Sintering Of YSZ/GDC Electrolyte Powders And Preparation Of LSCF Cathode Powders Of SOFC

Solid oxide fuel cell is an electrochemical device that converts chemical energy directly into electrical energy.It has many advanta ges such as high efficiency,non-pollution,all-solid-state structure and wide adaptability to various fuel gases.8YSZ?8mol%Y₂O₃ stabilized ZrO₂?and Gd₂O₃ doped CeO₂?GDC?because of their higher ionic conductivity,very low electron transfer,good chemi cal and thermal stability,easy manufacturing process and other advantages,so often used for SOFC electrol yte materials.SOFC in low temperature is the inevitable trend of the development of the tech nology,which has a higher requirement for all parts of the SOFC materials.And the total loss of the solid oxide fuel cell is mainly caused by the polarization of the cathode,therefore,the preparation of high performance SOFC cathode materials is conducive to the promotion of the develop ment of SOFC at low temperature.In this paper,the sintering process of yttrium oxide fully stabilized zirconia?8YSZ?nano powder s was studied.The densification process of nano powders sintering was discussed.The effect of sintering process on the density and grain size of the nano powders was analyzed.The optimal pressureless sintering temperature of 8YSZ nano powder s was 1500?,and the holding time was 4h.The water absorption rate of 0.13%,the relative density of 98.64%,the grain size of 5.84 ?m of 8YSZ sintered body with excellent performance can be obtained according to the results of using this process.This paper takes the Gd_0.1Ce_0.9O_1.95 powders?D50=9.0?m?produced by a factory in Shenzhen,and the Gd_0.1Ce_0.9O_1.95 powders?D50=32.0?m?produced by Ningbo SOFCMAN as the research object s.The Shenzhen GDC powders?D50=9.0?m?are very fine,uneven particle size and conglobate.Therefore,it is necessary to take the Shenzhen GDC powder s calcinated at intermediate temperature,so that the too fine grain s grow up,which is convenient for the subsequent granulation,tablet compressing and sintering.Considering all properties,the optimal presintering temperature is 1000 ?.The optimal sintering condition is 1400 ? for 4h.Under this condition,the water absorption rate of 0.05%,the apparent porosity of 0.36%,the volume density of 7.088 g/cm3,the relative densit y of 98.06% and the shrinkage rate of 16.13% of Shenzhen GDC sintered body can be obtained with excellent performance.While coarser Ningbo GDC powders?D50=32.0?m?with wider particle size distribution,the high er sintering temperature,smaller sintering shrinkage rate and larger porosit y rate,which lead to the GDC sintered body is non densification.The bigger particles of the powders become smaller and the particle size distribution of the powders becomes narrower via rapid ball milling.The optimal sintering condition is 1500 ? for 4h.Under this condition,the water absorption rate of 0.09%,the apparent porosity of 0.60%,the volume densit y of 7.005 g/cm3,the relative densit y of 96.91% and the shrinkage rate of 14.27% of Ningbo GDC sintered body can be obtained with excellent performance.LSCF nano powders were pre pared by microwave assisted sol-gel method.It was concluded that the nano powder was La_0.6Sr_0.4Co_0.2Fe_0.8O_3-? through the anal ysis of TG-DTA,XRD,SEM and EDS of the powder.The microstructure of the nano powder is composed of a large portion of the lamellar structure and a small amount of the porous hollow tubular structure.A small amount of the porous hollow tubular structure increases the length of the three phase boundary and the site of the activating reaction of the cathode.