Abstract: A metal matrix composite (MMC) material that is castable, or can be rendered castable, is melted and cast into a mold or crucible, and at least a portion of the plurality of reinforcement bodies is permitted to at least partially settle out of their suspension in the molten matrix metal. The casting is solidified, and the sparsely loaded supernatant is separated from the zone of the casting containing the sediment—either by cutting, sawing, etc., or by decanting the supernatant when the casting was still in a molten condition. In a preferred embodiment, during the settling and/or the solidification process, mechanical energy, such as in the form of oscillations, is applied to the MMC melt. The applied energy permits the reinforcement bodies to nestle and pack more efficiently, thereby increasing their volumetric loading in the cast composite.

Abstract: A mirror having low density, low CTE, high thermal conductivity, high elastic modulus, and a reflective, polishable surface. The instant mirror features a silicon-based metal coating as the reflective surface, and a composite body as a support or substrate for the reflecting surface. The composite body features carbon fibers reinforcing a matrix containing silicon metal and optionally some silicon carbide. The metal coating can be elemental silicon metal, possibly in amorphous form, and can be applied by a vapor deposition process such as chemical vapor deposition (e.g., plasma enhanced CVD) or physical vapor deposition such as evaporation or electron beam PVD.

Abstract: A low CTE metal-ceramic composite material featuring carbon fibers reinforcing a matrix featuring silicon metal or silicon alloy. The fibers have a low coefficient of thermal expansion (CTE) in the axial direction, and preferably negative. The principles of making Si/SiC composites can be adapted to produce the instant Si matrix composites. The CTE of the composite body depends not only upon the relative CTE's of the fibers and matrix, and their relative amounts (e.g., loadings), but also upon the relative elastic moduli of the fibers and matrix. Thus, Si/SiC matrices produced by a reaction-bonding process inherently possess low CTE, but the instant inventors prefer to make such composites having relatively large fractions of unreacted silicon, thereby driving composite CTE lower still. Here, the carbon fibers are protected from reaction with the silicon infiltrant with one or more materials disposed between the fibers and the infiltrant.

Abstract: A “hybrid” or macrocomposite guideway, wherein the “traditional” or existing guideway material (e.g., hardened steel) is maintained as the wear resistant, low friction surface intended to be in physical contact with one or more bearings, and further wherein this surface is backed up or supported by a substrate comprising a stiff, lightweight material. This macrocomposite guideway combines the desirable friction and wear characteristics of the traditional bearing materials with the stiffness and low mass of advanced materials. Candidate substrate materials include composites having a ceramic and/or a metallic matrix, monolithic ceramics or monolithic light metals. A cladding comprising the hardened steel wear surface layer may be attached to the rigid, lightweight substrate by adhesive bonding, mechanical fasteners or other mechanical fit such as a friction or interference fit. Preferably, though, the attachment is by means of a metallurgical bond.

Abstract: A “hybrid” or macrocomposite guideway, wherein the “traditional” or existing guideway material (e.g., hardened steel) is maintained as the wear resistant, low friction surface intended to be in physical contact with one or more bearings, and further wherein this surface is backed up or supported by a substrate comprising a stiff, lightweight material. This macrocomposite guideway combines the desirable friction and wear characteristics of the traditional bearing materials with the stiffness and low mass of advanced materials. Candidate substrate materials include composites having a ceramic and/or a metallic matrix, monolithic ceramics or monolithic light metals. A cladding comprising the hardened steel wear surface layer may be attached to the rigid, lightweight substrate by adhesive bonding, mechanical fasteners or other mechanical fit such as a friction or interference fit. Preferably, though, the attachment is by means of a metallurgical bond.

Abstract: A low to near-zero metal matrix composite material featuring high modulus carbon fibers reinforcing a lightweight metal or semimetal. The fibers have a negative coefficient of thermal expansion in the axial direction. Laminates featuring parallel arrays of fibers may be cross-plied to produce quasi-isotropic properties in the composite body. The CTE of the composite body depends not only upon the relative CTE's of the fibers and matrix, and their relative amounts (e.g., loadings), but also upon the relative elastic moduli of the fibers and matrix. By intentionally introducing porosity into the matrix, the elastic modulus of the matrix is reduced, and thus the CTE of the composite body is influenced more by the CTE contribution of the fibers. In effect, the composite CTE is shifted toward that of the fibers, which shifting represents a reduction in composite CTE. Hydrogen outgassing upon solidification of the metallic matrix is one technique for producing such porosity.