| Gelcasting was used for preparing mullite reinforced Aluminum-ch romiun-phosphete composite ceramics. The main material is mullite reinforced Aluminum-chromiun-phosphete composite ceramics power,and monomer, crosslinker, initiator and catalysis separately are acrylamide, N-N methylene acrylamide bouble, N-N-N'-N' tetramethyle thylenediamine and ammoni-um persulfate, the gelcasting of the composition ceramic was research. Aluminum-chromiun-phosphete composite ceramics power dispersion mechanism in the water by the test method of sedimentation check Zeta potential and the slurry viscosity was studied. The effect of monomer, dispersant, PH value,ball milling time and solid loading for which mullite reinforced Aluminum-chromiun-phsphete composite ceramics gelcasting rheological properties of the slurry was discussed by the univariate tests method. And the influence of monomer, initiator, catalyst content and gelation temperature for gelcasting time. The phenomena on bodies surface pealing was discussed by different organic molecules using inhibition mechanism, and drying ways on body. Mainly analyzed those factors such as monomer content and solid loading which influencing the properties of electric and microstructure and mechanical about ceramic was also studied. The results shows that:After three dispersants was studied, we find that a dispersant named PAA-NH4 was the best. The Zeta potential shows is the highest,the viscosity is relatively small at p H=10. By comprehensive analysis,we know that mullite reinforced Aluminum-chromiun-phsphete composite ceramics powder dispersed in water belongs to the electrostatic stabilization mechanism.By analysied the rheology of the slurry suspension we found that when the suspension with 53% solid loading at p H=9, 0.48% dispersant,ball minlling time 8h and monomer content about 14wt%, the viscosityof smallest. The gelation time was controlled by the monomer content on 14wt%, the amount of catalyst 0.375ml/g, the amount of initiator was 0.625ml/g, gelation temperature is about 50?, the slurry gelation time can control the gel-point to 20~30 min after added agents and catalysts, the gelation time was better.By the research of body surface skin pealing phenomena and drying deformation studies, with the help of three kinds of organic polymer about PVP, polyacrylamide and glycerol, added glycerol with2wt% slurry viscosity is low, the time of gelation was suit, inhibit the skin from the body surface phenomena was better. Compared with the means of In air at room temperature and different content PEG solution drying wet body, the dried body water loss rate maximum in a solution of 45% PEG.The test results after monomer content, solid loading of green and sintered bodies with the mechanical properties, dielectric properties and microstructure showed that the monomer content has little influence on the body's flexural strength, linear shrinkage of the sintered body, the bending strength of the sintered body and other effects.The solid loading greater impact on the mechanical properties and dielectric properties of body and sintered body. With the solid loading of 53vol%, the properties of mullite reinforced Aluminum-chromiun-phsphete composite ceramics was best. The Bending strength,vickers hardness, the density, and the average dielectric constant of sintered bodies was respecting 181.30 MPa, 975.64, 2.75g/cm3 and 3.84.By the microstructure analysis, internal fracture specimens mainly from the source material the internal porosity. |
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