Hypersonic plasma particle deposition of Si-Ti-N nanostructured coatings

J. Hafiz, X. Wang, R. Mukherjee, W. Mook, C. R. Perrey, J. Deneen, J. V.R. Heberlein, P. H. McMurry, W. W. Gerberich, C. B. Carter, S. L. Girshick

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20 Scopus citations


Si-Ti-N coatings with various compositions were deposited on molybdenum substrates using hypersonic plasma particle deposition (HPPD). In this method, vapor phase precursors (TiCl4, SiCl4 and NH3) are dissociated in a DC plasma arc and the hot gas is quenched in a rapid nozzle expansion to nucleate nanoparticles. These nanoparticles are then accelerated in hypersonic flow, causing them to deposit by ballistic impaction on a substrate placed downstream of the nozzle. Films of 10-25 μm thickness were deposited at rates of 2-10 μm/min, depending on reactant flow rates, at substrate temperatures ranging from 200 to 850 °C. When the reactant gases were premixed the coatings consisted of nc-TiN, nc-TiSi2, nc-Ti5 Si3 and amorphous Si3N4. For the unpremixed reactants case, the coatings consisted of free Si, nc-TiN and amorphous Si3N4. Hardness of as-deposited films was evaluated by nanoindentation of polished film cross-sections. Measured hardness values, averaged over 10-15 locations for each film, ranged from 16-24 GPa. In separate experiments with the same conditions, particle size distributions were measured by placing a sampling probe at the same location as the film substrate. The sampled aerosol was rapidly diluted and delivered to a scanning mobility particle sizer (SMPS). In-situ particle size distribution measurements confirmed that the coatings were formed by impaction of nanoparticles in the 5-15 nm range, with higher reactant flow rates producing larger particles. Focused ion beam (FIB) milling was used to observe film cross-section and porosity. For as-deposited films containing pores, in-situ plasma sintering was used to densify the film without grain growth.

Original languageEnglish (US)
Pages (from-to)364-370
Number of pages7
JournalSurface and Coatings Technology
Issue number1-3 SPEC.ISS.
StatePublished - Nov 2004

Bibliographical note

Funding Information:
This work was supported by NSF Grant # DMI-0103169 and NSF IGERT Grant # DGE-0114372.


  • Hardness
  • Nanostructured
  • Plasma synthesis
  • Si-Ti-N
  • Size distribution


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