Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/08—Tin or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
  • C22C9/02—Alloys based on copper with tin as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
  • C22C9/06—Alloys based on copper with nickel or cobalt as the next major constituent
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less

Definitions

• the present invention relates to new and improved copper base alloys having substantially improved resistance to oxidation and tarnishing in moist and contaminated atmospheres.
• Copper base alloys have found wide and varied uses in industry and commerce in general; however, the many useful physical properties of these alloys are almost invariably negated to some degree by their extremely low resistance to oxidation and to tarnishing, especially in moist and contaminated atmospheres. This poor oxidation and/or tarnishing resistance has limited the utility of copper base alloys and has resulted in long and continuing eiforts to overcome this disadvantage.
• an oxidation resistant copper base alloy is formed by bulk alloying with copper at least two alloying ingredients in concentration ratios to form certain complex oxides on the surface of the alloy, i.e., the alloying ingredients are added in concentration ratios so that they diffuse to the surface of the alloy in proportion to the concentration of the individual alloying ingredient in the complex oxide.
• the above patent provides an alloy representing a considerable advance in the art and atfording a high degree of oxidation resistance.
• the alloys therein are particularly advantageous at elevated temperatures and provide extensive oxidation resistance at, for example, 800 C.
• it is a disadvantage of these alloys that less protection is afforded over a wide range of temperatures.
• the first of said two elements is selected from the group consisting of: aluminum; gallium; indium; and beryllium
• the second of said two elements is selected from the group consisting of: silicon; germanium; tin; and beryllium, provided that when beryllium is the second element, aluminum is the first element.
• the ratio of the first to the second of said elements is from 0.03:1 to 10:1.
• this forms a first outside layer of copper oxides and oxides of the alloying additions 25 to 5000 angstroms in depth and a second oxidation resistant layer of a thickness of at least 50 angstroms immediately beneath said first layer containing a discrete dispersion of a complex oxide ineluding at least one of the alloying additions.
• the first layer may be bright and shiny and oxidation resistant; however, this first layer could be and often is mottled or darkened in appearance. The first layer may, therefore, be removed to bare the second highly ennobled oxidation resistant layer which affords considerable protection to the alloy.
• the present invention is related in concept to the aforementioned co-pending application and represents an improvement over said co-pending application.
• the oxidation and tarnish resistance of both the first and second layer is greatly improved. This is particularly surprising in view of the already extensive protection afforded in accordance with the above co-pending application.
• the first layer actually contains two strata, with the first or outermost stratum being rich in copper oxides and the second or innermost stratum 'being rich in oxides of one of the alloying elements.
• certain additional alloying elements are provided which greatly enhance the oxidation and tarnish resistance of the second or innermost stratum.
• the additional alloying elements of the present invention enhance the oxidation and tarnish resistance of the second highly oxidation resistant layer.
• the novel alloys of the invention may be prepared by (A) providing a copper base alloy containing from 0.01 to 0.50% by weight of a Group V element selected from the group consisting of phosphorus, arsenic, antimony, bismuth and mixtures thereof, and from 2.0 to 25.0 percent by weight of two elements, with the ratio of the first to the second of said elements being from 0.03:1 to 10:1, the first of said elements being selected from the group consisting of: aluminum; gallium; indium; and beryllium, the second of said elements being selected from the group consisting of: silicon; germanium; tin; and beryllium, provided that when beryllium is the second element, aluminum is the first element; and
• an additional alloying element is provided.
• This may be either cobalt, cerium or iron or mixtures thereof with the total of these materials being provided in an amount from 0.05 to 5.0%, preferably 0.2 to 0.8%. These materials provide still greater improvement in properties in the present alloy.
• the relative ratio of the first to the second of said elements must be maintained with the following ratio, from 0.03:1 to 10:1. That is, the ratio of the first to the second of said elements must be maintained within the foregoing ratio.
• the ratio which is chosen for a particular system will vary widely within the foregoing broad ratio depending upon the particular system and the relative atomic weights of the elements which are added.
• the two elements are aluminum and silicon, which is preferred, the following ratio of aluminum to silicon should be employed, from 2.5 :1 to 0.5 :1.
• the beryllium-silicon system utilizes the following ratio of beryllium to silicon, 2.021 to 0.15:1.
• the indium-silicon system utilizes the following ratio of indium to silicon, 10:1 to 02:1.
• the gallium-silicon system utilizes the following ratio of gallium to silicon, 10:1 to 0.2:1.
• the aluminum-germanium system utilizes the following ratio of aluminum to germanium, :1 to 02:1 and the aluminum-tin system utilizes the following ratio of aluminum to tin, 3:1 to 0.03:1.
• the following ratios apply to the following systems: aluminum to beryllium, 10:1 to 0.5 :1; gallium to germanium, 5:1 to 0.1:1; gallium to tin, 3:1 to 01:1; indium to germanium, 10:1 to 02:1; and indium to tin, 5.021 to 01:1.
• the alloy of the present invention also contains from 0.01 to 0.50% by weight of a Group V element selected from the group consisting of phosphorus, arsenic, antimony, bismuth and mixtures thereof, and preferably from 0.05 to 0.20% by weight.
• a Group V element selected from the group consisting of phosphorus, arsenic, antimony, bismuth and mixtures thereof, and preferably from 0.05 to 0.20% by weight.
• the preferred Group V element is phosphorus.
• a total from 0.05 to 5% by weight of either cobalt, cerium or iron or mixtures thereof be employed, preferably from 0.2 to 0.8% by weight, with cobalt being the preferred additive.
• the present invention contemplates within its scope the use of other materials in combination with copper and the foregoing ingredients in order to achieve particularly desired results or to provide a particular alloy.
• still greater oxidation resistance may be obtained by adding the following in addition to the two principal alloying ingredients: boron; manganese; zinc; cadmium; and beryllium where beryllium is not one of the alloying ingredients.
• particularly desired properties may be enhanced by the addition of other alloying ingredients while retaining oxidation resistance.
• the particular method of alloying copper with the chosen alloying additions is not particularly important and conventional methods may be readily employed provided that the molten copper to which the alloying elements are added is initially oxygen free so that the alloying elements are not present in the alloy as oxides prior to solidification.
• the elements may be added as master alloys or in elemental form.
• the resultant alloy is heated in an oxidizing environment for at least one minute, and preferably at least five minutes, at a temperature of from C. to 850 C., and preferably from 400 C. to 850 C. Temperatures from 180-400 C. are insufiicient to form the second layer, forming only the first layer containing the first and second strata. Temperatures in excess of 400 C. form both the first and second layers.
• the alloy is heated in an I oxidizing atmosphere, such as air, to desired temperatures at a rate of at least 5 C. per hour.
• I oxidizing atmosphere such as air
• desired temperatures at a rate of at least 5 C. per hour.
• the particular temperature of treatment will vary depending upon the particular system and the particular results desired. However, in the preferred embodiment a temperature range of from 500 C. to 800 C. is employed.
• the time of holding the alloy at these elevated temperatures should for practical purposes be less than 2 days, although longer heating times may be utilized if desired.
• the optimum heating time is from one (1) hour to 10 hours.
• the alloy be heated in an oxidizing environment.
• Any oxidizing environment may be readily employed, for example, preferably air or oxygen and also molten oxidizing salt baths may be employed, such as those containing sodium nitrate.
• the alloy After the alloy has been held under the above conditions the alloy is cooled to room temperature.
• the foregoing process results in an alloy having a first outside layer and a second highly oxidation resistant layer.
• the first outside layer is 25 to 5000 angstroms in depth and contains a first outermost stratum rich in copper oxides and a second innermost stratum rich in oxides of said first element, i.e., either aluminum, gallium, indium or beryllium.
• the second highly oxidation resistant layer is immediately beneath the first layer, is at least 50 angstroms in depth and contains a discrete dispersion of a complex oxide including at least one of said two elements.
• the first layer consists of two strata.
• the first or outermost stratum is predominantly copper oxides. This stratum is generally colored and provides little or no oxidation or tarnish resistance, therefore, is preferably removed.
• the thickness of this stratum will vary depending on the temperature of formation.
• the second or innermost stratum of the first layer is predominantly oxides of the first element, i.e., predominately oxides of aluminum, gallium, indium or beryllium. In accordance with the present invention this stratum provides considerable oxidation and tarnish resistance. This stratum is transparent, thus retaining the original luster and color of the substrate alloy. In accordance with Ser. No. 43 6,746, referred to above, in 1-2 months spots of discoloration appear on the second stratum in sufficient number to destroy the decorative utility of a fabricated article.
• the copper oxides of the first stratum can be readily removed, for example, by dissolving them away with dilute sulfuric acid solution leaving the improved second stratum of the present invention.
• the second stratum itself provides a high degree of resistance to further oxidation and to outdoor tarnishing.
• the improved second layer which is oxidation and tarnish resistant.
• the Group V element effects an improvement in the second layer, although a less marked improvement than is effected in the second stratum.
• the Group V element is not present in discrete form in the second layer.
• the depth of the second layer will vary widely depending upon the particular treatment conditions, with in all cases the thickness being at least 50 angstroms. In general, in order to provide reasonable oxidation protection, the second layer should be a minimum of 50 angstroms in depth and preferably at least 200 angstroms. The maximum depth of the second layer is completely dependent upon the treatment conditions and the particular system utilized, that is, longer holding times and higher temperatures will provide a thicker second layer. Normally,
• a second layer of around 2 mils is the preferred value, although for some uses it may be preferable to get a thicker second layer or even if desired obtain a second layer which comprises all of the rest of the alloy.
• the second layer or highly oxidation resistant layer is characterized by containing a discrete dispersion of complex oxides including at least one of said two elements.
• the discrete dispersion is present in the metal matrix.
• the second layer is bright and shiny in appearance and provides extensive oxidation and tarnish resistance over a wide temperature range at or below the formation temperature range.
• oxidation and tarnish resistance is provided in a bright and shiny alloy having characteristics desired in alloys of this type over a wide temperature range up to the temperature of the heat treatment step.
• This second layer behaves chemically as if it were a more noble metal than copper, i.e., it resists chemical attack by strong chemical reagents which are normally used for pickling copper.
• Beneath the second layer is normally the copper base alloy itself. This base would normally have only the original oxidation resistance in the absence of the oxidation resistant layer of the present invention, but would not have the enhanced resistance.
• the cobalt, cerium or iron additions provide still further improvement. Oxidation at elevated temperature causes grain growth.
• the cobalt, cerium or iron additions form a fine dispersion of the additive and/or intermetallic compounds formed with them which inhibits grain growth.
• the alloy of the present invention contains a fine dispersion rich in cobalt, cerium or iron.
• EXAMPLE I A series of copper base alloys were prepared utilizing high purity copper and high purity alloying additions. The alloys were prepared by tilt mold casting into 1% x 1% x 4 inch shape, heating to 1600 F. (871 C.), hot rolling in a number of passes to 0.190 inch, and cold rolling and annealing into 10 mil sheet. The resultant alloys had the compositions indicated in the Table I below where amounts of ingredients are percentages by weight. In all the alloys, the balance was essentially copper.
• the weight gain in micrograms per square centimeter is shown in Table II below.
• alloys B and C film growth has virtually stopped at a lower oxygen uptake at temperatures of 600 C. or less, i.e., those alloys with phosphorus or phosphorus and cobalt present.
• EXAMPLE IV The following example demonstrates the unique character of the second stratum of the alloys of the present invention. Alloys A and B after the treatments of Example lI oxidized at 600 C., were dipped in dilute H 80 to remove the first stratum and to bare the second stratum. The parallel resistance of a fixed area of film was measured by means of an AC capacitance bridge. At a frequency of one kilocycle, alloy B attained a peak resistance of 80,000 ohms for a one square centimeter area compared to only 20,000 ohms for alloy A. This demonstrates that alloy B with the phosphorus addition has four times the electrical resistance as alloy A and is four times as good an electrical insulator.
• EXAMPLE V The following example demonstrates that the alloy of the present invention has improved oxidation resistance in the second layer. Alloys A and B were oxidized as in Example II for two hours at 800 C. The first layer of both samples was removed, including both the first and second stratum, by strong acid etching, removing about 5000 micrograms per square centimeter for each sample. Each sample was then reoxidized for two hours at 450 C. Alloy B registered no weight gain within the limits of detectability of the microbalance (approximately 0.5 microgram per square centimeter), while alloy A registered a weight gain of 2 micrograms per square centimeter.
• EXAMPLE VI The following example demonstrates the unique character of the second stratum in alloy C. Alloy C after the treatment of Example II oxidized at 650 C., was treated as in Example IV and the parallel resistance measured as in Exmple IV. At a frequency of one kilocycle, alloy C attained a peak resistance of 103,000 ohms for a one square centimeter area.
• EXAMPLE VH In the following example alloy C was oxidized as in Example II for two hours at 650 C. The first stratum was removed by sulfuric acid pickling and the second stratum was removed by means of a gas propelled abrasive unit. The sample was exposed for several months on a rooftop in an industrial atmosphere and retained its original golden luster, with no mottling and no haze.
• a process for the preparation of a copper base alloy capable of substantial resistance to oxidation which comprises:
• a process for the preparation of a copper base alloy capable of substantial resistance to oxidation which comprises:
• said alloy (A) contains from 0.05 to 5.0% by weight of a material selected from the group consisting of cobalt, cerium, iron and mixtures thereof.
• a copper base alloy capable of substantial resistance to oxidation comprising:
• An alloy according to claim 5 including from 0.05 to 3,341,369 9/1967 Caule et a1 1483 5.0% by weight of a material selected from the group con- 3,347,717 10/ 1967 Eichelman et a1. 75162 X sisting of cobalt, cerium, iron and mixtures thereof. 3,366,477 1/ 1968 Eichelman et a1. 75153 X References Cited 5 CHARLES N. LOVELL, Primary Examiner UNITED STATES PATENTS U.S.Cl. X.R.

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Cited By (26)

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• 1966
  • 1966-10-04 US US584097A patent/US3475227A/en not_active Expired - Lifetime
• 1967
  • 1967-09-26 GB GB43695/67A patent/GB1184118A/en not_active Expired
  • 1967-09-28 SE SE13356/67A patent/SE346573B/xx unknown
  • 1967-10-02 CH CH1378167A patent/CH505903A/de not_active IP Right Cessation
  • 1967-10-04 NL NL6713475A patent/NL6713475A/xx unknown
  • 1967-10-04 AT AT902167A patent/AT281439B/de not_active IP Right Cessation
  • 1967-10-04 FR FR1549380D patent/FR1549380A/fr not_active Expired
  • 1967-10-04 BE BE704652D patent/BE704652A/xx unknown
  • 1967-10-04 DE DE19671558628 patent/DE1558628B2/de active Pending

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