Mechanical Properties of LaTi2Al9O19 and Thermal Cycling Behaviors of Plasma-Sprayed LaTi2Al9O19/YSZ Thermal Barrier Coatings

Abstract

Recently, extensive efforts have been made to develop new thermal barrier coating (TBC) materials which can operate at temperatures above 1523 K over a long term. In this article, LaTi 2 Al 9 O 19 (LTA) was synthesized by solid-state reaction at 1773 K, and the mechanical properties of the LTA bulk were evaluated. The microhardness is about 14 GPa, comparable to that of YSZ bulk, whereas the YoungÕs modulus is about 44 GPa, lower than the value of YSZ. However, the fracture toughness of 0.8-1 MPa m 1/2 is much lower than that of bulk YSZ. A double-ceramic-layer LTA/YSZ TBC structure was proposed and the TBC sprayed by plasma spraying. Thermal cycling tests of the TBC specimens were performed at 1373 K with a dwell time of 10 min. The LTA remained good stability with ZrO 2 and Al 2 O 3 . However, the single layer LTA TBC was cracked at the LTA/bond coat interface after about 300 cycles, due to its poor thermal shock resistance, while the YSZ TBC yielded a lifetime of about 1000 cycles. The LTA/YSZ TBC remained intact even after 3000 cycles, exhibiting a promising potential as new TBC materials.

Thermal cycling behavior and failure mechanism of LaTi2Al9O19/YSZ thermal barrier coatings exposed to gas flame

“…Recently, attention has been paid on LaTi 2 Al 9 O 19 (LTA) [25][26][27], which is featured with a huge unit cell, complex atoms arrangement and lower symmetry. LTA reveals excellent phase stability between room temperature and 1600°C and desirable thermophysical properties, which can be attributed to its crystallographic feature [27].…”

“…However, LTA TBC has a very short life due to its relative low fracture toughness. The lower fracture toughness could be compensated by a doubleceramic layered design, and the LTA/YSZ TBC exhibited improved thermal cycling performance at 1100°C as compared to the single LTA layer TBC [25]. As a new TBC material candidate, further experiments have to demonstrate whether this material is suitable for higher temperature applications.…”

Comparison of Thermal Shock Behavior of 7ysz, 15ysz and Sysz Thermal Barrier Coatings Produced by Aps Method

“…The nanozones contained a large volume fraction of pores with sizes ranging from several tens to several hundreds of nanometers. This porous structure enhances the thermal insulation effect of TBCs [16][17][18][19][20].…”

“…Therefore, investigation of novel TBC materials with ultra-high temperature capability, low thermal conductivity and long-term life time is a key problem for the next generation of turbine engines. Some ceramic materials such as La 2 O 19 and other kinds of rare earth doped zirconia [9][10][11][12][13][14][15][16][17][18][19] have been investigated as potential TBC materials. In recent years, nanostructured zirconia based TBCs deposited by atmospheric plasma spraying have been the focus of attention.…”

Thermal stability and sintering behavior of plasma sprayed nanostructured 7YSZ, 15YSZ and 5.5SYSZ coatings at elevated temperatures

“…Therefore, investigation of novel TBC materials with ultra-high temperature capability, low thermal conductivity and long-term life time is a key problem for the next generation of turbine engines. Literature review show that some ceramic materials such as La 2 O 3 -Y 2 O 3 -ZrO 2 , Gd 2 O 3 -Y 2 O 3 -ZrO 2 , La 2 Zr 2 O 7, La 2 Ce 2 O 7 , LaMgAl 11 O 19 and other kinds of rare earth doped zirconia [9][10][11][12][13][14][15][16][17][18][19] have been investigated as potential TBC materials. In recent years, nanostructured zirconia based TBCs have been the focus of devotion.…”