US3108000A

US3108000A - Ruthenium fabrication

Info

Publication number: US3108000A
Authority: US
Publication date: 1963-10-22
Anticipated expiration: 1980-10-22

Description

Oct. 22, 1963 R. a. coma:

RUTHENIUM FABRICATION Filed 001;- 17, 1961 \EwiWQ vOiw OW X IO 20 Conmcrme P ESSU E /5: 1.

INVENTOR. ,Poaqw- @50 6: COPE Array/vs Unite States atent 3,1t38,000. RUTHENIUM FABRTCATEGN Robert G. Cope, Troon, Ayrshire, Scotland, assignor to The International Nickel Company, Tum, New York,

N.Y., a corporation of Eeiaware Filed Get. 17, 1961, Ser. No. 145,721 iaims priority, appiication Great Britain Oct. 24, 1960 3 Claims. (Cl. 75-214) The present invention relates to the production of metal articles and, more particularly, to the production of ruthenium metal articles.

It is known to produce fabricated platinum by decomposing a platinum salt to yield platinum powder, pressing the powder into compacts, sintering these compacts and working them to the final form by hot or cold working, or both.

However, when attempts are made to produce fabricated ruthenium by a similar process, faults generally arise at one or more of the different stages. The powder produced may not readily compact, the compacts may crack during sintering and otherwise sound sintered compacts may yet crack during hot working. Although attempts were made to overcome the foregoing difficulties and other disadvantages, none, as far as I am aware, was entirely successful when carried into practice commercially on an industrial scale.

It has now been discovered that by a specially controlled powder metallurgical process, the drawbacks of the prior art can be avoided and that dense ruthenium articles can be manufactured.

It is an object of the present invention to provide a novel process for the production of ruthenium metal articles.

Another object of the invention is to provide a novel process for the production of ruthenium metal articles employing commercially available techniques.

The invention also contemplates providing novel ruthenium metal articles.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawing which is a graphic illustration of the relationship among ruthenium particle size, percentage of theoretical density and compacting pressure as contemplated in accordance with the present invention.

Generally speaking, the present invention contemplates a novel process comprising compacting ruthenium powder having a surface area of between 2 and 10 square meters per gram (m. gm.) and advantageously between 2 and about 5 m. /gm., under a pressure less than about 20 long tons per square inch (t.s.i.) such that the sintered density will be greater than 90% of the theoretical density of solid ruthenium, sintering said compact at a temperature in excess of about 1350 C. and advantageously in excess of about l400 C. and up to about 1600 C. to form a sintered compact having a density greater than about 90% theoretical and thereafter hot working the sintered compact at a temperature in excess of about 1200 C.

If the sintered density is less than 90%, there is a danger that during subsequent working, stress concentrations caused by excessive porosity, will be set up and cracking will ensue. With powder having a surface area, measured in accordance with the procedure described by P. Hersch in the Journal of the Institute of Metals, 1957, volume 86, pages 509 to 511, greater than m. gm. there is a danger of cracking during sintering. With powder having a surface area of less than 2 m. /gm., the required density of the sintered compact can be obtained only if very high sintering temperatures are used. These 7 3,108,000 Patented Get. 22, 1963 ice powder of low surface area, say 2.0 m. /gm., high pressures, up to 20 t.s.i. are generally required. The relationship among compacting pressure, surface area of the ruthenium powder and percentage of theoretical density for a sintering temperature of 1450 C. is illustrated by the drawing. Referring now thereto, it is to be noted that by employing compacting pressures of about 0.5 t.s.i. to about 12 t.s.i. in combination with powders having a surface area of about 2.71 m. /gm. to about 9.85 m. /gm., compacts having at least about theoretical density are obtained after sintering at about 0 C.

The sintered density also depends on the sintering temperature used, increasing as this temperature increases. The compacting pressure required will thus thus be lower the higher the sintering temperature.

Powder having the surface area required can be obtained by directly igniting ammonium ruthenium chloride in hydrogen at temperatures between 400 C. and 550 C. If the temperature is below 400 C., powder of surface area greater than 10 m. gm. is produced and, if it is above 550 C., then powder with a surface area of less than 2 m.'/ gm. is obtained.

The powder can also be produced from other simple compounds such as ruthenium chloride and ruthenium dioxide, and from more complex compounds of ruthenium which, on ignition or reduction, leave either a residue which can readily be separated from the ruthenium, or no residue other than the ruthenium itself.

The range of temperature to which the ruthenium compound should be heated to obtain ruthenium powder will depend on the particular compound chosen. As the temperature increases, the surface area decreases and whatever compound is used, must be heated to a temperature such that powder having a surface area of between 2 and 10 m. /gm. is produced.

The sintering can be carried out in a neutral or reducing atmosphere, including a vacuum. Advantageously, the sintering is conducted in a vacuum. The temperature of sintering should be above 1350 C., for below this temperature the grain structure obtained does not deform in a suitable manner when the sintered product is hot worked. Advantageously, the sintering temperature is below about 1550 C.

When sintering in a vacuum, a suitable sintering temperature is about 1500 C., or somewhat higher temperatures if the powder has a low surface area within the range according to the invention. If the powder is sintered without using a vaccum, cracking occurs more readily during hot working.

The hot working may be carried out within the same tempreature range as the sintering. Rolling or swaging can be efiected with conventional roll gap or die sizes.

For the purpose of giving those skilled in the art a better understanding of the invention and/or a better appreciation of the advantages of the invention, the following illustrative example is given:

Example Some ammonium ruthenium chloride was ignited at 525 C. under hydrogen. The surface area of the powder thus produced was 4.86 m. /gm. The powder was then compacted by hydrostatic pressing at 5 t.s.i. The

compact in the form of a rod was sintered in vacuo at 1450 C. at a pressure of 0.0001 mm. of mercury for 15 hours. The sintered compact having a density of 93% of the theoretical density of solid ruthenium was hot swaged using a holding furnace temperature of 1450 C. and a protective hydrogen atmosphere during reheating between swaging passes. There was a 96% reduction in area of the rod, of which the diameter was reduced from 0.5 inch diameter to 0.1 inch diameter. The fabricated rod was found, on examination, to be prefectly sound, apart from inconsequential surface cracks of the usual kind.

The present invention is particularly applicable to the production of rods, wires, sheets, crucibles, tubes, etc.

lthough the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be restored to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim: l. A process for the production of wrought ruthenium metal comprising compacting ruthenium metal powder having a surface area of about 2 to about 10 square meters per gram at a pressure of about 0.5 long tons per square inch to about 20 long tons per square inch, sintering said compacted powder at a temperature of about 1350 C. to about 1600 C. to provide a sintered compact having a density greater than about 90% theoretical and thereafter hotworking said sintered compact at a temperature in excess of about 1200 C.

2. A process as claimed in claim 1 wherein the ruthenium powder has a maximum surface area of about 5 square meters per gram.

3. A process as claimed in claim 1 wherein the, ruthenium metal powder has a surface area of about 2.71 to about 9.85 square meters per gram, the meal powder is compacted under a pressure of about 0.5 to about 12 long tons per square inch and the sintering is conducted at a temperature of about 1450 C.

OTHER REFERENCES Journal of the Less Common Metals, vol. 1, No. 4,

August 1959, pp. 269-291.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 108,000 October 22, 1963 Robert G. Cope It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 23, strike out "thus", second occurrence;

line 0 for "tempreature" read temperature column 3, line 10, for "prefectly" read perfectly lines 16 and 17 for "restored" read resorted column 4, line 13, for "meal" read metal Signed and sealed this 28th day of April 1964,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims

1. A PROCESS FOR THE PRODUCTION OF WROUGHT RUTHENIUM METAL COMPRISING COMPACTING RUTHENIUM METAL POWDER HAVING A SURFACE AREA OF ABOUT 2 TO ABOUT 10 SQUARE METERS PER GRAM AT A PRESSURE OF ABOUT 0.5 LONG TONS PER SQUARE INCH TO ABOUT 20 LONG TONS PER SQUARE INCH, SINTERING SAID COMPACTED POWDER AT A TEMPERATURE OF ABOUT 1350*C. TO ABOUT 1600*C. TO PROVIDE A SINTERED COMPACT HAVING A DENSITY GREATER THAN ABOUT 90% THEORETICAL AND THEREAFTER HOT WORKING SAID SINTERED COMPACT AT A TEMPERATURE IN EXCESS OF ABOUT 1200*C.