The Effect Of Y₂O₃and Er₂O₃Codoping On The Structure And Propeties Of La₂Zr₂O₇Ceramic

There have been decades of history, thermal barrier coatings (TBCs) is used to protect high temperature end parts of the turbine engine. On the current, the widespread use of thermal barrier coatings is the structure of double layers, which are the bonding layer of McrAlY(M=Ni and Co) on the high temperature alloy substrate and the ceramic layer of8YSZ (8%mass fraction of yttria partialy stablilized zirconia) outside the bonding layer. With the continuous development of the aerospace business, a new generation of turbine engine is requested to be able to withstand higher flame temperature. However, the limit of traditional thermal barrier coatings material of8YSZ is a long-term use does not exceed the temperature of1200℃. The material, obviously, is no longer suitable for the protection of high temperature components of turbine engine. As a new generation of thermal barrier coatings, the materials of rare earth zirconate has attracted a lot of attention because of its superior performance. Compared with the ceramic coating material of8YSZ, the better performance of zirconate material reflects on,(1) the better phase stability in the high temperature,(2) the lower thermal conductivity,(3) the higher resistance rate of sintering,(4) the lower oxygen ion transmittance. Nevertheless, the deficiency of zirconate ceramic material is lower thermal expansion coefficient than ceramic coatings material of8YSZ.Research shows that rare earth oxides doped on the system of zirconate ceramic had significantly effected the material properties. In this paper, we hope getting a new ceramic material with low thermal conductivity and high thermal expansion coefficient by yttrium oxide and trbium oxide codoping the ceramic material system.This experiment is conducted with zirconium oxide and rare earth oxides of lanthanum oxide, yttrium oxide and erbium oxide as raw materials.(La12xYxErx)2Zr2O7system ceramic materials were synthesized through the5hours solid phase reaction at the temperature of1500℃. The applications of X-ray diffractometer and Raman spectrometer were used to analyse phase structure of the ceramic materials. Using scanning electron microscope to analyse cross section of the samples. The thermal expansion analyzer is used to test the thermal expansion cofficient of the ceramic materials. The thermal diffusion coefficient of the samples is tested by the laser thermal conductivity meter. Combined with the density and the heat capacity values of materials calculated the thermal conductivity. Test results shows that the experimental design of9groups ceramic samples all synthetic single cubic prochlore structure. Cross-section microstruture shows that with the increase of doping content, ceramic samples were oversintering. The largest thermal expansion cofficient is the material of x0.02mol. The thermal diffusion coefficient and the thermal conductivity of samples, with the increase of doping content, shows the tendency of decrease. The thermal diffusion coefficient and the thermal conductivity of materials (x0.07mol) were0.573～0.583mm2/s and1.62～1.89Wm-1K-1from room temperature to1000℃.