|Publication number||US3396054 A|
|Publication date||Aug 6, 1968|
|Filing date||Mar 13, 1964|
|Priority date||Mar 18, 1963|
|Also published as||DE1471436A1, DE1471436B2|
|Publication number||US 3396054 A, US 3396054A, US-A-3396054, US3396054 A, US3396054A|
|Original Assignee||Lorraine Carbone|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (8), Classifications (28)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Aug. 6, 1968 R. REMION 3,396,054
METHOD AND APPARAT FOR METALLIC IMPREGNATION OF CARBON AND GRAPHITE Filed March 13, 1964 2 Sheets-Sheet 1 1 V4// i I 11 lnvenlor y Mm! Aug. 6, 1968 R. GREMION 3,396,054
METHOD AND APPARATUS FOR METALLIC IMPREGNATION OF CARBON AND GRAPHITE Filed March 13. 1964 2 Sheets-Sheet 2 Fig.2 Fig.3
4a 7 4a /A 7 7 Fig.6
9 Claims. (61. 117-227 ABSTRACT OF THE DISCLOSURE Carbon or graphite material is impregnated with a metal by surrounding it and the metal in solid form by powdered natural graphite. The latter is sufficiently fluid or deformable to transmit the pressure and sufficiently impermeable to prevent the melted impregnating metal from penetrating through it when subjected to a pressure of 150 to 200 kg./cm. and heated by direct release of heat within the carbon or graphite material and the metal.
The present invention relates to processes for metallic impregnation, to apparatus therefor, and to members impregnated thereby.
The impregnation of graphite -by means of molten metals such as copper, silver or lead is generally effected in an autoclave. After evacuation of the autoclave wherein the members to be impregnated are located in contact with the molten metal, a gaseous pressure may then be applied in order to aid impregnation. These operations using vacuum and pressure alternately may be repeated.
The present invention has for an object a new process for impregnation which does not necessitate the use of an autoclave and a gaseous pressure, While ensuring an equivalent rate of impregnation.
The invention consists in a process for impregnating carbon or graphite with a metal, in which the carbon or graphite and the metal in solid form are surrounded by an electrically conductive material which is substantially impermeable to the metal when molten and subjected to a pressure of from 150 to 200 kg./cm. a pressure of from 150 to 200 'kg./cm. is applied to compress said material, and the carbon or graphite, the metal and the electrically conductive material are heated by direct heating to a least the melting point of the metal.
In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings, in which:
FIGURE 1 is a diagrammatic longitudinal section of apparatus for carrying out the process of the invention,
FIGURES 2 to 5 are diagrammatic longitudinal sections on a smaller scale illustrating the successive operations of assembling the apparatus shown in FIGURE 1; and
FIGURE -6 is a diagrammatic longitudinal section of another embodiment of apparatus for carrying out the process of the invention.
In a graphite matrix 1 is located the member (or members) 2 of carbon or graphite to be impregnated and the metal 3 which it is desired to cause to penetrate into the graphite. The matrix 1 has a base-plate 7 which can subsequently serve as a mould-ejector.
The assembly of the member 2 and impregnating metal 3 is surrounded by a packing of compressed natural graphite 4a and 4b. At the two ends of the packing are located graphite pressure members 6 each in direct contact with a copper electrode 8.
The upper and lower electrodes 8 are connected with nited States Patent a source of electrical current schematically indicated at 14 by a flexible braided conductor 9 and a rigid conductor 1% respectively. Heating is effected in such a manner that the impregnating metal 3 is melted, and mechanical pressure is applied by means of a graphite piston 5 fitting in the matrix 1 and a screw-jack 12, the pressure being transmitted by the pressure members 6 and by the natural graphite 4a and 4b. The packing comprises a natural graphite powder, of suitable grain size, for example from 10 to microns, and is sufiiciently fluid to transmit the pressure and sufiiciently impermeable to preevnt the melted impregnating metal from penetrating through it when subjected to a pressure of from to 200 kg./cm.
The screw-jack 12 is mounted in a strong metal stirrupshaped frame 13, and the whole assembly of the graphite matrix 1 and its contents, the pressure members 6 and the electrodes 8 is insulated from the screw-jack 12 and the frame 13 by means of Bakelite plates 11.
The following nonlimiting examples describe embodiments of the invention, in particular impregnation with copper and sliver.
Example I .-Impregnnti0n with copper In a graphite matrix 1 (-FIGURE 2) having a natural graphite base-plate 7, is prepared a packing of natural graphite 4a compressed at 200 kg./cm. A cavity is made, e.g., by machining, in the packing 4a (see FIG- URE 3) in which is located the member 2 to be impregnated and a quantity of copper 3 (see FIG- URE 4). The Whole is covered with natural graphite 4b compressed at 150 l g./cm. (see FIGURE 5). The metal 3 may be in any suitable form. for example powder or grains. To the piston 5 and the base-plate '7 are applied the pressure members 6 and the electrodes 8 (FIGURE 1), which electrodes may be, for example, of copper, and heating is effected by means of the direct Joule effect, maintaining the pressure applied below 150 kg./cm. When the temperature at the core of the packing is at least 1083 C., i.e., the melting point of copper, pressure is progressively increased to reach 200 kg./cm.
Cooling is effected while maintaining pressure for several minutes. The impregnated members, having a porosity of 10%, are found to contain up to 30% of copper, this quantity being established by the ratio:
weight of copper Weight of the member after impregnation It has been found that the ratio of impregnation is equal to that of members impregnated in an autoclave under a gas pressure of 50 kg./cm.
Example ll.lmpregnation with silver The same method is followed with silver as with copper. The results obtained are comparable and even better, since the amount of silver which penetrates into the carbon or graphite members may be as high as 35%.
Several variations may be effected in the process without exceeding the scope of the invention. It is thus possible to replace the graphite matrix by a metal matrix, protecting it by a refractory and insulating body such as carbon black, or preferably by magnesium oxide. FIG- URE 6 diagrammatically represents an embodiment in which a metal matrix 1 is internally coated with magnesium oxide 1a or with carbon black.
In the same way the direct heating may be obtained by means other than the Joule effect, thus high frequency heating may be used.
The pressure may be applied by means other than a screw-jack, for example by a hydraulic jack.
The materials impregnated by the process of the invention, comprises carbon or graphite impregnated with molten metal, have numerous applications as regards friction materials, materials for brushes, electrical traction shoes, collectors, electrical connectors and materials used in the field of chemistry and nuclear energy.
1. In a process for impregnating a substance selected from the group consisting of carbon and graphite with a metal selected from the group consisting of copper and silver, the steps of surrounding said substance and said metal in solid form by a powdered natural graphite which is substantially impermeable to said metal when molten and subjected to a pressure of from 150 to 200 kg./cm. applying a pressure of from 150 to 200 kg./ cm. to compress said powdered natural graphite, and heating said substance, said metal and said powdered natural graphite by internal generation of heat therein to raise the temperature to at least the melting point of said metal.
2. In a process according to claim 1, the steps of applying electrodes to pressure members in contact with said powdered natural graphite, and effecting said internal generation of heat by the Joule effect.
3. In a process according to claim 1, the step of effecting said internal generation of heat by high frequency heating.
4. A process according to claim 1, wherein said powdered graphite is from 10 to 75 microns in grain size and acts as a fluid pressure-transmitting medium.
5. A process according to claim 1, wherein said pressure and temperature are sufficient to cause 30% to 35% by weight of said metal to penetrate said substance.
-6. Apparatus for impregnating a substance selected from the group consisting of carbon and graphite with a metal selected from the group consisting of copper and silver, comprising a matrix of refractory material, arranged to surround a packing of powdered natural graphite enclosing said substance and said metal, said packing being substantially impermeable to said metal when molten and subjected to a pressure of from 150 to 200 kg./cm. means for applying a pressure of from 150 to 200 kg./cm. to said packing, and means for heating said substance, said metal and said packing by internal generation of heat therein to raise the temperature to at least the melting point of said metal.
7. Apparatus according to claim 6, wherein said matrix is of metal with a refractory and insulatory lining selected from the group consisting of magnesium oxide and carbon black.
8. Apparatus according to claim 7, wherein said lining is of magnesium oxide.
9. Apparatus according to claim 7, wherein said lining is of carbon black.
References Cited UNITED STATES PATENTS 1,088,734 3/1914 Schroers 117227 2,255,120 9/1941 Kiefer et a1. ll7227 X 2,847,332 8/1-958 Ramadanofi ll7228 2,898,243 8/1959 Wenden ll7229 X 2,934,460 4/1960 Ramandanoff 1l7-228 3,294,572 12/1966 Piccione et a1. l17228 X ALFRED L. LEAVITT, Primary Examiner.
J. -R. BATTEN, 1a., Assistant Examiner.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US1088734 *||Mar 14, 1913||Mar 3, 1914||Teerverwertung Gmbh||Carbon electrode having protective covering, and process for producing same.|
|US2255120 *||Oct 13, 1939||Sep 9, 1941||Stackpole Carbon Co||Weldable silver-graphite contact and method of making it|
|US2847332 *||Sep 7, 1955||Aug 12, 1958||Union Carbide Corp||Method for introducing metallic silver in carbon with uniform distribution|
|US2898243 *||Mar 14, 1958||Aug 4, 1959||Wenden Henry E||Method of changing the resonant frequency of a quartz crystal|
|US2934460 *||Mar 31, 1958||Apr 26, 1960||Union Carbide Corp||Method for impregnating a carbonaceous brush with silver|
|US3294572 *||Mar 8, 1963||Dec 27, 1966||Pittsburgh Activated Carbon Co||Impregnation of carbon with silver|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3549408 *||Mar 1, 1968||Dec 22, 1970||Lorraine Carbone||Impregnation of a material based on carbon by molten metals|
|US3912500 *||Oct 26, 1973||Oct 14, 1975||Bocharova Tamara Timofeevna||Process for producing diamond-metallic materials|
|US4471023 *||Mar 29, 1983||Sep 11, 1984||Ltv Aerospace And Defense Company||Enhancement coating and process for carbonaceous substrates|
|US4617053 *||Sep 20, 1985||Oct 14, 1986||Great Lakes Carbon Corporation||Metal reinforced porous refractory hard metal bodies|
|US4830919 *||Apr 15, 1986||May 16, 1989||Ltv Aerospace & Defense Company||Composition for forming a protective coating on carbon-carbon substrates and article|
|US5453324 *||Aug 6, 1984||Sep 26, 1995||Loral Vought Systems Corporation||Carbon-carbon substrates having protective coating and their preparation|
|DE3240709A1 *||Nov 4, 1982||May 10, 1984||Ringsdorff Werke Gmbh||Impregnated carbon body|
|EP0051435A1 *||Oct 28, 1981||May 12, 1982||Eltech Systems Corporation||Three-layer laminated matrix electrode|
|U.S. Classification||427/114, 427/125, 118/620, 427/356, 118/407, 427/113, 419/11|
|International Classification||H01B1/04, C04B41/45, H01B1/00, C22C32/00, C04B41/51, H01B1/02, C04B41/88|
|Cooperative Classification||C22C32/0084, H01B1/04, C04B41/88, C04B41/51, H01B1/00, H01B1/02, C04B41/009|
|European Classification||C04B41/00V, H01B1/02, C22C32/00E, H01B1/00, C04B41/51, H01B1/04, C04B41/88|