Silicothermic reduction method was applied to produce ferrosilicon which contains Mg and other alkali earth metals and which is a powerful nodularizer of graphite in cast iron. Ferrosilicon was melted in a high frequency induction furnace using a MgO-lined crucible and treated by fluxes of powdered MgO, CaO, SrO, BaO or CaCO₃+MgCO₃.
  Mg content of the ferrosilicon increased with the reaction temperature. Contents of other alkali earth metals were approximately in proportion to their boiling points. The nodularizing characteristics of the ferrosilicon were compared by examining the cast iron treated by them microscopically. The fading tendencies of nodularizing action were evaluated indirectly from the effect of the holding time after inoculation on the chilling depth of gray cast iron treated by various ferrosilicon and calcium silicide. From the results of these tests, it was concluded that the ferrosilicon containing small amounts of Mg and Ca reduced from their oxides can be used as an effective nodularizer for cast iron.

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  The content of elements in the thin pipes of low carbon steel cast centrifugally in metal molds decreased near the inner surface of the pipe wall which was 10mm in thickness. This phenomena which is the reverse of that in centrifugally cast thick pipes was considered to be the result of oxidation during the centrifugal casting process. Mechanical properties of these thin wall pipes did not vary at different mold spinning speeds or with inner-mold coating thickness, but depended upon chemical composition. The authors considered that centrifugal forces and cooling rates in the range of these experiments was not able to affect the microstructures of these thin wall pipes.

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  Shear property which was considered to be closely related to compaction behavior of powder was studied with molding sand using a direct shear apparatus. The relationship between the shear stress and the normal stress at the shear plane was determined in the direct shear test of the molding sand, and it was found to be in good agreement with Mohr-Coulomb's equation. Applying the theoretical equation relative to pressure distribuiton in compressing powder mass to the squeeze compaction of molding sand, the pressure transmission rate was calculated using the values of the internal friction angle and the wall friction angle which were obtained in the direct shear test. Comparision of the calculated result with the experiment indicated that there were considerable discrepancy between these values, but also indicated that the equation could be used as an empirical equation.

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  It is generally considered difficult to reclaim foundry waste sand containing water glass into clean sand by dry and wet methods. In particular, sand reclaimed by the usual dry method has limited quantity for reuse, because Na₂O accumulates in the sand. In our previous report, we stated that the sand containing water glass became easy to scrub and clean after high temperature treatment, because the treatment lowers the bonding force of water glass. But this kind of sand easily sticks together at high temepratures, therefore generally speaking, thermal treatment can not be applied in practice for reclamation. We report the dicovery of a new thermal method which uses a special lean fluidized bed for the reclamation of sand containing water glass which does not stick together at high temperatures.

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  In order to clarify the mechanism of enveloping ceramics with cast iron that was reported in the previous paper, enveloping the ceramics with columnar shape which exert a uni-oxial compressive load and also compressive deformation with a cubic shape were tested. Buckling occurred on the ceramics with a smaller diameter when it was enveloped, although it was possible to envelop the ceramic pipe soundly. It is thought that the notable difference in soundness of these composite castings mainly arises from the shape of the ceramics enveloped. There is no tensile stress on any section of the ceramic pipe when there is compressive load on the outer surface.
  The stress-strain curves of the ceramics compressed was similar to that of metal. Hence, the nominal compressive strain of the ceramics enveloped corresponded to the stress-strain curve. It was located in the range of little over the elastic limit when the buckling was slight. It became clear that further study was required to produce a sound ceramic enveloped casting, with a suitable combination of core sand, and composition of ceramics and metal.

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  With the aid of scanning electron micrography, the diffusion process of the catalyst into the furan binder and the bridge between sand grains were investigated. The dispersion of phosphoric acid and p-toluenesulfonic acid (PTS) catalysts crystallized in the hardened binder was characterized by ease of diffusion into the furan binders of high and low urea-formaldehyde (UF) contents. This is consistent with the observed hardening rate of the binder. When phosphoric acid was used for the furan binder of low UF content, a spongy surface was observed on the binder resin by a row of pinholes aroud the bridge between sand grains. Consequently, the compression strength of the sand mold decreased, while the flexibility increased. The bridge cracked when UF content of the binder was high. Numerous hair-cracks appeared when catalyzed by PTS whereas there were only a few long cracks by phosphoric acid. Neither type of cracks decrease the compression strength of the sand mold, when they appeared only on the resin surface.

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