POROUS GLASS MEMBER

Abstract

Provided is a porous glass member less likely to crack during production. A porous glass member has a porosity of 10 to 85% and contains, in terms of % by mass, 80 to below 100% SiO.sub.2, over 0 to 10% ZrO.sub.2, and 0 to 10% Al.sub.2O.sub.3.

Claims

1. A porous glass member having a porosity of 10 to 85% and containing, in terms of % by mass, 80 to below 100% SiO.sub.2, over 0 to 10% ZrO.sub.2, and 0 to 10% Al.sub.2O.sub.3.

2. The porous glass member according to claim 1, having a median value of a pore distribution of 1 to 100 nm.

3. The porous glass member according to claim 1, having an aspect ratio of 2 to 1000.

Description

EXAMPLES

[0043] Hereinafter, the present invention will be described with reference to examples, but is not limited to these examples.

[0044] Table 1 shows examples (Sample Nos. 1 to 5) of the present invention.

Table 1

[0045]

TABLE-US-00001 TABLE 1 No. 1 No. 2 No. 3 No. 4 No. 5 Glass glass composition base (% by mass) material SiO.sub.2 60 57 55 53 53 B.sub.2O.sub.3 17.5 19.8 21.3 22.9 22.9 Na.sub.2O 5.5 6.2 6.7 7.1 7.1 ZrO.sub.2 6 6 6 6 6 Al.sub.2O.sub.3 3 3 3 3 3 CaO 8 8 8 8 8 Porous glass composition glass (% by mass) member SiO.sub.2 92.9 93.1 93.3 91.4 95.6 ZrO.sub.2 3.1 3.5 3.7 4.8 2.6 Al.sub.2O.sub.3 4 3.4 3 3.4 1.8 median value (nm) of 58 70 78 5 10 pore distribution porosity 68 77 78 25 40 cracking during drying good good good good good

[0046] Raw materials formulated to give each of the compositions in the table were put into a platinum crucible and then melted therein at 1400 C. for six hours. In melting the glass batch, molten glass was stirred using a platinum stirrer to homogenize it. Next, the molten glass was poured onto a carbon sheet to form it into a platy shape and then annealed at 500 C. for 30 minutes, thus obtaining a glass base material.

[0047] The obtained glass base material was thermally treated in an electric furnace at 675 C. for 24 hours to separate it into phases. The glass base material separated into phases was cut and polished to a size of 5 mm5 mm0.5 mm (thickness). Next, the glass base material was immersed into 1 N nitric acid (at 90 C.) for 48 hours, then washed with ion-exchange water, and then allowed to stand in the atmosphere for 24 hours to volatilize water, thus obtaining a porous glass member. As for Samples Nos. 1 to 3 and 5, the obtained porous glass member was immersed into 3 N sulfuric acid (at 95 C.) for 48 hours to remove ZrO.sub.2 colloid, then washed with ion-exchange water, and then allowed to stand in the atmosphere for 24 hours to volatilize water. As for Samples Nos. 1 to 3, the porous glass member from which ZrO.sub.2 colloid was removed was immersed into 0.5 N sodium hydroxide aqueous solution (at 25 C.) for 3.5 hours to remove SiO.sub.2 colloid, washed with ion-exchange water, and then allowed to stand in the atmosphere for 24 hours to volatilize water.

[0048] When the surfaces of the obtained porous glass members were observed with an FE-SEM (SU-8220 manufactured by Hitachi, Ltd.), all the glass members had a skeleton structure based on spinodal phase separation. Furthermore, the obtained porous glass members were evaluated in terms of composition, the median value of the pore distribution, porosity, and cracking during drying.

[0049] The composition was measured with an energy dispersive X-ray analyzer (EX-250 manufactured by Horiba, Ltd.).

[0050] The median value of the pore distribution and the porosity were measured with a pore distribution measurement device (QUADRASORB SI manufactured by Quantachrome Instruments). Note that the porosity was determined from the volume (cm.sup.3) of pores and the volume (cm.sup.3) of the skeleton of the porous glass member according to the above-described equation and the density of the skeleton of the porous glass member, 2.5 (g/cm.sup.3), was used in calculating the volume (cm.sup.3) of the skeleton of the porous glass member.

[0051] With respect to cracking during drying, porous glass members not confirmed to have cracked during drying were evaluated as good and porous glass members confirmed to have cracked during drying were evaluated as poor.

[0052] Samples Nos. 1 to 5, which are examples of the present invention, were not confirmed to have cracked during drying.

INDUSTRIAL APPLICABILITY

[0053] The porous glass member according to the present invention is suitable for a wide range of applications, including a separation membrane, a diffuser tube, an electrode material, and a catalyst carrier.