The Process Preparation And Performance Study Of Rare Earth Oxides Compound Mixed Spinel

Due to the excellent properties and wide application of the high temperature infrared radiation materials,it becomes a research hotspot of scholars both at home and abroad.Influenced by its service environment,materials need to have good radiation performance in near infrared and far infrared band,and maintain the stability of the structure.Therefore,this article chooses the spinel kind material which has stable performance,and carries on research mainly from the preparation process and materials of spherical reunion powders.Study of the preparation process of spherical reunion powder mainly includes two aspects.First,in the preparation process of slurry,the influence degree of three different levels of the four major influence factors（namely slurry PH,particle size distribution of solid particles in the slurry,bonding agent content and the content of dispersant）to powder quality is studied.Using Cr₂O₃,NiO for raw materials,this article carries out 9 experiments with the orthogonal experiment design.Second,in spray drying process,the influence degree of four different levels of the four major factors（namely slurry sand grinding time,the temperature of the spray drying,the solid content of slurry and the feeding speed of the pump）to powder quality is studied,which also use Cr2O3 and NiO as raw material,and design for systematic study of 16 experiments with the orthogonal experiment design,including error column.Through the test of reunion powder liquidity as well as the trend analysis of every single factor effect curve and double factors effect curve in the experiments,this article seeks the best spherical reunion powder preparation technology,in order to lay the material foundation of the infrared radiant coating with excellent properties.The material aspect research mainly includes two parts.First part is mainly about the preparation of positive and negative spinel structure mixed spinel,which explores whether the NiMn2O4 spinel with spinel structure can be directly compounded and its infrared radiation properties;whether the CoMn2O4 spinel can be directly compounded and its infrared radiation properties;whether the Ni and Co can occur isomorphic substitution in order to improve the radiation properties of the material;explores the influences of different adding amount of Co₃O₄ and MnO₂ to the infrared radiation performance of the complex spinel and provides the carrier with good infrared radiation performance and stable structure in the final compound of rare earth oxide;Second part mainly studies the“doping effect”conducted by the different rare earth oxides(CeO₂,Pr₆O₁₁1 and Tb₄O₇)to the mixed spinel which composed by the NiCr₂O₄ spinel with normal spinel structure and the NiMn₂O₄ with inverse spinel structure.This article uses melvin granulometer to test the distribution of solid particles in the slurry,in order to determine the right time to sanding.And uses scanning electron microscope（SEM）to observe the spherical reunion powder and coating microstructure,the hall current meter to test the powder liquidity after reunion sintering,as well as determines the sintering temperature with TG-DSC and analyzes the sintered powder composition with XRD.After the test and analysis,the mixed spinel which composed by the NiCr₂O₄ spinel with normal spinel structure and the NiMn2O4 with inverse spinel structure has a good infrared radiation performance and stable structure（in 600-1000℃,the highest radiation rate of mixed spinel itself only can be up to 0.884）,which is the best carrier of rare earth oxides compound.Compounding the mixed spinel which composed by NiCr₂O₄ spinel and NiMn₂O₄ spinel with rare earth oxides CeO2 which could promote the spinel clinker and rare earth oxide Pr₆O₁₁,Tb₄O₇ with natural anionic"absence",which could improve radiation performance ranging from 10 to 20μm long wavelengths.The thermal radiation rate of material we talked above is mainly acquired by testing the coating material,which also concerns with the coating surface morphology and many other factors.After the performance test analysis,the three kinds of rare earth oxides compounded together can make the normal rate of total radiation of the material reach to more than 0.9 in the range of 2.5²5 mu m band,and the highest range of wavelengths can close to 0.94.