From the authors' another investigation, it was found that the amount of suspending silica in the oxidized molten iron increased. As the cast iron obtained from oxidizing melt is said to have an irregular structure, such as eutectic graphite or ledebulite, this irregularity is supposed to occur by the suspending silica. This study was made intending to clarify this point.
  In order to ascertain the effect of suspending silica without making any composition change in the melt, the mixture of turning scrap of iron and silica powder was melt down in argon gas atmosphere at 1300°C. The structure of these specimens showed the same irregularity with the oxidized one, and as the amount of mixed silica increased up to 15%, graphitization was hindered more and more.
  Then, the oxide analysis of these specimens was performed. From this, the analytical value of silica increased proportionally to that of the mixed silica. Thus, this irregular structure was due to the suspending silica is concluded. Secondarily, a mechanism of structural change due to suspending silica was investigated by thermal analysis. In this experiment, eutectic point was supercooled in the iron containing much suspending silica. Supercooling, in normal state, is said to be caused by rapid cooling, therefore, the above mentioned irregularity was supposed to be due to the same process as rapid cooling.
  Moreover, Al₂O₃ and TiO₂ was mixed to the melt by the same way as mixing silica, and their structures were also changed similarly. Thus, the suspension of inclusion, not always silica, was considered usually to be the cause to make iron structure irregular.

抄録全体を表示

  The purpose of this investigation is to know the foundamental knowledge of cupola operation, through surveying the relation between its construction or something else of cupola and the reactions in furnace, and also through surveying the effects of these factors upon the conditions of melting in furnace.
  In order to know the type of air flow blown from the blast pipe in furnace, a model like midget cupola was constructed and, under the non-burning condition, the blast pressure at wind box and at each section in the furnace was checked by varying the tuyère ratio, the effective height ratio, the coke size and the blast volume, and so on. And after giving considerations on the effects of these factors upon the flow of blast in furnace, some results obtained are as follows :
 (1) As the tuyère ratio increases, the blast pressure in wind box becomes higher gradually, and especially as the tuyère ratio is very large, it becomes extremely high, though the blast volume increases a little.
 (2) As the effective height ratio increases, the blast pressure in wind box becomes higher gradually and the relation between the both is nearly illustrated by a linear curve, and as the blast volume increases, the slope of the straight line becomes sharp.
 (3) As the coke size decreases, the blast pressure in wind box increases like a hyperbola, and the inclination is remarkable in case of the mixed cokes of various sizes are used.
 (4) When the furnace was filled with coke, the smaller the coke size the smaller the index of space, and when two different sizes of coke are mixed with the index of space becomes make it much smaller than the above figure.
 (5) Between the wall and the center in the furnace, when the coke size is large, the blast pressure in the furnace differs a little, but, when the coke size is small, the blast pressure of the wall in furnace rises greatly, and the wind flows along the wall side in furnace. This tendency is very remarkable in case of the two kinds of coke are mixed.

抄録全体を表示

  The addition of a small amount of fluorspar to molten iron before magnesium treatment increased the efficiency of the treatment (or nodularlizing treatment) for nodular graphite cast iron.
  By this treatment, the amount of magnesium needed for the production of nodular graphite cast iron decreased to 1/4-1/10 of the usual amount and even the pig iron which had been understood unsuitable for nodular graphite cast iron, could be easily nodulized.

抄録全体を表示

  This research has been carried out as a succeeding experimentation of the previous report.
  The joining phenomena was investigated by contacting small pieces of brass having various Zn concentrations, with those of pure Cu sheets, in Ar gas atomosphere at its high temperatures.
  It has ascertained that the joining of metals is achieved only by the factor of temperature, i.e., if the holding time at high temperature is enough to occure the intermetallic diffusion, the joining is sure to be occured without introducing any fusing condition in metals.
  However, the joining seems much easier to be occured when the concentration gradient of both metals is greater.

抄録全体を表示