Lithia bodies having virtually zero porosity when fired between 1260° and 1320°C, were obtained by using pyrophyllite and lithium carbonate. These bodies were characterized by nearly zero thermal expansion, high mechanical strength, and excellent thermal-shock resistance.
The detected mineralogical compositions from X-ray analysis of these bodies consist of β-spodumene and/or β-spodumene-SiO₂ solid solution only, and the suitable molecular compositions of these bodies lie between 1.06 Li₂O⋅1.00 Al₂O₃⋅5.33 SiO₂ to 1.09 Li₂O 1.00 Al₂O₃⋅5.62 SiO₂.

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The expansion characteristics of pyrophyllite and sericite during dehydroxylation were examined measuring linear expansion on pressed specimens with or without previous treatmeat of particle orientation, combining with X-ray diffraction data. The causes of the expansion were discussed comparing with the cases of talc and kaolinite that showed thermal shrinkage during dehydroxylation.
The results are summarized as follows.
1) It was concluded that the expansion of pyrophyllite and sericite compacts resulted from the permanent lattice expansion along c-axis which reached 1.6-2.0% and 0.5-0.7%, respectively, and from the particle rearrangement induced by their lattice expansion.
2) Sericite compacts showed almost same degree of permanent linear expansion as that of pyrophyllite in spite of much less amount of lattice expansion of sericite, which would be attributed to the greater rearrangement of sericite particles owing to their feasible flexibility.
3) It is supposed that the lattice expansion of pyrophyllite or sericite is closely related to the mechanism of dehydroxylation (homogeneous) in which no cation movement takes place except for proton, while in the case of talc or kaolinite the reconstruction of lattice caused by the cation movement leaving pores behind (inhomogeneous), brings about the shrinkage of the bulk volume of the aggregates.

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Closely joined couples of single-crystalline MgO with single-crystalline Al₂O₃, single-crystalline MgO with poly-crystalline Al₂O₃, poly-crystalline MgO with single-crystalline Al₂O₃ and poly-crystalline MgO with poly-crystalline Al₂O₃ were heated at certain temperatures below 1600°C for certain periods shown in Table 1, so as to form spinel layers. The joined surfaces of single crystals were {100} for MgO and {0001} for Al₂O₃.
The orientation of crystals at certain parts of the formed spinel layers were found comparing the intensity of diffractions from many faces.
The following conclusions were obtained.
(1) The textures of spinel formed on either side of the initial interface is different each other. (2) The mode of orientation of the spinel crystals formed at the position of single-crystalline Al₂O₃ is that the direction of the hexagonal closed packing of oxygen in the Al₂O₃ coincides with the direction of the cubic closed packing of oxygen in the spinel. (3) The mode of orientation of the spinel crystals formed at the position of single-crystalline MgO is that a-face of the MgO coincides with the a-face of the spinel. (4) The mode of orientation of the spinel crystals formed at the position of poly-crystalline MgO and Al₂O₃ are random.

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Kinetic equations for analyzing the initial combined sintering of volume and surface diffusions were derived from conventional models under the assumption that the volume diffusion coefficient was very small compared with the surface diffusion coefficient and the particle diameter of sample was less than 10^-4cm. The shrinkage data of NiO, Al₂O₃, Fe₂O₃, and MgO were best described with equation (1) for the first three samples and with equation (2) for the last one.
(ΔL/L₀)^7/2/t-δt=KΔL/L₀+H………………(1)
(ΔL/L₀)^7/2/t-δt=K_C(ΔL/L₀)^3/2+H………(2)
The plots of Eqs. (1) and (2) gave the values of K (or K_C) and H. The activation energies for volume diffusion and surface diffusion were estimated from Arrhenius plots of K (or K_C) and H values.
The activation energies for volume diffusion were in good agreement with those measured by tracer self-diffusion techniques. The values of the activation energies for surface diffusion obtained were about 1/2 or 2/3 of those for volume diffusion. The surface diffusion coefficient was expressed as D_S=D₀ exp (-E_S/RT). The values of D₀ for NiO, Al₂O₃, Fe₂O₃, and MgO were 3.36×10^-4, 1.06×10², 1.14×10⁵, and 6.21×10^-1 and E_S were 20.8, 63.8, 79.3, and 40.9 kcal/mol. These values were compared with those obtained by other authors.

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The so called “Mo-Mn process” and “Mo process” are the methods for forming ceramic-to-metal hermetic seals by metallizing, nickel plating and successive hard-soldering.
Author has reported in his previous paper on alumina ceramic-to-metal seals by the Mo-Mn process. In this research, high alumina ceramic discs containing MnO (92 wt% Al₂O₃) were sealed to Kovar parts by the Mo process. Tensile strengths of sealed layers and vacuum tightness of the seals were studied.
The layers were examined by optical and scanning type electron microscope and by electron probe microanalyzer.
Quartz glass-Mo foil seal was additionally observed, in order to achieve an insight on the sealing mechanism of the Mo process.
The results were as follows:
1) Seal strength was the highest and the best vacuum tightness was obtained when the ceramics were metallized at 1450°C-1500°C for 60 minutes.
2) The sealing layers were consisted of multiple layers which were arranged in the following order; Ceramic-Metallizing layer-Ni plating layer-Hard solder-Ni plating layer-Kovar
In the seals by Mo-Mn process, the intermediate layer was observed between ceramic and metallizing layer. However, no intermediate layer was recognized in the seals by the Mo process.
3) In the seal of quartz glass-Mo foil, the surface layer of Mo metal was oxidized and Mo oxide thus formed diffused in to the quartz glass forming a transition layer, which was quite useful in reducing sealing stress and in improving adhesion.
4) Pores in the Mo metallizing layer were filled with glassy phase in the system SiO₂-MnO-Al₂O₃ and nickel; the former came out from ceramic body and the latter from nickel plating layer. Infiltration and interdiffusion of these materials gave strong and vacuum-tight sealing layers.

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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.

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We carried out the thermal fatigue test by partial heating in furnace using the test pieces in disk form, on the other hand computed elastic stresses using it's mechanical properties and experimental conditions. From those results, we get the stress-fatigue life curve of the refractory.
We can guess the fatigue life of the refractory, if we can decide the maximum thermal stress in it's practical condition both theoretically and experimentally.
This testing method is useful for thermal fatigue test of the shelves for tunnel kiln.

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The adsorbent for heavy metal ions was synthesized by the hydrothermal treatment of pumice or shirasu and sodium hydroxide-sodium chloride solution.
The synthesized adsorbent was identified by the X-ray diffraction method, and it's cation exchange capacities were measured. The adsorption capacities of the synthesized adsorbent were 0.4-1.9meq/g for Cu, Cr, Cd etc.

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