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 composite adhesive featuring a matrix phase that includes a cyanate ester and a filler or reinforcement phase that includes a plurality of bodies of at least one material comprising a high shear strength and/or high modulus material. Preferably, the filler also possesses at least one of high thermal conductivity and low coefficient of thermal expansion. Unlike certain commercially available cyanate esters, those of the instant invention substantially maintain or even increase in strength upon addition of the filler to the system. The instant composite adhesives may also display reduced coefficients of moisture expansion relative to the unfilled or “neat” resin. Such a composite adhesive is extremely useful for joining articles where high strength and minimal swelling in moist environments are required, such as in the precision equipment industry.

Abstract: A composite adhesive featuring a matrix phase that includes a cyanate ester and a filler or reinforcement phase that includes a plurality of bodies of at least one material comprising a high shear strength and/or high modulus material. Preferably, the filler also possesses at least one of high thermal conductivity and low coefficient of thermal expansion. Unlike certain commercially available cyanate esters, those of the instant invention substantially maintain or even increase in strength upon addition of the filler to the system. The instant composite adhesives may also display reduced coefficients of moisture expansion relative to the unfilled or “neat” resin. Such a composite adhesive is extremely useful for joining articles where high strength and minimal swelling in moist environments are required, such as in the precision equipment industry.

Abstract: A composite adhesive featuring a matrix phase that includes a cyanate ester and a filler or reinforcement phase that includes a plurality of bodies of at least one material comprising a high shear strength and/or high modulus material. Preferably, the filler also possesses at least one of high thermal conductivity and low coefficient of thermal expansion. Unlike certain commercially available cyanate esters, those of the instant invention substantially maintain or even increase in strength upon addition of the filler to the system. The instant composite adhesives may also display reduced coefficients of moisture expansion relative to the unfilled or “neat” resin. Such a composite adhesive is extremely useful for joining articles where high strength and minimal swelling in moist environments are required, such as in the precision equipment industry.

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.

Abstract: A composite material having a fiber system embedded in a host matrix material. The fiber system has a protective reaction barrier around the embedded fibers to prevent deleterious chemical or mechanical reaction between the fiber and matrix. The fiber coating is applied by immersion of the fiber system into an alkoxide solution of the desired oxide precursor with controlled immersion and withdrawal rates with subsequent drying, heating to convert to a pure oxide state, and where required, post processing, to convert the oxide coating to a carbide or nitride, for example.

Abstract: A porous body consisting of a felted fibrous skeleton covered with and bonded together by a ceramic material is provided. Also provided are methods for making such a porous body which comprise the use of ceramic polymer solutions.

Abstract: The present invention is directed to a semiconductor device in which a wafer of semiconductor material is soldered to a graphite substrate.

Abstract: A transpiration cooled ceramic blade for a gas turbine is shown wherein a spar or strut member defining a root portion and an airfoil portion provides the main structural component of the blade. The air foil portion contains longitudinal grooves in the surface in flow communication with an air flow passage in the root portion and a flexible perforated ceramic tape is wrapped around the air foil portion with the perforations therein in registry with the grooves in the core. The flexible ceramic tape and the strut assembly are heated initially to a low temperature to drive off the binder forming the tape and then heated to a relatively high temperature to fuse the ceramic component of the tape together and to the strut to form a unitary blade structure with internal air flow paths and transpiration cooling orifices through the skin.

Abstract: A transpiration cooled ceramic blade for a gas turbine is shown wherein a spar or strut member defining a root portion and an airfoil portion provides the main structural component of the blade. The air foil portion contains longitudinal grooves in the surface in flow communication with an air flow passage in the root portion and a flexible perforated ceramic tape is wrapped around the air foil portion with the perforations therein in registry with the grooves in the core. The flexible ceramic tape and the strut assembly are heated initially to a low temperature to drive off the binder forming the tape and then heated to a relatively high temperature to fuse the ceramic component of the tape together and to the strut to form a unitary blade structure with internal air flow paths and transpiratin cooling orifices through the skin.

Abstract: A ceramic composition suitable for use as a high-temperature structural material, particularly for use in apparatus exposed to oxidizing atmospheres at temperatures of 400 to 1600.degree. C., is found within the triangular area ABCA of the Si.sub.3 N.sub.4 --SiO.sub.2 --M.sub.2 O.sub.3 ternary diagram depicted in FIG. 1. M is selected from the group of Yb, Dy, Er, Sc, and alloys having Yb, Y, Er, or Dy as one component and Sc, Al, Cr, Ti, (Mg +Zr) or (Ni+Zr) as a second component, said alloy having an effective ionic radius less than 0.89 A.

Abstract: This invention relates generally to ceramic materials formed from powder, and more particularly to hot-pressed structural materials comprising silicon nitride (Si.sub.3 N.sub.4) wherein the oxygen content is controlled by maintaining the molar ratio of MgO and SiO.sub.2.