Effect Of Electric Current Pulse On Preparation Of Y2O3 Powder

With the rapid development of science and technology,nano materials have attracted great attention for their excellent properties.However,agglomeration occurs in the process of preparing nano powders.On the other hand,electric current pulse(ECP)processing,as a new technology for metal material preparation,has attracted much attention in recent years and has gradually been used to improve the properties of metal materials.Therefore,ECP provides a new way to improve the aggregation of nano powder.In this paper,six hydrated yttrium nitrate(Y(NO3)3·6H2O)and ammonia were chosen as raw materials for the preparation of Y2O3 precursor.At the same time,different frequencies and voltages of ECP were also added.Scanning electron microscopy(SEM)was used to observe the morphology and agglomeration of precursor.The composition of the precursor was analyzed by thermogravimetric analysis(TG-DSC)and X diffraction(XRD).The following experimental results were obtained:When there was no ECP:(1)When the experimental concentration was 0.8,1.2 and 1.6 mol/L and pure ammonia water was used as precipitant,the agglomeration of precursors was all very serious and the composition did not change.(2)The concentration of precipitant had some influence on the morphology of the precursor.When the concentration of precipitant was 1:9(ammonia water concentration is 1.4 mol/L),the precursor particles were relatively homogeneous and had lamellar structures.(3)The concentration of precipitant had certain influence on the pH in the process of experiment.When pure ammonia was used as precipitant,pH did not decline.When 1:9 ammonia was used as precipitant,pH would decrease.When ECP was added:(1)The pulse parameters had certain influence on the agglomeration of precursor.When the precipitant was pure ammonia and the concentration of solution was 0.8mol/L,flake precursor structure turned more and more obvious with the increase of pulse frequency;When the concentration of 1.2 and 1,6 mol/L,the precursor still indicated granular structure at low pulse frequency.With the increase of frequency,the lamellar microstructure turned more and more obvious.However,when the concentration was 0.1 mol/L,the precursor structure did not change obviously due to the low conductivity of the solution.(2)The pulse parameters had certain influence on the pH in the precipitation process.When the pulse was added,the pH was about 0.25 lower than that without ECP.(3)The pulse parameters had certain influence on the morphology of the precursor.When the pulse of 15V was added,the structure changed from original agglomerated particles into a single direction lamellar structure and was made up of single-sheet tissues.(4)The pulse parameters had some influence on the composition of the precursor.When the concentration of the precipitant was 1:9,the condensation of Y is lower than that without ECP.At the same time,the main composition of precursor changed from Y2NO3(OH)5·1.5H2O,Y2(OH)5.14(NO3)0.86·H2O to Y(OH)1.5(NO3)1.5·H2O and YO0.75(N03)1.5.After calcination,the agglomeration of precursor was obviously improved.