Westinghouse Electric Corporation

Eaton Corporation

William R Lovic

Graham A Whitlow

Alan T Male

Natraj C Iyer

Paul Graham Slade

Maurice G Fey

Mehmet N Gungor

A new class of low chop contact materials based on Ag-chromium carbide and Ag--Cr compositions have an essentially 100% dense, porosity free microstructure. These materials combine the advantageous properties of Ag--WC and Cu--Cr contacts without their disadvantages. A method of making this new class of low chop contact materials includes the steps of cold pressing a mixture of Ag and chromium or chromium carbide to form an unsintered blank and the elevated temperature infiltration of silver into the unsintered blank to obtain an essentially 100% dense, porosity free microstructure.

Electrical contact compositions and novel manufacturing method

A 100% dense, porosity free copper-chromium contact has been prepared in which deleterious porosity has been eliminated. This copper-chromium contact has been produced by pressurizing liquid copper to infiltrate an evacuated chromium based, lightly sintered, highly porous preform. The electrical contact has one of either a homogeneous Cr distribution and a graded Cr distribution. The apparatus used to effect the molten metal infiltration has two independent, physically separated chambers--a first cold chamber and a second hot chamber. The first chamber is under no applied pressure except inside a gating system used to transfer molten Cu into the porous preform in the first chamber. The new contact has about 15-30% Cr material and a high erosion resistant contact surface. The graded Cr distribution has a Cr rich layer with about 25-50% by weight Cr, an intermediate Cr layer with about 15-20% by weight Cr, a low Cr layer with about 5-15% Cr and a Cr poor layer with about 1-5% Cr above a copper substrate.

Porosity-free electrical contact material, pressure cast method and

A new class of low chop contact materials based on Ag-chromium carbide and Ag-Cr compositions have an essentially 100% dense, porosity free microstructure. These materials combine the advantageous properties of Ag-WC and Cu-Cr contacts without their disadvantages. A method of making this new class of low chop contact materials includes the steps of cold pressing a mixture of Ag and chromium or chromium carbide to form an unsintered blank and the elevated temperature infiltration of silver into the unsintered blank to obtain an essentially 100% dense, porosity free microstructure.

A method to form a superconducting wire or ribbon contains the steps: (1) forming ceramic powder, (2) forming pellets from the powder, (3) inserting the pellets in a metal sheath, (4) reducing the cross-section of the sheathed pellets to form a composite, (5) sealing the composite in a deformable container, (6) hot isostatically pressing the composite at a temperature over 600.degree. C., where the temperature is close to or just above the melting point of the core, and (7) annealing the pressed composite in a source of oxygen at a temperature from 770.degree. C. to 870.degree. C. for at least 40 hours.

Hot isostatic processing of high current density high temperature

High density compacts are made by providing a compactable particulate combination of Class 1 metals selected from at least one of Ag, Cu and Al, with material selected from at least one of CdO, SnO, SnO.sub.2, C, Co, Ni, Fe, Cr, Cr.sub.3 C.sub.2, Cr.sub.7 C.sub.3, W, WC, W.sub.2 C, WB, Mo, Mo.sub.2 C, MoB, Mo.sub.2 B, TiC, TiN, TiB.sub.2, Si, SiC, Si.sub.3 N.sub.4, usually by mixing powders of each, step (1); uniaxially pressing the powders to a density of from 60% to 95%, to provide a compact, step (2); hot densifying the compact at a pressure between 352 kg/cm.sup.2 (5,000 psi) and 3,172 kg/cm.sup.2 (45,000 psi) and at a temperature from 50.degree. C. to 100.degree. C. below the melting point or decomposition point of the lower melting component of the compact, to provide densification of the compact to over 97% of theoretical density; step (3); and cooling the compact, step (4).

Methods of making high performance compacts and products

A process of hot pressing of materials to form articles or compacts is characterized by the steps: (A) providing a compactable particulate mixture; (B) uniaxially pressing the particles without heating to provide article or compact (22); (C) placing at least one article or compact (22) in an open pan (31) having an insertable frame (32) with edge surfaces (34) that are not significantly pressure deformable, where the inside side surfaces of the frame are parallel to the central axis B--B of the open pan, and where each article or compact is surrounded by fine particles of a separating material; (D) evacuating air from the container and sealing the articles or compacts inside the container by means of top lid (36); (E) hot pressing the compacts at a pressure from 352.5 kg/cm.sup.2 to 3,172 kg/cm.sup.2 to provide simultaneous hot pressing and densification of the articles or compacts; (F) gradually cooling and releasing the pressure; and, (G) separating the articles or compacts from the container, where there is no heating of the compacts in the process before step (E).

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New Kensington, PA, United States of America

William R Lovic