Abstract: A preform for a composite material which has high strength and excellent air permeability and hence is applicable to a high-speed die casting method and which is capable of forming a metal composite material having excellent mechanical properties by a high-speed die casting method. Also provided is a process for producing such a preform. Ceramic fibers or/and ceramic particles are mixed with a silica sol and calcium carbonate and sintered at a predetermined temperature to form a calcium/silicon sinter obtained from the silica sol and calcium carbonate. The calcium/silicon sinter coats the ceramic fibers or/and ceramic particles so that a preform having the fibers or/and the particles bound to each other by the calcium/silicon sinter is obtained. The preform for a composite material has high strength and excellent air permeability and is applicable to the high-speed die casting method capable of attaining high productivity.

Abstract: A metal composite material is obtained by casting a melt of a metal and has an outer surface on which aluminum borate particles maintained in a porous form are exposed. Therefore, an oil is allowed to infiltrate the aluminum borate particles on the outer surface, to be retained therein and to ooze out during sliding. As a consequence, the sliding life during which desired sliding properties are maintained can be significantly prolonged. The metal composite material may be produced from a preform obtained by sintering aluminum borate particles covered with electrically neutralized silica and alumina particles which have been formed by mixing a silica sol and an alumina sol with aluminum borate particles in an aqueous solution to cover aluminum borate particles.

Abstract: A metal composite material which can show high wear resistance and durability when used as a sliding member and a process for producing such a metal includes material are proposed. The metal composite material (10) comprises a porous preform (1) containing porous aluminum borate particles (3) in which pores (3a) of the aluminum borate particles (3) are filled with a metal as a result of impregnation of a melt of the metal into the porous preform under pressure. In the metal composite material (10), the metal base material and the aluminum borate particles (3) are tightly bound to each other. Therefore, the metal composite material (10) has high strength and hardness and can show excellent wear resistance when used as a sliding member.

Abstract: A preform for a composite material which has high strength and excellent air permeability and hence is applicable to a high-speed die casting method and which is capable of forming a metal composite material having excellent mechanical properties by a high-speed die casting method. Also provided is a process for producing such a preform. Ceramic fibers or/and ceramic particles are mixed with a silica sol and calcium carbonate and sintered at a predetermined temperature to form a calcium/silicon sinter obtained from the silica sol and calcium carbonate. The calcium/silicon sinter coats the ceramic fibers or/and ceramic particles so that a preform having the fibers or/and the particles bound to each other by the calcium/silicon sinter is obtained. The preform for a composite material has high strength and excellent air permeability and is applicable to the high-speed die casting method capable of attaining high productivity.

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: A method of forming a metallic composite product having a specific gravity no greater than 1.8 and a thermal expansion no greater than 16.times.10.sup.-6 .degree. C. in a preheated mold. The portion of the mold between a cavity and the gate has a stainless steel wire gauge for retaining particles. The mold is filled with screened fly ash, glass, hollow spheres having a particle size in the range of 50 to 200 micrometers and a globularness of at least 90%, which has been preheated to the same temperature as the mold. Molten aluminum alloy is injected into the mold at a pressure in the range of from 40 to 80 kgf cm.sup.2 at the gate and at a flow velocity in the range of 0.08 to 0.20 m/second.

Abstract: A light weight, strong, and wear resistant rocker-arm of a high strength aluminum alloy with Si 5-25% , Cu less than 6%, Mg less than 1.5%, P 0-0.2% and the balance Al. An element with lubricating properties can be used in the alloy. The cross-section of the rocker-arm is generally T-shaped, or inverted T-shaped.

Abstract: In a fabricating process of a metallic honeycomb structure, a plurality of bar soldering materials are laid on a plurality of metallic structure members previously assembled as a honeycomb structure and melted in a heating kiln to complete the soldering joint.