22, 2002 10:30 AM in Room Golden West

Monday Morning

Start	Invited?	Item
10:30 AM		B4-1-1 When Emerging Coating Technologies Meet the Marketplace D. Quinto (Balzers Inc.) Some of the most interesting technical developments in coating technology applied to the tool industry are reviewed. The breakthroughs in microstructural and compositional design of coatings and associated process and equipment innovation have traditionally been presented in this conference, a few of which achieved commercial success. E.g., PVD TiAlN is an ongoing success story, diamond coating has been relegated to niche applications, while cBN seems unable to escape its emergent status. If acceptance by industry is the ultimate barometer for emerging technologies, there needs to be a better understanding of the competitive factors at play in the marketplace of high performance products. This means that the scientists have to broaden their perspective of the technical problems they seek to solve and to accept that translating research data into customer solutions is as big a challenge.
11:10 AM		B4-1-3 High Power Pulsed Magnetron Sputtered CrN_x Films A.P. Ehiasarian, W-D Münz (Sheffield Hallam University, United Kingdom); L. Hultman (Linköping University, Sweden); I. Petrov (University of Illinois at Urbana-Champaign); U. Helmersson (Linköping University, Sweden) Microstructure and macroscopic properties of droplet free CrN films deposited by the recently developed high power pulsed magnetron sputtering (HIPIMS) technique are presented. Magnetron glow discharges with peak power densities reaching 3000 Wcm^-2 were used to sputter Cr targets in both inert and reactive gas atmospheres. The flux arriving at the substrates consisted of neutrals and ions (approximately 70/30) of the sputtered metal and working gas atoms with significantly elevated degree of ionization compared to conventional magnetron sputtering. The high speed steel and stainless steel substrates were metal ion etched using a bias voltage of -1200 V prior to the deposition of CrN films. The film-to-substrate interfaces, observed by transmission electron microscope cross sections, were clean and contained no phases besides the film and substrate ones or recrystallized regions. CrN films were grown by reactive HIPIMS at floating potential reaching -160 V. Initial nucleation grains were large compared to conventional magnetron sputtered films, indicating a high adatom mobility in the present case. The films exhibited polycrystalline columnar growth morphology with evidence of renucleation. No intercolumnar voids were observed and the corrosion behavior of the film was comparable to arc deposited corrosion-resistant multilayers. High density of lattice defects was observed throughout the films due to the high floating potential. A residual compressive stress of 3 GPa and a hardness value of 25 GPa were measured. A low friction coefficient of 0.4 and low wear rates against Al₂O₃ in these single layer films are explained by the absence of droplets and voids known to contribute to extensive debris generation.
12:10 PM		B4-1-6 A New Concept for the Design of Tribological Coatings M. Morstein, T. Cselle (Platit AG, Switzerland) The control of friction and wear of engineering materials is of utmost technical importance. In metal machining, hard coatings have, for a long time, been successfully applied to engineer the tribological properties of virtually every type of tool. The most successful coatings family is formed by the transition metal nitrides, carbonitrides and carbides, which nowadays comprise a wide variety of metal and nonmetal stoichiometries. As these coatings are increasingly subjected to the even more demanding conditions of dry or minimum-lubrication metal machining processes, the design of highly optimized coatings for each specific application turns into a key question. In the present study, we show a new, systematic approach for the selection, design and deposition of transition metal carbonitride tribological films. Hardness predictions based on the theoretical valence electron concentration (VEC) model [1] are compared to nanoindentation data obtained for fcc cubic solid solutions such as the ZrC_xN_1-x system, x = 0 to 1, for various C/N ratios. We further demonstrate that such predictions may be extended to advanced hard coatings that incorporate main group metals such as aluminum, as long as the cubic structure is maintained. The interrelation between VEC and coefficient of friction is also discussed. Several examples for the application of this optimization strategy to the design of new vacuum arc PVD coatings are reported. All aspects of tool performance will be addressed, with a particular emphasis on friction, which, besides wear resistance, is the most important factor for many modern machining applications. [1] S.-H. Jhi, J. Ihm, S.G. Louie, M.L. Cohen, Nature 399, 132 (1999).