Abstract: There is provided a ball mill having a milling chamber into which metal powder is fed. The ball mill is also provided with milling means for milling metal powder into fine metal powder having a particle size less than a predetermined size. When the ball mill operates, a quantity of heat (Qo) is generated in the milling chamber. The milling chamber is cooled by liquid cooling means and gas cooling means according to the present invention. The liquid cooling means causes cooling liquid to flow along the outside wall of the milling chamber to remove a quantity of heat (Q1) during the ball mill operation. The gas cooling means causes cooling gas to flow through the milling chamber to remove a quantity of heat (Q2) during the ball mill operation. The generated quantity of heat (Qo) can be counterbalanced with the sum of the removed quantities of heat (Q1) and (Q2) so as to prevent the inside of the milling chamber from overheating, so that the ball mill can operate in the condition of Qo/V≧0.

Abstract: There is provided a ball mill having a milling chamber into which metal powder is fed. The ball mill is also provided with milling means for milling metal powder into fine metal powder having a particle size less than a predetermined size. When the ball mill operates, a quantity of heat (Q0) is generated in the milling chamber. The milling chamber is cooled by liquid cooling means and gas cooling means according to the present invention. The liquid cooling means causes cooling liquid to flow along the outside wall of the milling chamber to remove a quantity of heat (Q1) during the ball mill operation. The gas cooling means causes cooling gas to flow through the milling chamber to remove a quantity of heat (Q2) during the ball mill operation. The generated quantity of heat (Q0) can be counterbalanced with the sum of the removed quantities of heat (Q1) and (Q2) so as to prevent the inside of the milling chamber from overheating, so that the ball mill can operate in the condition of Q0/V≧0.

Abstract: A hard facing chromium-base alloy consisting essentially of 30.0 to 48.0% by weight of nickel. 1.5 to 15.0% by weight of tungsten and/or 1.0 to 6.5% by weight of molybdenum, the balance being more than 40.0% by weight of chromium, and the maximum sum of tungsten and molybdenum being 15.0% by weight. The alloy may also contain one or more of iron, cobalt, carbon, boron, aluminum, silicon, niobium and titanium. When the alloy is used in powder form as a material for hard facing by welding, the alloy may further contain 0.01 to 0.12% by weight of aluminum, yttrium, misch metal, titanium, zirconium and hafnium. 0.01 to 0.1% by weight of oxygen may also be added to the alloy. The alloy has a high degree of toughness wear resistance and corrosion resistance. The alloy can be used as a hard facing material to be applied to various objects, such as automobile engine valves.

Abstract: A hard facing chromium-base alloy consisting essentially of 30.0 to 48.0% by weight of nickel, 1.5 to 15.0% by weight of tungsten and/or 1.0 to 6.5% by weight of molybdenum, the balance being more than 40.0% by weight of chromium, and the maximum sum of tungsten and molybdenum being 15.0% by weight. The alloy may also contain one or more of iron, cobalt, carbon, boron, aluminum, silicon, niobium and titanium. When the alloy is used in powder form as a material for hard facing by welding, the alloy may further contain 0.01 to 0.12% by weight of aluminum, yttrium, misch metal, titanium, zirconium and hafnium. 0.01 to 0.1% by weight of oxygen may also be added to the alloy. The alloy has a high degree of toughness, wear resistance and corrosion resistance. The alloy can be used as a hard facing material to be applied to various objects, such as automobile engine valves.