1997 TMS Annual Meeting: Monday Session

ADVANCES IN COATINGS TECHNOLOGIES II: Session II

Session Chairperson: TBA

1:30 pm

OXIDE AND NITRIDE SUPERLATTICE COATINGS: William D. Sproul, BIRL, Northwestern University, 1801 Maple Avenue, Evanston, IL 60201

Over the past 10 years, three major advances in reactive sputtering technology have made it possible to deposit both conductive and non-conductive fully-dense films at high rates. These three advances are unbalanced magnetron (UBM) sputtering, partial pressure control of the reactive gas, and pulsed DC power. Multicathode UBM sputtering systems provide a dense secondary plasma that produces well-adhered, fully dense films. With both pulsed-dc power and partial pressure control, films such as aluminum oxide can now be deposited reactively at rates up to 78% of the pure metal rate. The reactive UBM sputtering process is used to deposit polycrystalline nitride superlattice films such as TiN/NbN or TiN/VN with hardnesses exceeding 50 GPa, more than double the hardness of either component in the film. The nitride superlattice work is being extended to oxide films. Clear, amorphous, nano-layered Al2O3/ZrO2 films have been deposited at high rates with a hardness of 10 GPa. Work is underway to deposit these films in a crystalline form, which should enhance their hardness.

2:05 pm

CONTROL OF INTERFACE STRENGTH IN NIOBIUM-ALUMINUM OXIDE MULTILAYERS BY ION BEAM ASSISTED DEPOSITION: G.S. Was, H. Ji, J.W. Jones, Cooley Bldg., University of Michigan, Ann Arbor, MI 48109; N. Moody, Sandia National Laboratory, Div. 8712, MS 9403, Livermore, CA 94551

The toughness of a niobium-aluminum oxide multilayer depends on the interface strength, which can be controlled by both the orientation relationship of the constituents and the composition at the interface. As a first approximation to multilayers, niobium films were deposited onto {0001} sapphire substrates by ion beam assisted deposition (IBAD) under various conditions. In addition to the {110} fiber texture, strong in-plane texture was introduced by simultaneous ion bombardment. Stronger in-plane texture was developed with higher ion energy and ion to atom arrival rate ratio (R ratio). Different orientation relationships at the niobium-sapphire interface were achieved by varying the orientation of the sapphire substrates with respect to the ion beam incident direction. The hardness and modulus of the niobium layer were also modified by the ion bombardment. A dopant (Ag) was introduced at the interface at levels from a fraction of a monolayer to one monolayer during niobium layer deposition.

2:40 pm

CONTROLLING THE EVOLUTION OF TEXTURE IN SPUTTER DEPOSITED Mo FILMS: S.M. Yalisov, J.C. Bilello, University of Michigan, Department of Materials Science and Engineering, Ann Arbor MI 48119

Evolution of crystallographic ordering in sputter deposited polycrystalline refractory metal films has been observed in several laboratories. While the ordering in the growth direction, out-of-plane texture, is well known, the ordering in the plain of growth, in-plane texture, has only been reported by the ion enhanced growth community. The work presented here, will describe the conditions required for this behavior in the presence of energetic ions. Mo films were sputter deposited on amorphous substrates and grown to a large variety of thickness. The homologous temperature does not exceed 0.2 in any of the experiments performed. These films were characterized by a large battery of synchrotron x-ray, electron microscopy, and surface analysis. The data have led to an atomistic model to explain and predict the in-plane texturing based on shadowing and anisotropic growth rates which force a competitive grain growth mechanism during the growth. Detailed comparison to experiment will demonstrate the role that limited diffusion and mass transport play in the final microstructure of the film. Examples of how this model can be exploited to design a particular microstructure will be presented.

3:15 pm

CERAMIC-METALLIC COATINGS BY ELECTRON BEAM PHYSICAL VAPOR DEPOSITION PROCESS: Douglas Wolfe, M. Movchan, Jogender Singh, Applied Research Laboratory, Pennsylvania State University, University Park, PA 16804

Electron beam physical-vapor deposition (EB-PVD) process is considered to be a cost-effective and robust coating technology that has overcome some of the difficulties or problems associated with the metals spray, CVD and PVD processes. The EB-PVD process offers many desirable characteristics such as relatively high deposition rates (up to 100-500 mm/minute with an evaporation rate ~10-15 Kg/hour), dense coatings, precise composition control, columnar and poly-crystalline microstructure, low contamination, and high thermal efficiency. Various metallic and ceramic coatings (oxides, carbides, nitrides) have been deposited at relatively low temperatures. EB-PVD has the capability of producing multilayered nanolaminated metallic/ceramic coatings on large components by changing the processing conditions such as ingot composition, part manipulation, and electron beam energy. Attachment of an ion beam source to the EB-PVD process offers additional benefits such as dense coatings with improved adhesion.

3:50 pm BREAK

4:05 pm

COMMERCIAL APPLICATIONS OF PLASMA SOURCE ION IMPLANTATION: J.T. Scheuer, K.C. Walter, Los Alamos National Laboratory, Los Alamos, NM; W.G. Horne, Empire Hard Chrome, Chicago, IL; R.A. Adler, North Star Research Corporation, Albuquerque, NM 87109

Commercial plasma source ion implantation (PSII) equipment built by North Star Research Corporation has recently been installed at Empire Hard Chrome, Chicago, IL. Los Alamos National Laboratory has assisted in this commercialization effort via two Cooperative Research and Development Agreements to develop the plasma source for the equipment and to identify low-risk commercial PSII applications. The PSII system consists of a 1m x 1m cylindrical vacuum chamber with a pulsed, inductively coupled rf plasma source. The pulse modulator is capable of delivering pulses with peak currents of 100 kV and peak currents of 300 A at maximum repetition rate of 400Hz. The pulse modulator uses a thyratron to switch a pulse forming network which is tailored to match the dynamic PSII load. This presentation will focus on early commercial applications to production tooling and manufactured components and characterization of implanted coupons.

4:40 pm

SPUTTERED CHROME NITRIDE AS AN ALTERNATIVE TO ELECTROPLATED CHROME: Michael Graham, Keith Legg, Paul Rudnik, Peter Chang, BIRL, Northwestern University, Evanston IL 60201

BIRL has been involved in hardcoating development for engineering applications for several years. A major effort over the past four years has focused on the replacement of electroplated chrome in applications where the steel substrates have moderate hardnesses (Rc38-42) and therefore only modest support for hard PVD coatings. Much of the development work has been supported by the government through DARPA as part of an environmental thrust to eliminate pollution sources and health hazards from their OEM's as well as their repair facilities. BIRL has developed the use of duplex processing (plasma nitriding + sputter-coating) and thick PVD coating (15-20um) with CrN and demonstrated wear performance characteristics superior to commercial chrome plating. This paper reviews some of the process developments involved in these programs and the wear test results. Production cost estimates have also been conducted for certain components, and it has been demonstrated that PVD coating is competitive with electroplating when the total manufacturing process is taken into account.

5:00 pm

CHARACTERISTIC OF TiN FILM DEPOSITED ON STELLITE USING REACTIVE MAGNETRON SPUTTER ION PLATING: Whungwhoe Kim, Joungsoo Kim, Surface Treatment Group, KAERI, Taejon, Korea, Mingu Lee, Heesoo Kang, Wonjong Lee, Dept. of Materials Science, KAIST Taejon, Korea

TiN films were deposited onto stellite 6B alloy (Co base) by the reactive magnetron sputter ion plating. As the substrate bias increases, TiN film changes from columnar structure to dense structure due to densification and resputtering by ion bombardment. Oxygen, the major impurity, is decreased greatly when the substrate bias is applied. The preferred orientation of the TiN films changes from (200) to (111) with decreasing N2/Ar ratio. The change of the preferred orientation is discussed in terms of surface energy and strain energy which are related with the impurity contents and the ion bombardment damage. The hardness of the TiN film increases with increasing compressive stress generated in the film by virtue of ion bombardment.