Study On Preparation And Properties Of Porous Y₂SiO₅ Ceramics

Porous ceramics with high porosity,low density,low dielectric constant and low thermal conductivity is finding wider and wider application in the field of heat insulation and air wave.However there are relatively few studies on porous Y₂SiO₅ ceramics,and there are some problems in the preparation process.If the porous Y2 Si O5ceramics are prepared by two-step method,the process ia complicated and the porosity of the obtained samples is low and the dielectric properties are less.Preparation of high porosity porous Y₂SiO₅ ceramics by gel-casting,?N,N-dimethyl formamide?DMF-based gel-casting system was used tostudy the rheological and stability and gelation behavior of the slurry,By optimizing the drying and discharging process of the green body,the porous body with small shrinkage and complete appearance,The effects of the in situ reaction sintering temperature on the porous Y₂SiO₅ ceramic phase and the microstructure of the porous Y₂SiO₅ ceramics were characterized.The mechanical properties and dielectric properties of the prepared porous Y₂SiO₅ ceramics were characterized.Finally,porous Y₂SiO₅ ceramics with high porosity and excellent force / electrical properties were obtained.SiO₂ and Y₂O₃ as raw materials,using DMF ass solvent,acrylamide as monomer,through the gel-casting preparation of porous body.Through the optimization of the discharge process to obtain a complete shape of the body.The effects of solvent type,dispersant type,catalyst and initiator content on slurry and gel behavior and bulk integrity were studied.The results showed that DMF was used as the solvent in the gel-casting,and the polyacrylic acid?1.6% of the powder content?was used as the dispersant.The amount of the initiator ammonium persulfate and the catalyst tetramethylethylenediamine was monomer 20% of the quality and 1%,you can get the surface smooth and complete,no cracks,shrink the smaller integrity of the body.The optimum dyeing process was carried out by TG / DSC.The optimum conditions were as follows: heating to 700? at a heating rate of 0.2? / min,and insulation for 2h at 150?,380?,540? and 700?.The effects of sintering temperature and solid content on the phase,porosity,pore size distribution and microstructure of porous Y₂SiO₅ ceramics were studied.It was found that when the sintering temperature was lower than 1450?,the prepared porous Y₂SiO₅ ceramics contained unreacted silica and yttrium oxide.Above this temperature,pure phase porous Y₂SiO₅ ceramics can be obtained.By adjusting the sintering temperature and solid content,the porosity and pore size can be adjusted.With theincrease of the sintering temperature,the sintering shrinkage of the porous Y2 Si O5ceramics increases,the porosity decreases,the pore size decreases,and the sintering temperature decreases.With the increase of solid content,the sintering shrinkage rate of porous Y₂SiO₅ ceramics decreased,the porosity decreased and the pore size decreased.The porosity of the prepared porous Y2 Si O5 ceramics is in the range of 64.59-81.00%and the average pore size is in the range of 1-2.3?m according to the different sintering temperature and solid content.When the solid content is 10% and the sintering temperature is 1450?,the prepared porous Y₂SiO₅ ceramics can obtain the highest porosity of 81.00%.The mechanical and dielectric properties of the prepared porous Y₂SiO₅ ceramics were characterized.The results show that the compressive strength of the prepared Y₂SiO₅ ceramic is in the range of 1.12-18.84 MPa,and when the solid content is 20%and the sintering temperature is 1500?,the compressive strength of the prepared porous Y2 Si O5 is in the range of 1.12-18.84 MPa.,The maximum compressive strength of porous Y₂SiO₅ ceramics is 18.84 MPa.In the high temperature stability,the porosity,pore size and phase composition of the porous Y₂SiO₅ ceramics prepared by this paper have not changed obviously after high temperature treatment.The dielectric constant of the porous Y₂SiO₅ ceramics increased from 1.78 to 2.49 with the porosity decreasing from 81.00% to 64.59%.When the porosity was sintered at 1500?,the porous Y₂SiO₅ ceramics with the solid content of 10% had the lowest electrical constant of 1.78.