摘要:
Disclosed is a method for producing an SiC preform of a high volume fraction used for the manufacture of a metal matrix composite. The method involves the steps of mixing SiC particles of different particle sizes each selected from a range of 0.2 to 48 &mgr;m with an organic binder, an inorganic binder, an aggregating agent, and distilled water, thereby producing a mixture, and stirring the mixture in accordance with a ball milling process, thereby producing a slurry containing the SiC particles, pouring the slurry containing the SiC particles into a mold having upper and lower molds respectively provided with absorbent bodies, and squeezing the slurry in the mold, thereby reducing a residual moisture content of the slurry, completely drying the slurry reduced in residual moisture content, thereby producing an SiC preform, and calcinating the SiC preform. The preform is impregnated with a metal matrix while maintaining a high reinforcement volume fraction of 70 vol % or more. Accordingly, this preform can be widely used for fundamental materials of metal matrix composites used to manufacture electronic packaging components and aerospace components requiring a low thermal expansion coefficient and a high thermal conductivity.
摘要:
The present invention relates to a method of preparing a preform with a high volume fraction of SiC particles. A slurry containing SiC particles and binders is ball-milled and pressed in an apparatus to give a primary preform. This primary preform is dried at room temperature and then, at a high temperature. The dried primary preform is subjected to calcination to prepare the preform. In the apparatus, which comprises a bottom die; a top mold with a cavity, placed on the bottom die, an upper punch for pressing a material for the preform in the cavity; and two water-absorbers, one being inserted between the bottom die and the top mold, the other being placed on the top mold, the slurry is introduced in the cavity and pressed by the punch while the water is absorbed in the absorbers or drained through a gap between the bottom die and the top mold, thereby improving the volume fraction of SiC particles. The preform can be used as a fundamental material in producing metal matrix composites having a high thermal conductivity and a low coefficient of thermal expansion, suitable for the application for, e.g., electronic packaging and space-air structures.
摘要:
Disclosed is a process for making an oxide dispersion-strengthened tungsten heavy alloy by mechanical alloying that includes the steps of: adding 0.1 to 5 wt. % of Y2O3 powder to a mixed powder comprising more than 90 wt. % of tungsten powder, and nickel and iron powders for the rest; and subjecting the resulting mixture to a mechanical alloying to prepare an oxide dispersion-strengthened tungsten heavy alloy powder. The oxide dispersion-strengthened tungsten heavy alloy prepared by the mechanical alloying is characterized in that fine Y2O3 particles are uniformly dispersed in the matrix which are stable at high temperatures results in enhanced high-temperature strength and a reduction of the shearing strain of the fraction during high strain rate deformation.
摘要:
The invention relates to methods for fabricating ceramic nanocomposite powders, comprising a ceramic matrix and carbon nanotubes homogeneously dispersed in the ceramic matrix. The ceramic nanocomposite powders of the invention can prevent property deterioration due to agglomeration of carbon nanotubes.
摘要:
The present invention relates to a metal nanocomposite powder reinforced with carbon nanotubes and to a process of producing a metal nanocomposite powder homogeneously reinforced with carbon nanotubes in a metal matrix powder.
摘要:
Graphene/metal nanocomposite powder and a method of preparing the same are provided. The graphene/metal nanocomposite powder includes a base metal and graphenes dispersed in the base metal. The graphenes act as a reinforcing material for the base metal. The graphenes are interposed as thin film types between metal particles of the base metal and bonded to the metal particles. The graphenes contained in the base metal have a volume fraction exceeding 0 vol % and less than 30 vol % corresponding to a limit within which a structural change of the graphenes due to a reaction between the graphenes is prevented.
摘要:
Disclosed is a method for fabrication of porous carbon fibers. More particularly, the method for fabrication of porous carbon fibers comprises the steps of: processing starch to prepare a gelled starch solution; adding organic acid to the gelled starch solution to prepare a starch solution; dissolving carbon nanotubes in a solvent and adding fiber formable polymer thereto to prepare a carbon nanotube/fiber formable polymer solution; mixing the starch solution with the carbon nanotube/fiber formable polymer solution obtained from the above steps, in order to prepare a carbon nanotube/starch/fiber formable polymer solution; electro-spinning or wet-state spinning the prepared carbon nanotube/starch/fiber formable polymer solution to produce starch composite fibers; oxidation heating the starch composite fibers, then, executing carbonization and vacuum heat treatment of the heated fibers, so as to fabricate the porous carbon fibers. The fabricated porous carbon fiber has high specific surface area and high capacitance, thereby being favorably applicable in manufacturing electrodes for a super capacitor, fuel cell, etc.
摘要:
The present invention relates to methods of preparing a polymer composite using a giant magnetostrictive material, and more particularly, to polymers composite having various improved properties, in which the advantageous structure of the giant magnetostrictive material produced by unidirectional solidification can be maintained by removing the eutectic phase from the magnetostrictive material and filling resulting voids with a polymer resin.
摘要:
The present invention provides a method of making a carbon nanotubes fiber by providing a polyethylene terephthalate substrate; contacting the polyethylene terephthalate substrate with a polyvinyl alcohol polymer solution to form a polyvinyl alcohol polymer layer on the polyethylene terephthalate substrate; contacting the polyvinyl alcohol polymer layer with a carbon nanotube solution, wherein the carbon nanotubes solution comprises one or more carbon nanotubes; forming a nanotube layer on the polyvinyl alcohol polymer layer; delaminating the polyvinyl alcohol polymer layer from the polyethylene terephthalate substrate to release a composite fiber layer; stretching the composite fiber layer; and drying the composite fiber layer.
摘要:
The present invention provides a method of making a carbon nanotubes fiber by providing a polyethylene terephthalate substrate; contacting the polyethylene terephthalate substrate with a polyvinyl alcohol polymer solution to form a polyvinyl alcohol polymer layer on the polyethylene terephthalate substrate; contacting the polyvinyl alcohol polymer layer with a carbon nanotube solution, wherein the carbon nanotubes solution comprises one or more carbon nanotubes; forming a nanotube layer on the polyvinyl alcohol polymer layer; delaminating the polyvinyl alcohol polymer layer from the polyethylene terephthalate substrate to release a composite fiber layer; stretching the composite fiber layer; and drying the composite fiber layer.