| The rheology charateristic of Al2O3 ceramic slurry was studied in this paper. The results show that the viscosity of Al2O3 slurry is not changed greatly when the content of talc is less than 4wt%. However, compared with the Al2O3 ceramic slurry without talc, the Al2O3 ceramic slurry with talc is of distinct thixotropy . The plate shape structure of the talc results in the thixotropy of the slurry. Furthermore, the thixotropy of the Al2O3 ceramic slurry decreases gradually with increasing ball-milling time of talc. For the same reason, the slurry with higher amount of kaolin is of thixotropay.The effects of SiO2/CaO and sintering procedure on the microstructure and properties of the 96 Al2O3 ceramic substrate were investigated. Results show that the relationship curve between density and SiO2/ CaO appears "saddle type" . The density is relevant with sintering procedure and glass phase. When the SiO2/CaO is about 2.16, the contents of glass phase is minimum, which results in underfiring, more air cavity, lower density, and higher dielectric loss . As the sintering temperature increases, the density of substrate (SiO2/CaO=2.16) increases, but the dielectric loss decreases. When sintered at 1550℃and 1600℃, the bend strength of 96% Al2O3 increases with increasing SiO2/CaO .The effects of talc on the properties such as the bend strength, density, and electricity properties of SiO2-CaO-MgO-Al2O3 system ceramic were studied. The function and effecting mechanism of MgO on the microstructure were discussed, and the optimum quantity of talc for forming fine grain 96Al2O3 ceramics at lower temperature was determined. |
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