US2343038A - Alloy for metal to glass seals and the like and method of producing same - Google Patents

Description

Feb; 29, 1944. we. ALLEN AL. ALLOYS FOR METAL T0 GLA S S, AND THE LIKE,

NG SAME AND METHOD "OF R D Filed Dec. 19, 41

I ENTOR 5 Viz-fa 0. [Ilia/1 Jas e a/I F- 014 ATTOR EY- Patented Feb. 29,1944 I ALLOY FOB METAL T GLASS SEALS AND THE-LIKE AND METHOD PRODUCING Victor-'0. Alien, Madison, and Joseph F. Polar,

UNITED STATES PATENT OFFICE Newark, N. 1., assignors to Wilbur 13. Driver Company, Newark, N. 1., a corporation of New Jersey Application December 19 liiil serial No. 423,566

1 cam. (01. 148- 6) This invention relates to metallurgy and more particularly to the metallurgy of beryllium-containing alloys and to metallic material adapted for use in combination with non-metallic material, such as glass, enamel, porcelain, refractories, thermionically active metal oxides, organic to provide a metal base for use in combination with the above identified non-metallic materials in the forming of said devices and products which has a surface specifically adapted to provide for the mechanical securing of the said nonmetallic material thereon, irrespective and independent of any other type of bond union therebetween.

Another object is to provide a metal base which has a'surface adapted to provide a mechanical interlocking of non-metallic material therewith.

Still anotherobiect is to facilitate the securin: together of metallic and non-metallic materials.

Other objects and advantages will be apparent as the invention is more fully hereinafter disclosed.

In accordance with these objects, we have discovered that-beryllium additions in fractional percentages up to'1%'to any of the base metals Cu, Ni, co and Fe and alloys consisting principally of at least one of these metals, consistently produces a surface condition which in brief comprises an area extending inwardly from the surface for a relatively small distance as compared to the'thickness or diameter of the base which area consists of metal grains or crystals of relatively small size as compared to the metal grains or crystals in the interior of the base and of relatively large grain boundaries as compared to the grain'boundaries which boundaries are normally filled with an acid and alkali soluble and glass miscible constituent appearing to mainly consist of beryllium oxide or oxide compounds consisting predominately of berylllum oxide."

containing alloys above identified provides, on appropriate removal of the grain boundary material by acid or alkali pickling or by fusion of glass compounds thereon, a surface having a plurality of microscopic surface cracks and fissures extending inwardly .in the fine grained area which provides key-ways for the mechanical interlocking and securing thereon of various non-metallic materials, such as glass, enamel,

'procelai'n, organic plastic materials and the like.

I'he particular structur obtained, the depth thereof and the size or width of the intergranular surface key-ways obtained. my be widely modified without essential depaiture from the present invention, and we have found that the most satisfactory types thereof are obtained by subjecting the metal while in the cold-worked condition to a recrystallization heat-treatment in an atmosphere reducing with respect to the oxide compounds of the base metal ormetals of the alloy, but oxidizing with respect to the Be content thereof. Under these conditions. we have found that with any given Be-containing alloy, by the proper selection of the heat-treating temperature and time, the grain size of the small grained surface area and the sizeof the grain boundary areas may'be eflectively controlled to obtain a grain size and grain boundary area best suited for the particular service use intended. v

As a specific embodiment of the present invention, but not as a limitation thereof, the adaptation of the same to glass sealing-in alloys will be described. Before describing the same reference should be made to the accompanying drawing. wherein: I v v Fig. l is a diagrammatic cross-section of a wire formed in accordance with the present invention;

Fig. 2 is a diagrammatic longitudinal section of the same, and

Fig. 3 is a diagrammatic'cross-sectional view of a glass to metal seal illustrating the nature of the improvement obtained therein by the practice of the present invention.

Referring to the drawing. the improved, metal I product of the present invention comprises a metal article, such as a metal wire, strip, sheet This characteristic structure of the berylliumconsisting of relatively fine grained ,metal havvby beryllium oxidation occurs ing relatively large sized grain boundaries as contrasted to the grain size and grain boundary area in the central or core portion 2 of the article.

In the art of making metal to glass seals various metals and metal alloys have been proposed,- such as copper, nickel, iron, nickel-iron, chromium-nickel-iron, nickel-cobaltiron, nickelcobalt-chromium-iron, copper-clad nickel-iron and the like alloys. In most of these prior art alloys the alloy composition. per se, is closely controlled to provide an alloy composition having a specific coemcient of expansion substantially equivalent to the glass with which it is to be employed. The alloy composition, per se, forms no part of the present invention except insofar as additions of beryllium metal thereto in fractional percentages below 1% are made for the purposes of the present invention and in accord-. ance with the present invention. The specific method of manufacturing the beryllium-containing alloy, per se, also formsno part of the present invention and various methods are available in the art.

Copper, as one example of the present invention, is one of the most common of the metals employed in forming glass to metal seals and joints, either alone or as a. surfacing metal for Substantially the same result is obtained where the beryllium-containing copper is employed as a surfacing material on metals which are with more difficulty formed into metal to glass joints such as Ni and Fe or various Ni and Fe-base alloys heretofore proposed for similar use in the art and known generally under the name dumet."

The addition of fractional percentages of beryllium to the Ni or Fe or to the various Ni and Fe-base alloys heretofore proposed for use in the forming of metal to glass seals or joints, also results in the formation of the surface condition hereinabove described with respect to copper, and schematically illustrated in the drawing.

As in copper, the effect is accentuated and made more predominate where the alloy is subjected to a recrystallizing heat-treatment in an atmosphere reducing with respect to the base 7 metal oxides, but oxidizing with respect to beryllium. In general, with beryllium-containing alloys consisting predominately of one of the base metals Cu, Fe, Co and Ni, an atmosphere suitable for this purpose consists primarily of hydrogen nickel and iron alloys and the most common such seal or joint is that known in the art and indicated in Fig. 3 as a leading-in wire W for conducting an electric current from the exterior to the interior of an incandescent filament lamp bulb or electronic device such as a radio tube through a press P.

In accordance with the present invention, we have found that by incorporating from small fractional percentages (as low as .025%) up to 1% of beryllium in the copper, the resultant copper-beryllium alloy may be bonded to glass without the necessity of oxidizing the surface of the copper as heretofore has been found necessary in the art. This result, is obtained preferably by annealing the copper-beryllium. alloy prior to use in the forming of a metal to glassv seal orjolnt in an atmosphere reducing withrespect to for its reducing effect on Cu, Fe and Ni oxides and secondarily of one of the'oxidizing gases 0:, H2O, CO2, together with-various amounts of an inert gas such as nitrogen and various percentages of auxiliary metal oxide reducing gases such as CO and volatile hydrocarbons. In those Fe, Ni and Co alloys which in addition to beryllium also contain some chromium, the surface .of the heattreated articlenormally will be covered with an adherent film of chromium oxide, which for the Q purposes of sealing the wire to glass is desirable copper oxide, but oxidizing with respect to beryl-- j lium. Under such conditions it is found that the surface of the wire for an extended distance indepth with respect to the wardly, varying in I beryllium content and with the time of exposure of the metal to the oxidizing action of theiatmosphere, develops a relatively fine grain size, as compared to themetal of the central portion, with relatively large grain boundaryiareas. as compared to the grain boundary areas of'the metal of the central portion. This result is acand of no detriment to the presentinvention.

, As an example, beryllium-containing copper, preferably is annealed at about 800 C. in an atmosphere consisting of substantially pure hydro gen saturated with water vapor at atmospheric temperature. Nickel, iron and cobalt and the various alloys consisting predominately of one of these metals which contain from small fractional percentages up to 1% Be and those which also contain chromium may be annealed at i200 C. in

r the same atmosphere. Alternatively we have found an atmosphere consisting 10f illuminating gas saturated with 1120 (water vapor) at atmospheric temperatures equally as; satisfactory in the annealing of these. alloysfor the purposes of the present invention.

As specific examples of alloys of the iron group I metals which heretofore have found wide utility centuated where the metal prior to heat-treatment is in the strain-hardened condition wheresimultaneously with recrystallization.

In general, we have found that within rather wide limits the finer the grain size of the surface area the better the bond between the glass and metal surface, the said bond appearing to be directly dependent upon the total number of interlocks per unit of surface area between the glass and metal surface in the plurality of enlarged grain boundaries present in the metal surface. As the beryllium oxide normally present in the grain boundaries is of relatively high solubility in fused silicates, fusion of the glass onto the metal surface results in an opening of these grain boundaries for the flowing thereinto of the fluid silicate material comprising the glass,

in the art of forming metal'to glass seals and which have been found to be responsive to the present'invention, the following alloys well known in the art may beidentifled;

:Main alloy, constituents AlloyNo. cu Ni Cr Co Fo Each of' the alloys 1 to 5' inclusive, identified above are specific alloys having coeilicients of expansion particularly adapting the alloy for use with glass having the composition usually em ployed in the lamp and radio tube industry. In each of the alloys (1 to 4 inclusive) we have found that Be in fractional percentages up to about 1% characteristically produces in the wire on final annealing in an atmosphere reducing with respect to the base constituents but oxidizand at the minimumamoun V the desired fine'graine l "cient of expansion of the. l

with most of the alloysflabove identiflqdathiy.

minimum amount appears to approximately scopic key-ways for. interlocking them 'the non-metallic material thereon;

ing with respect to the beryllium, a surface area extending inwardly an appreciable distance consistingof. relatively small grains as compared to the grain. size interiorly and havingkrelatively large grain boundary areas as comparedto the 1 grain interior filled with oxidized material'con-j sisting mainly of beryllium oxide compounds; Alloy 5 is known in the art as ffdumet" wireo copper-clad nickel-iron" and in place'oi coppet' in accordance with thepresent invention,1Be'-Cu alloy containing fractional-Q percentages-oi not over about 1% arefsubstitu surfacing the nickel-ire h specifically, we have ioun that to maintain the Be content tion-reductionheat .tre" rially over this amount Alternatively, substantially pure pure iron frequently have been'employed glasssealing in alloys. We have found that the addi v tion of Be in from smallfraotionalpercentages up to 1% to substantially pure Ni andFemate rially improves the sealing in properties cunemetalsand moreover improves t-lli-lltillty oi, the nickel particularly asa meta'i forthe'rmir onically active cathodes, for-example, cathodes of the oxide coatedtype wherein the oxide coating is applied to the metal surface. v,

The oxidation-reduction annealing operation hereinabove described may be conducted as a continuou process known in thelart as "strand anemone known in the: art, the most common of which are known generally by the trade namesrLucite, I Bakelite, etc, andchemicaliy as cellulose acetate} 5 pheriol resins; protein condensation. products. 1 Eachof the organic plastics are characterized by being chemically; inert and non-reactive with --smetalsygeneral-ly and substantially all metal to organioplastic unions are pressureuniona; The interlocking'ljoint obtained by the practice of.

the present invention provide not only for the metal stir-face;v fbut' for the maintainin of the bond jtherebetween ov r relatively wide temperatureransesi' The; present jf inventionalso j. is particularly mannin g enameledfwirefproducts. such enameledjcopperwire;as one skilled inthe art wi ll,'read ily prClVek -In slich' use, it is preferable; to maintainfthe'beryllium copper toa very :low fractional percentagejapproximating .025% Y in order to eliminate deleterious loss in electrical conductivity in the copper,- especially where the I wire is to be employed as coil windings in eiee--x trical devices,

. Having hereinabovefdescribed the present invention generically and' specifically, it is believed apparentzthatthe same may be widely varied .withoutessential; departure therefrom and all such-adaptations and modiflcationsthereoi' are .contemplatedasimay' iallxwithin the scope of the .foliowingclaims. I a

i-what welclaim' is: l

I -1 .]The methodoftreating an alloy consisting predominately oi at least one of the base metals FgCQQNl) and containingiractional percentages of to'develo'p' therein-a crystal structure con-' {sisting of afflne grained surfaceiarea of appreannealing Or by the batch?inflthdd"with0ut essential departure from the-present:invention.

In general, in strand annealing,higher teml litures and shorter time intervals maybe eiripltill d;

than in batch annealing, a well as quicken'cooF; ing rates as is well recognize'dwin theartypar:

ticularly where recrystallization simultaneously with oxidation-reduction annealing is'desiredyf' Having hereinabove described the presentiin vention generically and specifically and given several specific embodiments thereof,"it; is-be-f lieved-apparent to one skilled inthe art that the same is adaptedfor wide utility. in'the gen f Y eral field of forming seals and joints betweena metal and a non-metallic material such' as glass, enamel, porcelain, organic plastic 9. like materials, by providingthe metal snri with a plurality of interioriy extending non-metallic material together.

, Where the non-metallic suriacin'g mat wire, sheet or strip prior to the application of The present invention ofiers particular plastic which at the present time is diflicult to utility in the art of 'forming tight, hermetic joints-between a metal and non-metal such as an organic obtain, such as, for example, in forming metal reinforced articles comprised of organic plastic. There are a largenumber of organic plastics lobar. Q

qfciable depth-having relatively wide boundaries overlying a'larger grained-core areanavmg relatively small boundaries; which comprises cold working: the alloy andheatrtreating the cold worked alloy at a recrystallizationtemperature inan atmosphere" reducing withrespect to the metal oxides of the base metal but oxidizing with respect to the 'said'beryllium-for a'time interval producing the desired'depth o'i,saidilne grained urrace area and to obtain the desired larger grain sized core.. 1 v

-,2.., 'I he ,method r claim 1; whereinsaid atmos j p ldi rig gases oxygen, water "vapor and carbon dioxidelii 1 z es v iwaternvab riando carbon dioxide; and said as consisting of nitrogen. 1

jCo,fNi,, and containing fractional percentages Beto develop therein a crystal structure con sisting of a flne grained; s"\1rface area of appreiable depth; having relatively wide boundaries worked alloy l at" a recrystallization temperaturewhich approximates i200 C.-in an atmosphere reducing with respect to'the metal oxides of the base ,metalbut oxidizing with respectto the said beryllium for a time interval producingthe demechanical bonding of the organic plastic to the adapted iorfuse in'connection withiorming elec- .phere consists, principallyrqf-hydrogen'andone of I ethodf of claim 1', wherein said atmos-,

ists of amixture oi reducing, inert and xi zingjgases,saidireducinggases consisting at Y one of the gases hydrogen. carbon mon and yolatile hydrocarbona, said oxidizing jconsi'stingbi at leastbnefoi .the gases oxy-' methodfoi treating an .alloyj 'consisting redominatelyot at least one of the base metals 1 'vrlyi'ng a lar -gergrained corevarea having rela-' ely small; boundaries, -which comprises; cold 1 orkin'g gth'e alloy and heat-treating the scold 4 sired depth or said fine grained surface area and to obtain the desired larger grain sized core.

5. The method of claim 1, wherein the temperature of heating approximates 1200 C. and wherein said atmosphere consisting of hydroien ntunted with water vapor at atmospheric tempentm'es.

6. A metallic :rticle of manufacture, said orticie consisting of an alloy produced by the processofclaiml. I

7. A metallic article or manufacture, said article consisting of an alloy produced by the process oi ciaimi.

VICTOR 0. ALLEN, J-"P, POLAR.

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