Abstract: The invention provides a super hard and tough, nano-crystal austenite steel bulk material having an improved corrosion resistance, and its preparation process. The austenite steel bulk material comprises an aggregate of austenite nano-crystal grains containing 0.1 to 2.0% (by mass) of a solid solution type nitrogen, wherein an oxide, nitride, carbide or the like of a metal or semimetal exists as a crystal grain growth inhibitor between and/or in said nano-crystal grains. For preparation, fine powders of austenite steel-forming components, i.e., iron and chromium, nickel, manganese, carbon or the like are mixed with a substance that becomes a nitrogen source. Mechanical alloying (MA) is applied to the mixture, thereby preparing nano-crystal austenite steel powders having a high nitrogen concentration. Finally, the austenite steel powders are consolidated by sintering by means of spark plasma sintering, rolling or the like.

Abstract: The invention provides a super hard and tough, nano-crystal austenite steel bulk material having an improved corrosion resistance, and its preparation process. The austenite steel bulk material comprises an aggregate of austenite nano-crystal grains containing 0.1 to 2.0% (by mass) of a solid solution type nitrogen, wherein an oxide, nitride, carbide or the like of a metal or semimetal exists as a crystal grain growth inhibitor between and/or in said nano-crystal grains. For preparation, fine powders of austenite steel-forming components, i.e., iron and chromium, nickel, manganese, carbon or the like are mixed with a substance that becomes a nitrogen source. Mechanical alloying (MA) is applied to the mixture, thereby preparing nano-crystal austenite steel powders having a high nitrogen concentration. Finally, the austenite steel powders are consolidated by sintering by means of spark plasma sintering, rolling or the like.

Abstract: The invention provides a high hard, strength and tough nano-crystal metal bulk material and a preparation process thereof. The metal bulk material comprises an aggregate of metal nano-crystal grains, wherein an oxide, nitride, carbide, boride or the like of a metal or semimetal exists as a crystal grain growth inhibitor between and/or in the nano-crystal grains. The respective fine powders of nano-metal bulk material-forming components are mechanically alloyed (MA), using a ball mill or the like, thereby preparing nano-metal powders. Then, hot forming-by-sintering treatment such as spark plasma sintering, extrusion and rolling or explosive forming is applied to the powders to obtain a high hard, strength and tough nano-crystal metal bulk material.

Abstract: The present invention is a porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.5 to 1.0. The porous ceramic material consists essentially of 100 parts by weight of perlite having a particle diameter of 0.50 to 2.0 mm, 100 to 200 parts by weight of at least one sintered material selected from the group consisting of fly ash, chamotte, wollastonite, slag, silica, volcanic ejecta, rock, and clay mineral as a matrix material, and 10 to 20 parts by weight of an inorganic binder, which have been sintered so that the matrix material, together with the binder, surrounds the perlite particles. The perlite particles form communicating openings at mutually contacting portions thereof, so that the internal pores are communicating pores.

Abstract: The present invention is a porous sound-absorbing ceramic form made of a porous ceramic material with communicating pores and having a bulk specific gravity of 0.5 to 1.0. The porous ceramic material consists essentially of 100 parts by weight of perlite having a particle diameter of 0.50 to 2.0 mm, 100 to 200 parts by weight of at least one sintered material selected from the group consisting of fly ash, chamotte, wollastonite, slag, silica, volcanic ejecta, rock, and clay mineral as a matrix material, and 10 to 20 parts by weight of an inorganic binder, which have been sintered so that the matrix material, together with the binder, surrounds the perlite particles. The perlite particles form communicating openings at mutually contacting portions thereof, so that the internal pores are communicating pores.

Abstract: A lay down arc welding electrode with improved weld penetration is described. The welding electrode includes a core wire surrounded by flux, a portion of which has been longitudinally removed or has been otherwise made thinner than the flux surrounding the remainder of the arc wire. The direction of arc is adjusted by varying the shapes of core wire and flux. During welding the arc welding electrode rests on a tack weld. This causes directional angle (.alpha.) to the root of the weld to increase and the divergence angle (.beta.) to decrease, resulting in improved penetration of disposed metal. An apparatus is described for continuous lay down arc welding using the described arc welding electrode.