Wurtzite-type BN powders produced by a shock compression method were treated at high temperatures and pressures. The reactions were carried out in the pressure range between 1atm and 80kb and temperature range between 650 and 2220°C for 30min. Phases present in a reacted sample were identified using X-ray diffraction method and scanning electron microscopic analysis.
Direct transformation from wurtzite to cubic BN was observed at fairly lower pressure region than that of direct transformation from hexagonal to cubic BN. The P-T region of cubic BN formation was determined.
The formation region of cubic BN obtained in the present experiments disagreed with the stable region of cubic BN. This may be attributed to sluggish rate of transformation from wurtzite to cubic BN. It was shown that Mg₃N₂ as a catalyst accelerates the transformation.
Tentative boundary among wurtzite, hexagonal and cubic BN was discussed from present results.

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The existence of ZnO-rich spinel solid solutions in the system ZnO-Al₂O₃ was confirmed by determination of lattice parameter and specific gravity, and also by application of the exsolution reaction in which the excess ZnO precipitates from the solid solution.
Structures of ZnO-rich, Al₂O₃-rich and stoichiometric spinels were studied using a program of the least square computation for X-ray powder data, compiled by the authors.
The defective structure in ZnO rich spinels was considered to be of anion vacancy type.

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The viscosites of K₂O-B₂O₃ and KF-B₂O₃ system glasses have been measured in the temperature range 600 to 900°C in order to examine the contribution of four-coordinated boron atoms in these glasses to the viscous flow. It has been found that when the observed values of viscosity are plotted against the N₄ which shows the theoretical fraction of four-coordinated boron atoms in these borate glasses, the change of viscosities for both systems can be represented by the same curve at each temperature. Each isotherm shows a minimum and a maximum at about 0.07 and 0.23 of N₄ respectively. The activation energies of viscous flow for both systems can be also represented by a single curve as a function of N₄, which shows a maximum at about 0.3 of N₄. By considering that the activation energies have been smaller than the bond energies of B-O and B-F linkages and the viscosity for both systems has not been dominated by the number of non-bridging or bridging bonds formed in the process of formation of four-coordinated boron atoms, it has heen expected that the viscous flow in these molten glasses may be treated as a problem of interaction among flow units remaining random network and the change of interaction energies might be attributed to the change of coordination ability of oxygen atoms in B-O-B networks due to the variation of N₄-value. The behavior of log viscosity isotherms for both systems has been discussed on the basis of the theory for absolute reaction rate process. Although the minimum and maximum in each isotherm can be interpreted in terms of the difference between the change of entropy for viscous flow and that of enthalpy, it has been considered, in the light of suggestion for flow mechanism in alkali silicate melts, that the anomalous behavior of viscosity might be attributed to the transformation of mode for viscous flow due to the variation of network modifier content.

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14Å tobermorite was easily synthesized by using silica glass as a starting siliceous material. Silica glass (SiO₂ 99.97%, Blaine specific surface 1, 550cm²/g) was mixed with CaO at Ca/Si mol ratio of 0.7. The water/solid ratio was 20:1 by weight. The slurry was cured at 100°C for 2 to 7 days in an autoclave with stirring.
The product was 14Å tobermorite of lath-like and platy crystals. The Ca/Si mol ratios were, 0.89 for 2 days reaction and 0.73 for 7 days reaction.
Dehydration of the 14Å tobermorite gave 11Å tobermorite, but the 11Å tobermorite could not be converted to 9Å tobermorite on heating at higher temperatures. The 11Å tobermorite, therefore, belongs to an anomalous type. This kind of anomaly in the thermal behaviour has not yet been reported to be found among 14Å tobermorites.

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The development of a new type of china very similar to bone china has been successfully secured by utilizing bone phosphate, a by-product of gelatin production, instead of using bone ash (calcined cow bone) as a characteristic raw material of the china. The fundamental study on the reaction process during firing this type of china was described in the present paper.
CaHPO₄⋅2H₂O as the major constituent of bone phosphate causes the reactions mentioned below when the green body was fired at temperatures over 1000°C, which is discriminated from the behavior of 3Ca₃ (PO₄)₂⋅Ca(OH)₂ as the major constituent of bone ash.
1) Bone phosphate releases a part of P₂O₅-component and makes it diffuse into the decomposed kaolinite and sericite, the whilst the former is transformed into β-Ca₃(PO₄)₂.
2) The P₂O₅-component which has diffused into the decomposition product of kaolinite or sericite facilitates the melting and promotes the sintering of the body.
3) Along with the melting of feldspar, the other part of P₂O₅-component released from bone phosphate diffuses into the melt of feldspar, while the bone phosphate is transformed into β-Ca₃(PO₄)₂.
From the results of various observations and measurements for the reactions mentioned above, it was secured that such a china body made in use of bone phosphate is successfully fired at a temperature lower by 100 to 200°C than the firing temperature for the conventional bone china and that the fired body consists of β-Ca₃(PO₄)₂ and glass. This is distinguishable from the traditional bone china made in use of bone ash which is known to consist of β-Ca₃(PO₄)₂, anorthite and glass.
The transverse strength of the china body was found to increase with progressing vitrification and with increasing elasticity due to densification resulting from viscous flow of the glassy matter formed during firing.

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For the development of a long duration open cycle MHD generating facility, one of the most difficult problems is the protection of the wall against the attack by seed materials. In general, potassium compounds such as KOH, K₂CO₃ and K₂SO₄ are used as seed material. They are very active, especially in molten state, and cause chemical and electrochemical damages to the wall. For designing the facility, much more information is required than available at present time about the effects of seed on the wall materials. The authors have continued the study on the reactions between potassium compounds and ceramics for MHD use i.e., Al₂O₃, MgO, ZrB₂ and ZrO₂, but in this paper, only the results about Al₂O₃ ceramics are reported. Results on other ceramics will follows.
Experiments were carried out in the electric furnace under the conditions close to the operating MHD generating channel. Test pieces 2.5×4.0×23.0mm in size obtained from three different Al₂O₃ ceramics were heat-treated in K₂SO₄ at 800 and 1300°C for the periods up to 2000 hrs.
For comparison, another set of pieces was heat-treated in air under the same conditions as given for K₂SO₄ treatment.
Changes in bending strength, hardness, volume, weight and microstructure of the specimens were examined and following conclusions were obtained.
(1) Properties of Al₂O₃ ceramics were scarcely affected by K₂SO₄ treatment at 800°C up to 2000 hrs.
(2) Properties of Al₂O₃ ceramics were storongly affected by K₂SO₄ treatment at 1300°C. Bending strength decreased significantly after initial 100 hrs for cold-press Al₂O₃. For hot-pressed Al₂O₃, on the other hand, it decreased gradually with treatment time up to 1000 hrs. Changes in volume and weight were also remarkable, which were mainly due to the change of the surface layer of specimens to β-Al₂O₃ which formed by the reaction with K-ion.
(3) After heat-treated in air at 1300°C for 2000 hrs, Al₂O₃ ceramics changed scarcely in weight and bending strength. Only slight increase in volume was recognized.

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The method of the determination of phosphorus in television tube glass was investigated by molybdovanadophosphoric acid method and X-ray fluorescence spectrometry.
The effect of diverse elements containing in television tube glass on the molybdovanadophosphoric acid method was investigated, and in the range containing in glass almost all elements except zirconium did not interfere the determination of phosphorus.
Zirconium interfered the determination of phosphorus by producing the precipitate of zirconium phosphate in the sample solution. But it was proved that zirconium was masked as the fluoride complex by the addition of fluoride ion and did not interfere the determination of phosphorus.
Considering the results obtained by the investigation about the effect of diverse elements and measuring conditions, the method for the determination of phosphorus in television tube glass was decided as follows:
1g of powdered glass sample is taken to the platinum dish and decomposed with hydrofluoric acid and perchloric acid. The residue is dissolved by 10ml of 1:1 nitric acid and diluted to 100ml with water, and then the solution is stored in a 100ml polyethylene volumetric flask. 50ml of the sample solution containing less than 3.0mg phosphorus as phosphorus pentoxide is transferred to a 100ml volumetric flask. 2.0ml of 1:1 nitric acid and 20ml of 0.221 per cent sodium fluoride solution are added successively and the solution is diluted to about 80ml with water. Then 5.0ml of 0.5 per cent ammonium vanadate solution and 5.0ml of 10 per cent ammonium molybdate solution are added in this order and diluted to 100ml with water. After 10 minutes the absorbance of the solution is measured at 430mμ in 1cm cell, and the content of phosphorus as phosphorus pentoxide is obtained comparing against a calibration curve.
Blank is run through the whole procedure. The calibration curve is similarly established.
By this method more than 0.05 per cent phosphorus as phosphorus pentoxide in television tube glass is determined with relative error of ±5%.
At the same time the X-ray fluorescence spectrometry was investigated. There is a linear relationship between the intensity of X-ray fluorescence of PK_α and phosphorus content as phosphorus pentoxide by this molybdovanadophosphoric acid methhod mentioned above, and it is proved that more than 0.05 per cent phosphorus as phosphorus pentoxide in television tube glass is determined by X-ray fluorescence spectrometry.

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α-燐酸カルシウムの水和反応が塩基性液中, 100℃以下で生じることを見出した. 反応は温度およびpH低下とともに遅くなり, 室温およびpH約5以下ではほとんど進行しなかった. 水和反応生成物は硬化体として得られた. 十分に水和させた生成物は, Ca/Pモル比=1.5のカルシウム欠損水酸アパタイトであると同定された. このアパタイト中には水分子, OH^-およびHPO₄^2-のHとして約4.7%の水成分が含まれていた. アパタイト構造は700℃までの加熱によって全含有水分の約75%を揮発させても安定であった. このときHPO₄^2-の消滅とP₂O₇^4-の生成とが確認された. 残りの水分は, OH^-の除去とβ-燐酸カルシウムの生成とを伴って, 755℃で急激に放出された. アパタイト-燐酸カルシウム分解反応の見掛け活性化エネルギーは65kcal/molであった.

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