Sputtering Technique and Methodology
Monday, April 30, 2001 10:30 AM in Room Golden West
B1-1-1 Critical Requirements for the Successful Industrial Deposition of Nanolayered Hard Coatings
W.-D. Münz (Sheffield Hallam University, United Kingdom)
B1-1-3 Mechanical Properties of Superhard Nanocomposites
S Veprek (Technical University Munich, Germany); AS Argon (Messachusetts Institute of Technology)
Novel superhard nanocomposites prepared on the basis of the generic design concept @footnote 1,2@ which is based on the formation of the appropriate nanostructure due to strong segregation and spinodal decomposition, show an unusual combination of mechanical properties, such as high intrinsic (i.e. not falsified by a large compressive stress) hardness of 40 to @>=@ 100 GPa, high elastic recovery (up to @>=@ 90 %), high resistance against crack formation ("apparent fracture toughness") even at a high strain of @>=@ 10 % and high thermal stability @footnote 2-5@. We shall review the available experimental data and discuss the probable origin of these mechanical properties. It will be shown that they can be relatively easily understood on the basis of conventional fracture mechanics scaled down to small dimensions of the nanocrystals, nanocracks and possible flaws introduced into the material during its preparation. The small dimensions and low concentration of the flaws is probably a consequence of the 'selforganization' of the system due to the thermodynamically driven formation of the stable nanostructure. @FootnoteText@ @Footnote 1@ S. Veprek, S. Reiprich and Li Shizhi, Appl. Phys. Lett. 66(1995)2640; S. Veprek, S. Reiprich, Thin Solid Films 268(1995)64; S. Veprek, M. Haussmann and S. Reiprich, J. Vac. Sci. Technol. A 14(1996)46. @Footnote 2@ S. Veprek, J. Vac. Sci. Technol. A 17(1999)2401. @Footnote 3@ S. Veprek, P. Nesladek, A. Niederhofer, F. Glatz, M. Jilek and M. Sima, Surf. Coatings Technol. 108/109, 138-147 (1998) 138. @Footnote 4@A. Niederhofer, P. Nesladek, H.-D. Maennling, K. Moto, S. Veprek and M. Jilek, Surf. Coatings Technol. 120-121(1999)173. @Footnote 5@ S. Veprek, A. Niederhofer, K. Moto, T. Bolom, H.-D. Männling, P. Nesladek, G. Dollinger and A. Bergmaier, Int. Conf. on Metallurgical Coatings and Thin Films, San Diego April 2000, Surf. Coating Technol. 2000, in press.
B1-1-4 C-N/MeNx Nanocomposite Coatings Used as Hard Solid Lubricants
J. Sobota (Institute of Scientific Instruments ASCR, Czech Republic); G. Sorensen, H. Jensen (Aarhus University, Denmark); V. Holy, Z. Bochnicek (Masaryk University, Czech Republic)
Nanocomposite coatings enable by using an optimal ratio of individual components creation of stable structure with unique properties, and in particular , combination of properties conventionally considered as excluding one another, such as high hardness and high toughness. Alcatel 650 and Leybold Z550 sputtering systems with metal and carbon targets operating in side-by side configuration, where substrate holder is passing continuously through two sputtering zones, were used for the deposition of nanocomposite coatings by r.f. magnetron sputtering. Argon and nitrogen gas flows were controlled using mass flow controllers enabling precise control of the deposition parameters. The coatings, typically 1-3 micrometer thick, were deposited at total pressure ranging from 0.2 to 1 Pa at relatively low substrate temperature not exceeding 250 deg.C. We deposited nanostructured multilayer coatings of the type C-N/MeNx, where Me could be Ti, Nb or Zr. Various substrates such as highly polished tungsten carbide, steel and silicon were used. This study will concentrated on tribological properties of C-N/MeNx nanostructured multilayers. The friction coefficient, wear and the film transfer in a ball -on disk tribometer is presented. The samples were measured after the deposition and then thermally treated at a constant temperature for 30 minutes in the air. Afterwards the samples were again measured and the temperature treatment at higher temperature was performed until the layer broke down. We investigate also the structure of the coating by means of low-angle x-ray reflection and high angle x-ray diffraction. The potential application of C-N/MeNx nanostructured multilayers as hard solid lubricant is discussed. Acknowledgements: this work has been supported by GACR (grant No.101/98/0553) and COST 523 (OC523.30) .
B1-1-5 Synthesis and Characterization of Multilayered TiC / TiB@sub 2@ Coatings Deposited by Ion Beam Assisted, Electron Beam-Physical Vapor Deposition (EB-PVD)
D.E. Wolfe (The Pennsylvania State Univeristy); J. Singh (The Pennsylvania State University); K. Narasimhan (Valenite Inc.)
TiB@sub 2@ / TiC multilayer coatings were deposited on WC-Co cutting inserts by ion beam assisted, electron beam physical vapor deposition. Adhesion to WC-Co substrates was found to be 52-56N for the multilayer coatings with a thickness of 5 microns. The hardness values ranged from 3294 VHN0.050 to 3991 VHN0.050. SEM analysis showed a reduction in grain size with increasing number of layers. EDS showed increasing amounts of argon incorporation as a function of total number of coating layers. The grain size decreased while the amount of argon incorporation increased with increasing number of coating layers. X-ray diffraction showed the degree of texture could be changed from a strong (200) orientation to a nearly random oriented coating.