| The purpose of this study is to prepare LaMgAl11O19 and rare-earth doped La0.8Ln0.2MgAl11O19 ( Ln=Pr , Nd , Sm , Gd , Tb ) composite materials and to investigate the thermal physical properties and the possibility of La1-x LnxMgAl11O19 as a new type of thermal barrier coatings in high-temperature environment .Thermal barrier coating materials of LaMgAl11O19 and La0.8Ln0.2MgAl11O19 were synthesized by solid-state reaction method and sintered in high temperature. The solid phase reaction processing was studied by using thermal analysis instrument. DSC results show that the formation temperature of LaMgAl11O19 and La0.8Ln0.2MgAl11O19 phases was between 1433℃~ 1483℃. The phase composition and microstructure of the specimens where characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. Add 1% MgO into precalcined powers and sintering then obtained pure LaMgAl11O19 which hexagonal structure as main phase. After rare earth elements Ln dissolved in LaMgAl11O19, the solid solution was formed. The plate grains piled up in the section of the sintered bodies.Heat capacity, thermal expansion coefficient, thermal diffusivity coefficient were investigated by DSC, thermal dilatometer and laser pulse method respectively. The thermal conductivity of the materials was calculated. With temperature increasing, heat capacity and thermal conductivity of the ceramic is increase gradually. The thermal diffusivity coefficient is decrease with temperature increasing. The thermal conductivity significantly is lower than that of 6 ~ 8%molYSZ. The thermal conductivity of Gd doped material is lower than that of Pr, Nd, Sm, Tb doped coating materials.
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