Sample Proposal

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  • Topic: Chemical vapor deposition, Thin film deposition, Physical vapor deposition
  • Pages : 21 (7273 words )
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  • Published : March 7, 2013
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SUPERADHERENT
HARD COATINGS
BY ION BEAM ENHANCED DEPOSITION

1. COVER SHEET (see attached)
2. IDENTIFICATION & SIGNIFICANCE OF THE OPPORTUNITY
The objective of this proposal is to demonstrate the feasibility of producing super adherent protective coatings at low processing temperatures using energetic ion beams in conjunction with conventional deposition techniques. This process, coined Ion Beam Enhanced Deposition (IBED), is depicted in Figure 1 and promises a new generation of exotic coatings with superior adhesion, near theoretical densities, very high hardness, and, at the same time, capable of being deposited at low temperature. T he effect of the ion beam (e.g., N) is to initially “intermix” the deposited atoms (e.g., Ti) with the substrate for superior adhesion as well as to provide energy to the grown layer for effectively “high temperature” processing at low substrate temperature res. Highly adherent coatings of “TiN” with low friction (Figure 2) have already been demonstrated by Kant et al (l) at Naval Research Laboratory by N-bombardment of deposited Ti. This proposal is to extend the range of protective coatings produced by IBED to include HfN, AI203 and to characterize such films for mechanical and chemical properties as well as micro structural analyses. Evaluation of mechanical properties will include adhesion tests and wear tests. Initially laboratory pin-on-disc tests will be used for screening purposes with in-situ component tests planned for later. Micro structural analyses deemed necessary include 1) sputter Auger electron spectroscopy for compositional analysis, 2) sputter ESCA for composition and chemical bonding information, 3) Glancing x-ray analysis for lattice structure, 4) ion backscattering for nondestructive composition vs. depth information, and 5) SEM and TEM for grain structure and lattice microstructure information. Hard, extremely adherent hard coatings synthesized by the ion beam enhanced deposition technique will be of immediate use to SDI. Primary candidates for these (ultra) thin coatings would be for i) precision aerospace bearings and ii) precision micro positioning platforms where a very thin (i.e., 0.1-0.5 micrometer) antifriction antiwar coating could be used without remachining or respecifying dimensions of critical components. Besides being an end-of-line process not requiring production changes, IBED coatings promise a convenient retrofit to existing tribological problems involving precision mechanisms.

2.1 BACKGROUND
There is an acute need for development of high quality, low temperature thin film deposition techniques that can achieve thin film qualities found in high temperature processes. Present low temperature thin film deposition techniques sometimes result in inferior micro structural features within the film such as columnar growth and not the preferred equaled grain structure ordinarily found in high temperature processes. Conventional methods of laying down films result in a greater or lesser degree of departure from bulk material properties (density, grain structure, etc.) depending, among other things, on the energy of the atoms as they arrive at and arrange themselves on the substrate surface. Table I shows the typical energy ranges associated with various physical vapor deposition and ion beam based techniques. The three PVD processes in the table above, namely evaporation, sputtering, and ion plating are discussed here briefly since eventually any coating produced by a new method, such as IBED, will have to be compared with those in common usage. (2)Evaporation can be done directly in a high vacuum to provide an extreme range of deposition rates with extreme versatility in the coating composition obtainable. Putter deposition, in general, has lower deposition rates than either evaporation or ion plating; however, high throughput production units utilizing magnetron type sputtering are being used industrially. In general, the adherence of films...
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