Patents by Inventor Karl M. Prewo

Karl M. Prewo has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4435455
    Abstract: A compliant tubular liner particularly adapted to withstand brisant forces is disclosed. These liners comprising graphite or silicon carbide fiber reinforced glass or glass-ceramic have a high fracture toughness, a relatively low elastic modulus and a high temperature resistance. These articles are particularly useful as gun barrel liners.
    Type: Grant
    Filed: January 10, 1983
    Date of Patent: March 6, 1984
    Assignee: United Technologies Corporation
    Inventors: Karl M. Prewo, John J. Brennan
  • Patent number: 4422725
    Abstract: A method is provided for minimizing thermal geometrical distortion of optical articles, such as a laser mirror, comprised in significant part of a graphite fiber reinforced-glass matrix composite. The temperature of the article, and effectively the composite, is maintained, at least for some particular interval, within a range of temperatures at which the absolute coefficient of thermal expansion of the composite (and thus the article) is substantially a minimum. In most instances that minimum is substantially zero and the temperature range is sufficiently wide, i.e. 25.degree. C. or more, as to be easily maintained. The desired temperature may be attained prior to operation of the article, as for a laser mirror. A suitable cooling and/or heating arrangement is associated with the article and may respond to maintain a sensed temperature within a desired range. Where heating is required, an electrical current passed through the article may provide resistance heating.
    Type: Grant
    Filed: March 16, 1981
    Date of Patent: December 27, 1983
    Assignee: United Technologies Corporation
    Inventor: Karl M. Prewo
  • Patent number: 4414011
    Abstract: 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.
    Type: Grant
    Filed: May 25, 1982
    Date of Patent: November 8, 1983
    Assignee: United Technologies Corporation
    Inventors: George K. Layden, Karl M. Prewo
  • Patent number: 4410394
    Abstract: Laser mirrors of high thermal conductivity and dimensional stability at high temperatures are disclosed which also contain cooling channels in close proximity to the laser radiation reflecting surface. Methods of making the same are also disclosed comprising using channel forming inserts laid up between layers of the graphite fiber and glass composition which are then hot pressed and removed either by the application of mechanical pressure or chemical dissolution. Alternatively, such inserts are laid on the mold and the graphite-glass composition hot pressed on the inserts which are then mechanically removed followed by bonding a flat sheet of a separately formed graphite-glass composite to the grooved surface. Another method includes forming grooves in a preformed graphite-glass composite followed by filling the grooves with channel forming inserts and hot pressing additional graphite-glass on the inserts.
    Type: Grant
    Filed: January 10, 1983
    Date of Patent: October 18, 1983
    Assignee: United Technologies Corporation
    Inventors: Robert K. Stalcup, Karl M. Prewo
  • Patent number: 4410635
    Abstract: Discontinuous silicon carbide fiber reinforced ceramic composites are disclosed having high strength, fracture toughness, and oxidative stability, even in high temperature oxidative environments. Disclosed composites include silicon carbide fiber reinforced aluminosilicate, lithium aluminosilicate, barium aluminosilicate, magnesium aluminosilicate, and combinations thereof. Flexural strengths in excess of 20,000 psi (138 MPa) at temperatures in excess of 1000.degree. C. are attainable with such composites. The composite is formed by starting with the ceramic matrix material in the glassy state and converting it from the glassy state to the ceramic state after densification of the composite.
    Type: Grant
    Filed: February 5, 1982
    Date of Patent: October 18, 1983
    Assignee: United Technologies Corporation
    Inventors: John J. Brennan, Karl M. Prewo
  • Patent number: 4399231
    Abstract: Discontinuous silicon carbide fiber reinforced glass composites are disclosed having high strength, fracture toughness, and oxidative stability, even in high temperature oxidative environments. Disclosed composites include silicon carbide fiber reinforced borosilicate glass, high silica content glass, and aluminosilicate glass. Flexural strengths in excess of 20,000 psi (138 MPa) at temperatures in excess of 500.degree. C. are attained with such composites.
    Type: Grant
    Filed: February 5, 1982
    Date of Patent: August 16, 1983
    Assignee: United Technologies Corporation
    Inventors: Karl M. Prewo, John J. Brennan
  • Patent number: 4386825
    Abstract: Laser mirrors of high thermal conductivity and dimensional stability at high temperatures are disclosed which also contain cooling channels in close proximity to the laser radiation reflecting surface. Methods of making the same are also disclosed comprising using channel forming inserts laid up between layers of the graphite fiber and glass composition which are then hot pressed and removed either by the application of mechanical pressure or chemical dissolution. Alternatively, such inserts are laid on the mold and the graphite-glass composition hot pressed on the inserts which are then mechanically removed followed by bonding a flat sheet of a separately formed graphite-glass composite to the grooved surface. Another method includes forming grooves in a preformed graphite-glass composite followed by filling the grooves with channel forming inserts and hot pressing additional graphite-glass on the inserts.
    Type: Grant
    Filed: December 23, 1980
    Date of Patent: June 7, 1983
    Assignee: United Technologies Corporation
    Inventors: Robert K. Stalcup, Karl M. Prewo
  • Patent number: 4357286
    Abstract: A laser mirror stable at high and low temperatures is described comprising graphite fibers in a glass matrix. The mirror is made by hot pressing a graphite fiber lay-up in a glass matrix in a die having a highly polished mirror replicating surface, the fibers laid up in such a way to produce a central plane of symmetry across the central plane of the composite. In use, the composite requires a separate laser reflecting surface layer. The resulting laser mirror has a low density but no porosity, high elastic stiffness, high strength, high fracture toughness, low thermal expansion, high thermal conductivity and environmental stability.
    Type: Grant
    Filed: November 5, 1980
    Date of Patent: November 2, 1982
    Assignee: United Technologies Corporation
    Inventors: Robert K. Stalcup, Karl M. Prewo
  • Patent number: 4341826
    Abstract: A high strength, fracture tough, high temperature oxidatively stable, heat insulating internal combustion engine combustion chamber component is described made of a silicon carbide fiber reinforced ceramic matrix or a silicon carbide fiber reinforced glass matrix material. An internal combustion engine containing combustion chamber components as above described is also disclosed.
    Type: Grant
    Filed: May 14, 1980
    Date of Patent: July 27, 1982
    Assignee: United Technologies Corporation
    Inventors: Karl M. Prewo, John J. Brennan
  • Patent number: 4341840
    Abstract: A bearing, seal or brake material is disclosed comprising a graphite fiber reinforced glass matrix material. The bearings, seals and brakes according to the present invention have a coefficient of friction of about 0.15 to about 0.7 and a steady state wear rate less than 40.times.10.sup.-10 cm/cm. The advantage of such bearings, seals and brakes are stability at higher operating temperatures, low reactivity to chemical and other severe environments, high thermal conductivity, superior dimensional stability, low coefficient of friction for seals and bearings, high coefficient of friction with increasing loads without fade for brakes, and low steady state wear rate.
    Type: Grant
    Filed: March 13, 1981
    Date of Patent: July 27, 1982
    Assignee: United Technologies Corporation
    Inventor: Karl M. Prewo
  • Patent number: 4324843
    Abstract: A silicon carbide fiber reinforced ceramic matrix composite is disclosed having high strength, fracture toughness, and oxidative stability even at high temperature use. The composite is made up of a plurality of ceramic layers, each layer reinforced with a plurality of unidirectional continuous length silicon carbide fibers, each layer having an axial flexural strength greater than 70,000 psi and a high fracture toughness, exemplified by a critical stress intensity factor greater than 10.times.10.sup.3 psi (inch).sup.1/2. The composite is formed by starting with the ceramic matrix material in the glassy state and converting it from the glassy state to the ceramic state after densification of the composite.
    Type: Grant
    Filed: February 13, 1980
    Date of Patent: April 13, 1982
    Assignee: United Technologies Corporation
    Inventors: John J. Brennan, Karl M. Prewo
  • Patent number: 4314852
    Abstract: Silicon carbide fiber reinforced glass composites are disclosed having high strength, fracture toughness, and oxidative stability, even in high temperature use environments. Disclosed composites include silicon carbide fiber reinforced borosilicate glass, high silica content glass, and aluminosilicate glass. Flexural strengths in excess of 40,000 psi up to temperatures as high as 1150.degree. C. are attained with such composites.
    Type: Grant
    Filed: May 7, 1980
    Date of Patent: February 9, 1982
    Assignee: United Technologies Corporation
    Inventors: John J. Brennan, Karl M. Prewo
  • Patent number: 4268562
    Abstract: A hot pressed, biaxially oriented, alumina fiber reinforced, ceramic composite having alternate layers of parallel running alumina fibers within a glass matrix such that the fibers of one layer are positioned at right angles to the fibers of any adjoining layer.
    Type: Grant
    Filed: August 30, 1979
    Date of Patent: May 19, 1981
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: James F. Bacon, Karl M. Prewo
  • Patent number: 4265968
    Abstract: Domestic cookware and laboratory and industrial processing apparatus are disclosed comprising graphite fibers in a glass matrix. The graphite is laid up in the glass matrix so as to produce a glass rich use or contact surface, which coupled with the materials selected provides versatility in article processing, high thermal conductivity and uniformity of heat distribution in the articles produced, chemical inertness, gas and liquid impermeability, and high impact resistance and flexural strength. The articles are produced by hot pressing a mixture of the fibers and glass in a mold at elevated temperture or by extrusion or pull-trusion processing. The high thermal conductivity of the articles of the present invention (e.g. in excess of 30 BTU inch hr.sup.-1 ft.sup.-2 .degree.F..sup.-1) contributes to all of the above properties and makes the composites particularly useful as domestic cookware and laboratory and industrial processing apparatus.
    Type: Grant
    Filed: March 28, 1980
    Date of Patent: May 5, 1981
    Assignee: United Technologies Corporation
    Inventor: Karl M. Prewo
  • Patent number: 4263367
    Abstract: A graphite reinforced glass composite is described comprising discontinuous graphite fibers in substantially planar orientation in a glass matrix with strength and fracture toughness greater than the unreinforced glass matrix. The resulting composite has superior strength, fluid impermeability, wear resistance, failure strain and fracture toughness. In fact, the stress-strain, curve for composites of the invention resembles that of metal making it particularly suitable for a variety of moldable shapes and machinable designs.
    Type: Grant
    Filed: November 7, 1979
    Date of Patent: April 21, 1981
    Assignee: United Technologies Corporation
    Inventor: Karl M. Prewo
  • Patent number: 4260441
    Abstract: A monolayer tape for use in making up a multilayer matrix or composite which is bonded at a high pressure and temperature by pressing the composite between heated platens in air to cause densification, the tape consisting of collimated fibers held together by metal wire woven with and at right angles to the fibers, the wire being the same material as the matrix to become a part thereof when the composite is bonded. The aluminum matrix in which the fibers are embedded is provided by aluminum foils alternating with the collimated fibers in the multilayer matrix.
    Type: Grant
    Filed: May 10, 1978
    Date of Patent: April 7, 1981
    Assignee: United Technologies Corporation
    Inventor: Karl M. Prewo
  • Patent number: 4256378
    Abstract: A laser mirror stable at high and low temperatures is described comprising graphite fibers in a glass matrix. The mirror is made by hot pressing a graphite fiber lay-up in a glass matrix in a die, the fibers laid up in such a way to produce a central plane of symmetry across the central plane of the composite. In use, the composite requires a separate laser reflecting surface layer. The resulting laser mirror has a low density but no porosity, high elastic stiffness, high strength, high fracture toughness, low thermal expansion, high thermal conductivity and environmental stability.
    Type: Grant
    Filed: July 2, 1979
    Date of Patent: March 17, 1981
    Assignee: United Technologies Corporation
    Inventors: Karl M. Prewo, Robert K. Stalcup
  • Patent number: 4110505
    Abstract: A tape of monolayer matrix for use in making up a multilayer matrix or composite which is bonded at a high temperature and pressure by pressing the composite between heated platens in air to cause densification, the tape consisting of collimated boron fibers bonded to a substrate aluminum foil with a resin binder.
    Type: Grant
    Filed: December 17, 1976
    Date of Patent: August 29, 1978
    Assignee: United Technologies Corp.
    Inventor: Karl M. Prewo