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50 巻, 7 号
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研究論文
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藤本 留吉1978 年 50 巻 7 号 p. 403-408
発行日: 1978/07/25
公開日: 2012/06/02
ジャーナル フリーThe following two methods were conducted in order to elucidate the relation between surface tension and apparent viscosity in fluid sand mixture process; (1) physical and chemical tests were performed to obtain the viscosity of the colloidal solution without sand, (2) slump test (JIS A1101) was performed to find out the workability of the slurrys with sand. From the second method, the following empirical formula were obtained.
H−hx=Kγe−bp and Kγ(H−hx)=S
where, hx is slump value, H is initial height of slurry, hx/H is coefficient of slump value, Kγ is constant, related to surface tension of binder, b is proportional constant, P is porosity and S is strength of sand specimen.抄録全体を表示PDF形式でダウンロード (708K) -
柳沢 平, 丸山 益輝1978 年 50 巻 7 号 p. 409-413
発行日: 1978/07/25
公開日: 2012/06/02
ジャーナル フリーCast iron containing steadite are used as highly wear resistant material. The plate-like cementites in steadite, especially, improves wear resistance of the materials considerably. However, the conditions and the mechanism for the formation of this structure are not yet defined and these were investigated in Fe-C-P-V-Si system. For the formation of plate-like cementites in steadite, the content of vanadium should be increased in cast iron when phosphorus and silicon contents are higher and cooling rate is slower. Plate-like cementite is considered to nucleate in highly supercooled residual liquid with high phosphorus and vanadium contents. The effect of phosphorus and vanadium upon plate-like cementite formation is explained by the change of the temperature difference between stable and metastable equilibriums and the supercooling-eutectic growth relationship.抄録全体を表示PDF形式でダウンロード (778K) -
小池 敬一1978 年 50 巻 7 号 p. 414-419
発行日: 1978/07/25
公開日: 2012/06/02
ジャーナル フリーA water soluble mold for high melting point alloys such as cast steels, may make the removal of mold very easy and the foundry environment free of noise and dust. Water soluble molds consisting of alumina as a base material and some metal oxides or hydroxides as a binder were studied as a candidate for mold in steel casting. The molds formed from a mixture of alumina (Al2O3), barium hydroxide (Ba(OH)2) and water, and dried at 200°C, showed the transverse strength of above 30kg/cm2 over a temperature range of 20°C−1,300°C, and of above 15kg/cm2 over a range of 1,400°C−1,500°C. Heating of the mold, up to 900°C, caused the reaction of Al2O3 and Ba(OH)2 resulting in the formation of barium aluminum oxide (BaAl2O4). BaAl2O4 is very stable and diffusion of Ba into Al2O3 and evaporation of BaO is small during solidification of steel. Therefore, BaAl2O4 can remain in the binding layer of the mold and the layer can be easily decomposed by water. After decomposition of the mold, alumina can be separated, and BaAl2O4 can be recovered as Ba(OH)2·8H2O and BaAl2O4·6H2O. From these results, the mold consisting of alumina and barium compounds may find a possible use as a mold for steel casting.抄録全体を表示PDF形式でダウンロード (769K) -
高瀬 孝夫, 中村 康彦, 護法 良憲1978 年 50 巻 7 号 p. 420-424
発行日: 1978/07/25
公開日: 2012/06/02
ジャーナル フリーIon nitriding has been successfully used to improve the anti-scuffing characteristics and the endurance limit of spheroidal graphite cast iron. Silicon, which is dissolved in great amounts in α-Fe, has an important effect on the ion nitriding. In this study, spheroidal graphite cast iron (3.5%C, 1.5−3.4%Si) with ferritic and pearlitic structures, which were cast in shell and metal molds, were ion nitrided using the following conditions: 510∼570°C, 1∼6hr, 5 torr total pressure, N2 : H2=70 : 30 (vol% ) and 25 : 75. These gas settings correspond to a nitrogen partial pressure of 4.61×10-3 atm and 1.64×10-3 atm.
The compound zone which was produced by ion nitriding is compact and porosity was not observed. This zone consists of ε, γ' and Si3N4. The existence of a fine Si3N4 was observed by means of electron microscopy. The maximum hardness of the compound zone increased together by increasing the silicon content which forms a fine Si3N4 nitride. The thickness of the compound zone and the total nitrided depth decreased in proportion to the silicon content and increased as the treatment temperature and time increased. The total nitrided depth in the sample of shell mold, was larger than that of metal mold. The rate of diffusion of nitrogen by ion nitriding is much higher than that of the Tufftride process.抄録全体を表示PDF形式でダウンロード (731K) -
磯部 俊夫, 久保田 昌男, 北岡 山治1978 年 50 巻 7 号 p. 425-430
発行日: 1978/07/25
公開日: 2012/06/02
ジャーナル フリーThe temperature range of semi-solid zone and the rate of increase in strength in the zone were empirically determined on a series of Al-Si, Al-Cu, Al-Mg and Al-Zn alloys, and their relation to the tendency of hot tearing was discussed. The results indicate that the temperature range of the semi-solid zone well agreed with the length of cracks of casting in Al-Si, Al-Cu and Al-Zn alloys, and in the case of the first two alloys the maximum values of the semi-solid temperature range and length of cracks were observed at the limit of solubility of non-equilibrium diagram, which was determined by this experiment. The length of cracks of Al-Mg alloys were affected by the rate of increase in strength rather than by the semi-solid temperature range. The low susceptibility to the hot tearing in Al-Mg alloy system is believed to be in the great increase in strength in the semi-solid zone. Thus, the hot tearing of aluminum alloys are mostly interpreted in terms of the semi-solid zone and increase in strength in the zone.抄録全体を表示PDF形式でダウンロード (708K) -
大城 桂作, 堤 正之, 松田 公扶1978 年 50 巻 7 号 p. 431-436
発行日: 1978/07/25
公開日: 2012/06/02
ジャーナル フリーHypo-eutectic Fe-C-Si alloys, refined by molten slag, are undercooled much more than expected on usual castings. By increase in undercooling, the size of a primary grain, composed of dendrite cells arraying in a specific crystallographic orientation, becomes larger, and the spacing of dendrite arms smaller. The morphology of primary austenite in the specimen solidified at 265°C undercooling, the maximum in this study, is globular rather than dendritic. While the austenite-graphite eutectic is undercooled up to 80°C in hypo-eutectic alloys, the undercooling of hyper-eutectic alloys is 30°C at most. The morphology of graphite changes from B type to E or D type by increased undercooling. At large undercooling of 35−80°C, B type graphite precipitates when the primary austenite and the eutectic nucleate nearly at the same time in the specimen with carbon equivalent higher than 3.8. The size of an eutectic cell with B type graphite becomes smaller with increase in the undercooling.抄録全体を表示PDF形式でダウンロード (774K)
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