Title: Comparison between plasma- and HVOF-sprayed ceramic coatings. Part I: microstructure and mechanical properties

Authors: G. Bolelli, L. Lusvarghi, T. Manfredini, F. Pighetti Mantini, R. Polini, E. Turunen, T. Varis, S-P. Hannula

Addresses: Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Universita di Modena e Reggio Emilia, Via Vignolese 905, 41100 Modena, Italy. ' Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Roma, Italy. ' VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland. ' VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland' VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland; Laboratory of Materials Science, Helsinki University of Technology (TKK), P.O. Box 6200, FIN-02015 TKK, Finland

Abstract: Few papers deal with High Velocity Oxygen-Fuel (HVOF) sprayed ceramics. This two-part study thoroughly compares HVOF sprayed Al2O3, nanostructured Al2O3, Cr2O3 to Atmospheric Plasma Sprayed (APS) ones. The first part discusses microstructure and micromechanics. HVOF-sprayed ceramics achieve superior cohesion (lower porosity and lower average pore area). Size effects in Vickers microindentation tests are different for HVOF and APS ceramics. At 1 N load, hardness is higher for HVOF coatings (no cracking). Under 5 N and 10 N loads, hardness decreases gradually for HVOF coatings; APS coatings are largely cracked at 5 N. HVOF-sprayed ceramics are tougher than APS ones and have higher elastic modulus.

Keywords: high velocity oxygen fuel; HVOF flame spraying; plasma spraying; ceramic coatings; Al2O3; Cr2O3; microstructure; properties correlation; Vickers microindentation; indentation fracture toughness; mechanical properties; nanostructures; micromechanics.

DOI: 10.1504/IJSURFSE.2007.013620

International Journal of Surface Science and Engineering, 2007 Vol.1 No.1, pp.38 - 61

Available online: 09 May 2007 *

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