US 4,954,170 AGranted

Methods of making high performance compacts and products

AssigneeWestinghouse Electric Corp.

InventorsMaurice G. Fey, Natraj C. Iyer, Alan T. Male, William R. Lovic

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Abstract

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).

Claims39

Dependent claims

A method of forming a pressed, dense compact, comprising the steps:

(1) providing a compactable particulate combination of:
(a) Class 1 metals selected from the group consisting of Ag, Cu, Al, and mixtures thereof, with
(b) material selected from the class consisting 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, and mixtures thereof;
(2) uniaxially pressing the particulate combination, having a maximum dimension up to approximately 1,500 micrometers, to a density of from 60% to 95%, to provide a compact;
(3) placing at least one compact in an open pan having a bottom surface and containing side surfaces where the compact contacts a separation material which aids subsequent separation of the compact and the pan;
(4) evacuating air from the pan;
(5) sealing the open top portion of the pan, where at least one of the top and bottom surfaces of the pan is pressure deformable;
(6) stacking a plurality of the pans next to each other, with plates having a high electrical resistance disposed between each pan so that the pans and plates alternate with each other, where a layer of thermally conductive, granular, pressure transmitting material, having a diameter of up to approximately 1,500 micrometers, is disposed between each pan and plate, which granular material acts to provide heat transfer and uniform mechanical loading to the compacts in the pans upon subsequent pressing, and where the plates and the granular material used to provide uniform loading having a melting point above that of the lowest melting component used in the compacts;
(7) placing the stack in a press, passing an electrical current through the pans and high electrical resistance plates to cause a heating effect on the compacts in the pans, and uniaxial pressing the alternating pans and plates, where the pressure is between 352.5 kg/cm.sup.2 (5,000 psi) and 3,172 kg/cm.sup.2 (45,000 psi) and the temperature is from 0.5.degree. C. to 100.degree. C. below the melting point or decomposition point of the lowest melting component in the press, to provide uniform, simultaneous hot-pressing and densification of the compacts in the pans to over 97% of theoretical density;
(8) cooling and releasing pressure on the alternating pans and plates;
and
(9) separating the pans from the plates and the compacts from the pans.

9 more elements

A method of forming a pressed, dense compact, comprising the steps:

(1) providing a compactable particulate combination of:
(a) Class 1 metals selected from the group consisting of Ag, Cu, Al, and mixtures thereof, with
(b) material selected from the class consisting 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, and mixtures thereof, where from 10 weight % to 75 weight % of non-Class 1 material (b) is in fiber form having lengths at least 20 times greater than their cross-section, and where from 30 weight % to 95 weight % of the particulate combination contains Class 1 metals;
(2) uniaxially pressing the particulate combination, having a maximum dimension up to approximately 1,500 micrometers, to a large section shape having a density of from 60% to 85%, to provide a large shaped compact;
(3) hot pressing the compact in a vacuum at a pressure between 352.5 kg/cm.sup.2 (5,000 psi) and 3,172 kg/cm.sup.2 (45,000 psi) and at a temperature from 0.5.degree. C. to 100.degree. C. below the melting point or decomposition point of the lower melting component of the compact, to provide simultaneous hot-pressing and densification of the compact to over 97% of theoretical density;
(4) reducing the cross-section of the compact to from 1/2 to 1/25 of the original cross-section so that fibers present are deformed in the lengthwise direction;
and
(5) cutting the reduced compact so that the fibers are oriented perpendicular to a compact surface.

5 more elements

A method of forming a pressed, dense compact, comprising the steps:

(1) providing a compactable particulate combination of:
(a) class 1 metals selected from the group consisting of Ag, Cu, Al, and mixtures thereof, with
(b) material selected from the class consisting of CdO, SnO, SnO.sub.2, C, Co, Ni, Fe, Cr, Cr.sub.2 C, W, WC, W.sub.2 C, WB, Mo, MoC, Mo.sub.2 C, MoB, Mo.sub.2 B, TiC, TiN, TiB.sub.2, Si, SiC, Si.sub.3 N.sub.4, and mixtures thereof;
and then
(2) preheating a press die cavity in a vacuum environment and placing the particulate combination, having a maximum dimension up to approximately 1,500 micrometers, in the die cavity, where the die cavity is machined close to the final desired compact dimensions and where the particulate combination is placed in the cavity in an amount calculated to provide appropriate dimensions at the required density;
and then
(3) evacuating air from the press in a controlled manner so that particulates are not carried out of the press with the escaping air, and to eliminate air voids between the particulate combination;
and then
(4) pressing the particulate combination at a pressure between 352.5 kg/cm.sup.2 (5,000 psi) and 3,172 kg/cm.sup.2 (45,000 psi) and at a temperature from 0.5.degree. C. to 100.degree. C. below the melting point or decomposition point of the lower melting component in the press, to provide simultaneous hot-pressing and densification, to form a compact having over 97% of theoretical density;
(5) cooling and releasing pressure on the compact;
and
(6) separating the compact from the die cavity of the press.

9 more elements

A method of forming a pressed, dense, compact, comprising the steps of:

(1) providing a compactable particulate combination of:
(a) Class 1 metals selected from the group consisting of Ag, Cu, Al, and mixtures thereof, with
(b) material selected from the class consisting 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, and mixtures thereof;
(2) uniaxially pressing the particulate combination, having a maximum dimension up to approximately 1,500 micrometers, to a density of from 60% to 80%, to provide a compact;
(3) sintering the compact at a temperature of from 50.degree. C. to 400.degree. C. below the melting point or decomposition point of the lowest melting component of the compact, to effectively eliminate interconnected voids and provide a compact having a density of from 75% to 97%;
(4) hot pressing the compact at a pressure between 352.5 kg/cm.sup.2 (5,000 psi) and 2,115 kg/cm.sup.2 (30,000 psi) and at a temperature from 502 C. to 300.degree. C. below the melting point or decomposition point of the lowest melting component of the compact, to provide simultaneous hot-pressing and densification of the compact to over 97% of theoretical density;
and
(5) cooling and releasing pressure on the compact.

5 more elements

A method of forming a pressed, dense compact, comprising the steps:

(1) providing a compactable particulate combination of:
(a) Class 1 metals selected from the group consisting of Ag, Cu, Al, and mixtures thereof, with
(b) material selected from the class consisting 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, and mixtures thereof, where from 10 weight % to 75 weight % of non-Class 1 material (b) is in fiber form having lengths at least 20 times greater than their cross-section, and where from 30 weight % to 95 weight % of the particulate combination contains Class 1 metals;
(2) uniaxially pressing the particulate combination, having a maximum dimension up to approximately 1,500 micrometers, to a large section shape having a density of from 60% to 85%, to provide a large shaped compact;
(3) placing at least one shaped compact in an open pan having a bottom surface and containing side surfaces, where the compact contracts a separation material which aids subsequent separation of the compact and the pan;
(4) evacuating air from the pan;
(5) sealing the open top portion of the pan, where at least one of the top and bottom surfaces of the pan is pressure deformable;
(6) hot pressing the compact through the pan at a pressure between 352.5 kg/cm.sup.2 (5,000 psi) and 3,172 kg/cm.sup.2 (45,000 psi) and at a temperature from 0.5.degree. C. to 100.degree. C. below the melting point or decomposition point of the lowest melting component of the compact, to provide simultaneous hot-pressing and densification of the compact to over 97% of theoretical density;
(7) reducing the cross-section of the compact to from 1/2 to 1/25 of the original cross-section so that fibers present are deformed in the lengthwise direction;
and
(8) cutting the reduced compact so that the fibers are oriented perpendicular to a compact surface.

8 more elements

Dependencies are inferred from the claim text.