Skip to main content Accessibility help

Electrical Conduction in Thermally Sprayed Thin Metallic Coatings

  • Atin Sharma (a1), Richard J. Gambino (a2) and Sanjay Sampath (a3)


The in-plane electrical conductivity and the apparent density of air plasma sprayed (APS) molybdenum coatings having thicknesses in the range 30 um to 450 um were measured as a function of coating thickness. Both conductivity and the apparent density were found to increase with thickness until a saturation density (∼ 80% of the bulk density of molybdenum metal) was achieved. Attributing this increase in the apparent density to the increased volume fraction of the metallic component (or decreased porosity volume) in the coatings allows for the treatment of the problem in a framework of percolation theories. In order to eliminate the contribution of surface roughness the results were further analyzed using a two-layer parallel resistor model of the coating. In this model the top layer, which was composed of coating roughness, was assumed to have fixed thickness and conductivity whereas the conductivity of the bottom layer was assumed to vary with thickness (density). A fit to the data obtained from the above model showed that the conductivity of the bottom layer obeys a power law relationship of the type σ α (V –Vc)n throughout the composition range (with n=1.72 and Vc =0.09). These results show that that the coatings behave as a three-dimensional percolation system [1] and also indicate the asymmetric shape of the metallic and insulator regions in the coatings [2].



Hide All
1. Dubson, M.A. and Garland, J.C., Phys. Rev. B 32, 7621 (1985) and references therein
2. Smith, L.N. and Lobb, C.J., Phys. Rev. B 20, 3653 (1979)
3. Sampath, S., Longtin, J., Gambino, R., Herman, H., Greenlaw, R. and Tormey, E. in Direct-Write Technologies for Rapid Prototyping Applications, edited by Piqué, A. and Chrisey, D. B., (Academic Press, San Diego, CA, 2002) pp. 261302
4. Ahn, K., Wessels, B.W., Sampath, S., J. Mater. Res. 18, 1227 (2003)
5. Zallen, R., Physics of Amorphous Solids, (John Wiley & Sons, NY, 1983) pp.183191
6. Blood, P. and Orton, J.W., The electrical characterization of semiconductors: majority carriers and electron states, (Academic Press, San Diego, CA, 1992) pp.108110
7. Kirkpatrick, S., Rev. Mod. Phys. 45, 574 (1973)
8. Coutts, T.J., Thin Solid Films 38, 313 (1976)
9. McLachlan, D.S., Solid State Commun. 60, 821 (1986b)
10. Watson, B.P. and Leath, P.L., Phys. Rev. B 9, 4893 (1974)



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed