| 摘要 |
Dealkalized sheet glass having a core region which is not dealkalized, having a pre-dealkalization bulk sodium ion concentration of at least 8%, calculated as weight percent sodium oxide in the sheet glass, which pre-dealkalization bulk sodium ion concentration continues to be maintained in the core region of the sheet glass, and having a surface which is dealkalized to a depth such that a sodium ion concentration gradient exists. The sodium ion depletion is maximum at the surface, the depth at which the sodium ion concentration is 90% of the pre-dealkalization bulk sodioum ion concentration is at least twice the depth at which the sodium ion concentration is 50% of the predealkalization bulk sodium ion concentration, and the sodium ion concentration at a depth of 50 nm is not more than 50% of the pre-dealkalization bulk sodium ion concentration. A long-lasting dealkalization is achieved because of a reduced tendancy to ionic migration due to the shape of said sodium ion concentration gradient. |
