The United States of America As Represented by the United States

The United States of America As Represented by the Department of Energy

University of Dayton

Eg&g Mound Applied Technologies

Daniel P Kramer

Richard T Massey

Lauri J DeVore

Michael D Kelly

Damon A Waker

Rick D Dalton

Thomas M Beckman

A method of joining metals to a ceramic material such as a ceramic matrix composite is provided which utilizes a compliant interlayer having a coefficient of thermal expansion between the coefficient of thermal expansion of the metal and that of the ceramic matrix composite. The compliant interlayer is bonded to the metal, and the ceramic matrix composite is then bonded to the bonded interlayer/metal. The method results in a high strength joint between a metal having a high coefficient of thermal expansion and a ceramic material having a low coefficient of thermal expansion.

Method of joining metals to ceramic matrix composites

There is provided an assembly having a light guiding medium sealed to a her. Preferably the holder is a metal shell and a light guiding medium is an optical fiber of glass or sapphire whisker. The assembly includes a sealing medium which sealingly engages the metal holder to the fiber. In the formation of the assembly, the seal is essentially hermetic having a capability of minimizing leakage having a helium leak rate of less than 1.times.10.sup.-8 cubic centimeters per second and high strength having a capability of withstanding pressures of 100,000 psi or greater. The features of the assembly are obtained by a specific preparation method and by selection of specific starting materials. The fiber is selected to have a sufficiently high coefficient of thermal expansion which minimizes strains in the component during fabrication, as a result of fabrication, and during use. The other components are selected to be of a material having compatible coefficients of thermal expansion (TEC) where the TEC of the holder is greater than or equal to the TEC of the sealing material. The TEC of the sealing material is in turn greater than or equal to the TEC of the fiber. It is preferred that the materials be selected so that their respective coefficients of thermal expansion are as close as possible to one another and they may all be equal.

Fiber optic assembly and method of making same

The invention is a method of making fiber optic-to-metal connection seals. The optical fiber and a preform made of a sealing material are inserted into a metal cup. The metal is then heated to a temperature which melts the sealing material to form a hermetic seal between the cup and the fiber optic. The hermetic sealing material is selected from glass, glass-ceramic or braze and the metal is selected form stainless steel, a metal alloy or a high-strength superalloy. In a preferred method, the optical fiber is coated with a plastic buffer or pliant metal jacket.

Method of making fiber optic-to-metal connection seals

In the fabrication of igniters, actuators, detonators, and other pyrotechnic devices to be activated by a laser beam, an integral optical glass window is formed by placing a preform in the structural member of the device and then melting the glass and sealing it in place by heating at a temperature between the ceramming temperature of the glass and the melting point of the metal, followed by rapid furnace cooling to avoid devitrification. No other sealing material is needed to achieve hermeticity. A preferred embodiment of this type of device is fabricated by allowing the molten glass to flow further and form a plano-convex lens integral with and at the bottom of the window. The lens functions to decrease the beam divergence caused by refraction of the laser light passing through the window when the device is fired by means of a laser beam.

Method of making an integral window hermetic fiber optic component

A method for manufacturing low-temperature hermetically sealed optical fi components is provided. The method comprises the steps of: inserting an optical fiber into a housing, the optical fiber having a glass core, a glass cladding and a protective buffer layer disposed around the core and cladding; heating the housing to a predetermined temperature, the predetermined temperature being below a melting point for the protective buffer layer and above a melting point of a solder; placing the solder in communication with the heated housing to allow the solder to form an eutectic and thereby fill a gap between the interior of the housing and the optical fiber; and cooling the housing to allow the solder to form a hermetic compression seal between the housing and the optical fiber.

Low-temperature hermetic sealing of optical fiber components

Hermetic fiber optic-to-metal components and method for making hermetic fiber optic-to-metal components by assembling and fixturing elements comprising a metal shell, a glass preform, and a metal-coated fiber optic into desired relative positions and then sealing said fixtured elements preferably using a continuous heating process. The resultant hermetic fiber optic-to-metal components exhibit high hermeticity and durability despite the large differences in thermal coefficients of expansion among the various elements.

Method for the continuous processing of hermetic fiber optic components

A glass-to-glass hermetic sealing technique is disclosed which can be used to splice lengths of glass fibers together. A solid glass preform is inserted into the cavity of a metal component which is then heated to melt the glass. An end of an optical fiber is then advanced into the molten glass and the entire structure cooled to solidify the glass in sealing engagement with the optical fiber end and the metal cavity. The surface of the re-solidified glass may be machined for mating engagement with another component to make a spliced fiber optic connection. The resultant structure has a helium leak rate of less than 1.times.10.sup.-8 cm.sup.3 /sec.

Hermetic fiber optic-to-metal connection technique

In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

Production of glass or glass-ceramic to metal seals with the application

A method for forming a glass-to-metal seal in which the glass has a higher melting point than the metal. The molten glass is vacuum injection molded onto the metal, thus melting a very thin layer of the surface of the metal long enough to form a seal, but not long enough to cause a distortion in the shape of the metal component.

Method for forming glass-to-metal seals

A method and apparatus for assembling and fusing glass to metal in a glass-metal electrical component is disclosed. The component includes a metallic shell formed with upper and lower cylindrical recesses connected together by longitudinal passages, a pair of metal rings and plural metal pins assembled to define electrical feed-throughs. The component parts are assembled on a fixture having a sleeve-like projection and a central mounting projection establishing concentric nesting surfaces to which the metal rings are slip-fitted in concentric alignment with each other spaced from sidewalls of the lower recess. The pins are in electrical contact with the metal rings. A glass pre-form is seated within the upper recess. The assembled structure is heated to a temperature sufficient to melt the glass pre-form which flows under gravity through the passages into the lower recess to provide an insulative seal between the metal parts. The gravity flow of glass is assisted by applying vacuum to the lower recess, ensuring that all spaces between the metal parts are filled with sealing glass without formation of bubbles.

Method and apparatus for performing in-situ vacuum-assisted metal to

A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

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Centerville, OH, United States of America

Daniel P Kramer