Other

At&t Technologies, Inc.

At&t Bell Laboratories

Bell Telephone Laboratories

Nathaniel R Quick

Murray Robbins

James C Kenney

Alan Michael Lyons

John T Plewes

Cletus W Wilkins, Jr

Delbert A Nauman

Frederick T Mendenhall, Jr

Edward J Milligan

Metal and ceramic particles of various morphologies are clad with a coating from the transistion metal group consisting of silver, gold, copper, nickel, iron, cobalt, aluminum etc., or combinations thereof, to provide improved coated particles for microelectronics or metal matrix composites or other uses. Refractory metal precursor core particles, such as tungsten, molybdenum, niobium and zirconium, as examples, are provided from a composite of tungsten and copper, for example, made by pressurizing and infiltrating or liquid phase sintering of molten copper into a porous tungsten skeleton. Precursor chip particles derived from a tungsten impregnated billet are used as starter particles which may be further enhanced by cogrinding in an attritor ball mill with smaller copper particles to thereby produce an enhanced copper clad-coating of tungsten particles with predetermined percent by weight of copper and tungsten content. The resulting particles exhibit improved electrical and thermal expansion coefficient matching properties for use on microelectronic ceramic substrates and when used for metal matrix composites, provides more uniform distribution of the dispersed strengthening particulate phase in the matrix. In another embodiment, ceramic particles are clad-coated with selected metals so that they can be used in ceramic-metal matrices, thereby producing systems wherein the components are uniformly dispersed throughout the system.

Method for clad-coating ceramic particles

In a preferred embodiment room temperature electrically conductive or semiconductive ceramic paths or areas are produced on carbide and nitride ceramic substrates by a process of controlled oxidation using localized thermal heating (e.g., laser heating) by tracing desired paths onto the substrates, where air is the source of oxygen. In another embodiment, nitride and carbide ceramic substrates are converted to electroconductive or semiconductive ceramics where the substrate is characterized as whiskers, fibers, flakes or platelets whose dimensions are in the micron range, by controlled oxidation as prescribed by laser beam processing. The resulting conductive or semiconductive paths or surfaces of the substrate comprise electrically conductive or semiconductive nonstoichiometric aluminum-nitrogen-oxygen ceramic, when the initial ceramic substrate material is aluminum nitride(A1N); and electrically conductive or semiconductive nonstoichiometric silicon-carbon-oxygen ceramic, when the initial ceramic material used is silicon carbide (SiC). The path cut into the surface on a flat substrate can serve e.g. as electrical interconnects akin to printed circuitry on a wiring board and patterns of semiconductors formed can serve e.g. as semiconductive devices akin to rectifier devices. In the instance of the whiskers, fibers, flakes or platelets, the electrically conductive surfaces thereof may be used directly or enhanced for example, by coating other conductor metal or alloys onto the surface for uses e.g. as composite materials in matrices at the microstructural level.

Converting ceramic materials to electrical conductors and semiconductors

Metal and ceramic particles of various morphologies are clad with a coating from the transition metal group consisting of silver, gold, copper, nickel, iron, cobalt, aluminum etc., or combinations thereof, to provide improved coated particles for microelectronics or metal matrix composites or other uses. Refractory metal precursor core particles, such as tungsten, molybdenum, niobium and zirconium, as examples, are provided from a composite of tungsten and copper, for example, made by pressurizing and infiltrating or liquid phase sintering of molten copper into a porous tungsten skeleton. Precursor chip particles derived from a tungsten impregnated billet are used as starter particles which may be further enhanced by cogrinding in an attritor ball mill with smaller copper particles to thereby produce an enhanced copper clad-coating of tungsten particles with predetermined percent by weight of copper and tungsten content. The resulting particles exhibit improved electrical and thermal expansion coefficient matching properties for use on microelectronic ceramic substrates and when used for metal matrix composition, provides more uniform distribution of the dispersed strengthening particulate phase in the matrix. In another embodiment, ceramic particles are clad-coated with selected metals so that they can be used in ceramic-metal matrices, thereby producing systems wherein the components are uniformily didpersed throughout the system.

Method for clad-coating refractory and transition metals and ceramic

Electrically conductive paths are produced on a polymeric substrate by laser writing, i.e., by tracing desired paths on the substrate by a laser beam. The resulting paths comprise electrically conductive carbon as produced by thermal decomposition of substrate surface material; the paths can serve; e.g., as electrical interconnections akin to printed circuitry on a wiring board. Optionally, the conductivity of paths can be enhanced by electroplating a suitable conductor metal or alloy onto the paths.

Direct writing of conductive patterns

Electrical contact tape having a base portion of nickel, copper or nickel-copper alloy and an overlay of metallic material on said base portion is improved by utilizing for such overlay a gold-nickel alloy of which the precentage by weight of nickel is in the range of from about 1.8% to 2.3%, the balance of the alloy being gold with or without one or more other metals other than nickel in trace amounts insufficient to produce precipitation thereof out of solution in the gold. Nibs of such tape are bonded to a leaf spring to form an electromechanical junction therewith, the gold-nickel alloy overlay of the nib being on its side away from the spring to provide an improved electrical contact surface for the spring contact assembly formed by such nib and spring.

Electrical contact means with gold-nickel alloy overlay

The apparatus and method for processing steel strand wire cable and the like for use in prestressed concrete is disclosed in which the outer surface of the cable produced has a substantial pure rust or hydrated oxide coating thereon enabling the cable to be utilized immediately in concrete configurations to thereby produce substantially higher flexural strengths in prestressed concrete than heretofore in the prior art. The apparatus and method specifically encompasses the use of ultrasonic cleaning equipment which causes cavitation cleaning effects in the liquid medium through which the cable passes during its cleaning process. In effect, the ultrasonic cleaning 'catalyzes' the chemical redox reactions by removing all surface inhibitors and reducing reactant diffusion barriers thus accelerating surface wetting of the strand cable with H.sub.2 O and O.sub.2, such that the rusting chemical reactions can occur spontaneously. The dominant bond developed between the steel and concrete is chemical. The bonding or wetting agent is ferro-orthosilicate, formed by the reaction of pure rust (FeO.Fe.sub.2 O.sub.3) with silicates (SiO.sub.2) in the cement mixture used for making the concrete structure.

Apparatus and method for processing wire stand cable for use in

A carbon transmitter utilizes an electrode prepared by in situ reaction between substrate copper and introduced sulfur. Good surface adhesion between the resulting CuS layer and the substrate is assured by use of a two-phase cobalt/copper substrate.

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Randolph, NJ, United States of America

Nathaniel R Quick