US2145746A - Anode for electrodeposition of tungsten - Google Patents

Description

Patented Jan. 31, 1939 UNITED STATES PATENT OFFICE ANODE FOR ELECTRODEPOSITION F TUNGSTEN Harry Howard Armstrong and Arthur Burley Menefee, Beverly Hills, Calif., assignors to Tungsten Electrodeposit Corporation, Washington, D. 0., a corporation of Delaware No Drawing. Application May 18, 1935, Serial No. 22,281

12 Claims. (Cl. 204-4) This invention relates to the electrodeposition intimate association with a second metal or metof metals, more particularly to the production and als.

use of special types of anodes peculiarly useful With these and other equally important and refor the electrodeposition of metals, such as tunglated objects in view the invention comprehends i sten and alloys thereof. the concept of producing special electrodes for 5 The present invention is in part a continuation effective employment in the electrodeposititon of of our prior applications Serial No. 744,566, filed tungsten and alloys thereof. January 5, 1935, and Serial No. 14,372, filed April The electrodes of the present inventiton, it is to 1935- be clearly understood, are employable either in 0 As disclosed in the prior applications above the process described in prior application Serial l0 referred to, we have found that adherent, dense, No. 744,566 or Serial No. 14,372, that is to say fine grained and acid resistant plates of tungsten either in an electrolytic bath in which all of with variable percentages of other metals may be the tungsten ions are produced by electrolysis of electrodeposited from suitable aqueous baths. a tungsten metal compound or in an electrolyte As there explained, under very wide permissive in which tungsten ions are initially made availlimits of hydrogen ion concentration, dilution, able by direct dissolution of a tungsten compound current density and so forth, tungsten alloys or in a suitable solvent, such as a bi-fluoride, and alloys of metals similar to tungsten may be deposthe tungsten concentration maintained by conited from aqueous fluoride baths. We have furtinuous or intermittent electrolysis of a tungsten 0 ther found, as explained in the designated applimetal compound.

cations, that the tungsten ions may be made As explained in prior application Serial No.

available in the bath either by dissolving tung- 744,566 eminently satisfactory plates may be sesten compounds directly in a suitable aqueous cured by first establishing a hot definitely acid solution of a fluoride or by subjecting a tungsten aqueous bath containing an acid fluoride, such as i containing electrode to anodic corrosion in a fluosodium acid fluoride and an agent, such as sodium ride bath. chloride, which imparts high conductivity to the We have now found that a relatively wide vabath, and then electrolyzing using a tungsten riety of specifically different tungsten containing containing anode, Such as tungsten carbide a compounds may be employed as the main anode tungsten alloy carbide. The electrolysis preffor the electrolytic cell or as, so-to-speak, reerably is carried out under conditions of high plenishing anodes, whereby an efiective concenacid concentration, of the order of pH 4 more or tration of tungsten ions and/ or other metal ions less. Upon satisfactory electrolysis the hydrogen may be maintained in the bath. ion concentration is then preferably adjusted toa An object of the invention, therefore, is to prolower value and the desired basis metal or cathode 5 vide novel types of electrodes, particularly useis then pl Tun c r i and tun n ful for the electrodeposition of tungsten or simalloy carb des Serve effectively for Such a p il t l d alloys thereof, ess. Such massive materials present a satisfac- Another object is to provide a tungsten containtory electrical conductivity and efiective corroing electrode of satisfactory electrical conduc- $1011 of the metal content? 0 tivity.

a number of specifically diiferent types of anodes Afurther ob ect is to provide a novel compos1te may be employed some these are particw g g for electrodeposltmg two or more larly useful in special adaptations of the process.

' Thus we have found that under properly conproducmg agent an electrode m? of a and temperature, the respective amounts of the tungsten colPPound of hlgh conductlvlty and constituent metals of the ultimate alloy may ready availabllltywidely be varied during a given plating operation. Yet anot e Obj is to Provide an electrode for In such a process it is desirable to have available the electrodeposition of tungsten comprising a a, rapidly or readily rodi l quantity of 50 p u d of tungsten a a non-metal of high 0nd metal or metals to be coplated with tungsten conductivityto form the final alloy. In these circumstances, A furthe O j i8 60 provide an electrode for as will be appreciated, it is advantageous to utilize use in the electrodeposition of tungsten alloys main anodes or replenishing anodes which pre- 5 comprised of a tungsten containing compound in sent a large area for wetting or contact by the In further experimentation we have found that 40 A still further object is to utilize as a tungsten. trolled conditions, particularly of current density electrolyte to thus accelerate the corrosion of the desired metal and provide a higher metal concentration in the bath. For the same reason in some circumstances it is desirable to make the second metal or metals available in the relatively pure and unassociated form, thus further accelerating the corrosion rate of this metal.

It will thus be seen that by providinga wide range of anodes of specifically different composition and character the plating process may be made much more flexible and the ramifications of use of the ultimate plate considerably widened. According to one phase of the invention, therefore, the tungsten supplying material may comprise substantially pure tungsten. This may consist of discrete tungsten metal packed or tamped in an acid proof anode container. Again the tungsten powder may be compressed under relatively high pressure and fitted as a core in a conductive acid proof anode. The relatively pure tungsten -may likewise be made available either as the main anode or a replenishing or regener-' ating' electrode by admixing tungsten powder with a suitable. bonding or cementing agent, preferably of a carbonaceous character, and subjecting the mass to heat and/or pressure to form a compact rugged electrode. Similarly tungsten powder may be compacted and cemented under heat and pressureto form an electrode of suitable strength and relatively large exposed area.

Such electrodes may be employed alone or in conjunction with inert or reactive anodes to carryout plating operations as described in the prior applications referred to. a

It will be appreciated also that in making up each of the anodes above described there may be added suitable quantities of other powdered metals, such as nickel, chromium, cobalt, iron, cadmium, antimony and'the like, when electrodeposited alloys of tungsten and one or more of such metals are desired.

Because of its adequate tungsten content, satisfactory conductivity and ready availability, tungsten carbide provides a good anode material for employment in the present process. Heretofore operations have been carried out utilizing massive tungsten carbide. We have found that tungsten carbide powder when compacted, or when cemented either with suitable cementing materials, or directly cemented under heat and pressure, likewise serves very eifectively. Like tungsten metal powder, this may be employed in relatively loose condition in a suitable acid proof anode container or be made up in the compacted selfsustaining form. Similarly predetermined percentages of relatively discrete or'packed and/or cemented mixtures of tungsten metal and tungsten carbide powder may be utilized. A wide range of relatively standardized anodes for plating different types of alloys may be fabricated by homogeneously incorporating in the tungsten carbide mass or in the tungsten metal-tungsten carbide units, predetermined amounts of other coplatable metals, such as nickel, cobalt, antimony, chromium and the like.

As has been fully described in the prior applications, one of the striking characteristics of theseveral fluoride baths defined therein is the capability of directly dissolving not only tungsten oxides, such ,as W02 and W03, but also the tungstates meta and para tungstates. Thus, as explained in application Serial No. 14,372, satisfactory electrodeposition of tungsten alloys may be sev cured by directly dissolving, say .atungstic acid anhydride in hot ammonium bifiuoride. Upon addition of other desirable adjuvants, such as sodium fluoride, boric acid, tartaric acid and a soluble salt of the second metal or metals to be alloyed with tungsten, an alloy plate may be procured when using an inert anode or an anode g of a metal other than tungsten.

This characteristic of the new electrolyte permits the use of special forms of anodes and by such use achieves improved results. Thus an anode may be made up which comprises a pre- 1' dominant quantity of tungsten containing compound, such as compacted tungsten metal powder, tungsten carbide powder or a mixture of tungsten metal powder and tungsten carbide powder, together with a minor percentage of a soluble tungsten compound, such as tungsten dioxide or tungsten trioxide. It will be appreciated by those skilled in the art that the quantity of the soluble tungsten compound may be so chosen that it will leach or dissolve out of the anode without materially impairing the structural strength of the anode. In these circumstances, therefore,.the tungsten ion concentration of the bath may be maintained by supplying tungsten not only by means of anodic corrosion of a conductive tung- 2 sten compound but also by slow dissolution of a soluble tungsten compound. Since the soluble tungsten compound is uniformly distributed throughout the anode, it is thus made available at a slow and relatively constant rate. It likewise 3 will be appreciated that in the bath of the character described, during electrolysis a relatively high concentration of hydrofluoric acid obtains at the anode, thus facilitating the dissolution of the tungsten oxide impacted. in the massive anode. 3

This type of anode may be made up as hereinbefore described. For example a predetermined quantity of tungsten metal powder may be homogeneously admixed with a minor quantity of a soluble tungsten compound and then compacted 4 under suitable conditions of temperature and pressure or the mass may be cemented by a suitable binder. A similar procedure may be employed in making up an anode comprising a mixture of predetermined major quantities of tung- 4 sten metal powder and tungsten carbide powder and a minor quantity of the soluble tungsten compound. As described above, anodes may be made up containing the tungsten powder, tungsten carbide powder, or a combination of the two in ad- 5 mixture with tungsten oxides or other soluble tungsten compound and contaimng in addition to these predetermined quantities of powdered or discrete metals which are to be coplated with the tungsten for the production of an electro- 5 deposited alloy. It is particularly to beobserved that when tungsten metal is to be employed for the anode, complete reduction need not be effected; that is to say when utilizing a bath of the characteristics defined herein, it is a possible to use tungsten metal containing a small percentage of tungsten oxide. Thus when the tungsten metal which is employed as the anode is made by reduction from the oxides, a complete reduction is not essential; hence cheaper forms 6 of relatively pure tungsten metal may be employed effectively in the present invention.

What has been said of the employment of tungsten metal and tungsten carbide applies similarly to tungsten alloys. Suitable commer- 7 cial tungsten alloys may be utilized as anode materials in the present invention. Again it will be understood that, if desired, the anode employed may itself be an electrodeposited alloy plate. Thus, for example, it is within the con- 7 cept of the invention to provide anodes by plating out tungsten and other metals, such as nickel, in the form of an alloy on a typical cathode. For this use the plate does not have to be as adherent or fine-grained as the ultimate plate and hence operative conditions may be so controlled as to secure the maximum amount of plated metal. Such alloy surface may be electrodeposited upon a basis metal or,.and preferably, upon a carbon core. Such alloys may be in the massive form or in the discrete or powdered form when suitably treated to provide a compact self-sustain electrode. Such materials likewise may be used in the relatively uncompacted form by utilizing an acid resistant anode container for the material.

While preferred modifications oi the invention have been described, it is to be understood that these are given merely as examples of the underlying principles involved and not as definitive of the exclusive methods of efiectuating such principles. It will be appreciated that within the scope of the concepts herein expressed, other and specifically different but equivalent electrodes may be fabricated which function in an analogous manner. All such modifications or extensions as are included within the scope of the appended claims are considered tobe comprehended within the spirit of the invention.

We claim:

1. An electrode for use in the electrodeposition of tungsten which comprises a compacted mixture of discrete tungsten metal and tungsten carbide.

2. An electrode for use in the electrodeposition of tungsten which comprises an intimate compacted mixture of tungsten metal and an oxide of tungsten.

3. An electrode for use in the electrodeposition of tungsten which comprises anintimate compacted mixture of tungsten carbide and an oxide of tungsten.

4. An electrode for use in the electrodeposition of tungsten which comprises an intimate compacted mixture of discrete tungsten metal, tungsten carbide and an oxide of tungsten.

5. An electrode unit for use in the electrodeposition of tungsten which comprises anintimate mixture of discrete tungsten metal, tungsten carbide and a cementing agent.

6. An anode for use in the electrodeposition of alloys of tungsten which comprises a compacted mixture of discrete tungsten metal and nickel.

7. An anode for use in the electrodeposition of alloys of tungsten which comprises a compacted mixture of discrete tungsten carbide and nickel.

8. An anode for use in the electrodeposition of alloys of tungsten which comprises a compacted mixture of discrete tungsten metal, tungsten carbide and nickel.

9. An anode for use in the electrodeposition of alloys of tungsten which comprises a compacted mixture of discrete tungsten metal and a second metal coplatable with tungsten and comprised within the group consisting of nickel, chromium, cobalt, iron, cadmium, and antimony.

10. An anode for use in the electrodeposition of alloys of tungsten which comprises a compacted mixture of discrete tungsten carbide and a second metal coplatable with tungsten and comprised within the group consisting of nickel, chromium, cobalt, iron, cadmium, and antimony.

11. An anode for use in the-electrodeposition of alloys of tungsten which comprises a compacted mixture of discrete tungsten metal, tungsten carbide, and a second metal coplatable with tungsten and comprised within the group.consisting of nickel, chromium, cobalt, iron, cadmium, and antimony.

12- An anode unit for use in the electrodeposition of alloys of tungstenwhich comprises a uniform mixture of tungsten carbide and discrete metals coplatable with tungsten and comprised within the group consisting of nickel, chromium, cobalt, iron, cadmium, and antimony.

HARRY HOWARD ARMSTRONG. ARTHUR BURLEY MENEFEE.