Glass surfaces corroded in water at 25°C in atmospheric environment as a function of depth from the surface were estimated by analysing O1s spectra. The SiO₂ content were compatible with those obtained by the ratio of relative intensity of ESCA spectra (I_cation/I_Si2p) and by the chemical shift of SiO₂ spectra. Compounds formed by corrosion were detected and identified by measuring chemical shift of cation spectra.
It was concluded that:
(1) In Na₂O-SiO₂, Li₂O-SiO₂ and Na₂O-CaO-SiO₂ system glasses, SiO₂ rich surface layer were formed by translation of cations in glasses. The layers on Na₂O-SiO₂ glasses were readily broken and peeled off by secondary reaction. For Li₂O-SiO₂ glasses the layers were not broken but grew.
(2) Na⁺ ions were more readily translated than Ca²⁺ ions in Na₂O-CaO-SiO₂ glass.
(3) The cations translated from the glasses formed compounds, such as Li₂CO₃, Na₂CO₃ and NaOH.
(4) SiO₄^4- network was formed from -^|Si_|-OH group by condensation reaction.

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Effects of oxidation on the room temperature strength of hot-pressed “balanced” β-sialon (z=2) were investigated. The specimens were oxidized in 1atm dry oxygen at temperature 1200° and 1300°C for 720h (30d) and characterized by measurements of bending strength, maximum surface roughness (R_max) and SEM observation of fractured surfaces.
The results are summarized as follows:
1) At 1200°C
During the oxidation up to 72h (3d), the strength tended to increase. The mechanism was suggested to be due to crack healing, although conceivably, stress healing and/or crack tip blunting by oxidation could have occurred.
After 72h (3d) to 168h (7d) oxidation, the strength decreased and the surface roughness increased indicating the increase of flaw size. The strength increased again at 360h (15d) in accordance with the dimunition of surface roughness and then the strength decreased progressively with the increase in oxidation.
2) At 1300°C
The effects of oxidation on the room temperature strength were not clear because of wide variation of the strength.
3) The origins of fracture were as follows:
a) boundary between oxidized layer and unoxidized substrate.
b) in the oxidized layer.
c) in the unoxidized substrate.
On the basis of the experimental results through the strength, maximum surface roughness (R_max) and SEM observation, the homogeniety of starting sintered material isc onsidered to be effective to improve the oxidation resistance and to minimize the decrease in strength.

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When a periodic stress was applied to a sodium borate glass under a constant electric field, the fluctuation of ionic current was observed. The fluctuation in a borate glass, as well as a silicate glass, had a close relation to the internal friction, i.e. the peak of the fluctuation corresponded to the low-temperature peak of the internal friction was observed. The peak was due to the migration of alkali ions induced by a stress. On the other hand, the peak of the fluctuation corresponded to the high-temperature peak of the internal friction was not observed. No observation of the peak was due to the absence of non-bridging oxygen ion.
The fluctuation of ionic current for non-periodic stress of a square wave type was measured. The fluctuation continued to appear but decreased gradually with continuous application of stress. Both results of borate and silicate glasses were almost equal except that the rate of decrease in a borate glass was slightly faster than that in a silicate glass.

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Work-of-Fracture for the measurement of effective fracture energy (γ_eff) of hot-pressed polycrystalline Na-β-alumina was studied. The hot-pressed Na-β-alumina samples with chevron notch angle (60°, 90° and 120°) were fractured at room temperature to 1300°C by three-point bending technique. The polycrystalline samples showed unstable fracture at the temperatures up to 1000°C in which the cracks propagated transgranularly. Above 1000°C, the polycrystals fractured semistably or stably. The fractured surfaces were intergranular one at stable fracture and intergranular-transgranular one at semistable fracture. In stable fracture γ_eff can be calculated from the load-time curves showing a stable fracture easily. To obtain a stable fracture, large chevron notch angle has been recommended, but large chevron notch angle of 120° did not always give the stable fracture in this study and rather gave semistable fracture, as in the case of smaller chevron notch angle of 60°. However, one can distinguish the unstable fracture area and stable fracture area in the fractured surface photograph of the semistably fractured samples, and γ_eff could be calculated from the area of stable fracture part of the photograph and the load-time curve even in semistable fracture. The obtained γ_eff value increased from about 20J/m² at 1000°C, to about 40J/m² at 1300°C. The reason of the rapid increase of γ_eff value with temperature may be attributed to the thermal blunting effect of crack tip. On the other hand, from the compliance analysis of the load-time curves of the stable fracture, a method for obtaining the relation between crack velocity (v) and stress intensity factor (K_I) was presented. This may be an easier method to obtain K_I-v relationship than Double-Torsion Method etc. and serve to consider the stress corrosion problem of ceramic materials in various atomospheres.

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4-point bending strength and the Weibull distribution were measured for hot-pressed β-sialon (Si₅Al₁O₁N₇) at room temperature, 1200°C and 1400°C in air.
The hot-pressed β-sialon was fabricated from SiO₂, Al and Si powders in N₂. The apparent specific gravity was about 3.14. The hot-pressed sample was consisted of single β-sialon as a crystalline phase by X-ray analysis, but glassy grain boundary phase was detected by SEM observation.
The room temperature strength was about 450MPa as the maximum value and the Weibull parameter, m, was 8.4. The m value decreased to 3.1 at 1200°C showing almost same maximum strength at room temperature. Decrease of m value was considered to be due to the formation of a few local pits which appeared on the surface. At 1400°C the strength decreased, while the m value increased to 4.0. This strength degradation was due to viscous grain boundary phase and increase of pit formation. Appearance of pits on all over the surface and formation of oxidized layer seemed to form relatively homogeneous surface and increased Weibull parameter, m, at 1400°C. The fracture toughness, K_1c, measured by 4-point notched bend test was almost constant value of about 3.2MPa √m from room temperature to 1500°C.

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The decrease in temperature of hot water in a thermos bottle has been formulated by considering the heat loss modes of the bottle.
The parameters for the equation have been determined by using the temperature test data from various kinds of thermos bottles.
The temperature of hot water in a thermos bottle at the time τ(h) is given by the following equation regardless of the capacity and the mouth size of the bottle, assuming that the initial temperature is 95°C: t_I=20+27.5exp(-0.6βτ)/1-0.5exp(-0.6βτ) where β is the insulating factor characteristic of each thermos bottle, which is determined by measuring the temperature of hot water in the bottle for a few hours.
The insulating effect test of a thermos bottle is currently judged according to the JIS method, although 24 hours are required.
However, using the above equation, the insulating effect is estimated in a few hours and the test time is reduced significantly.

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The optical absorption of high index glasses of systems La₂O₃-BaO-B₂O₃ and La₂O₃-PbO-BaO-B₂O₃ prepared from the raw materials of very high purity has been measured in the near ultraviolet region. The wavelength of absorption edge of the glasses of the system La₂O₃-PbO-BaO-B₂O₃ was much longer than that of the glasses of the system La₂O₃-BaO-B₂O₃, and it shifted toward longer wavelength with the increasing amount of PbO content. Although the absorption of the glasses of the system La₂O₃-BaO-B₂O₃ was largely affected in the wavelength region from 210nm to 400nm with impurity Ce, it was possible to obtain a colorless glass even if Ce was contained about 70ppm, provided that the content of other impurities such as transition metal were reduced to less than 1ppm.

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The kinetics of the carbonation of calcium oxide was studied thermogravimetrically from 12 to 55 Torr of CO₂ pressure at 500°C. The starting material, calcium oxide, was prepared by the thermal decomposition of calcium carbonate at 800°C for 1h in vacuum.
The results obtained were as follows:
(1) The recarbonation of calcium oxide proceeded through two stages. The first stage was the process represented by the linear rate law, where the reaction at the gas-solid interface was rate controlling. The second stage was obeyed the parabolic rate law which represented the diffusion rate controlling.
(2) The dependences of rate constants of these two processes on CO₂ pressure were also obtained respectively.

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The compressive strength of the mortars was investigated by using two series of samples; CaAl₂O₄-type solid solutions and mechanical mixtures of CaAl₂O₄ and SrAl₂O₄ with composition of Ca_1-xSr_xAl₂O₄. In the samples of mechanical mixture, the strength of the mortars decreased with increasing amount of SrAl₂O₄. In contrast, an increase in strength was observed on the sample of CaAl₂O₄-type solid solution. The effect of Sr-substitution on compressive strength of the mortars was studied by the observation of the texture of hydration products and the measurement of the heat of hydration. The results obtained are summarized as follows.
(1) With increasing Sr-substitution in the CaAl₂O₄-type solid solution, the compressive strength increased and the maximum strength for 30 days was found between 0.3 and 0.4 mole Srsubstitution. The maximum value of strength, 1000kg/cm², was about 1.7 times higher than that of pure CaAl₂O₄.
(2) On the fracture surface of the mortars prepared from Sr-substituted CaAl₂O₄-type solid solution, the hydration products packed each other and connected to the aggregate so tightly that the boundaries between them were not clearly recognized. This texture appeared after 1 day-curing and remained even after 30 days.
(3) With increasing Sr-substitution in the CaAl₂O₄-type solid solution, the heat evolution due to hydration slowed down and the heat accumulated up to completion of hydration remarkably decreased, in comparison with that of pure CaAl₂O₄. In the mechanical mixtures, however, a drastic evolution of heat was observed in the early period of hydration.

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A soda-lime-silica and an alkali lead silicate glass with varying amounts of water between 0.009wt% and 0.085wt% and between 0.009wt% and 0.063wt%, respectively, were prepared by heating in dried nitrogen and bubbling water vapor. Low temperature viscosities, thermal expansion coefficients, glass transition temperatures and Vickers hardnesses of these glasses were measured as functions of the water content. The decrease in logη at 550°C was about one for the increase of the water content of 0.76wt% in the soda-lime-silica glass and of 0.054wt% in the alkali lead silicate glass. No systematic variation with the water content was observed for the thermal expansion coefficient. The glass transition temperature was lowered by about 25°C for the increase of the water content mentioned above. The Vickers hardness was lowered with increasing water content; it decreased from 480kg/mm² for 0.009wt% water to 440kg/mm² for 0.085wt% water for the soda-lime-silica glass and from 430kg/mm² for 0.009wt% water to 395kg/mm² for 0.063wt% water for the alkali lead silicate glass. These changes in properties were explained on the basis of the concept that water produces weak break points in the structure of glass.

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