Study On Gel-casting With High Solid Loading Forming Process For MgAlON Transparent Ceramic

Transparent MgAlON, which is regarded as a novel transparent ceramic material,has outstanding optical transparency and excellent mechanical properties. Andgelcasting is an in situ polymerization technique making components with big sizeand complex shape. In this work, in order to improve the optical property ofMgAlON ceramics, the bodies with good uniformity, high strength and density wereprepared firstly through high solid loading aqueous gelcasting forming and isostaticpressing. At last, transparent MgAlON with good properties were achieved.At the beginning, the paper attached importance to improving solid loading involume and reducing the viscosity of slurry. The effects of dispersant, pH value,mixing time and solid loading in volume on the viscosity of slurries were discussed.Then MgAlON slurries with high solid loading （>50vol%） and low viscosity（<110mPa·s） were prepared through the optimized parameters that were pH in9,the amount of dispersant TAC in0.3wt%and6hours of mixing time.After preparing the slurries, the gelation behaviors of the slurries were studied.The influences of monomer concentration, crosslinker amount and solid volumefraction on the bending strength and microstructure were investigated. Besides, theeffects of the amount of initiator and catalyst on the beginning gelling time were alsoresearched.The optimized gelling conditions were achieved that the amount of MAMis20wt%, the mass ratio of MAM/MBAM is10:1, the content of initiator and catalystis1.0vol%and0.5vol%respectively. And the bodies with the highest bendingstrength （12.32±0.5MPa） were obtained when the solid volume fraction in52vol%.At last, the effects of solid loading on the liner shrinkage and the isostaticpressing on the properties of bodies were discussed. Then the bodies with gooduniformity, high strength（14.23±0.7MPa） and density（60.75%） were achieved.After calcining, the obtained samples were pressureless sintered at1875℃for24h innitrogen atmosphere. Then the transparent MgAlON ceramics with relative density of99.91%, transmittance of71.73%and Vickers hardness of13.73±0.15GPa have beenobtained.