Papers by Keyword: Continuous Casting Technique

Abstract: Lotus-type porous carbon steel (lotus carbon steel) plates were fabricated by continuous casting technique in a pressurized nitrogen atmosphere. The experiments were done both with adding 0.3wt% of NiO powder in molten carbon steel in a ceramic crucible and without NiO powder. The lotus carbon steel fabricated without NiO powder under nitrogen pressures of 0.1 and 0.5 MPa had single pores which grew independently. On the other hand, the lotus carbon steel fabricated with adding NiO powder had pores which coalesced each other and became in irregular shapes. Under nitrogen pressure of 2.5 MPa, the pores formed with adding NiO powder were smaller than that formed without NiO powder. The porosity increased by adding NiO powder in every pressurized nitrogen atmosphere. From these results, NiO powder in molten carbon steel is considered to act as nucleation sites for pores at the solid-liquid interface and to increase of the pore number.

Abstract: We investigated the pore morphology in lotus-type porous copper fabricated by continuous casting technique as a function of transference velocity range from 1 to 100 mm･min-1 under hydrogen gas pressure of 1.0 MPa. Lotus-type porous copper with long cylindrical pores aligned in one direction parallel to the transference direction was fabricated, which posses a sufficient uniformity of the porosity and pore size. The pores formed at transference velocity of 1 mm･min-1 were larger than other condition. Necks were observed in these pores, whose formation may be attributed to bubbling in the melt. The pore size decreased with increasing transference velocity, while the porosity was not varied much by transference velocity.

Abstract: Lotus-type porous metals with low thermal conductivity are fabricated by continuous zone melting technique, which possess directional elongated pores. The porous metals have been able to be fabricated through the conventional casting method by utilizing the solubility gap between solid and liquid in pressurized gas atmosphere. However, there is a shortcoming that the pores are coarsened in the part farther from the chill plate in the ingot. In order to overcome such a shortcoming, we developed the continuous zone melting technique and successfully produced the lotus-type porous metals with even low thermal conductivity such as stainless steel and superalloys. Furthermore, from the viewpoint of mass production with low cost, we invented novel ”continuous casting technique”. The molten metals dissolving gas are solidified continuously by passing through the mold cooled with chiller and thus, lotus-type porous metal plate as long as one meter was produced for short time. Sufficient uniformity of the porosity and pore size was obtained in such long porous ingots. This technique is prospective method for commercial mass production.