著者
橋本 謙一
出版者
公益社団法人 日本セラミックス協会
雑誌
窯業協會誌 (ISSN:00090255)
巻号頁・発行日
vol.70, no.798, pp.C225-C233, 1962-06-01 (Released:2010-04-30)
参考文献数
53
著者
石堂 善彦 藤井 欽二郎
出版者
公益社団法人 日本セラミックス協会
雑誌
窯業協會誌 (ISSN:00090255)
巻号頁・発行日
vol.81, no.931, pp.115-117, 1973-03-01 (Released:2010-04-30)
参考文献数
5

Fused magnesia and magnesia clinker which were pulverized to such a fineness as shown in Table 1, were proven to react rather readily with glacial acetic acid at a temperature from 20° to 65°C. When the fractions of magnesia reacted were followed at each constant temperature by determining magnesium acetate formed in the reaction mixture which was soluble in methanol, the reactions proceeded after Jander's rate-equation except later reaction-stage as shown in Fig. 1 with an apparent activation energy of 21.8kcal/mol, though any diffusion layer didn't be observed around magnesia grains under microscope. In a semi-adiabatic condition, the temperature of the mixture should rise owing to the heat of reaction, resulting in acceleration of the rate of reaction more and more to cause the mixture to boil. These situations were examined at an initial temperature from 30° to 60°C. The results were shown in Fig. 3 in comparison with those obtained by numerical calculation using the rate data at constant temperatures and heat contents of the matters concerning to the reaction system.
著者
久保 靖 山口 悟郎 笠原 晃明
出版者
公益社団法人日本セラミックス協会
雑誌
窯業協會誌 (ISSN:18842127)
巻号頁・発行日
vol.75, no.862, pp.183-192, 1967-06-01
被引用文献数
1

In relation to three hydrated phases which were obtained by the reactions between the water vapor and the solid phases of nepheline=carnegieite compositions in the foregoing paper, attempts were made to establish a correlation between the structure of the starting solid and the product with a hope that the structure of the starting solid might be inherited to the product. Dehydration experiments of the products were carried out also in relation to clarifying their structural relationships.<br>X-ray powder diffractions of the nepheline hydrate I and the species Y obtained in the previousp aper and of the nepheline hydrate II which is of a low-water type closely relating to these hydrates and obtained by hydrothermal reaction after Barrer's method, were examined and are listed in Table 3-6. All these patterns can be tentatively indexed based on orthorhombic cells which are shown in the tables and also summarized in Table 7. Indexing was made by trial and error based on the available electron diffraction patterns. Some discrepancies, however, are still observed, which may suggest that dehydration occurs to some extent under high vacuum and also by electron bombardment during the electron optical observation.<br>The high temperature X-ray diffraction patterns and thermal analysis curves are illustrated in Fig. 1-8 for the nepheline hydrate I, the species Y, and the hydroxy-sodalite of the present experiments and for a nepheline hydrate II. It seems that in the former three species, some lattice distortion takes place upon partial dehydration as shown by the splitting of the diffraction peaks. The original structure, however, is nearly resumed by further dehydration and eventually goes to a nepheline structure. At the final stage of dehydration double exothermic effects in D. T. A. curves are characteristic for all of these three hydrated phases, which seems to be due to complicated transformation processes including the formation of intermediate sodium aluminosilicate phases. As compared with these, the thermal change of nepheline hydrate II is so simple that dehydration brings about the direct formation of nepheline structure as low as at 600°C. Though little can be said of the actual structures of these phases at present, close relationships between the original solid phase and hydrated product can be demonstrated by a comparison between the lattice parameters as illustrated in Fig. 13 and 15. The lattice dimensions suggest that the structural units of aluminosilicate as illustrated in Fig. 14 are inherited throughout the hydrothermal processes.
著者
久保 靖 山口 悟郎 笠原 晃明
出版者
公益社団法人日本セラミックス協会
雑誌
窯業協會誌 (ISSN:18842127)
巻号頁・発行日
vol.75, no.861, pp.140-146, 1967-05-01

Differing from the previous studies by various investigators, the present research concerns with the formation of hydrated sodium aluminosilicates by the water vapor-solid reactions. Sodium aluminosilicate phases, amorphous or crystalline with nepheline-carnegieite compositions, which were obtained by heating the mixtures, Al<sub>2</sub>O<sub>3</sub>⋅2SiO<sub>2</sub>⋅2H<sub>2</sub>O(kaolinite)+<i>a</i>Na<sub>2</sub>⋅CO<sub>3</sub>(<i>a</i>=1.00-2.00), up to various temperatures below 1300°C, were used as the starting solids. A silver capsule was filled with the starting solid and suspended above the liquid water in a Moley-type autoclave (Fig. 1). The bottom of the capsule was not sealed to allow the water vapor to penetrate into the capsule. The saturated water vapor pressure within the autoclave at 310°C is 100kg/cm<sup>2</sup>. This condition was used throughout the present experiments. Under this condition, the reaction may well be called a hydrothermal metamorphosis.<br>As compared with the previous studies in which the thermodynamic equilibria are attained in the given homogeneous systems, the reactions in the present experiments start at the interfaces between the water vapor and the solid with a consequence that the reaction products are not necessarily equilibrated under the given experimental conditions. As the result, three sorts of hydrated phases, hydroxy-sodalite, nepheline hydrate I, and species Y (a new phase of the composition, Na<sub>2</sub>O⋅Al<sub>2</sub>O<sub>3</sub>⋅2SiO<sub>2</sub> 1.33-1.5 H<sub>2</sub>O, which has not been found in the previous hydrothermal studies), were formed during 1-7 days' run according to the nature of the starting solid phases. Correlations among the starting solids and the resulting hydrates are summarized in Table 2 and Fig. 2. In the table the first three columns stand for the preparation of starting solids and the forth the duration of metamorphosis, the fifth the products under the respective experimental conditions.<br>During the hydrothermal treatment, grains of the original solids as shown in the electron microphotographs of Figs. 3 (a)-(c), changed to well-shaped crystallites of the hydrates, nepheline hydrate I and species Y, as shown in Figs. 4(a)-(c), except hydroxysodalite which was formed only in massive grains. Considerable amount of water molecules may have been adsorbed on the surface of solid to gelatinize the surface and eventually to recrystallize the solid into the hydrate crystallites. The original structural framework may still be retained to some extent under these conditions. The metastable phase formation in this experiment will be treated from this point of view in a following paper.
著者
藤井 欽二郎 石堂 善彦
出版者
公益社団法人日本セラミックス協会
雑誌
窯業協會誌 (ISSN:18842127)
巻号頁・発行日
vol.73, no.832, pp.13-16, 1965-01-01
被引用文献数
1

高温における純シリカゲルの変化を再検討した. テトラエチルオルソシリケートから調製した微粉状シリカゲル (I) を圧縮成形してつくった円板は, 石英ガラス容器中, 約1150℃の加熱でガラス化して半透体になる. 白金容器中では, このゲルはクリストバライトに変りやすい. 4塩化珪素を加水分解して塊状に乾燥したシリカゲル (II) は, 上記より多少低温, 1050℃で透明になり, 1100℃では, 少量成分おそらく内包された水分を放出してポッピングを起し始める.
著者
土谷 敏雄 堀内 哲郎 森谷 太郎
出版者
公益社団法人日本セラミックス協会
雑誌
窯業協會誌 (ISSN:18842127)
巻号頁・発行日
vol.85, no.979, pp.127-133, 1977-03-01

Ag<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>系ガラスは60mol% Ag<sub>2</sub>Oまでガラス化出来た. 赤外吸収の比較から, Ag<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>とNa<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>は同じ様な構造を持つが, Ag<sub>2</sub>O含有ガラスの1280, 1100cm<sup>-1</sup>の低波数へのshiftは, Ag-O-Pボンドが共有結合的性格を持つことが示唆された. 電気伝導の結果から, logσはAg<sub>2</sub>O量の増大と共に増加し, 熔融温度と時間の増加と共に増加した. Ag<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>はNa<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>にくらべ, logσが非常に高く, 低い温度係数を示した. 一方, 誘電測定からのε', ε''は, Ag<sub>2</sub>O量の増加と共に急激に増加し, Na<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>よりも非常に大きな値を示し, 誘電緩和の大きさ<i>Δ</i>εは約50mol% Ag<sub>2</sub>Oで極大が観察された. Ag<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub>ガラスの誘電緩和は, 40mol% Ag<sub>2</sub>Oより少ない組成ではmigration loss, 50mol% Ag<sub>2</sub>O以上の組成ではMaxwell-Wagner lossにもとづく. 銀を含むガラスの特異性は, 他のアルカリイオンの様に, Ag<sup>+</sup>を単なる1価のイオンと見なして電気的性質を理解する事は, 困難である事が示唆された.
著者
高良 淳
出版者
公益社団法人日本セラミックス協会
雑誌
窯業協會誌 (ISSN:18842127)
巻号頁・発行日
vol.69, no.792, pp.C484-C485, 1961-12-01
被引用文献数
1
著者
野村 勁 藤井 欽二郎
出版者
公益社団法人日本セラミックス協会
雑誌
窯業協會誌 (ISSN:18842127)
巻号頁・発行日
vol.77, no.888, pp.271-277, 1969-08-01

The weight loss in nitrogen atmosphere of compact mixed powders of MgO and carbon at temperatures 1400°-1800°C was followed thermogravimetrically.<br>At any given temperature, the reaction proceeded as a first order reaction (activation energy, 43.8kcal/mole) in an early stage, and zero order reaction followed (53.8kcal/mole). It is considered that the zero order reaction is the characteristic of the reaction of this system, and it will be explained as the effusion of gas evolved in the compact from the surface pores at constant rate (1.3mg⋅cm<sup>-2</sup>⋅min<sup>-1</sup> at 1700°C) irrespective of mixing ratio, shaping pressure, or sample weight. The partial pressure of gas in the compact was obtained from the Knudsen effusion equation. For 1700°C, 4.24×10<sup>-6</sup> atm was found, and it corresponds to the vapor pressure of MgO at the same temperature.