Abstract: The present invention is to provide a vertical casting apparatus capable of easily manufacturing castings without causing shrinkage cavities and entrainment of gas, by filling a molten metal into a mold cavity at a high speed and by effectively pressurizing the molten metal in the closed cavity, which has high work efficiency, ease of maintenance, and a low cost of equipment, and a vertical casting method using the vertical casting apparatus. The vertical casting apparatus is provided with an apparatus body comprising a fixed mold 1 on the lower side and a movable mold 2 on the upper side, a closing means 13 for closing a molten metal in-flow gate 10 formed in the fixed mold 1, and a pressurizing means 20 for pressurizing the molten metal in the closed mold cavity, and a casting means for supplying and filling the molten metal into the mold cavity from the underside. The casting means has a gas-pressurized molten metal pouring ladle 6 attachable to and detachable from the apparatus body.

Abstract: A process for producing aluminum nitride comprises a step of nitriding directly a mixed powder comprising of, a bulky aluminum powder composed of aluminum or an aluminum alloy powder which occupies 50 to 97% by weight and whose sieve opening of JIS is not less than 210 .mu.m (70 mesh); and a nitriding accelerator powder composed of at least one kind of an aluminum powder and an aluminum alloy powder which occupy the balance of 50 to 3% by weight and whose sieve opening is less than 210 .mu.m (70 mesh); under a nitrogen gas atmosphere of the temperature ranging from 500 to 1000.degree. C. In the present invention, there can be obtained an aluminum nitride which is easy to be crushed by hand by using a mortar.

Abstract: An aluminum product having the metal diffusion layer in the present invention has, on the surface thereof, a metal diffusion layer comprising aluminum and a diffusion metal which is diffused setting aluminum as a matrix and which includes at least one selected from the group consisting of Ni, Cr, Cu, Zn, Mg, Ti and Ag; wherein the diffusion layer is formed by diffusing inclinatorily not less than 1 .mu.m from the surface thereof; and the diffusion metal is not less than 1.0% by weight when the whole of the metal diffusion layer is set to be 100% by weight. Also, in a process for producing an aluminum product having a metal diffusion layer, the surface of the aluminum product is brought into contact with the processing agent including at least the diffusion metal powder; and in this state by conducting heat treatment in the atmosphere including nitrogen, the diffusion metal is diffused on the surface of the aluminum product and the metal diffusion layer is formed.