PSZ/ステンレス鋼系遮熱コーティングの熱サイクル破壊挙動 [in Japanese] Fracture Behavior of PSZ/SS Thermal Barrier Coatings Studied by Cyclic Burner Heating Test [in Japanese]
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The main problem in thermal barrier coatings (TBCs) applied to gas turbine components is the spallation of ceramic coating under thermal cyclic environments. To clarify the spalling behavior of ceramic coating under cyclic thermal loading, plasma-sprayed TBCs are evaluated by the burner heating test which simulates the actual thermal environment. In the test the top surface is heated by combution flame and the bottom is cooled by water flow. The monitoring of acoustic emission (AE) allows us to in-situ detection of cracking in the ceramic over coat during testing. The TBCs consist of NiCrAlY bond coat and ZrO<SUB>2</SUB>-8wt. %Y<SUB>2</SUB>O<SUB>3</SUB> top coat, where both coating layers were deposited by air plasma spraying on stainless steel substrates.<BR>The spalling mechanism has been discussed on the basis of the crack observation, frequency of AE events and the variation of effective thermal conductivity. We have concluded the sequence of spalling behavior to be; vertical crack formation on the top surface during cooling, parallel crack formation at the top coat/bond coat interface during heating, and the growth of parallel cracks and their coalescence which leads eventually the ceramic coat to spall.
- J. Jpn. Soc. Powder Powder Metallurgy
J. Jpn. Soc. Powder Powder Metallurgy 44(8), 734-739, 1997-08-15
Japan Society of Powder and Powder Metallurgy