Ceramic Composites Based on Lanthanum Orthophosphate and Alumina: Preparation and Properties

• Published in: Glass physics and chemistry Vol. 48; no. 3; pp. 219 - 231
• Main Authors: Mezentseva, L. P., Osipov, A. V., Ugolkov, V. L., Kruchinina, I. Yu, Ivanova, P. I., Khamova, T. V., Lubimtsev, A. S.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.06.2022; Springer Nature B.V
• Subjects: Aluminum oxide; Ceramic powders; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composite materials; Composites; Flocculation; Fracture surfaces; Gas turbines; Glass; Heat treatment; Lanthanum; Leaching; Materials Science; Microhardness; Natural Materials; Physical Chemistry; Precursors; Radioactive wastes; Sintering (powder metallurgy); Sol-gel processes; Synthesis; Thermal conductivity; Thermodynamic properties; LaPO; 1; Vickers microhardness; sol-gel synthesis; chemical stability; –; Al; thermal conductivity; O; ceramic composites; fracture surface
• ISSN: 1087-6596; 1608-313X
• DOI: 10.1134/S1087659622030075

An original approach to synthesis of nanosized (1 – x )LaPO 4 · n H 2 O– x Al(OH) 3 precursor powders for (1 – x )LaPO 4 – x Al 2 O 3 ceramic composites preparation was considered. Sol-gel synthesis was carried out separately using reverse flocculation of components. Thermal behavior of precursor powders was studied by DSC/TG. Ceramic composites with microhardness up to 30‒40 GPa were obtained by pre-heat treatment of powders and subsequent step wise sintering in the 1000–1600°C temperature range. The fracture surface of ceramic samples at different sintering temperatures was examined using electron microscopy. Ceramic samples exhibited low thermal conductivity at various temperatures and open porosity 3‒5%. Chemical stability of 0.8LaPO 4 –0.2Al 2 O 3 sample was studied by leaching experiment in a solution of a mixture of NaCl and Na 2 SO 4 salts. The resulting set of properties of (1 – x )LaPO 4 – x Al 2 O 3 ceramic composites made it possible to offer these materials as heat barriers for rotors in high-speed micro gas turbines, and as ceramic matrices for immobilization of nuclear waste.