The study on porosity and thermophysical properties of nanostructured La_2Zr_2O_7 coatings

摘要

Lanthanum-zirconium nano-powders were synthesized by molten salts method Nanostructured lanthanum-zirconium coatings were deposited by air plasma spraying. Scanning electron microscopy and X-ray diffraction were carried out to analyze the as-sprayed coatings and powders. The pore size distribution and buck density of coatings were identified by mercury intrusion porosimetry. The thermophysical properties of the nanostructured coatings were also examined through laser flash technique and differential scanning calorimetry. The results demonstrate that the as-sprayed nanostructured coatings consist of the pyrochlore-type phase. The as-sprayed nanostructured lanthanum-zirconium coatings have a very low porosity. The thermal conductivity of the as-sprayed nanostructured lanthanum-zirconium coating is lower than that of the conventional coating between 200 ℃ and 950 ℃, but when the temperature between 950 ℃ and 1300 ℃, the result is reverse.