The warping caused by the differential contraction (Δl) between sheet steel and enamel layer was studied. Warping is a phenomenon of bending, so it should be considered that the internal moment of force must exist. The internal stresses, originating from Δl, act as a moment (M₁), and on the other hand a moment of resistance (M₂) of enameled sheet for warping must occured. From this view point, we could find a fundamental equation of warping under the condition of equilibrium M₁=M₂, as shown by equation (6) and (9).
In the equations, the warping is a function of factors that are differential contraction (Δl), modulus of elasticity of sheet steel (E_s) and enamel layer (E_e), thickness of sheet steel (s) and enamel layers (E or u and f), and moment of inertia of enameled sheet. But, by the decision of mechanical section, we can easily calculate the moment of inertia.
From the equation, the relation between warping and structural dimensions (S and E or S, u and f) at room temperature with the assumption of Δl=0.001 were calculated minutely within the range of common application shown in the diagrams (Fig. 7-Fig. 10).
As the warping is approximately proportional to the Δl, here the results are useful to observe the variations of warping relating with structures and to obtain the value of Δl at room temperature approximately from the data of measurement of warping and sectional dimensions without complicated calculations.
Obtaining the variation of warping with the change of temperature by experiment, we can calculate the Δl in the cooling period after firing of enameled sheet, and able to make clear the contractive conditions in cooling, but it is necessary to know the variations of E_s and E_e by the change of temperature previousely. Therefore the warping was measured with the change of temperature on several kinds of enamels, and the results are shown in the diagrams (Fig. 13-Fig. 17).
With the decision of neutral line of mechanical section we are able to examine the distribution of internal stresses in warping or bending. These examples are shown in the diagrams (Fig. 18-Fig. 21). If we consider the stress and strength of enamel layer, we can find the safety condition of enameled sheet, in case of mechanical dealing is required.

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On the basis of a Chrome-magnesite brick removed from the front wall of a 40-ton basic open-hearth furnace after 114 heat services, studies on the process of slagging reaction against the refractory have been carried out, with the aids of petrological microscope, integration-stage and chemical analysis. Mineralogical compositions of the reacted brick were deduced from the results of its chemical analysis. The results obtained may be enumerated as follows:
(1) A large amounts of iron oxide and lime were permeated into the hot working face of the brick from the furnace atmosphere during the operation.
(2) The permeated iron oxide was fixed as solid solution with chrome spinet in the brick.
(3) The permeated lime caused to form monoclinic pyroxene, after reacting with the matrix in the hot face.
(4) The original low fusible silicate in the hot face migrated into the intermediate part behind the hot face, resulting in the formation of the second zone enriched in lime, magnesia and silica.
(5) In the intermediate zone, about a half of the free magnesia was fixed into the spinel solid solution, while the remainder was distributed throughout the matrix as periclase.

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About Shiobara and Murakami sericite, some physical, chemical, and ceramic properties were studied.
The slip of sericite has high viscosity and show plastic flow at low concentration (15%). It is very sticky when wet, but has low plasticity. Base-exchange capacity is about 30 m. e. per 100g.
Sericite inverts readily to mullite at low temperature, and thermal-expansion curves show an absence of free silica, X-ray photograph show that between 1050°-1100° it inverts to anhydrous sericite, mullite and γ-Al₂O₃, and γ-Al₂O₃ diminish at 1200°.
Electron microscopes of sericite show very thin flakes, commonly grouped together in irregular aggregates, some of them have a distinct hexagonal outline. The thinnest flakes are approximately 30 Å thick. when fired, from 600° to 1100° it expands parallel to C-axis, and above 1200° its slarp edge disappears and become round.
The P. C. E. of sericite is SK 30, and when mixed with quartz it become SK 29-26, this difference is characterized by silica mineral.
The fired product is extremely white and smooth, and highly resistant to alkali and acid solution, and also has low tan δ if admixtures are properly selected. Insulation resistance is also high in spite of its high alkali content. Thermal conductivity is fairly lower than normal porcelains, and has good translucency.

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