United Technologies Corporation

United States of America As Represented by the Secretary of the Air Force

USA As Represented by Secretary of the Navy

George K Layden

Karl M Prewo

Roscoe A Pike

Michael A DeCrescente

John J Brennan

A method for molding fiber reinforced articles with superior mechanical properties by injection molding. The method comprises heating a mixture of molding compound and chopper fiber to produce highly viscous substance. Pressure is applied to force the substance through an elongated injection slot oriented perpendicular to the major axial dimension of the finished article, causing the fiber planes to become oriented in a unique whorled, accordion like manner. The unusual fiber plane orientation reinforces the article such that it is resistant to crack propagation.

Injection molding of fiber reinforced articles

A method for molding fiber reinforced articles with superior mechanical properties by injection molding. The method includes heating a mixture of molding compound and chopped fiber to produce highly viscous substance. Pressure is applied to force the substance through an elongated injection slot oriented perpendicular to the major axial dimension of the finished article, causing the fiber planes to become oriented in a unique whorled, accordion like manner. The unusual fiber plane orientation reinforces the article such that it is resistant to crack propagation.

A silicon carbide fiber reinforced glass-ceramic matrix composite article is disclosed. The matrix is a lithium alumino silicate glass-ceramic composition which may include from 1 to 5 weight percent B.sub.2 O.sub.3. The fiber reinforced glass-ceramic matrix composite article exhibits both high flexural strength at elevated temperatures and oxidative stability at elevated temperatures in an oxidizing environment.

Oxidation resistant fiber reinforced composite article

An improved composite material consisting of silicon nitride whiskers uniformly dispersed through a glass matrix and a method for making the composite which comprises the step of dispersing the whiskers in a suitable liquid and separating off the fines and, optionally, the step of treating the dispersed whiskers with HF.

Silicon nitride whisker reinforced glass matrix composites

A hot pressed, fiber reinforced matrix composite consisting essentially of a plurality of alumina fibers in a lithium aluminosilicate glass matrix. The composite is fabricated by hot pressing alumina fibers impregnated with lithium aluminosilicate glass frit and heat treating the hot pressed composite at an elevated temperature for 12 to 36 hours.

Alumina fiber reinforced lithium aluminosilicate

The present invention discloses a process of forming glass, glass-ceramic or ceramic matrix, fiber reinforced composite articles. The method comprises preparing both the matrix and the reinforcement into fibers, which are then chopped into relatively short lengths. These chopped fibers are then formed into hybrid felt papers comprising a mixture of both reinforcing fibers and matrix fibers. These felt papers are then cut into preforms and stacked one on top of the other to form a lay-up. The lay-up is then placed in a die and densified to form the composite article.

Method for forming fiber reinforced composite articles

A method of making fiber reinforced glass composite articles utilizes preregnated preforms which are bound with a temporary plastic binder. The binder is removed in a gradient oven and the frit or preform is drawn through a pultrusion die assembly heated to the degree necessary to render the frit workable. Deformation in the heated die assembly is maintained during cooling, resulting in a formed glass composite article.

Pultrusion of glass and glass-ceramic matrix composites

The present invention discloses a method of making fiber reinforced glass, glass-ceramic or ceramic matrix composite articles. The method comprises forming the matrix material into fibers and then into yarn which is woven or knitted into cloth. The matrix cloth is then cut into preformed shapes and interleaved with preformed pieces of fabric which have been woven or knitted from yarn containing the fiber reinforcement. The interleaved preformed structure is then placed in a die and densified under pressure and temperature to form the composite article. Also disclosed is a method wherein the yarn of reinforcing fiber and matrix fibers is woven or knitted together to form a hybrid cloth. This hybrid cloth is then cut into predetermined forms and placed in a die and densified under heat and pressure to form the composite article. Further, a hybrid cloth comprising yarn of both matrix and reinforcing fibers may be formed and then cut into predetermined forms, placed in a die and densified under heat and pressure forming a component article. In addition, these fibers and yarns may be formed into near net structures which can then be densified to form complex composite articles.

Method for forming composite articles of complex shapes

A method of producing fiber reinforced glass composites of complex shapes (e.g. having curved portions such as cylindrical) is disclosed. A continuous length of fiber, such as silicon carbide, is passed through a slurry of glass powder and a carrier liquid containing a polymeric binder to impregnate the fiber. The impregnated fiber is next dried and woven into a predetermined structural shape. Plies of the woven fiber cut to near net shape may also be stacked into the desired shape. The thus laid fibers are hot pressed into a fiber reinforced glass matrix composite article having glass matrix distributed substantially uniformly therethrough and multiaxial strength in at least three mutually exclusive perpendicular directions.

Method of producing woven fiber reinforced glass matrix composite

A method of making complex shaped (e.g. having curved surfaces or walls) fiber reinforced glass matrix composites by injection molding is described. The injection molding can take place by heating and injecting a mixture of glass powder and chopped fibers or whiskers directly into the mold, or a billet of glass matrix material containing the chopped fibers or whiskers made with a density approximately equal to the density of the final composite can be prepared first. In one embodiment the billet is formed by admixing a polymeric binder, glass powder, and a carrier liquid with the reinforcing fibers, drying the mixture, cold pressing the mixture to less than its original volume, and hot pressing to the density desired in the final product. Either the glass powder-chopped fiber or whisker combination or the formed billet is next placed in the injection molding apparatus where it is heated at least to the softening point of the matrix glass and injected into the predetermined mold shape. It is then allowed to cool to a temperature below the strain point of the glass and ejected or otherwise removed from the mold. In addition to providing a method of making fiber reinforced glass parts which can be automated and mass produced, articles are produced which have fiber orientation and strengths in three dimensions.

Molding process for fiber reinforced glass matrix composite articles

A method of transfer molding fiber reinforced glass composite articles is described. The method has particular utility for providing strength in a particular direction in such a composite. The fibers are aligned in a mold cavity in a predetermined orientation to provide composite strength in particular directions, and a glass billet is heated and transferred to the mold. The article is cooled and removed from the mold producing a composite having longitudinal strength along the axes of the aligned fibers in the composite.

Transfer molding method of producing fiber reinforced glass matrix

A method of securing fiber reinforced glass matrix composite material to structural members is disclosed. Two materials to be secured together are provided with a hole or other opening for insert of the fastening means. A fastening means, preferably a rivet or bolt is provided by hot pressing glass matrix material in and around unidirectionally oriented continuous length silicon carbide fibers. Such material is coined and optionally provided with threading. After formation, the bolt or rivet is inserted into the opening provided to attach the materials together and the open end of the rivet or bolt closed either by nut means or by heat deforming. The resultant secured composite-structural member remains inseparable in use, for example, in an environment of extreme temperature fluctuation. The structural member can also be fiber reinforced glass composite material, metal, unreinforced ceramic or other high temperature composite. The rivet or bolt is formed by hot-press forming a fiber reinforced composite material, slicing longitudinal rectangular sections from the composite and coining the longitudinal sections. Heads are also coined on the longitudinal sections thus formed. For the bolt embodiment, threads are also machined on the coined part.

Method of securing fiber reinforced glass matrix composite material to

A method of making fiber reinforced glass composite articles of complex shape is disclosed which overcomes problems associated with the debulking process common with such procedures. Sheets of woven or non-woven fiber reinforcement are impregnated with a layer of thermoplastic binder containing glass powder and optionally, additional carrier liquid. The thus treated sheets are then dried and cut into a plurality of preforms corresponding to the predetermined pattern of the article being fabricated. The thus treated preforms are then stacked in a mold and warm molded to form an intermediate article of near net shape, during which molding operation much of the ultimate debulking occurs. The intermediate article is then hot pressed to form the final fiber reinforced glass matrix article of net shape and high strength and toughness. These multiple heating steps may also be accomplished in a single molding operation.

Method of producing fiber reinforced glass matrix composite articles of

Compositions are disclosed for securing Si.sub.3 N.sub.4 parts together, these compositions being in the .beta.'-Y.sub.2 Si.sub.2 O.sub.7 --Y.sub.3 Al.sub.5 O.sub.12 tetrahedron, e.g. compositions in mole % comprising (1) 15% Si.sub.3 N.sub.4, 79.1% Y.sub.2 Si.sub.2 O.sub.7 and 6.9% Y.sub.3 Al.sub.5 O.sub.12 or (2) 25% Si.sub.2 AlON.sub.3 and 75% Y.sub.3 Al.sub.5 O.sub.12 Y. A method of securing Si.sub.3 N.sub.4 parts together comprises placing the composition between the parts to be bonded and heating to brazing temperature (about 1600.degree. C.) in nitrogen.

Bonding Si.sub.3 N.sub.4 ceramics

Porous carbon sheets suitable for use as fuel cell electrode support plates are produced by stabilizing acrylic filament precursors through the controlled addition of oxygen thereto. The stabilized filaments are thereafter chopped into short lengths, felted and pressed into sheets with the pressing step being performed at a temperature determined by the oxygen content of the stabilized filaments. The sheets are thereafter pyrolyzed to produce the desired porous substrate material.

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Wethersfield, CT, United States of America

George K Layden