|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1995 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1994 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Freeze Dry processing is one method which can prepare particles for fine ceramics from a liquid feed. In this processing, a dried body, which is made in a vacuum camber from a frozen body of a metal-salt aqueous solution, has a lot of fine micro pores. The pores are traces of ice crystals sublimation. In the succeeding processing as calcination and sintering, the original pore configuration is held.
In this research we tried to apply the above processing for preparation of a fine porous ceramics with highly oriented pores. The basic proessing is solidification of a metal-salt aqueous solution into a frozen body controlling its freezing direction. When one way solidification is performed, ice crystals grow in one oriented diretion. Therefore, the dry body contains oriented pores configuration. Then heating of it makes a fine porous ceramics with highly oriented pores.
Various operational conditions, such as concentrations of feed magnesium sulfate aqueous solutions, freezing temperatures, and heating rates and temperatures, were investigated to make clear the effects on the pore characteristics. SEM observations, measurements of pore size distributions, pore volumes, specific surface areas and porosity fractions, and also measurement of compressing strength were performed.
We have obtained the following results :
1.The orientation of pores in a fine magnesia ceramics body are well controlled in one direction.
2.The pores are classified into two groups, one is a macro pore group which takes pore diameters of 1 to 10 mum, the other a meso pore group with 0.3 to 0.005 mum pore diameters.
Pore volume is in a range from 2 ml/g to 8 ml/g, specific surface area is from 30 m^2/g to 80 m^2/g, porosity is from 88% to 97%.
4.Compressing strength shows the following values, 5*10^4 - 2*10^3 N/m^2.