Investigation of Molding Process and Consolidation of Preforms from Mechanically Synthesized Powders of Europium and Cerium Hafnates

Abstract

Purpose of research. To study the process of molding and consolidation of preforms from mechanically synthesized powders of europium and cerium hafnates.Methods. Complex compounds of europium hafnateEu2HfO5 and cerium hafnate Ce2HfO5 have been synthesized from europium, hafnate and cerium oxides using mechanochemical synthesis in a planetary centrifugal mill. The rotational speed of the disk was 600 - 900 rpm and the rotational speed of the drums is 1000 - 1800 rpm, with the ratio of grinding bodies to the mass of the powder charge (35 - 45): 1, in an argon atmosphere. Synthesis lasts 5 - 120 minutes.Results. An X-ray phase analysis has been performed showing the formation of Eu2HfO5 and Ce2HfO5; as well as the study of the morphology of particles of the obtained powders, their technological properties, granulometric composition, formability and compaction, as well as the process of their consolidation.Conclusion. On the basis of the experimental studies aimed at studying the molding process and consolidation of preforms from mechanically synthesized powders of europium and cerium hafnates, it has been revealed the optimal mode of synthesis of cerium and europium hafnates. We have obtained a cerium hafnate powder with a particle size of 30-100 nm and a europium hafnate powder with a particle size of 40-70 nm by the method of mechanical activation. Using X-ray phase analysis, TEM and SEM methods, the mixed structure of lanthanide hafnates powders obtained by mechanosynthesis have been studied. The technological properties of mechanically synthesized powders of cerium and europium hafnate, as well as, their compaction and formability after pressing and sintering have been determined and studied. Samples from europium hafnate powder have a relative density higher than samples from cerium hafnate powder after consolidation at temperatures of 900-1200 ° C and isothermal holding time from 30 to 120 min. A study of the microhardness of lanthanide hafnate samples after sintering has shown that europium hafnate samples have greater hardness than cerium hafnate samples .