窒化ケイ素の泥しょう鋳込成形と焼結体の機械的特性(第2報) : 直接窒化窒化ケイ素粉体の真空・加圧鋳込成形

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To develop a complicated shape forming method for the fabrication of Si_3N_4 engineering ceramic parts the vacuum-pressure assisted slip casting was studied. A well-dispersed and high solids containing slurry (77 wt% solids) was prepared, and the consolidation kinetics of the slurry using the vacuum-pressure assisted slip casting system with a porous polymer resin mold and the mechanical properties of the sintered body were investigated. From the slurry containing 77 wt% solids (92 wt% α-Si_3N_4, 4 wt% α-Al_2O_3, 4 wt% Y_2O_3), 0.01 wt% deflocculant, 0.1 wt% defoamer, 4 wt% binder, the high-density green body (2.01-2.07 g/cm^3) was formed in the pressure range of 0.1-0.7 MPa. The rate of filter cake buildup (k) was experimentally determined to be 2.25×10^<-13>P [m^2/s]. On the other hand, the k was calculated to be 4.61×10^<-13>P [m^2/s] using the Adcock and McDowall's equation. The difference between the experimental and calculated values of k seemed to be mainly due to that the calculation of k using the BET-surface area of α-Si_3N_4 powder in place of the "permeability surface area" resulted in the overestimation of k although the actual solids had the wide particle size distribution. The green density was mostly independent on the forming pressure in the range of 0.2-0.7 MPa. The Si_3N_4 sintered at 1770℃ for 4h at about 0.9 MPa N_2 with the addition of 4 wi% binder showed a density of 3.22 g/cm^3, a flexural strength of 612 MPa and a Weibull modulus of 7.4. It was found that the vacuum-pressure assisted slip casting was useful for the forming of silicon nitride.
社団法人日本セラミックス協会の論文
1992-08-01

窒化ケイ素の泥しょう鋳込成形と焼結体の機械的特性(第2報) : 直接窒化窒化ケイ素粉体の真空・加圧鋳込成形

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