The permeability of shell molds is a key property for investment casting technologies because it affects casting defects like non-fill and de-wax cracking. Currently, the permeability measurement method for investment casting shell molds is not specified in Japanese Industrial Standard (JIS). Permeability is presently measured by two common methods : Ping pong ball method and Pipe method. Because the mold cracks during the preparation of shell mold samples, there is room for improving these methods.

  In JIS, permeability measurement for ceramics materials is specified in JIS R 2115 (2008). Thus, in this study, we investigated a method to prepare shell mold samples and a method to measure investment casting shell molds based on JIS R 2115 (2008). Moreover, the influence of stucco size and firing temperature on the permeability value were reviewed. The results showed that the permeability value is affected by the sintering extent and crack number or its size.

  In order to compliant the stringent exhaust emission regulations, higher fuel efficiency and cleaner exhaust gas in combustion engines have been required. To improve combustion efficiency, an exhaust gas temperature is increasing, therefore higher temperature resistance is required for components in exhaust system, especially turbine wheel in turbocharger. IN100 looks quite attractive candidate as it has high temperature properties with low density, however it has low castability due to poor ductility at high temperature. In this study, the balance of Al and Ti composition was optimized from the base alloy IN100 to improve the high temperature ductility by expanding the γ single phase region below the solidification temperature, while obtaining the high temperature strength by maintaining the volume fraction of γ ´ phase equivalent to IN100 around 1000℃. Furthermore, the high temperature creep rupture life increased by adding a small amount of Ta. The alloy developed in this study has high castability, low density and high specific strength at high temperature.

  The casting defects inside the aluminum alloy castings in the expendable pattern casting (EPC) process were evaluated by measuring the density of castings. The effect of melt velocity on the density of plate aluminum alloy castings was investigated experimentally. There was the tendency for the casting density to decrease with increasing melt velocity. This result seemed to be due to the increased entrainment of pattern decomposed liquid resin into the molten metal. In the case of bottom pouring, the casting density with reduced pressure is larger than that with non-reduced pressure. The result seems to be due to the increase in the discharge of the liquid resin at the coat surface through the coat layer. However, when the pouring temperature was high, in the high melt velocity region, there was the tendency for the casting density to be lower than that with non-reduced pressure. This phenomenon seemed to be caused by the forward flow of molten metal. In the case of top pouring, the casting density was higher than that in bottom pouring, and the effect of the reduced pressure was not significant. From the result of observing the castings by an X-ray computed tomography (CT) imaging, it was predicted that the density decrease of the castings might be due to voids by the residual resin defects.

  Molten Al-Mg alloys are known to have the tendency to generate large amounts of oxides in the casting process, but not necessarily all the time. Therefore, in this study, we investigated the phenomenon why large amounts of oxides are formed in molten Al-Mg alloys only in some cases, focusing on the binder used for castable refractories. The results obtained were as follows.

  In the case of castable refractories using alumina cement binder, the amount of oxide produced was relatively small. On the other hand, when phosphate binder was used, significantly large amounts of oxide were produced. One reason for this may be due to heterogeneous nucleation of magnesium phosphate formed in the early stage of the casting.