Abstract: In a hydrogen-containing tantalum powder of the present invention, a value obtained by dividing the hydrogen content (ppm) by the specific surface area (m2/g) is in the range of 10 to 100. This tantalum powder has a large specific surface area, and when the tantalum powder is used as an anode of a solid electrolyte capacitor, a solid electrolyte capacitor having a large capacitance and a low leakage current can be obtained.

Abstract: During continuous casting of metals, a non-moving, vibrating magnetic field is applied to a molten metal in a casting mold to impose only vibration on the molten metal. This continuous casting method can produce a cast slab much less susceptible to flux entrainment, capture of bubbles and non-metal inclusions near the surface of the molten metal, and surface segregation. The magnetic field is preferably produced by arranging electromagnets in an opposing relation on both sides of the mold to lie side by side in the direction of longitudinal width of the mold, and supplying a single-phase AC current to each coil. The single-phase AC current preferably has frequency of 0.10 to 60 Hz. A static magnetic field can be applied intermittently in the direction of thickness of a cast slab. This technique can produce a cast slab substantially free from the flux entrainment and the surface segregation. Preferably, the static magnetic field is intermittently applied under setting of an on-time t1=0.

Abstract: In a hydrogen-containing tantalum powder of the present invention, a value obtained by dividing the hydrogen content (ppm) by the specific surface area (m2/g) is in the range of 10 to 100. This tantalum powder has a large specific surface area, and when the tantalum powder is used as an anode of a solid electrolyte capacitor, a solid electrolyte capacitor having a large capacitance and a low leakage current can be obtained.

Abstract: There is provided a niobium alloy powder suitable for manufacturing solid electrolytic capacitors having small leakage currents and high capacitances, where the powder is obtained by enhancing the thermal stability of the niobium oxide coating film while improving the temperature dependence of the sintering behavior of the powder. The niobium alloy powder includes one or more of molybdenum, chromium, and tungsten each with a content of 0.002 to 20% by mass, and phosphorus and boron each with a content of 0.002 to 5% by mass, and moreover, includes hydrogen with a content of 0.005 to 0.10% by mass, the balance being substantially niobium; the specific surface area of the powder is from 1 to 20 m2/g; the powder has a cumulative pore volume of 0.2 ml/g or more; and the cumulative volume of the pores each having a diameter of 1 ?m or less makes up 10% or more and the cumulative volume of the pores each having a diameter of 10 ?m or less makes up 40% or more in relation to the total cumulative pore volume.

Abstract: There is provided a niobium alloy powder suitable for manufacturing solid electrolytic capacitors having small leakage currents and high capacitances, where the powder is obtained by enhancing the thermal stability of the niobium oxide coating film while improving the temperature dependence of the sintering behavior of the powder. The niobium alloy powder includes one or more of molybdenum, chromium, and tungsten each with a content of 0.002 to 20% by mass, and phosphorus and boron each with a content of 0.002 to 5% by mass, and moreover, includes hydrogen with a content of 0.005 to 0.10% by mass, the balance being substantially niobium; the specific surface area of the powder is from 1 to 20 m2/g; the powder has a cumulative pore volume of 0.2 ml/g or more; and the cumulative volume of the pores each having a diameter of 1 ?m or less makes up 10% or more and the cumulative volume of the pores each having a diameter of 10 ?m or less makes up 40% or more in relation to the total cumulative pore volume.

Abstract: There is provided a niobium powder to make a capacitor which is small leakage current, also limited leakage current even after application of thermal load, and high capacitance which is attained by enhancing the thermal stability of the niobium oxide coating film in the capacitor. The niobium powder includes at least one or more selected from molybdenum: 0.002 to 20% by mass, chromium: 0.002 to 10% by mass, and tungsten: 0.002 to 20% by mass; and hydrogen: 0.005 to 10% by mass, and the specific surface area of the powder is 1 to 10 m2/g. It is preferable that the niobium powder further includes magnesium: 0.002 to 1% by mass and aluminum: 0.002 to 1% by mass, and the average particle size of the secondary particles of the niobium powder is from 10 to 200 ?m.

Abstract: During continuous casting of metals, a non-moving, vibrating magnetic field is applied to a molten metal in a casting mold to impose only vibration on the molten metal. This continuous casting method can produce a cast slab much less susceptible to flux entrainment, capture of bubbles and non-metal inclusions near the surface of the molten metal, and surface segregation. The magnetic field is preferably produced by arranging electromagnets in an opposing relation on both sides of the mold to lie side by side in the direction of longitudinal width of the mold, and supplying a single-phase AC current to each coil. The single-phase AC current preferably has frequency of 0.10 to 60 Hz. A static magnetic field can be applied intermittently in the direction of thickness of a cast slab. This technique can produce a cast slab substantially free from the flux entrainment and the surface segregation. Preferably, the static magnetic field is intermittently applied under setting of an on-time t1 0.

Abstract: A niobium powder is provided for producing a niobium capacitor enhanced in the thermal stability of oxide films on niobium, with less leak current and less deterioration of leak current after application of thermal loads. The niobium powder contains form 0.005 to 0.10 mass % of hydrogen and from 0.002 to 5 mass % of sulfur and, further preferably, one or both of magnesium and aluminum in an amount from 0.002 to 1 mass % in total. The specific surface area of the powder is 1 to 10 m2/g and the average particle diameter of the secondary particles is 10 to 200 &mgr;m.

Abstract: During continuous casting of metals, a non-moving, vibrating magnetic field is applied to a molten metal in a casting mold to impose only vibration on the molten metal. This continuous casting method can produce a cast slab much less susceptible to flux entrainment, capture of bubbles and non-metal inclusions near the surface of the molten metal, and surface segregation. The magnetic field is preferably produced by arranging electromagnets in an opposing relation on both sides of the mold to lie side by side in the direction of longitudinal width of the mold, and supplying a single-phase AC current to each coil. The single-phase AC current preferably has frequency of 0.10 to 60 Hz. A static magnetic field can be applied intermittently in the direction of thickness of a cast slab. This technique can produce a cast slab substantially free from the flux entrainment and the surface segregation. Preferably, the static magnetic field is intermittently applied under setting of an on-time t1=0.

Abstract: A niobium powder is provided for producing a niobium capacitor enhanced in the thermal stability of oxide films on niobium, with less leak current and less deterioration of leak current after application of thermal loads. The niobium powder contains form 0.005 to 0.10 mass % of hydrogen and from 0.002 to 5 mass % of sulfur and, further preferably, one or both of magnesium and aluminum in an amount from 0.002 to 1 mass % in total. The specific surface area of the powder is 1 to 10 m2/g and the average particle diameter of the secondary particles is 10 to 200 &mgr;m.

Abstract: Disclosed is a method of refining of a high purity steel capable of effectively lowering impurities in molten steel into respective ultra-low ranges. In secondary refining for molten steel after a molten iron prerefining process and a converting process, a reducing agent and a flux are added on the bath surface within a ladle containing the molten steel decarburized in a converter so that the composition of slag on the bath surface is adjusted in such a manner that the total concentration of FeO and MnO becomes 5 wt % or less, and subsequently, impurities in the molten steel are effectively lowered into respective ultra-low ranges using a RH vacuum degassing unit.