Abstract
The castability in dental 32Ni-23Cu-25Mn and 84Ni-9Cr cast alloys was examined, using the coil-type cast mould patterns with spiral-like and up and down-like shapes.In case of the spiral coil-type specimen having 1.0mm diameter in the alloys, the castability was not effected notably by the crucible form and the sprue position.The value(about 89%)in the low-melting 32Ni-23Cu-25Mn alloy became twice more than that(approximately 40%)of the high-melting 84Ni-9Cr alloy.On the contrary, the castability of the coil-type(up and down)mould pattern in the low-melting alloy decreased when a diameter in coil-part had a larger value than that in sprue-part of the cast specimen.Namely, when the value of(dc/ds)2 varied less than 1.0, the castability had the approximately constant value but tended to decrease notably at the value of 2.0.It was, in addition, clarified that the castability decreased in increasing the weight ratio of(Mingot/Mcoil).
