Abstract: A tool steel having strength and high impact toughness incudes 0.7 to 0.9 wt % of C, 0.4 to 0.6 wt % of Si, 0.4 to 0.6 wt % of Mn, 7.0 to 9.0 wt % of Cr, 1.5 to 2.5 wt % of Mo, up to 1.0 wt % or less (excluding 0 wt %) of V, 0.01 to 0.06 wt % of Ce, and a remainder of Fe and inevitable impurities, wherein the tool steel has a hardness of 59 to 65 HRC and an impact toughness of 30 to 42 J/cm2. The tool steel has super-high-strength combined with high impact toughness due to inclusion of Ce, thus reducing primary carbide content in an as-cast state and after solution treatment and tempering.

Abstract: Disclosed is super-high-strength tool steel having high impact toughness, including 0.7 to 0.9 wt % of C, 0.4 to 0.6 wt % of Si, 0.4 to 0.6 wt % of Mn, 7.0 to 9.0 wt % of Cr, 1.5 to 2.5 wt % of Mo, 1.0 wt % or less (excluding 0 wt %) of V, and at least one of 0.1 wt % or less (excluding 0 wt %) of Ti and 0.1 wt % or less (excluding 0 wt %) of Ce, with the remainder of Fe and inevitable impurities. The super-high-strength tool steel having high impact toughness includes at least one of Ti and Ce, thus reducing primary carbide content in an as-cast state and exhibiting improved impact toughness at a high hardness level after solution treatment and tempering. In addition, a method of manufacturing super-high-strength tool steel having improved impact toughness at a high hardness level is provided.

Abstract: Provided is a method of making a composite ceramic material for a fuel cell. The composite ceramic material for the fuel cell forms a cored structure where perovskite ceramic particles having a small particle diameter surround lanthanum cobaltite particles having a large particle diameter. Lanthanum cobaltite is added as a starting material in a process of synthesizing the perovskite ceramic particles. The composite ceramic material for the fuel cell made according to this method improves an electric connection characteristic between a separation plate and a polar plate of the fuel cell, and is chemically and mechanically stable.

Abstract: Provided is a method of making a composite ceramic material for a fuel cell. The composite ceramic material for the fuel cell forms a cored structure where perovskite ceramic particles having a small particle diameter surround lanthanum cobaltite particles having a large particle diameter. Lanthanum cobaltite is added as a starting material in a process of synthesizing the perovskite ceramic particles. The composite ceramic material for the fuel cell made according to this method improves an electric connection characteristic between a separation plate and a polar plate of the fuel cell, and is chemically and mechanically stable.

Abstract: Provided is a fuel cell system in which a plurality of electricity generating units each including a unit cell in which an anode electrode and a cathode electrode are formed on both sides of an electrolyte film to use an electrochemical reaction of a fuel and an oxidizing agent to generate an electrical energy and a pair of separating plates which are disposed on both surfaces of the unit cell and have passages through which a fuel and an oxidizing agent are supplied to the anode electrode and the cathode electrode are laminated in which the electricity generating unit has a structure where a fuel flowing direction and/or a flowing direction of the fuel or the oxidizing agent are different between neighboring electricity generating units.

Abstract: Provided is a composite ceramic material for a fuel cell and a method for manufacturing the same. The composite ceramic material for the fuel cell forms a cored structure where perovskite ceramic particles having a small particle diameter surround lanthanum cobaltite particles having a large particle diameter, and lanthanum cobaltite is added as a starting material in a process of synthesizing the perovskite ceramic particles to be synthesized. The composite ceramic material for the fuel cell described herein improves an electric connection characteristic between a separation plate and a polar plate of the fuel cell, and is chemically and mechanically stable.

Abstract: An Fe-Mn vibration damping alloy steel having a mixture structure of .epsilon., .alpha.' and .gamma.. The alloy steel consists of iron, manganese from 10 to 24% by weight and limited amounts of impurities. The alloy steel is manufactured by preparing an ingot at a temperature of 1000.degree. C. to 1300.degree. C. for 12 to 40 hours to homogenize the ingot and hot-rolling the homogenized ingot to produce a rolled alloy bar or plate, performing solid solution treatment on the alloy steel at 900.degree. C. to 1100.degree. C. for 30 to 60 minutes, cooling the alloy steel by air or water, and cold rolling the alloy steel at a reduction rate of greater than 0% and below 30% at around room temperature.