Influence of GdTaO4 doping concentration on thermophysical and mechanical properties of GdPO4/GdTaO4 composites

Tremendous efforts have been devoted to exploring alternative materials to 8 wt% yttria-stabilized zirconia used for thermal barrier coatings . In this work, novel composite ceramic GdPO 4 /GdTaO 4 was designed by introducing GdTaO 4 as second reinforcement phase into GdPO 4 matrix. Mechanical and thermophysical properties of resulting composites were studied as a function of doping concentration of GdTaO 4 . Results suggested GdPO 4 /GdTaO 4 composite ceramics consisting of GdPO 4 monazite and GdTaO 4 monoclinic phases, indicating GdPO 4 and GdTaO 4 with maintained excellent chemical compatibility at high temperatures. GdPO 4 /GdTaO 4 composite ceramics achieved superior hardness of 5.82 GPa, fracture toughness of 2.72 MPa m 1/2 , and thermal conductivity of 1.36 W•m −1 •k −1 at GT doping concentration of 50 wt% owing to grain refinement and scattering of phonons caused by the doped GdTaO 4 phase. In sum, excellent mechanical and thermophysical properties of GdPO 4 /GdTaO 4 composite ceramics look potential for thermal barrier coatings materials.