In casting in cement sand mold sand holes tend to increase with increasing either pouring time or pouring rate. To eliminate sand holes it needs to control the two factors in an adequate way. Sand holes are formed more often in cement sand mold than in sand molds bonded with clay, sodium silicate or oil. There is no relation between the occurence of sand holes and the strength of sand mold measured at room temperature, but a close relation between the formation of sand holes and the value of shock at high temperatures.

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  When aluminum powder is added to monoaluminum phosphate solution, a gelling reaction takes place. This reaction can be applied for self-hardening sand molding. For example, a mixture of 100 silica sand, 5 monoaluminum phosphate and 0.25 aluminum powder by weight hardened by itself and a test piece of 1-1/8 in dia. x 2 in gave a compressive strength of 20kg/cm² after it had been let alone for 8 hours (Fig. 1). The similar reaction could be made by using iron or zinc powder. The compressive strength of the molded sand was increased with increasing monoaluminum phosphate content while it was less influenced by the amount of metal powder added excessively. The properties of the mold was not changed when it was stored and there was no tendency for the mold to be wet by absorbing moisture in air. It needed not dry the mold, because the sand mixture originally contained little water. The collapsibility of the sand mold was good, because the mold lost its compressive strength when it was red heated. The mold had a disadvantage that when it was heated at high temperatures, it caused veining. Therefore, it needed to add a small content of dextrin for preventing the mold from veining.

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  Molten iron was heated at 1,450°C and poured into metal molds preheated at temperatures ranging from 950° to 1,120°C. The solidification processes thus cast were measured by a highspeed automatic thermorecorder provided with Pt-Pt:Rh thermocouple.
  The temperature-time solidification curve of cast iron thus obtained consisted of two parts, namely metastable solidification and stable one. In case of grey cast iron the degree of undercooling during eutectic solidification increased with increasing cooling rate until the cooling rate had attained a critical value. The graphite eutectic temperature increased with increasing silicon contents, while the ledeburite eutectic temperature reversely decreased with increasing them. Therefore, the graphite eutectic freezing range was made wider with increasing silicon contents.

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  The purpose of this study is to evaluate the reducing power of the atmosphere in a cupola for partially reduced ore used for cupola charge under ordinary cupola operating conditions.
  An experimental melt was carried out in a 2 ton water-cooled hot blast cupola of 540mm diameter at the tuyere level, using a hot blast temperature of 510°C. The blast rate of 42.5 Nm³/min was controlled with an air-volume controller-recorder.
  Under an operating condition of a charge composed of 80% sponge iron and 20% pig iron, using coke rate of 40%, the combustion rate of 0.29 in the cupola was obtained and the average metal temperature was 1,460°C.
  In setting up the equations and the material balance, 33 Kmols of carbon per ton of iron produced are gasified at the tuyeres with a moist blast. The sum of the chemical reaction of the indirect reduction of FeO and solution loss is the same with the direct reduction of FeO. Accordingly, the final results are stoichiometrically the same irrespective of whether the carbon is gasified by reacting with CO₂ gas or with solid FeO. Above the tuyere, 4.9 Kmols of carbon are gasified with oxygen from the charge. A net ton of iron produced contains about 6.97 Kmols of FeO and about 0.62 Kmols of Fe₂O₃ by calculating from analysis values of FeO or Fe₂O₃ and the recovery rate of sponge iron charged. Therefore, calculation for direct reduction ratio is possible and the value obtained was 55.4%. Therefore, the changes in the composition of the gas stream in the cupola can be calculated. As shown in Fig.1, bosh gas is converted to shaft gas which in turn is converted to top gas.
  The reducing power of the atmosphere gas in the cupola in which FeO is reduced to metallic iron, can be evaluated with the value of CO/CO₂ ratio which exceeds the equilibrium of iron oxides in CO and CO₂ gaseous mixtures. A CO/CO₂ ratio of 2.85 in the bosh gas would mean the less reducing power of the cupola atmosphere.
  To maintain the reducing power of the bosh gas, a CO/CO₂ ratio of at least 7 should be maintained in consideration of gas-solid equilibrium. Accordingly, a higher coke rate or a limited blast rate to maintain the reducing power and to satisfy the heat requirement is necessary in cupola operating conditions.

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  Zinc alloys used had various copper contetents of 1.0, 1.5, 2.0 and 2.5%. They were melted under vacuum lower than 0.1mm Hg in a furnace of special design and subsequently pressurized by nitrogen up to 2, 6 or 9.5 kg/cm² at 600°C. The melt was poured into a metal mold of Y-block form throuhg a small tap hole in the bottom of graphite crucible, where the mold was watercooled. As compared with alloy ingots cast under an atmospheric pressure, the ingots cast under high pressures had the following features: there was found no shrinkage hole at the intersection of the Y-block castings; the size of crystal grains grew with increasing the pressure; as a result of tensile strength test it was found that the bottom part of the ingots was stronger than the other part of them; the tensile strength was increased with increasing the pressure up to 6 kg/cm² but reversely decreased when the pressure was increased up to 9.5 kg/cm²; the efeffect of pressurs was the most distinct in the alloy having copper content in a range between 1.5 and 2.0%; in the case of zinc alloy of 2.0% copper its grain size was finest when casting was made under 6.0 kg/cm².

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