High index glass prisms were set at enamel surface to form an Abbe refractometer. Focused gas laser beam was injected into the enamel layer. Surface birefringence was measured by using scattered light as a light source.
Surface stress was calculated from the birefringence. The method was applied to enamels on soft steel plates. Stress values of 8-19kg·mm^-2 were obtained, which were in the same level with values derived from material constants and by destructive or model experiments.

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Boron nitride films were prepared on nickel substrate by chemical vapor deposition using a gas mixture of BCl₃, NH₃, H₂ and Ar. The deposition conditions and the structure of the films were investigated in comparison with those of the CVD-BN films obtained previously on carbon steel substrate. The optimun flow rates of the reaction gases were determined as follows; NH₃: 0.8ml/s, BCl₃: 0.2ml/s, H₂: 0.5ml/s, Ar: 0.7ml/s, where the NH₃+H₂ stream was mixed with the BCl₃+Ar main stream near the substrate.
The BN films were grown in the temperature range of 800° to 1050°C. An amorphous and transparent BN film was formed at 800°C, while an opaque BN film, which is composed of a mixture of amorphous and crystalline phases, was grown at 950°C. At 1050°C, a crystalline and translucent h-BN film was found to deposit on a partially molten nickel substrate. A catalytic activity of nickel for the formation reaction of h-BN would be higher than that of iron.

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The effect of Ca-addition upon the vaporization of LaCrO₃ has been studied in vacuum.
Powder samples having the composition, La_1-xCa_xCrO₃ (x=0-0.15) were synthesized at 1400°C in air from the mixture of La₂O₃, Cr₂O₃, and CaCO₃ and pressed to pellets and sintered at 1700°C. The pellet was vaporized in a vacuum furnace equipped with a W-heater in the temperature range of 1700°-1900°C at pressure of -10^-5 Torr. The vaporization rate was obtained from the weight change of the pellet.
The porous layer of La₂O₃ formed at the surface did not suppress the vaporization. The vaporization rate was independent of Ca content within experimental errors. From the temperature dependence of the vaporization rate, the apparent activation energy of the vaporization of Cr₂O₃ component was obtained as 137±3kcal/mol.
The surface and the cross section of the sample were analyzed by XRD and EPMA after a vaporization run, and it was found that there was a Ca depleted perovskite region near the boundary adjacent to the La₂O₃ layer, and the composition of the boundary region was similar to LaCrO₃.
The vaporization of Cr₂O₃ component was not affected by Ca-addition, and thus the vaporization rate of La_1-xCa_xCrO₃ did not depend on Ca content significantly.

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Erosion of sintered Si₃N₄-Al₂O₃ and Si₃N₄-MgAl₂O₄ by molten blast furnace slag at 1500°C was studied by rotating cylinder method.
Six kind of materials were prepared. They were sintered Si₃N₄-Al₂O₃ which contains 20, 40 or 60eq% Al₂O₃, and sintered Si₃N₄-MgAl₂O₄ which contains 10, 20 or 40mol% MgAl₂O₄. The material containing 60eq% Al₂O₃ showed poor erosion resistance, but the other five materials showed superior erosion resistance to that of sintered alumina.
After the erosion test, the blast furnace slag adhered on the surface of the materials, and the slag permeated into pores in the material. At the slag-material interface, some solid particles which are considered to be β-Si₃N₄ or β′-sialon particles dispersed into the slag.
It can be considered that the erosion mechanism of the sintered Si₃N₄-Al₂O₃ and Si₃N₄-MgAl₂O₄ by molten blast furnace slag is dissolution of some components of the material and dispersion of undissolved particles in the material into the slag. When the material contacts with the molten blast furnace slag, the slag permeates into the material through pores, and dissolves some components of the material. By the reaction, the quantity of liquid phase in the material increases. It is considered that the dissolution rate of β-Si₃N₄ and β′-sialon particles are lower than that of X phase sialon, Al₂O₃ and MgAl₂O₄ particles. Therefore, β-Si₃N₄ and β′-sialon particles scarcely dissolve into the molten slag. But because the quantity of liquid phase in the material increases, they disperse into the slag remaining the form of solid phase.

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Ceramics, at high temperature stage, rediates the infrared rays much more than other materials, it was reported. We confirmed it by the spodumene series ceramics. We took note of this ceramics, and made it non-porous and high density from new practical making. And the tube heater used this ceramics has been compared with several actual heaters for drying from market. In this 1st report, the infrared radiation intensity is measured for the purpose of comparison among heaters. As the result, this β-spodumene series ceramics has the properties of not only strong anti-thermal shock and high mechanical strength, but also superior infrared radiation than all above heaters, it was confirmed.

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The influences of SiO₂ content, alkali fraction (called AF value) and the kind and amount of divalent cation oxides on the fading rate and the saturation darkening of silver halide photochromic glass were studied to obtain extremely slow-fading glass. It was suggested that photochromic glasses having a given half fading time and saturation darkening could be obtained by selecting SiO₂ content, AF value and the kind and amount of divalent cation oxides. Especially, extremely slow-fading glass with half fading time of more than 100h was obtained in the glass compositions containing more than 70wt% of SiO₂ and a few percent of BaO and PbO, and of AF=0.35-0.43. It was found that the fading was accelerated by IR irradiation. The half optical bleaching time was about 100s for both glasses with extremely long half fading time of more than 100h and relatively short half fading time of 25min. Thus, the rate of optical bleaching was independent of thermal fading rate.

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In order to protect rear window glasses from the dew growth by electrically heating with thick film conductors of ribbon form, one must obtain the conductor with a specific resistance of about 9×10^-6ohm·cm to which the metallic terminal is attached with an adhesive strength of more than 30kg/cm². Characteristics of conductors formed by firing silver pastes containing various additives at 645°C for 5min have been studied as functions of composition. The addition of 3% MnO₂ increased the specific resistance up to 10×10^-6ohm·cm from 3×10^-6ohm·cm but decreased the adhesive strength down to 15kg/cm² from 90kg/cm². Addition of 1.6% TiO₂ gave the specific resistance of 8×10^-6ohm·cm and the adhesive strength of 10kg/cm², whereas addition of 0.08% Rh gave the specific resistance of 9×10^-6ohm·cm and the adhesive strength of 56kg/cm². Thus, the conductors with desired characteristics were found to be prepared by adding organic compound of Rh to silver pastes. The specific resistance was discussed on the basis of the assumption that it is inversely proportional to the contact area of sintered silver particles.

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With the intention of improving the quality of slag wool by utilization of waste materials, the properties of glasses in the iron blast furnace slag-waste glass system were examined. With the increasing proportion of a waste glass in the glass batch, the viscosity of the melt increased, the viscosity change with temperature in the vicinity of liquidus temperature decreased and the initiation temperature of exothermic peak in the DTA curve measured in cooling process also decreased. Thus it seemed that the substitution of waste glass for blast furnace slag suppressed the devitrification tendency of the melt and extended the temperature range showing the viscosity suitable for drawing slag wool.
The resistance to alkali attack appreciated by the amount of weight loss after immersion in alkaline solution was fairly good in the glasses which were prepared from the batches containing the waste glass less than 60wt%, although the surfaces of such glasses were considerably rough after the immersion.

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