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The effects of powder size, heating rate, and sintering time on dimensional change, oil impregnation, radial crushing strength, and microstructure were examined in sintered Cu-10% Sn mixture. The copper powder sizes were -150 mesh and -270 mesh, and tin powders were -230 +325 mesh and -400 mesh. The specimens were sintered in hydrogen-nitrogen atmosphere at 797℃ for sintering time up to 15 minutes. The dimensional change of Cu-Sn mixture compacts occurred mostly during the heating up stage. Larger powder size, in particular, larger tin powder size and faster heating rate caused more expansion. The oil impregnation and radial crushing strength changed in a way similar to the density change. The observed dependence of growth on particle size and heating rate can be explained by densification effects of the solid state and liquid state sintering and the growth due to the penetration of copper particle boundaries by tin rich melt. The specimen of fine powder mixture sintered for 15 minutes showed uniform bronze structure with large grains. The practical implications of the present results are discussed.

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In order to investigate into the wear-resisting property of the austenitie high manganese steel, the wear rate per unit load (M) was measured using the wear tester manufactured to simulate the abrasive condition. Hardness of the bulk (H_B) and the abraded surface (H_(A·S)) and the metallographic structure were also studied in relation to the abrasive wear resistance of the steel. It is shown the wear rate per unit load (M) is related with each of the bulk hardness and the abraded surface hardness as follow expressions: 1) M×10^5=(14.008±1.758)-(0.0291±0.046) H_(A·S) ㎎/㎝-㎏. 2) M=2/1000(60)^(-n)×1/H_B ㎎/㎝-㎏. Where n is strain-hardening coefficient. Expression 1) is empirical while expression 2) is semiempirical formula which has a relation with the intrinsic property of the steel. On the view of microstructure of the steel, it is found the hnitial grain size (r) has no effect on the wear-resisting property of the Steel but the intercarbide spacing (d) has an marked influence on the wear-resistance. And the obtained relationship is as follow; 3) M×10^5=(5.4±0.3)-(43.0±6.07)1/√d ㎎/㎝-㎏.

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The production of formed coke has been realized in use of a non-coking coal as the main raw materials through the world, but It has not studied in our country about that. So I have studied the following two problems in order to develop the formed coke process. 1) Investigation of formed coke-process conducted through the world. 2) Studies on the production of a formed coke by using anthracite as a raw materials. As the result I have recognized the following three points. 1) The composition of ratio of raw materials was Jung Sung anthracite 74%, coking coal 16% (C. BI. 6) and added 10% of coaltar pitch. 2) Drum Test index (DI^(150)_(15) by JIS) had 85∼86% while conventional coke had 79∼80%. 3) Because of the uniformity of size, shape and weight of the formed coke, using in the blast furnace is convenient.

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Increasing demand of cast iron or cast metal, more and more cupolas and its facilities have been installed, which have resulted in the increase of the amount of dust and exhaust gas. Consequently it has become one of the important problems to remove them. And author manufactured for trial a new apparatus by which the following jet condition, jet water, the efficiency of removing dust can be obtained. According to the experiment, when contained gas and jetting waterdrops were made to run perpendicularly by letting waterdrops jet in radius direction from the center of the cylinder the highest efficiency could be obtained, with lower price and less water quantity the conventional Venturn Scrubber or Cyclone Scrubber. In that case, it was shown that the ability of absorbing the dust was highest when the diameter of the jet waterdrops is 0.4-1.1 ㎜ø. The amount of water was most suitable when it was 70 to 110ℓ/min, and its efficiency was 92.5%, which means the dispersed amount of dust in the air 0.884gm/Nm³ against the whole amount of dust 5.8gm/Nm³. Judging from the result of this experiment, author thinks that the investigation in the hydro-mechanical way for the formation of the most suitable group of waterdrops will make it possible to obtain the dust-removing apparatus with simple structure and higher efficiency.

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Impact toughness of 0.36% C-Ni-Cr-Mo steel, whose composition is similar to the AISI 4340 steel, has been studied in relation to microstructures: tempered martensite, tempered lower bainite +10% martensite and tempered upper bainite. The transition temperature determined by the average energy criterion, has been found to be lowest in the tempered martensite and highest in the tempered. upper bainite. The relation between impact toughness end distribution of cementite precipitates in the microstructures has been discussed.

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Potentiodynamic polarization behavior of 304 stainless steel has been recorded with a scan rate of 600mV/min in 25℃, stagnant 10 v/o sulfuric acid solutions containing various concentrations of ferric ion. The shape of the polarization curves was changed in that manner generally predicted by the mixed potential theory, but analyses of them revealed that the adsorption of ferric ion on the electrode surface was occurring. Reduction of ferric ion proceeded at a diffusion limited rate over a wide range of electrode potential. The passive film once formed in the course of potential scan from active to noble side appeared so stable as to reduce the active peak current to a small value during the repeated potential scan. Some electrochemical parameters related to the dissolution of passive film by ferric ion was also examined. Active peak potential and oxygen evolution potential were little changed with the addition of ferric ion in the limit of experimental error.

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Kinetics of the reaction of hydrogen with zirconium was studied in the temperature range of 600-900℃ using weight gain method in the flow system of Ar atmosphere. The rate controlling step of the reaction is shown to be diffusion of hydrogen through the zirconium lattice. Diffusion of hydrogen in δ-zirconium hydride was studied in the temperature range of 660-850℃. Hydrogen diffused from a surface of constant concentration into a homogeneous phase, developing a second phase on the surface. For the above conditions, the diffusion equation was solved using the method treated by Wagner for this case, By correction with the measurement of the displacement of moving boundary, average concentration at 750℃ in given by. C￣=4.680D^(1/2)/h·t^(1/2) where D is diffusivity, t is time and h is specimen thickness. Similar expressions can be obtained for the other temperatures. By plotting C￣ vs. t^(1/2), we can calculate diffusivity from the slope. The temperature dependence of diffusion coefficient is given by. D^δ=6.20×10^(-3) exp[-(15,800±1,800)/RT]㎠/sec

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Among the several known processes of semiconductorgrade silicon production, the hydrogen reduction of trichlorosilane (TCS) is found to be the most convenient and economical method. In this study of high purity silicon production, the tube flow process is used to redus TCS with hydrogen. The 99.9% pure TCS, manufactured by Ventron, is distilled for the starting material in the reduction. The distilled TCS is vaporized by bubbling with small quantity of hydrogen in a glass tube at 0℃. The resultant yield is especially compared with the theoretical one calculated thermodynamically. The yield of silicon is 60-70% at the optimum condition of 1050-1100℃ reaction temperature and 60-100 mole ratio of hydrogen to TCS. Surface of the deposited silicon, a polycrystalline dense mass of lustrous appearance, is treated with hydrofluoric acid. By the emission spectroscopy the purity of silicon thus produced is determined to be higher than 99.999%.

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The effect of prestrain on creep phenomena to low carbon steel has been investigated. Prestrain was changed from 0 to 7.1% for 0.1% c-steel and from 0 to 5.59% for 0.43% c-steel. Prestrain over the yield point was resulted in the uniform plastic deformation by increasing load. Creep was examined in the range of temperature from 400℃ to 500℃, and of stress from 24.59(0.1% c-steel) to 34.68㎏/㎟(0.43% c-steel). Creep strength rises with increased prestrain and carbon content. The ratio transition creep rate against steady creep rate was increased with increasing prestrain and carbon content.

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