US2798036A - Electroplating of beryllium - Google Patents

Description

United States Patent ELEC'I'ROPLATING 0F BERYLLIUM Joseph J. Utz, Whittier, Caiifi, assignor, by direct and mesne assignments, to the United States of America as represented by the United States Atomic Energy Commission N0 Drawing. Application July 12, 1954, Serial No. 442,903

4 Claims. 01. 204-32 This invention relates to a method of electroplating various metals on beryllium. More particularly, this invention relates to a pretreatment of beryllium or beryllium alloy surfaces to insure a good bond between the beryllium base and the plating metal.

The preplating treatment of beryllium and the alloys containing a major portion of beryllium has been found to be very critical. Conventional acid and alkaline etching methods, both immersion and electrolytic, uniformly fail to allow satisfactory adhesion of the electrodeposits. Various other methods of coating beryllium have been attempted without attaining the desired results. These methods include carbonyl reduction, iodide reduction, roll cladding, and weld jacketing.

The essence of this invention is in providing an electrodeposited first layer on the beryllium base metal which establishes a sound metallic bond between such base metal and that layer. The nature of the first electrodeposited layer is such that various metals may be plated thereon by conventional plating techniques.

The principal object of this invention is to provide a method of plating various metals on beryllium and its alloys.

A further object of this invention is to provide a method of pretreating the surface of beryllium and its alloys prior to conventional plating procedures.

A still further object of this invention is to provide a method of depositing a preliminary electrodeposited layer on beryllium.

An additional object of this invention is to provide a smooth, dense, homogeneous metallic layer on beryllium having the characteristic visual qualities associated with conventional nickel plates.

A further object of this invention is to provide an electrolytic preplating treatment for beryllium and its alloys.

A still further object of this invention is to provide a uniform, strongly bonded coating on beryllium metal objects.

An additional object of this invention is to provide an intermediate bonding agent for plating conventional metals on beryllium and its alloys.

Other objects of invention will become apparent from the following description.

Various types of beryllium and beryllium alloys may be treated by the instantly disclosed process. The process has been found to be particularly applicable to wrought beryllium but may also be used with sintered powdered compacts and vacuum cast extruded beryllium. The disclosure and claims comprehend the inclusion of pure beryllium, beryllium alloys, beryllium compacts, as well as various objects of beryllium in the broad term beryllium used in the specification and claims.

The basic invention basically comprises the steps of cleaning the beryllium surface, placing a cobalt strike on said surface and conventionally electroplating on said cobalt surface. It has been found that it is necessary to thoroughly clean the surface prior to the cobalt strike.

2,798,036 Patented July 2, 1957 The cobalt strike should be applied immediately after the cleaning operations. The cleaning is done by rinsing the beryllium in clean acetone, normally at room temperature, for a few minutes. Other ketones, such as diethylketone or methyl ethylketone may be used in this degreasing and activation step. Normally the ketone rinsing will be for a period of from 3 to 5 minutes. After the ketone rinse the beryllium material is water rinsed for a period of approximately 1 minute at a temperature from 20 to 40 C. The time lag between the ketone rinse and the water rinse must not be so great that the ketone film is allowed to evaporate exposing dry beryllium. Thus the ketone provides an air barrier on the surface of the beryllium. Care must be taken that the water rinse contains no contaminants to interfere with the cobalt strike.

A particular composition of matter has been formulated for the cobalt strike. This striking bath is made up of cobalt sulfate of the hydrous or anhydrous type in the proportions of 0.2 molar-0.6 molar and ammonium sulfate in similar proportions. The cobalt sulfate and ammonium sulfate are made up in an aqueous solution which has high chemical stability. The bath is normally operated at room temperature without external facilities for either heating or cooling. The bath, however, may be in the temperature range of 1040 C. The plating bath is maintained at a current density of from 25 to 45 amps. per sq. ft. and at a pH of from 46. Normally stainless steel or carbon anodes are used and the metallic cobalt is plated directly from the bath. Such carbon anodes are in the form of bagged graphite.

The cobalt strike is normally carried out for a period of from 1 to 5 minutes dependent upon the thickness of the coat desired. It is to be understood that if thicker coats are desired the time within the cobalt strike bath will be increased.

The following example shows a specific formulation of a cobalt strike solution and operating conditions which are usable to deposit a 0.00075 inch layer of cobalt on various beryllium objects. Hydrous cobalt sulfate in the amount of 126 grams per liter (0.45 M) and 59.4 grams per liter (0.45 M) of ammonium sulfate were made up in an aqueous solution. The strike was made at room temperature (24 C.) at a current density of 25 amps. per sq. ft. using stainless steel anodes. After the beryllium had been rinsed for approximately 3 minutes in clean acetone and quickly water rinsed, the beryllium was placed in a cobalt strike bath for approximately 3 minutes. A smooth, dense, homogeneous layer having the characteristic visual qualities associated with conventional nickel plates and of a thickness of 0.00075 inch resulted from such pretreatment.

The above-described process provides an intermediate bonding agent which will allow various electrodeposited metals to adhere to beryllium. Such metals as copper, zinc, silver, chromium, and mckel may then be electroplated directly on the cobalt bonding agent by conventional electroplating techniques.

By reason of the cleaning procedures and the cobalt strike from a bath having a cobalt-ammonia ion complex therein it is possible to adheringly plate a variety of conventional metals on a beryllium substructure.

The instant process is usable wherever there is a need for soldering or otherwise attaching beryllium to itself or to other metals. For example, when the beryllium is used as a window or port in X-ray tubes, where its low atomic number and density make the port pervious to even long wave X-rays, such beryllium much be attached to the remainder of the tube by some means. The instant preplating treatment permits the edges of the beryllium port to be soldered to the tube structure due to the ease of soldering on the above-mentioned electrodeposited metals as distinguished from straight beryllium. Likewise,zthe :non-sparkingrqualities of beryllium make such a -light, hard -metal applicable ..for -shielding ,purposes in A.-C. motors developed for use in semi-hazardous or explosive atmospheres. Here also the instant invention provides a means'for' attaching the -beryllium to other ;parts of the motor.

Theedges of beryllium oscillatingor stationary mirrors, which mirrors have high reflectivity in ".the ultra-violet range, may :be treated :in the manner prescribed :by the instantinvention to :provide both .solderable :surfaces and a tboundary surface to minirnize :the effects of :galvanic action atlocalizedcontact areas-of 'the dissimilar metals.

Although the invention has been described and-illustrated in detail, it is :to beclearly understood that the same is by way :of illustration :and example only rand is not to be:taken by way of limitatiomthe spirit and scope of this invention being limited :onlyby theterms of the appended claims.

I claim:

1. The-method of pretreating beryllium compositions priorto electroplating comprising degreasingsaid beryllium witha ketone, rinsing saidberyllium in water prior to evaporationof said ketone, and then subjecting the resulting water-wet beryllium toa cobalt strike in a bath comprising from 0.2-0.6 molar cobalt sulfate and'from 0.2-0.6 molar ammoniumsulfate.

2. The invention as described in claim 1 in which the ketone is acetone.

3. The invention as described in claim 1 in which the cobalt striking bath is kept at a temperature of from 1040 C. and at a current density of from 25-45 amps. per sq. ft.

4. A preplating treatment for beryllium and alloys containing a major portion of beryllium, comprising degreasing said beryllium with a ketone, rinsing said beryllium with water prior to evaporation of said ketone, and then subjecting the resulting water-wet beryllium to a cobalt strike in a bath comprising an aqueous solution of cobalt sulphate and ammonium sulphate.

References Cited in the file ofthis patent UNITED STATES PATENTS Beach et a1 Ian. 3,.1956

Claims (1)

1. 4. A PREPLATING TREATMENT FOR BERYLLIUM AND ALLOYS CONTAINING A MAJOR PORTION OF BERYLLIUM, COMPRISING DEGREASING SAID BERYLLIUM WITH A KETONE, RINSING SAID BERYLLIUM WITH WATER PRIOR TO EVAPORATION OF SAID KETONE, AND THEN SUBJECTING THE RESULTING WATER-WET BERYLLIUM TO A COBALT STRIKE IN A BATH COMPRISING AN AQUEOUS SOLUTION OF COBALT SULPHATE AND AMMONIUM SULPHATE.