Nanomechanical behaviour of plasma sprayed PZT coatings

Abstract

Nanomechanical properties of the plasma sprayed lead zirconate titanate (PZT) coating have been investigated using nanoindentation technique. PZT coating processed at higher plasma power of 32 kW exhibited lower elastic modulus E of 98 GPa compared with the modulus (113 GPa) of the coating processed at plasma power of 20 kW. The variation in the elastic modulus is attributed to the fine porosity of the PZT coating, which is formed during plasma spraying. Porosity increases by evaporation of PbO phase during plasma spraying. Overall effective elastic modulus of both coatings is computed using micromechanics models and compared with the experimentally obtained values. Hashin–Shtrikman and rule of mixtures models predict values that closely match with nanoindentation values.

Microstructure and Properties of Plasma Sprayed Lead Zirconate Titanate (PZT) Ceramics

“…Polished cross section of the PZT coating; light microscopy. Microhardness of the free-standing body is 3.5 ± 0.9 GPa pointing to harder material than other reported PZT coatings [6]. Five Vicker's indents are indicated by arrows on Figure 6.…”

“…Annealing at the usual sintering temperatures, for PZT at 1280-1300 °C, was necessary in order to completely restore the original crystal structure. The elastic modulus measured by the nanoindentation technique for plasma sprayed PZT coatings sprayed at 20 and 32 kW power [6] was 113 and 98 GPa, respectively. Nanohardness, at 8 mN load, for a 20 kW coating was found to be 1.53 GPa but reduced to 1.44 GPa for a 32 kW coating.…”

Effect of cyclic indentation on epitaxial GaN films

“…The GaN films/c axis sapphire system can interact with the indenter tip to form a deformed zone; the threading dislocations then enter into the films at certain depths, thereafter causing the pop-in event. We conjecture that the mechanism of the event was caused by slip bands 28,30 and/or dislocation nucleation. 29 The section profile of the AFM image of the sample after nine loading-reloading cycles also revealed the presence of pyramidal slips and partial cracks from the residual indentation mark, even when the indentation depth was changed.…”

Fabrication and post heat treatment of 0.5Pb (Mg 1/3 Nb 2/3) O 3 -0.5Pb(Zr 0.48 Ti 0.52 )O 3 coatings by supersonic plasma spray

“…It has been known that defects such as pores and cracks have great influence on mechanical and physical properties. Besides that, porosity and microstructure caused by the volatilization of PbO during plasma spraying lead to sever behavior on elastic modulus and hardness [18].…”