Mg2SiO4 as a novel thermal barrier coating material for gas turbine applications

Forsterite-type Mg2SiO4 was investigated systematically for thermal barrier coating (TBC) applications. Results showed that Mg2SiO4 synthesized by solid-state reaction possessed the good phase stability up to 1573 K. The thermal conductivity of Mg2SiO4 at 1273 K was lower (similar to)20% than that of yttria stabilized zirconia (8YSZ). Mg2SiO4 also presented moderate thermal expansion coefficients, which increased from 8.6 x 10(-6) K-1 to 11.3 x 10(-6) K-1 (473(similar to)623 K). Mechanical properties including hardness, fracture toughness, and Young's modulus of Mg2SiO4 were comparable to those of BYSZ. The sintering results indicated a promising low-sintering activity of Mg2SiO4. Mg2SiO4 samples were subjected to water quenching test at 1573 K and showed a superior thermal shock resistance compared to 8YSZ. Mg2SiO4 coating with stoichiometric composition was produced by atmospheric plasma spraying. The thermal cycling test result showed that Mg2SiO4 coating had a lifetime more than 830 cycles at 1273 K, which is desirable for TBC applications.