US3674575A

US3674575A - Tungsten carbide dispersion in age-hardenable cupro-nickel

Info

Publication number: US3674575A
Application number: US82769A
Authority: US
Inventors: Arnold L Prill; Stuart E Tarkan
Original assignee: Chromalloy American Corp
Current assignee: Chromalloy Gas Turbine Corp; Alloy Technology International Inc
Priority date: 1970-10-21
Filing date: 1970-10-21
Publication date: 1972-07-04
Anticipated expiration: 1989-07-04
Also published as: GB1348569A; DE2060446B2; CA944977A; DE2060446A1; JPS5134364B1; FR2111568A5

Abstract

A SINTERED REFRACTORY METAL CARBIDE COMPOSITION IS PROVIDED COMPRISING ABOUT 35 V/O TO 70 V/O OF AT LEAST ONE REFRACTORY METAL CARBIDE SELECTED FROM THE GROUP CONSISTING OF WC, CBC, VC AND TAC DISPERSED SUBSTANTIALLY UNIFORMLY THROUGH A CUPRO-NICKEL MATRIX MAKING UP ESSENTIALLY THE BALANCE, THE CUPRO-NICKEL MATRIX CONSISTING ESSENTIALLY BY WEIGHT OF ABOUT 55% TO 90% COPPER AND THE BALANCE ESSENTIALLY ABOUT 45% TO 10% BY WEIGHT OF NICKEL. THE CUPRO-NICKEL ALLOY MATRIX IS PREFERABLY AGE-HARDENABLE. THE COMPOSITION IS PARTICULARLY ADAPTED TO THE MANUFACTURE OF NON-MAGNETIC WEAR AND CORROSION RESISTANT ELEMENTS FOR USE IN SALINE ENVIRONMENTS, SUCH AS A MATING RING IN ROTATING MECHANICAL SEAL APPLICATIONS IN TORPEDOES AND THE LIKE.

Description

y 4, 1972 A. L. PRILL ET AL TUNGSTEN CARBIDE DISPERSION IN AGE-HARDENABLE CUPRO-NICKEL Filed Oct. 21, 1970 FIG.

INVENTORS ARA/0L D L. PIP/L L STUART E. TARKAN 3,674,575 TUNGSTEN CARBIDE DISPERSION IN AGE- HARDENABLE CUPRO-NICKEL Arnold L. Prill, Edmond, Okla., and Stuart E. Tarkan,

Munsey, N.Y., assignors to Chromalloy American Corporation, West Nyack, N.Y.

Filed Oct. 21, 1970, Ser. No. 82,769 Int. Cl. C22c 29/00, 31/04 US. Cl. 148-325 14 Claims ABSTRACT OF THE DISCLQSURE A sintered refractory metal carbide composition is provided comprising about 35 v/o to 70 v/o of at least one refractory metal carbide selected from the group consisting of WC, CbC, VC and TaC dispersed substantially uniformly through a cupro-nickel matrix making up essentially the balance, the cupro-nickel matrix consisting essentially by weight of about 55% to 90% copper and the balance essentially about 45% to by weight of nickel. The cupro-nickel alloy matrix is preferably age-hardenable. The composition is particularly adapted to the manufacture of non-magnetic wear and corrosion resistant elements for use in saline environments, such as a mating ring in rotating mechanical seal applications in torpedoes and the like.

This invention relates to a sintered refractory metal carbide composition and articles of manufacture thereof, such as shaft seals, which are characterized as being nonmagnetic and having improved wear and corrosion resistance in saline environments. The invention also relates to a method for producing such compositions.

Marine alloys are generally non-ferrous alloys containing copper as a major alloying ingredient to provide resistance to corrosion in saline environments. An example of such alloys is cupro-nickel. However, such alloys have their limitations in rotary seal applications due to low resistance to wear. Attempts at improving wear resistance by adding strengtheners, such as Ta, Cr, Al, Zr, etc., have not been very satisfactory, the maximum hardness obtainable generally ranging up to about 35 R Due to the inherent lack of wear resistance in typical marine alloys, manufacturers of marine equipment have made attempts at other solutions to the problem, such as employing (1) a hard chrome plate, (2) flame or plasma spray coatings, and the like. The foregoing proposals had certain inherent problems, such as spalling and chipping problems due to the lack of ductility of the coating relative to the more ductile substrate.

It thus became apparent that the solution to the problem would have to reside in providing a composition having the corrosion resistance of marine alloys but with markedly improved hardness without substantially adversely affecting the corrosion resistance.

It is thus the object of the invention to provide a hard, wear resistant and corrosion resistant composite alloy composition suitable for use in saline environments.

Another object is to provide, as an article of manufacture, a non-magnetic wear and corrosion resistant element, such as rotary shaft seals, having particular use in saline environments.

A still further object is to provide a wear resistant alloy composition characterized by a high degree of inherent hardness and characterized further by being further hardened through heat treatment.

The invention also provides as an object a powder metallurgy method for producing hard wear resistant alloys suitable in marine applications.

These and other objects will more clearly appear when Patented July 4, 1972 taken in conjunction with the following disclosure and the accompanying drawing, wherein:

FIG. 1 depicts one embodiment of a mating ring for use in a mechanical seal; and

FIG. 2 is illustrative of one use of the novel composition as a mating ring seal for rotating shafts, especially where shafts are employed in marine equipment, such as torpedoes.

Stating it broadly, the invention resides in a sintered composition formed of at least one of the primary carbides WC, CbC, VC and TaC (e.g. about 35% to 70% by volume) dispersed substantially uniformly through a matrix of a cupro-nickel alloy making up the substantial balance, the matrix alloy consisting essentially by weight of about 55% to copper and the balance essentially about 45% to 10% nickel. By primary carbide is meant any one or more of the aforementioned carbides which is added to the matrix as such, using powder metallurgy techniques of powder blending, of compressing the blended mixture into the desired shape and sintering the shape at an elevated sintering temperature, such as at the melting point of the matrix metal. The matrix metal may advantageously contain strengthening elements, such as age hardeners, for example, 0.5% to 3% by weight of alumi-I num.

Summarizing the foregoing, the refractory carbide may range from about 35 v/o to 70 v/o or, more advantageously about 40 v/o to 60 v/o, and the balance cupronickel matrix alloy ranging from about 30 We to 65 We and about 40 We to 60 v/o, respectively. A particularly specific composition is 45 v/o WC and 55 v/o matrix alloy.

As stated hereinabove, the composition of the matrix alloy may range from about 55% to 90% by weight of copper and the balance essentially about 45% to 10% nickel, the range more advantageously being by weight about 60% to 75% copper and about 40% to 25% nickel, with or without about 0.5% to 3% by weight aluminum as an age hardener, and 0 to about 5% iron, more preferably 1 to 3% iron. A specific composition of the matrix metal by weight is 68.5% copper, 30% nickel and 1.5% aluminum. The alloy matrix may contain by Weight up to about 2% manganese and, more preferably, 0.5 to 1%.

As illustrative of the various embodiments of the invention, the following examples are given:

EXAMPLE 1 An age hardenable wear and corrosion resistant composition was produced by dispersing 45 v/o WC through a matrix of 55 We of cupro-nickel alloy containing by Weight about 68.5% copper, about 30 nickel and 1.5 aluminum. In producing the carbidic composition, about 60% by weight of WC powder is mixed with about 40% by weight of the alloying ingredients employed in producing the matrix metal as follows:

Grams WC (1 to 8 microns) 600 Cu (electrolytic, minus mesh) 274 Ni (carbonyl, 3 to 8 microns) .a 107 NiAl (minus 325 mesh) 19 The aluminum is added to the mixture in the form of nickel aluminide to avoid the loss thereof by evaporation during the early stages of high temperature sintering.

To the 1000 gram mixture is added 1% by weight of paraffin wax and the mixture ball milled for about 60 hours in a stainless steel ball mill half filled with stainless steel b'alls using hexane as a vehicle. After milling, the mixture is dried on a hot plate at 68 C. F.) until all the hexane is driven oif. The dry powder is then pressed into compacts or slugs at 15 tons per square inch. The compacts thus produced are preferably subjected to liquid phase sintering in vacuum by heating them to about 1400 C. in vacuum for about 2 /2 hours and then held at temperature for about three-quarters of an hour, followed by cooling to 1200 C., in 60 minutes and then furnace cooled from the foregoing temperature to room temperature. The sintering is advantageously carried out on a ceramic plate of previously fired Magnorite (a commercial MgO refractory).

The sintered density of the sintered compact was about 99.3% of theoretical and the compact exhibited an assintered hardness of about 51 R and a solution annealed hardness of about 38 to 40 R when heated to 1650 F. and held at temperature for about one hour followed by air cooling. Heating the quenched alloy at an age hardening temperature of about 932 F. for about 16 hours resulted in a hardness of 52 R The sintered alloy in the annealed state is easy to machine to precise shapes prior to age hardening and exhibits good resistance to seawater corrosion. While the' metallographic structure is composite in nature, galvanic couples do not occur and, therefore, the alloy is not subject to galvanic corrosion.

This alloy is excellent as seal material for rotary shafts in marine equipment. Other potential uses are non-sparking tools, weld wire guides for its good electrical conductivity and wear resistance.

EXAMPLE 2 Vol. percent Primary carbide About 55 Matrix metal About 45 1 CbC.

The nominal composition of the matrix by weight is as follows:

Percent The foregoing composition is produced as in Example 1.

EXAMPLE 3 Vol. percent Primary carbide About 60 Matrix metal About 40 The nominal composition of the matrix by weight is as follows:

Percent 100 EXAMPLE 4 Vol. percent Primary carbide -About 70 Matrix metal About 30 The nominal composition of the matrix metal by weight is as follows:

Percent 4 EXAMPLE 5 Vol. percent Primary carbide -About 40 Matrix metal About 60 The nominal composition of the matrix metal by weight is as follows:

The nominal composition of the matrix metal by weight is as follows:

Percent Cu 8 8 Ni 10 Fe l 1 A1 1 Broadly speaking, the sintering temperature may range from about 1050 C. to 1600 C., the time at temperature ranging from about 10 minutes to 4 hours. The sintering is preferably carried out in vacuum. However, vacuum need not be employed so long as the pressed compact is sintered in a non-reactive environment, such as in hydrogen, argon, etc.

Following sintering, the sintered body (where the matrix metal is age hardenable) is preferably solution annealed by heating to a temperature in the range of about 750 C. (1382 F.) to 950 C. (1742 F.) for about 1 to 4 hours, the annealed body thereafter cooled to room temperature, such as by agitated air cooling. The age hardening treatment consists of heating the solution annealed body at a temperature of about 300 C. (572 F.) to 700 C. (l292 F.) for about 1 to 25 hours and then air cooling.

The composite alloy produced in accordance with the invention is characterized in that it is machinable, is substantially non-magnetic, is particularly wear resistant and suitable for use in saline environments, such as seals for rotary shafts. A seal ring 10 is shown in FIG. 1, said seal ring having use as a mating ring in the mechanical seal of FIG. 2. The mechanical seal of FIG. 2 is formed of an assembly of an annular stainless steel cup 11, having confined in the cup-like annulus thereof a graphite ring 12. The graphite ring has an annular right angled cutout 13 in which is confined an elastomer O-ring 14 for maintaining a positive seal between the seal ring and the cup. A mating ring 10A is shown produced from the composite alloy of the invention in abutting relationship with the graphite seal and shaft 15, the mechanical seal assembly being supported on shaft 15 as shown.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted 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 the appended claims.

What is claimed is:

1. A sintered, machinable, non-magnetic, wear and corrosion resistant carbidic composite alloy suitable for use in saline environments, said alloy being formed of a sintered composition consisting essentially of about 35 v/o to 70 v/o of primary grains of at least one refractory carbide selected from the group consisting of WC, CbC, VC and TaC dispersed substantially uniformly through a cupro-nickel matrix making up essentially the balance, said cupro-nickel matrix consisting essentially by weight of about 55 w/o to 90 w/o copper, about 05%- to 3% aluminum, to about iron, 0 to 2% manganese and the balance essentially of about 45 w/o to w/o nickel, said cupro-nickel matrix being in the age-hardened condition.

2. The wear and corrosion resistant alloy of claim 1, wherein the amount of refractory carbide ranges from about 40 v/o to 60 v/o, and wherein the cupro-nickel alloy matrix ranges from about 60 v/o to 40 v/o.

3. The wear and corrosion resistant alloy of claim 2, wherein the refractory carbide is tungsten carbide, and wherein the cupro-nickel matrix alloy contains by weight about 55 w/o to 75 w/o copper and about 45 w/o to 25 w/o nickel.

4. The wear and corrosion resistant alloy of claim 3, wherein the amount of tungsten carbide is approximately 45 w/o and the balance essentially the cupro-nickel alloy matrix containing approximately 1.5% by weight of aluminum.

5. The wear and corrosion resistant alloy of claim 2, wherein the refractory carbide is columbium carbide.

6. The wear and corrosion resistant alloy of claim 2, wherein the refractory carbide is vanadium carbide.

7. The wear and corrosion resistant alloy of claim 2, wherein the refractory carbide is tantalum carbide.

8. As an article of manufacture, a machinable, nonmagnetic wear and corrosion resistant element suitable for use in saline environments, said element being formed of a sintered composition consisting essentially of about 35 v/o to 70 v/o of primary grains of at least one refractory carbide selected from the group consisting of WC, CbC, VC and TaC dispersed substantially uniformly through a cupro-nickel matrix making up essentially the balance, said cupro-nickel matrix consisting essentially by weight of about 55 w/o to 90 W/o of copper, about 0.5 to 3% aluminum, 0 to 5% iron, 0 to 2% manganese and the balance essentially of about 45w/o to 10 w/o nickel, said cupro-nickel matrix being in the age-hardened condition.

9. The wear and corrosion resistant element of claim 8, wherein the amount of refractory carbide in the composition ranges from about 40 v/o to v/o, and wherein the cupro-nickel alloy matrix ranges from about 60 v/o to 40 v/o.

10. The wear and corrosion resistant element of claim 9, wherein the refractory carbide is tungsten carbide, and wherein the cupro-nickel alloy matrix contains by weight about 55 w/o to w/o copper and about 45 w/o to 25 W/o nickel.

11. The wear and corrosion resistant element of claim 10, wherein the amount of tungsten carbide in the composition is approximately 45 v/o and the balance essentially the cupro-nickel alloy matrix containing approximately 1.5% by Weight of aluminum.

12. The wear and corrosion resistant element of claim 9, wherein the refractory carbide in the composition is columbium carbide.

13. The wear and corrosion resistant element of claim 9, wherein the refractory carbide in the composition is vanadium carbide.

14. The Wear and corrosion resistant element of claim 9, wherein the refractory carbide in the composition is tantalum carbide.

References Cited UNITED STATES PATENTS 2,160,659 5/1939 Hensel 29-1821 2,430,306 11/1947 Smith 75-159 3,293,029 12/1966 Broderick et al. 75-154 X 3,340,049 9/1967 Quaas et al. 75-154 3,369,891 2/1968 Tarkan et al 148142 X 3,369,892 2/1968 Ellis et a1 148142 X 3,399,057 8/1968 Richardson et al. 75-153 X 3,496,682 2/1970 Quaas et al 75-153 X FOREIGN PATENTS 491,837 4/1953 Canada 75-159 CHARLES N. LOVELL, Primary Examiner US. Cl. XJR. 29-182.7, 182.8; 75-159