The effect of vermiculite on the degradation and spallation of plasma sprayed thermal barrier coatings

作者：Shinozaki M; Clyne T W^*

来源：Surface and Coatings Technology, 2013, 216: 172-177.

DOI：10.1016/j.surfroat.2012.11.054

• Thermal barrier coating (TBC)
• Yttria-stabilized zirconia (YSZ)
• Plasma spraying
• Spallation
• Vermiculite
• Calcia-magnesia-alumina-silica (CMAS)

A study has been made of the effect of vermiculite (VM) on the sintering-induced spallation of plasma sprayed zirconia thermal barrier coatings (TBCs). The glass transition (similar to 1040 degrees C) and melting (similar to 1360 degrees C) temperatures of VM are representative of a broad class of so-called CMAS (calcia-magnesia-alumina-silica) particulates likely to be ingested into gas turbines. Selected loadings of VM powder were introduced onto the surface of free-standing coatings, followed by heating (1500 degrees C) for periods of up to 80 h. The presence of VM induces various microstructural changes in the coatings and also accelerates the rise in their (in-plane) Young's modulus. Finally, results are presented concerning the effect of VM on spallation resistance, using coatings sprayed onto dense alumina substrates. Spallation lifetimes can be substantially reduced by VM, even at relatively low levels (similar to 1 wt.%). This is related to acceleration of the sintering-induced increases in coating stiffness.

• 出版日期2013-2-15