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Among the deteriorate produced in the spheroidal graphite cast iron, shrinkage cavity could be the most important influence. In order to find out the causes of formation of the shrinkage cavity, effects of volume change of molten metal at various temperatures and eutectic solidification have been investigated for both spheroidal and flaky graphite cast iron with same composition. The results obtained from the study are summarized as follows. (1) Volume changes of molten metal at various temperatures are 1.5∼1.7%/100℃ and similar both in spheroidal and flaky graphite cast iron. (2) Solidification of spheroidal graphite cast iron melt is a severe mushy type resulting eutectic solidification expansion which is seemed to introduce influence to the sand mold and produces large cavity.

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The ductile metallic tungsten was obtained at low temperature (1000-1300℃), using the metallic activator and the so called "chemical agitation" to facilitate the sintering effects. About 0.3 w/o Ni was impregnated into W as activator and the sintering atmosphere was chemically activated in the atmosphere of the mixture of H₂ and H₂O vapor saturated at 30℃. With this atmospheric control the activated sinterings effect was improved by 30%. With this double activation method, the sintered tungsten of the density 17.1 g/㏄ and that of 16.3 could be obtained by the sintering at 1300℃ for 1 hour and at 1200℃ for 1 hour, respectively. The mechanical-and physical properties of the ductile tungsten metal obtained by this method were superior compared to those obtained from the traditional "coolidge method", except their electrical conductivity. The activation energy E for the sintering was calculated with the temperature range of 850℃ to 1300℃. E for the double activated sintering was 43 ㎉/mole above 1000℃ and 57 ㎉/mole under 1000℃, and E for the activated sintering with 0.3% Ni-activator was 52 ㎉/mole above 1000℃ and 75 ㎉/mole under 1000℃. The microstructural observation and the study of sintering mechanism were also performed and discussed.

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A formula describing the progress of shrinkage of a powder compact has been derived for the case of sintering of nonspherical particles as follows: f=constant(t/T)^m exp[-mQ_v/(RT)] Here f is the ratio of change in a linear dimension of a powder compact during sintering to the original dimension, and t, T, R, Q_v and m are the sintering time, the sintering temperature on the absolute scale, the gas constant, the activation energy for the volume diffusion and the geometric factor respectively. The shrinkage of tantalum powder compacts composed of powders with the various shapes has been analyzed based on the formula. The activation energy for the volume diffusion of tantalum has been evaluated to be about 80,000 cal per mole. The various expressions on shrinkage of a powder compact have been discussed based on the formula.

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The kinetics of the dissolution of synthetic lead sulphate and of ropasted cosalite(2Pbs·Bi₂S₃) in solutions of sodium chloride and calcium chloride were investigated. When pressed pellets of synthetic lead sulphate were leached in sodium chloride, the following reaction was observed. PbSO₄+2NaCl=PbCl₂+ Na₂SO₄ Over the temperature range 60℃ to 90℃ the reaction displayed linear kinetics and the leaching rate was a function of stirring rate that were interpreted as indicating rate control by diffusion through the liquid boundary layer. The apparent activation energy for the dissolution process are 9.5±0.5 ㎉ and 12±1 ㎉ at stirring speeds of 950 r.p.m. and 630 r.p.m. respectively. Lead in the roasted cosalite appears to dissolve different from the synthetic material. Dissolution rate of lead in cosalite in a solution of NaCl is faster than that of CaCl₂.

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When the dissociation of ferrous sulfate(FeSO₄) takes place, the reaction mechanism and the composition of carbon that is used as reduction agent for accelerating dissociation were studied. The formation of ferric sulfate(Fe₂(SO₄)₃) occurs in the process of the dissociation of ferrous sulfate. The formation of ferric sulfate always delays the dissociation of ferrous sulfate. The formation of ferric sulfate and the oxidation of SO₂ through the catalytic action of Fe₂O₃ must be avoided to increase the dissociation rate. At this time the ratio of carbon required to prevent this formation is 6% of the sample under the inert condition and the sooner the sample is heated, the better. For the dehydration of FeSO₄·7H₂O and the roasting of FeSO₄ about 2250.8(㎉/㎏·Fe₂O₃) is required at 960℃.

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The effect of chromium on hardenability in high carbon steel was studied by U-curve method at quenching temperature of 800℃. The relation among the cracking induced by quenching, Ms temperature and hardenability was also studied. The activation energies for growth of austenite grain were as follows. Q_c=23,000 ㎈/㏖ Q_(0.3Cr)=32,000 ㎈/㏖ Q_(0.5Cr)=36,800 ㎈/㏖ Hardenability was dominated under constant heat-treatment condition by amounts of dissolved carbide and the precipitating velocity of carbide from austenite rather than austenite grain size before quenching. At constant hardenability, the cracking induced by quenching was prevented by reducing diameter of specimen and chromium amount. As the hardenability was smaller, the chromium reduction rate for reducing diameter of specimen must be bigger to prevent cracking induced by quenching.

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In the present study, the vacancy concentration of pure cobalt was investigated by measuring the resistivity. The discontinuity of resistivity increase was appeared near the transition point. The vacancy formation energy was determined as E_f=0.99 ev (the vacancy formation energy of the sample quenched from the temperature below the transition point). The moving energy of vacancy was calculated as E_m=0.43 ev (the vacancy moving energy of the sample quenched from 711°K).

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