B_2O_3-Na_2O系アルコキシド溶液のゲル化領域とゲル化反応

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Influence of water addition and catalysts such as HCl and NH_4OH on the gel region and the gelation behavior of alkoxide solutions was examined in the B_2O_3-Na_2O system.The resuls are as follows: (1) With the water addition r=0-1, where r=water added/water necessary for complete hydrolysis, gel region was found in the range of B_2O_3=60-90 mol%. With water addition of r>1 gel region was reduced. Crystals precipitated with the addition of HCl. The gel region with NH_4OH addition was the same as that observed with water addition. (2) Gelation time was reduced by water addition. No effect on gelation time was found by NH_4OH addition. (3) From the measurements of pH and temperature rise in the B (OBu)_3-NaOCH_3 mixtures, it was inferred that sodium-borate precursors (complex) such as B(OBu)_3(ONa) and B(OBu)_<3-n>(ONa)_n formed in the B(OBu)_3-NaOCH_3 mixtures. With water addition, the formation of hydroxide complex such as B(OH)_3ONa and B(OH)_<3-n>(ONa)_n was also inferred.
社団法人日本セラミックス協会の論文
1993-04-01