Die castings have various defects which depend on the initial solidification phenomenon. The metal drop method is useful for clarify the formation of these defects.
  In this study, a melted aluminum droplet in a crucible was dropped onto a plane copper mold by pressure. The external shape and the shape of a vertical section of solidified specimens were examined. The maximum thickness of the specimens was measured. Also measured were area, periphery length, and shape factor of the bottom of the specimens quantitatively. Experiments using water drop were also performed.
  The shape of the solidified specimen changed from TypeA, TypeB to TypeD as increasing maximum pressure (TypeA : disk-like or columnar, TypeB : doughnut-like at peripheral region and thin plate-like at center TypeD : complex at main part and simple at dispersed parts). A TypeB-D shape was also observed, which was neither the shape of TypeB nor that of TypeD. The solidification mechanism was proposed to obtain these shapes.

抄録全体を表示

  Iron foundries generate 2,256,000 tons of industrial waste every year (1995 estimate). Of this only 1,399,000 tons are used effectively, and the rest are disposed (857,000 tons).
  This is because minor foundries which make up a great portion of iron foundries in Japan do not separate industral wastes in colletion due to insufficient costs and human resources. Due to the increasing reinforcement of laws and regulations every year, needs to produce slag from industrial wastes by high tempera tare melting are growing. In this stndy, we therefore produced slag from industrial wastes by high temperature melting, and investigated the changes of the content elements during the process with the aim of reusing industrial wastes generated in iron foundries.
  It was found that heavy metals of Zn and Pb evaporated in slag production at high temperature melting of 1773K. Slagged samples were also found to separate into the slag layer and iron layer. Vitrified samples on the other hand crystallized when added with CaO and Al₂o₃.

抄録全体を表示

  In this study, the effects of complex sulfides of cerium(Ce) and manganese(Mn) on the graphitization of flake graphite cast iron were investigated. To clarify the behavior of sulfides in cast iron, Mn and Ce were added individually or together. Mn formed a polygonal shaped compound with sulfur(S) in the cast iron and the growth stage of this compound was observed with time. Manganese sulfide did not act as a substrate for graphite crystallization. 0.2%Ce was added to the melt containing 0.6%Mn, 0.08%S in consideration of stoichiometric balance with the amount of S. When Ce added to Mn contained melts, MnS was surrounded by Ce and the latter formed a compound with S in the form of Ce₂S₃ immediately. After that, MnS and Ce₂S₃ formed spherical shaped compound as a result of eutectic reaction. Ce and Mn formed sulfides with S in the melt and these complex sulfides acted as substrates for graphite nucleation in the flake graphite cast iron melt, resulting in remarkable graphitization. In time, the complex sulfide separated to MnS on the ontside and Ce₂S₃ on the inside. This form of sulfide did not serve as a substrate for graphite formation.

抄録全体を表示

  This study investigated how holding time influenced the graphite type, chill depth and mechanical properties of rare earth added flake graphite cast iron. Iron was heated and held for 0 to 30 minutes in two types of furnace. ; high frequency furnace and electrical resistance (SiC rod type) furnace. When the iron was hold in the high frequency furnace, chill depth increased with increasing of holding time. On the other hand, specimens hold in the electrical resistance furnace showed no remarkable changes. Tensile strength and hardness decreased with increasing holding time in both furnaces. EPMA analysis showed that complex sulfide of manganese and rare earth in cast iron as substrates for graphite nucleation. The morphology of the graphite nuclei of rare earth added cast iron changed from a round shape into a polygon as the holding time increased. The composition of sulfide separated from (RE, Mn) S into RE₂S₃ and MnS as the holding time increased.

抄録全体を表示